tips on building a peanut port big block combo


Staff member

346236 1975-87 454 Open 113cc .PEANUT



polishing and smoothing these combustion chambers,surfaces, removing the sharp ridges etc, has shown noticeable benefits in both reduction in a tendency to detonate, and a bit better power and since its not all that difficult to do its well worth the effort
properly prepped, or mildly ported peanut port heads (most are p/n 346236 )
flow a bit better than small block vortec heads which are rated fairly well as stock small block heads, the peanut port heads have the obvious advantage of slightly larger ports and canted valves and larger valves but the important fact is that if mildly ported on a 454 they can support over 450 hp if matched to the proper combo
piston down in hole at TDC.jpg



the stock OEM heads are limited to about a .500 lift clearance so if you intend to use a cam with greater lift you'll need to verify clearances and in many cases upgrade the valve train to both better springs with more clearance and a adjustable rocker valve train as the stock rockers are not adjustable like the older bbc design


Ive never figured out why guys get all giddy over using vortec heads on a SBC and then dismiss the peanut port heads on a BBC, if you put vortecs that flow about 230cfm, on a 383 or 400 sbc, with a matching compression and cam timing, you generally can build a real mid rpm torque monster, but guys don,t seem to realize mildly reworked peanut port heads easily flow 260 cfm, and on a 396-427 that flow rate can easily result in a 500hp plus combo, with the correct cam and compression

READ THRU THIS LINK ... ewall.html
if you have the chance de-shroud and polish the combustion chambers on peanut port heads and blend the chamber edges slightly to remove sharp edges that can cause hot spots/detonation at times
port throats generally run 80%-85% of total valve diameter because you need to maintain sufficient valve seat contact area to allow sealing and cooling and some wear during operation

viewtopic.php?f=52&t=2630&p=6788&hilit=shrouding#p6788 ... rs&f=false

Ok you have the small peanut port heads and everyone you talk to says dump them in the nearest dumpster, but your budget, won,t allow you to buy a nice set of performance heads, what do you do?
Here is an excerpt from an AERA TB,,

Exhaust Valve Guide Caution On
1965-98 GM Big Block Engines

These engines' valve guides were not intended as a replacement item from GM.
The guides were located into the head castings after the head was cast and
the exhaust guide is "water cooled".
The water-cooled guide also has two different size press fit diameters. Adding additional confusion to the matter, they also switched the location of the larger diameter sometime in 1985.

To determine which outside diameter guide you have and which direction to
remove an exhaust valve guide, the following procedure is suggested:

Drive the guide no more than .250" (6.35 mm) toward the valve spring side of
the head and stop. Then, measure the newly exposed area of the guide
OD next to the spring pad.

If the measurement is .620" it is the first style guide. To remove this
style guide, continue driving it toward the valve spring side of the head.

If the measurement is .616" , it is the second style guide. To remove
this style guide, you must drive it the opposite direction toward the combustion
chamber side of the head.
well your far from alone in the budget restrictions and if your building a street car combo those ("WORTHLESS PEANUT PORT HEADS") may actually have a good deal more potential than most guys would believe....what many guys don,t realize is that those heads with a minor valve pocket bowl clean up will out flow the sbc vortec heads many guys rave about, and the canted valves also increase flow rates.
be aware that use of full length headers and a low restriction exhaust system is almost mandatory to building a responsive low to mid rpm big block combo, with a 454 using peanut port heads.

mildly porting those heads in the bowl area under the valves and getting a good blended valve seat and pocket area and back cutting the valves with a 30 degree back cut to increase low rpm flow rates will be well worth the time and effort

theres a very limited selection of matching intake manifolds available ... q=&f=false ... q=&f=false





but if you take the time to cam the engine to maximize the torque/hp in the 4000rpm-5000 rpm and get the compression ratio up in the 10:1 range, you can build a surprisingly effective combo, If your familiar with building basically stock Pontiac and caddy engines you'll be familiar with the restrictive port flow and having to limit your power curve to under about 5500rpm,and having to rely on that lower rpm torque curve, so the gearing obviously needs to match,to maximize that torque curve, but on the plus side you can just about forget about valve float, and bearing wear issues from high rpm detonation problems

heres some results a home porting job had on peanut port heads(easily enough flow to support 530hp, if used with the correct matched components)
lift int..........stock int_ported exh_stock exh_ported
0.200..........125 ..........129 ..........87.......... 95
0.300 ..........183.......... 196.......... 111.......... 125
0.400 ..........215.......... 242 ..........130.......... 146
0.500 ..........233.......... 259 ..........144 ..........162
0.600.......... 235 ..........269.......... 150 ..........182

Both data sets are at 28†water, with no pipe on the exhaust ports. This is for stock 2.07â€/1.72†valves with stock (rather poor) valve job and 3/8†valve stems.





a decent vacuum secondary 750cfm holley helps on a 454 bbc

if your looking for a flat tappet cam ... x=27&y=10( crower 01915)
good choice c for heavy car, towing and stock converter ... &x=27&y=10 (crower 01292)

slightly more radical, and pushing clearances, but decent stock engine choice

if your looking for a hydraulic roller?(very definitely you'll need to verify clearances)and youll need an adjustable valve train and new springs that handle a .620 lift, and a 3.54-3.73 rear gear and a manual transmission or 2800rpm stall speed converter)

crower 01404LM

youll want better pistons if your serious about maximizing power, something in about a 10.3:1 cpr range would be good if used with the correct cam and drive train gearing ... s&P_id=367

this ERSONS well known for working well with a manual trans and at least 10.5:1 compression , and a 3000rpm stall converter and 3.73:1 rear gears , used in several engines ... rers_id=27 ... 0001563647
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Staff member

Assuming your building an engine for a muscle car application like a GTO,NOVA,CAMARO,CHEVELLE,IMPALLA ETC
and limited to the 25"-29" diam. tires those cars can use, youll want rear gears that match the rpm band, usually that will fall in the 3.07:1-to-3.73:1 range, depending on tire diam.
and your dealing with a displacement in the 454-496 cubic inch range
your not going to be exceeding about 6000rpm at the most so ideally youll be using a hydraulic cam, ideally a hydraulic roller cam, so Id point out the stock non-adjustable valve train and springs are a BIG restriction to your potential choices in selecting a cam to maximize the peanut port heads
youll want to use a retro fit adjustable valve train, and if the budget allows roller rockers and beehive valve springs with their lighter weight retainers

Directions for crankshaft grinding and polishing

Crankshaft journal surfaces should be ground and polished to a surface finish of 15 micro inches roughness average Ra or better. Journals on highly loaded crankshafts such as diesel engines or high performance racing engines require a finish of 10 micro inches Ra or better.

The above is a simple straight forward specification which can be measured with special equipment. However, there is more to generating a ground and polished surface than just meeting the roughness specification. To prevent rapid, premature wear of the crankshaft bearings and to aid in the formation of an oil film, journal surfaces must be ground opposite to engine rotation and polished in the direction of rotation. This recommendation and examination of the following illustrations will help make the recommendation more clear.

Metal removal tends to raise burrs. This is true of nearly all metal removal processes. Different processes create different types of burrs. Grinding and polishing produces burrs that are so small that we can't see or feel them but they are there and can damage bearings if the shaft surface is not generated in the proper way. Rather than "burrs", let's call what results from grinding and polishing "microscopic fuzz." This better describes what is left by these processes. This microscopic fuzz has a grain or lay to it like the hair on a dog's back. Figure 1 is an illustration depicting the lay of this fuzz on a journal. (Note: All figures are viewed from nose end of crankshaft.)


The direction in which a grinding wheel or polishing belt passes over the journal surface will determine the lay of the micro fuzz.

In order to remove this fuzz from the surface, each successive operation should pass over the journal in the opposite direction so that the fuzz will be bent over backward and removed. Polishing in the same direction as grinding would not effectively remove this fuzz because it would merely lay down and then spring up again. Polishing must, therefore, be done opposite to grinding in order to improve the surface.

In order to arrive at how a shaft should be ground and polished, we must first determine the desired end result and then work backwards to establish how to achieve it. Figure 2 depicts a shaft turning in a bearing viewed from the front of a normal clockwise rotating engine. The desired condition is a journal with any fuzz left by the polishing operation oriented so it will lay down as the shaft passes over the bearing (Figure 2).


The analogy to the shaft passing over the bearing is like petting a dog from head to tail. A shaft polished in the opposite direction produces abrasion to the bearing which would be like petting a dog from tail to head. To generate a surface lay like that shown in Figure 2, the polishing belt must pass over the shaft surface as shown in Figure 3.


The direction of shaft rotation during polishing is not critical if a motorized belt type polisher is used because the belt runs much faster than the shaft. If a nutcracker-type polisher is used, then proper shaft rotation must be observed (Figure 4). Stock removal during polishing must not exceed .0002" on the diameter.


Having determined the desired surface lay from polishing, we must next establish the proper direction for grinding to produce a surface lay opposite to that resulting from polishing. Figure 5 shows the grinding wheel and shaft directions of rotation and surface lay for grinding when viewed from the front or nose end of the crankshaft. This orientation will be achieved by chucking the flywheel flange at the left side of the grinder (in the headstock). Achieving the best possible surface finish during grinding will reduce the stock removal necessary during polishing.


The surface lay generated by grinding would cause abrasion to the bearing surfaces if left unpolished. By polishing in the direction shown in either Figure 3 or 4, the surface lay is reversed by the polishing operation removing fuzz created by grinding and leaving a surface lay which will not abrade the bearing surface.

Nodular cast iron shafts are particularly difficult to grind and polish because of the structure of the iron. Nodular iron gets its name from the nodular form of the graphite in this material. Grinding opens graphite nodules located at the surface of the journal leaving ragged edges which will damage a bearing. Polishing in the proper direction will remove the ragged edges from these open nodules.

All of the above is based on normal clockwise engine rotation when viewed from the front of the engine. For crankshafts which rotate counterclockwise, such as some marine engines, the crankshaft should be chucked at its opposite end during grinding and polishing. This is the same as viewing the crank from the flanged end rather than the nose end in the accompanying figures.

Unlike many engine bearings available today, Clevite engine bearings utilize a superior Clevite TriMetal™ material design. Stamped "Clevite®," this design incorporates the strength of a copper-lead alloy layer on a steel back and finally, a precision electroplated white metal "babbitt" third layer. TriMetal™ is an ideal bearing design producing good to excellent characteristics when judged for conformability, embedability, slipperiness and fatigue resistance.

We constantly monitor the function and operation of our full line of bearings, staying in touch with any changes or developments that new engines may require. And that translates into bearings that are better for your engine. If you're looking for the engine bearings that set the standards, specify Clevite®. Because you won't settle for second best.

your not going to be able to change the fact that the basic port cross sectional area will restrict you to about the 5500rpm and below range so ,if your trying to build a performance application using peanut port heads youll want to use a converter stall speed and rear gear that maximizes the 3000rpm-5500rpm band , with peanut port heads Id suggest a 2600rpm-2800rpm stall converter and about a 220-235 duration @ .050 cam with a tight 106-108 lsa and about a .540-580 lift, a matching oval port intake and 1.3/4"-1 7/8" full length headers. with 36"-40" primaries
youll want to port match the intake (most likely a minor mis-match in out of the box condition) and do as much pocket porting under the valve as your comfortable with removing ridges, casting flash and narrowing the valve guides, general port clean up


obviously theres no big obvious difference in the appearance of a BBC using peanut port heads vs regulat oval port heads at first glance

notice that even in stock as cast condition the ports out flow sbc vortec heads so they are not hopelessly restrictive but will require a basic understanding of their limitations
flow as cast /ported
Bad port
.200 137/155
.300 201 /221
.400 230 /257
.500 241 /275
.550 244 281
.600 247/282
Good port .
.200 139/152
.300 199 /220
.400 235 /273
.500 246 /291
.550 249/ 292
.600 249/292

TRICKFLOW ... 4294867081
1-330-630-1555 • 1-888-841-6556


Dart Machinery; 248/362-1188;

toll free: 877-892-8844
tel: 661-257-8124

Patriot Performance
Patriot Performance; 888/462-8276;


Toll Free: 877-776-4323
Local: 901-259-1134

EDELBROCK ... main.shtml
Edelbrock; 310/781-2222;

BMP (world products)
Tel: 631-737-0372
Fax: 631-737-0467




links that may help, well worth the time to read




viewtopic.php?f=52&t=333 ... index.html





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Staff member
Installing Exhaust Guides in 366-396 cid and 427-454 cid GM Big Block Engines

The valve guide may not be replaceable in some of the above GM Big Block engines. Because of GM's factory production method of placing the valve guides in the head castings after the cylinder head was cast, original valve guides may not be concentric or parallel to the outside diameter.

The only practical method to determine if this is a problem is to install new a new guide, grind the valve seat, and pressure test the cylinder head. If both a uniform seat width and leak-free seal around the guide can be obtained, then the original concentricity was not a problem. Also note that the exhaust valve guides are water-cooled and have two different-size press-fit diameters.


1. Measure and record the installed height above the cylinder head of the original valve guide.

2. First of all, note that from year model 1985, GM has used a different method of sealing the water passages. Unfortunately, there is no known method to determine the size and type of guides in the cylinder head.

SBI recommends driving the guide toward the spring seat approximately 0.250˝ (6.35 mm). Measure the guide's outside diameter closest to the spring seat. If the guide's O.D. is .620˝ it is the old-style guide, which interchanges with SBI valve guide number 140-1972. Drive the guide out from the combustion chamber towards the spring seat.

If the guide measures .616˝, it is the new-style guide. (Please refer to application listing to guide part number.) To remove this new-style guide, perform the exact opposite procedure mentioned above for removing the old-style guide: Drive the guide out from the spring seat towards the combustion chamber.

CAUTION: If the valve guides are removed in the wrong direction, the head may be damaged, which may result in water leakage into the combustion chamber as well as offset seat-to-guide concentricity.


1. Make sure the correct guide is being installed when replacing a guide in the different type cylinder heads. Aluminum cylinder head castings use the same guide for both intake and exhaust valves, with the undercut on one end only. On the other hand, cast iron cylinder heads have an exhaust guide that is undercut on both ends and an intake guide that is undercut on one end only.

IMPORTANT: For valve guides that are undercut on both ends, insert the end of the guide that measures .616˝/.617˝ in diameter toward the combustion chamber. If both ends of the valve guide measure the same diameter, insert the end with the lesser chamfer toward the combustion chamber.
2. Remove debris from guide hole. The guide hole must be clean for the new guide to seal the water passage.

3. Insert the correct undercut end of the guide into the hole; make sure that the correct end of the valve guide (as instructed above) points towards the combustion chamber side of the cylinder head. The guide must be driven into the cylinder head from the same side as removed: If the original guide was removed from the spring seat side, the replacement guide must be installed from the spring seat side; conversely, if the original guide was removed from the combustion chamber side, the replacement guide must be installed from the combustion chamber side.

4. Pressure test the cylinder head for leakage. If water from the water passage leaks around the valve guide, repeat removal and installation steps before discarding the cylinder head. Always remember that not all guides in these cast heads are replaceable due to variations in the factory production methods.

– Tech Tip courtesy of S.B. International.


Staff member
rods ... s&P_id=550
a couple known dependable engine builders

this will be what you want in a lower end if your maximizing a basic 545 into a 489 displacement, real low to mid rpm torque monster with those peanut port heads once they are mildly ported and that wilder crower roller cam listed above is used

if your looking for a hydraulic roller?(very definitely you'll need to verify clearances)and youll need an adjustable valve train and new springs that handle a .620 lift, and a 3.54-3.73 rear gear and a manual transmission or 2800rpm stall speed converter)

crower 01404LM

youll want better pistons if your serious about maximizing power, something in about a 10.3:1 cpr range would be good if used with the correct cam and drive train gearing
HEAD TEST ... der_heads/
Big Block Cylinder Head Casting Numbers

RECTANGULAR PORT - Valve size 2.19 intake, 1.88 exhaust Casting Years CID Chamber CC HP/RPO/Comments

3856208 1965 396 Closed 109cc 375hp/425hp z-16 chevelle
3873858 1966-67 396/427 Closed 109cc 375 L-78
3904391 1967 396/427 Closed 107cc L-71/L-72, 1.72
3904392 1967 427 Closed 106.8 430, 435 L-88/L-89, 1.72 ex
3919840 1967-69 396/427 Closed 107 375 L-78 425, 435 L-71/L-72, 425 COPO
3919842 1968-69 396/427 Closed 106.8 375 L-89 430, 435 L-88/L-89, 1.84 ex
3946074 1969-71 396/402/427/454 Open 118cc 375 L-89 430 L-88/ZL-1 425, 465 LS-6/LS-7
3964291 1969-70 396/402/427/ Closed 109cc 396/402/427/454 large or small spark plug
3964292 1970 454 Closed 109cc 450 LS-6,
3994025 1971 454 Open 118cc 425 LS-6,
3994026 1971 454 Open 118cc LS6
6258723 1971 454 Open . .
6272990 1970 454 Open 118cc service replacement mkIV
10045427 400/454/455 . . Pontiac/chevy aluminium small port /race
10051128 1990-94 454 Semi Open 72cc IP 400cc, bowtie, sym port
12363401 1996-up . Open 118cc bowtie aluminium mkIV gen.V gen.VI
12562934 2000-up 502 Open . gen.VI 502 marine
14011077 1989-94 454 Open 118cc IP 295cc, replacement, C port
14044861 1989-94 454 Open 115 425, 105.0cc, IP 380cc, bowtie, W port
14096188 1970-71 454 Open 118cc service replacement ls-6 markIV
14097088 1991-up 454/502 Open 118 .
24502585 1997 . . . olds/chevy aluminium

OVAL PORT - Valve size 2.06 intake, 1.72 exhaust

Casting Years CID Chamber CC HP/RPO/Comments
330864 1970-81 366/427/454 Open . .
330865 1970-84 366/427/454 Open . .
330866 1968-78 366/427 Open . .
330867 1968-73 427t Open . .
336765 1973-84 427/454 Open . .
336768 1973-76 427t Open . .
336781 1973-85 454 Open 113cc .
343771 1968-85 366/427/454 Open . .
343772 1976-84 366/427/454 Open . .
343783 1975-78 454 Open . car & truck
346236 1975-87 454 Open 113cc .PEANUT
346238 1975-87 454 Open 113cc .
352625 1970-76 454 Open . truck
353049 1970-73 402/454 Open 113cc .
366725 1974-78 427 . . .
473328 1968-85 366 Open . .
3856206 1965-66 396 Closed 97.2cc 325
3856213 1966-70 366 Closed . truck
3856260 1968 396 Closed . truck
3872702 1966 396/427 Closed . 325, 360 L-34/L-35 390, L-36 98.4cc
3876875 1966-70 427 Closed . truck
3904390 1966-67 396/427 Closed . 325, 350 L-34/L-35 390, 400, L-36/L-68 98.4cc
3904393 1966-68 366 Closed . truck
3908952 1967 427 Open . truck marine
3909802 1966-67 396/427 Closed 109cc L-34/L-35 L-36/L-68
3917215 1967-69 396/427 Closed 109 325, 350 335, 385, 390, 400 L-34/L-35
3917219 1966-70 366/427 Closed . truck
3931063 1969-70 396/427 Closed 109cc 325, 350 335, 385, 390, 400L-34/L-35
3933148 1969 366/396 Open 122cc 2V/427 265 car & truck
3933149 1969-70 427 Open 122cc truck
3935401 1968-76 427 Open . .
3964280 1966-70 427/454 Closed . 335, 385, 390, 400 LS-5
3964290 1969-70 396/402/427/454 Closed 109cc 325, 330, 350 400 ls-5
3965198 1969 396 . . truck
3975950 1968-70 366/427 Closed . truck
3986133 1970-85 366/427 Closed . truck
3986135 1969-73 366/427 Open . .
3986136 1970-84 366/427 Closed . truck
3993820 1971 402/454 Open 113cc 300, 330 LS-3 365 LS-5
3999241 1972 402/454 Open 113cc 240, 300, 330 LS-3 365 LS-5
6272292 1971 402/454 Open . 240, LS-3 270, LS-5
10052902 427 Open . MKIV
10101136 1991-94 454 Open . truck
10114140 1991-up 366/427 Closed . gen.V
10114156 1991-up 454 Open 118cc gen.V
10121033 1978-88 454 Open . truck
10141279 1996-up . Open 100cc Vortec7400
10487052 1977-90 366 Open . .
12352783 1979-93 454 Open . truck
12363391 1996-up . Open 110cc aluminium MKIV gen.V gen.VI
12558162 2001-up 496 Closed . VII Voretc 8100 truck
12560241 1998 -up . Closed 100cc Voortec 7400
14025175 1983-93 454 Open . truck
14081044 1986-90 454 Open . truck
14081045 1978-87 454 Open . .
14081052 1985-87 366/427/454 Open . truck Marked HIPERF
14092359 1986-89 427 Open . truck
14092360 1985-89 454 Open . truck PEANUT
14101398 1986-90 454 Open . truck
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Staff member
if you've got peanut port heads its not always a bad thing, now common wisdom is they are only good as door stops but the truth is that Chevy engineers knew that even the old oval port head design lacked the port speeds to make really effective volumetric efficiency required to maximize the engines torque in the 1500rpm-4500rpm range that most guys actually spend 90% of the time cruising at , and if your goal is both good gas mileage and outstanding torque in the most frequently used rpm range for a truck or car used for transportation theres not a thing wrong with the peanut port head design that careful port and bowl clean up can,t significantly improve on.remember most of todays cars have over drive transmissions and rear gear ratios in the 3.07 range so your going to spend a great deal of time in the 1500rpm--4500rpm power band if your drive train gearing remains stock.
the one thing they did screw up in my opinion was the selection of compression ratio and roller cam valve timing, both can be changed to make significant improvements in torque. keep in mind the stock peanut port heads already out flow the vortec SBC heads everyone raves about.
now to maximize the heads potential you need to both use the correct intake and increase the compression and use decent headers designed for the targeted rpm range, which most commercial headers are NOT designed to do as the primaries are to short, but careful selection of the headers you do select and add a long collector if required can partially off set and compensate for the the shorter than ideal primaries.
youll want to calculate the max compression and cam timing and match components. now your never going to get true exciting sky high power numbers but you can produce impressive tree pulling torque and clouds of tire smoke and have an engine that gets semi decent mileage which just might be the best route to take with $4 gas prices seemingly common.
having a good high capacity baffled oil pan on your engine adds considerably to its potential durability and potential life span

currently the only intake I know thats factory made to exactly match the peanut port heads is the weiand design

but any decent hot rodder can modify the far better flowing edelbrock oval port RPM AIR GAP intake with some epoxy and a die grinder to flow a great deal more air

your not going to be spinning this combo over 5500rpm so a good cast steel crank and hypereutectic 10:1 cpr piston will be fine ... s&P_id=116


a decent hydraulic roller cam could do a great deal for power


keep in mind that the stock OEM valve springs and clearances would not allow this cam to be used, the heads REQUIRE the machine work and better valve springs to run that cam
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reliable source of info
I built a peanut port for a jet boat once, I'm assuming I wasn't optimized for the heads because i switched to a set of ported 049's and gained 78 horsepower and leaned the mixture at the same time. ;)


Staff member
your never going to make great really race worthy competitive peak hp,from peanut port heads, on a big block chevy, but 450-475horse power from the heads in stock condition is doable hp, and getting to near 575 ft lbs of torque is doable, with ported peanut port heads and a properly matched set of components .
if you think more along the lines of building a killer Pontiac 455 than a typical 454 chevy when selecting the cam timing and compression ratio you'll tend to get better results as both stock Pontiac, 455 and the peanut port big block chevy have restrictive factory heads

horse power is calculated like this
torque x rpm /5252=hp
if you make 600 ft lbs of torque at 4000 rpm thats only 456 hp, but subject that 456 hp to the tires with a 3.73 rear gear ratio, and at over 2200 ft lbs the tires instantly turn to smoke, while a 327 making 370 ft lbs at 6500 rpm makes identical hp theres no way its going to smoke the tires in a similar way with that 3.73 rear gear.


Postby vortecpro »
Finished up a 467 Peanut port build today. 4.310 X 4.00, ported 236 peanut port heads 2.190 1.880 valves, Edelbrock performer RPM intake, carb was a vacuum secondary holley 770, with a 1 inch 4 hole spacer, compression was set at 9.4 using a custom CNC dome Mahle piston, cam was a custom ground 228 @ .050 Hyd flattappet, lobe separation was 112 installed @ a 108, GM stamped LS6 rocker arms were used, factory 4 quart GM pan, M77 oil pump.



peanut port heads prepped by vector pro



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Staff member


notice the huge difference in intake runner cross sectional area,between rectangle and peanut port heads
READ THIS LINK ... ewall.html












Some engine specs:

10.25 hyper KB pistons, PP heads #360 2.125 intake 1.88 exh ported by local guy, 224/230 flat tappet Comp Cams at 110 ls, installed at 106. Holley 3310 750 vac on stock dual plane snowflake big port aluminum intake.
this is the type of torque curve mildly ported peanut port heads and a mild performance cam can produce in a 427 set up to run on low octane pump gas

headers for the standard deck height block usually fit similar cars with minor or no mods required with tall deck blocks and peanut port heads,
peanut port heads on a big block chevy need to be pocket ported to flow semi decently ,Ive always found the dual quad intakes like the more modern air gap design easily out perform the tri-power or three deuce intakes, but as were on a budget Id select a decent oval port intake
the only factory dedicated peanut port intake is this one ... 80rev1.pdf

BUT I HAD BETTER RESULTS WITH THIS INTAKE even though the ports don,t exactly match the heads port locations perfectly, for the $12 extra in my opinion theres no reason to buy the 8122 when the 8019 works noticeably better, ,look on craigs list and local flea markets you occasionally see them used for under $120

Flow test on the un ported 236 heads with a 2.190 intake valve installed. Its interesting to compare these flow numbers with other heads of the muscle car era.

Bad Port

.200 143
.300 205
.400 228
.500 238
.550 Done

Good Port

.200 144
.300 206
.400 238
.500 245
.550 Done

2.190 intake valve, no back cut, 4.310 bore, tested @ 28 inches.

flow numbers after porting.

Bad Port

.200 159
.300 224
.400 254
.500 277
.540 287

Good Port

.200 153
.300 227
.400 269
.500 300
.540 306

Exhaust flow 190 cfm un ported with a 1.880 valve, with pipe @ 28 inches.




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Staff member
I just got off the phone with FRANK, who owns a 1967 LEMANS, in northern Colorado.
I enjoy talking to the guys I grew up with that call occasionally, especially the guys I used to build hot running muscle cars, or did engine swaps with, back in the 1970s-90s, but most have either moved out of the area or no longer deal in similar interests.
He has owned for several years, and it spends most of its time in his garage .
It has a muncie 4 speed trans , and a 3.36:1 rear gear. A few months back he called to discuss a rebuild on a 350 pontiac, engine he had but mentioned the original Pontiac 350 v8 burned a bearing and rather than rebuild it he had a collection of parts he got reasonably cheap, that included a late model pick-up truck, gen VI 454 chevy engine with peanut port heads ,he got the low mileage engine, fairly cheap BECAUSE the previous owner rolled the truck, had zero insurance and felt the PEANUT PORT HEADS, made the engine basically not worth much,.
This is not really true because in the case of the peanut port chevy big block heads a bit of port and bowl clean-up and the extra 100 cubic inches of displacement and canted valve heads provide a distinct advantage in flow over most stock Pontiac 350 heads on stock engines.
the only changes he made during the big block chevy engine rebuild, was swapping in fresh rings and bearings, a new timing chain set, and gaskets and upgrading to adjustable rocker arms the upgrade and a crane 168721 mild roller cam was done to replace the original roller cam.He reused the original roller lifters,and swapped in new valve springs with new retainers,to gain valve spring clearance and add a bit more spring load as the old valve springs tested rather low. and he added a flea market, purchased oval port intake manifold, so he could re-use the 350 q-jet carb.
the oil pan he used is off a 1967 chevelle , and he already had a blow proof bell housing.
the engine he got from the pick-up came with most of the pulleys and accessory brackets, and he got them to fit after some minor fabrication issues
He called to say he was very impressed with the results , even though he used some shorty headers that he had to fabricate a connection to his old exhaust system too,he has not had it dyno tested but hes sure the torque has had a huge increase because , while he had to revve the old engine to spin the tires, the new engine will do that near effortlessly.
He said the only reason he rebuilt the 454 was he thought it would be far smarter to do it before the engine was installed than to find out it was required after it was installed.
What impressed me most was he claimed that he had less than $1200 in the engine, purchase, upgrades and the minor rebuild , parts,and swap process combined, and it took less than three weekend,s to complete, and mostly of that time was running around looking for small parts like clutch linkage , and belts & hoses, and a used oil pan.this is the kind of old school engine swap Ive done dozens of times
FRANKS lemans is dark green, with a light green interior , but remarkably similar to this picture I found posted
1967LeManss.jpg ... 3f28737c22



and BTW when I asked if he checked valve train clearances and geometry I got a familiar answer, " he stated he checked for spring bind and retainer to valve seal clearance but never checked the rocker or push rod geometry" so I asked him to verify that as a precaution
this is a good example of what experience and a good bit of what we used to refer too as a "SALVAGE YARD SWAP", can accomplish, and when done correctly the result is frequently a low cost swap with very impressive results.
I know it may not sound impressive, and probably its got less than 400-430 flywheel hp but Id bet the car would easily out perform most cars today and I,d sure rather own a clean 1965-70 muscle car than most of the daily drivers I see on the road, and the torque curve fits the cars gear ratio well.
if you just assume that the machine shop must have cleaned the parts they worked on carefully...

head bolts that show any thread damage should be replaced,
and be aware that NEW ARP studs put far less sress on threads,and are potentially stronger, than using bolts to secure heads to the block


if your doing a SBC to BBC engine swap, you might need this bit of info on frame mounts


the best solution from a performance perspective is to do the required calculations to select the longest length connecting rod and the lowest weight piston,
of a decent design that will reduce the reciprocating mass significantly more.
the tall deck has a 10.2" deck height, a good dual plane aluminum high rise intake manifold will tend to provide the best compromise if you use a low compression and mild cam duration,
while it might seem like a waste of time, now, reading the links and sub-links will provide a good base to work from, later and save you a great deal of wasted time and money

you have a choice, you can slap the components you own together, now and live with what you have built regardless of the results , or you can put some real thought into making the result perform and carefully select parts and significantly boost power... yes that routes more expensive up front, but in the long term it tends to get better results and cost LESS.
common BB CHEVY piston compression heights are
remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height

if you wonder why I suggest using SCAT (H) beam style cap screw connecting rods vs stock or most (I) beam designs this picture should show the increased cam to connecting rod clearance

notice the pin height in the pistons pictured above allow a longer or shorter connecting rod length


heres a selection of commonly available big block chevy connecting rod lengths


1.765 compression height, pistons in standard 9.8" deck block, a 10.2" tall deck requires a longer connecting rod
most likely a 6.535" aftermarket connecting rod

threads you should read through carefully,and the sub links in them are below,
the tall deck block is put to much better use building a 496 with a 4.25" stroke and a .060 over bore and 6.385" connecting rods
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Staff member
we all have our favorite body styles but one of my favorites is the 1967 lemans/GTO body style
I was getting gas yesterday when a guy driving an extra clean one with a white interior and black paint that was freshly restored pulled into the gas station, and we talked very briefly, he had installed a 467 cubic inch Pontiac engine, with a mild cam and an aluminum tri power intake with three holley carbs that Ive never seen before on any pontiac, on the car, I never got to ask him the intake manufacturer, but he said it used a 500 cfm holley center carb and two 350 cfm holley end carbs that had to be custom modified.
Btw heres a tip learned through experience , if your 496 -540 displacement BBC combo includes an engine with at least 10:1 compression and a cam with at least 240 duration at .050 lift, and oval port heads, youll almost always find a single plane intake has some advantages over a dual plane intake.







yup! hard to beat the value in hp/vs cost outlay,
in a well designed and carefully assembled, BBC :thumbsup:
if your willing to build a fairly high compression version that runs race octane fuel or E85 you can get amazing power, Ive build several dozen 496 BBC engines over the past 4 decades , and getting 600hp-800hp, or more or more depending on your checking account balance and how willing you are too hear it scream in agony, as you rip its heart out, if youve got a reasonable budget is no big challenge , especially if you select the better aftermarket aluminum heads
if your assembling any engine,
ideally you and your friends should have and hopefully read and did read carefully the linked info.
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Thanks Grumpy.

Mopar Bob said Run the Tall Deck 427 BBC.


Staff member
I got off the phone with FRANK, who owns the 1967 LEMANS, mentioned earlier and he had a question, like most of us he has little to no spare cash, so he asked if it was ok to re-use old bearings in his engine if they look nearly perfect and plasti-gauge shows the bearing clearances are still tight, and the crank journals look like new?
I simply asked a question.....whats your other option?
he said "well, I'd installing new bearings and carefully checking clearances"
OK lets think about install new bearings and start the engine to break-in the new cam , lifters, bearings etc., right? now what happens the second time you want to drive the car?
"well, what do you mean? "
I said, unless you plan on installing new bearings and carefully checking clearances, just before you drive the car every time , your 100% sure to be driving the car USING USED BEARINGS
"well, you know I never thought of it that way "





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Staff member
working with what you have, in the way of lower cost components,
When your limited to working with what you have available, on a really tight budget and making the car your building with those components perform significantly better than it would with the O.E.M. parts, that you would usually just simply bolt together seems to be a rather lost art
yes its far simpler to buy the much improved aftermarket performance component designs, but many of us don,t have the budget to allow us to purchase what we would if we had the option.
yes there are plenty of aftermarket cylinder heads that could be used with higher compression and wilder longer duration cams to make very good power, but if your forced to work with what you have on a limited budget!..
now I had a long talk with Frank and the subject mostly concerned the peanut port heads and the fact that there are so many heads available for the big block chevy that seriously out flow those small ports.
when ever the subject comes up , theres always a mad rush to find "BETTER" cylinder heads and damn little time is spent by most guys who have a set of peanut port heads on the original engine because internet "wisdom dictates that they are replaced A.S.A.P. considering the current aftermarket cylinder heads potential,VS the know restrictive flow potential of those peanut port heads.
"which BTW easily exceeds many of the other original muscle car engine cylinder heads"
a mildly reworked set of peanut port heads , while not very impressive ,by todays big block performance cylinder head flow numbers, if measured against or by comparing them with todays aftermarket heads , are still not the complete waste of time many guys would have you think, they are.
if you look back at this thread youll see that the FASTER muscle cars as tested in their day mostly ran in the low 13 second to very high 12 second range
be aware that head bolts enter the block coolant passages,
so if you failed to dip the bolt threads in sealant when they were assembled,
through the heads coolant can seep up along the head bolts,
into the area under the valve cover

btw read this
I've rarely bothered to retorque heads, and when I do I simply torque check the head bolts at full value without loosening, and only rarely see movement,
keep in mind I dip the bolt or stud threads (and use ARP studs or bolts):like: in a good matching the application ,sealant before the install.



both of these work great at sealing head bolt threads,
yeah! I know everyone has a dad or uncle that swears he had a 11 second mustang or nova, pontiac GTO, or camaro or firebirds, or a 401 AMX back in the late 1960-80 time frame , but that was 35 years ago, and memories and REALITY VARY A GREAT DEAL
the truth is that most of the cars that the guys remember being really fast ran a 13-14 second 1/4 mile time and the tires and suspensions of that time frame allows those old road runners, chevelles and 390 ford fairlanes with the transmissions of the day to easily smoke the tires back then.
now if you figure out your cars power to weight ratio and look at the older cars speeds and E.T. it becomes rather obvious, that the RATED horse power and the TRUE rear wheel hp of the older muscle cars we mostly dream about owning were not equipped with the MAGICAL POWER NUMBERS MOST OF US THINK WE REMEMBER, OR READ ABOUT in those muscle car magazine articles.
before you spend a good deal of money porting and un-shrouding any iron cylinder heads, keep in mind aluminum heads are easily repaired in a skilled and experienced automotive machine shop thats equipped to do those repairs but damaged iron cylinder heads are either much harder to repair or good door stops


the truth is that a properly built 454-496 big block chevy engine with a properly prepared set of peanut port heads would not only be competitive, if correctly matched to components that take full advantage of the smaller port size and high port velocities, but given todays, better designed, cams,tires and header technology, it could easily allow a car to keep up with most of the HOTTER street cars back in the day.
guys have built 450 hp/580 ft lb torque monsters using peanut port heads and very few of the original muscle cars would match or even approach making those power numbers.
Now I'm not saying a set of peanut port heads are ideal, but they are far from the totally restrictive door stops that almost everyone suggests they are!
I know I would have zero issue in building an engine designed for brisk street performance if I could rework the heads and carefully select the rest of the engine and drive train to match and effectively use the massive low and mid range torque curve. you might never have a competitive race car engine but smoking the tires at will and running low 13 to high 12 second 1/4 mile times is certainly a goal you can reach, if you build a big block correctly using those cylinder heads G.M. even builds a low compression 502 with those heads , part # 88890534

mike1231 said:
The flow test of the 236 oval port heads are in. Stock flow as cast:
Bad port
.200 137
.300 201
.400 230
.500 241
.550 244
.600 247,
Good port
.200 139
.300 199
.400 235
.500 246
.550 249
.600 249.

btw if he uses the larger 2.19/1.88 valves you can easily expect at least a 5% higher airflow at any lift, on a basic peanut port head with minor clean-up

so the result would look like this on a large valve peanut port head,
assuming thats with proper port and bowl clean-up
0.300 ..........202.......... 132
0.400 ..........225.......... 154
0.500 ..........269..........170
0.600..........270 ..........196

HERES a CORRECTLY Ported head:
Bad port
.200 155
.300 221
.400 257
.500 275
.550 281
.600 282,
Good port:
.200 152
.300 220
.400 273
.500 291
.550 292
.600 292.
Intake valve size 2.125x3/8 stem,
30 degree back cut.

here are the numbers, dyno tested on a superflow 901, 300 RPM per second, 475 CID, 9.2 compression, Isky 280 mega cam, hyd flat tappet,
ported 236 heads
2.125 Int, 1.880 Exhaust, performer RPM intake quick fuel ss 830. 501.6 HP @ 5100, Peak 541.4 HP @ 5400 RPM, 532.3 HP @ 5700 RPM. Torque: 575.2 @ 3800 RPM, peak 583.3 @ 4000 RPM, 526 @ 5400 RPM.
think back,to those muscle car engines,
hemi, and 440 six pack equipped road runner, engine's , L88 corvettes and 450 hp BBC chevelles were running high 12 second to low 13 second 1/4 mile times


notice the open slot between the rear main cap supporting the oil pump and bearing shell support and the area supporting the rear main seal, this prevents PRESSURIZED oil from the bearings reaching the rear main seal.

the as cast recess in the rear main cap where the oil pump mounts can be rather restrictive and shallow, and if your replacing a missing main cap , with one from a different block you'll very likely be required to have the block?cap too be line honed to get the correct alignment and fit clearances for the crank shaft




heres a couple calculator's too use
your average muscle car like a GTO, BIG BLOCK FORD FAIRLANE,or CHEVELLE probably weighed in at 3600-3800 lbs with a driver and tank of fuel, and it was a damn rare car back in the day that put in excess of 400 hp to the pavement!







pea8.png ... der-heads/ ... heads.html ... to_08.html


heres an engine built with peanut port heads and a bit lower compression and a bit milder cam than ideal for hot street performance. keep in mind the ports are fairly small in cross section and they benefit a great deal from larger valves, a 3 angle blended valve job and port and bowl area clean up, and you can use a single plane intake design as the port velocity remains fairly high even at moderate rpm levels and if matched to the correct cam timing and headers designed to effectively scavenge the cylinders they can make rather high torque, certainly a better power potential in a 454-496 BIG BLOCK than a set of the raved about vortec heads will provide on your typical 350-406 small block engine! ... z-427.html
heres a chevy crate engine


Ive had good results using the peanut port heads with this intake and this cam. (crower cam)

INT/EXH - Dur @ .050” Lift: 232°/242° RR: 1.7/1.7 Gross Lift: .525”/.537” LSA: 108° RPM: 2000-2400 to 6000 Redline: 6500 Learn More

and YES SWAPPING TO BETTER SPRINGS and retainers that give you .050 more lift clearance is MANDATORY as is swapping to adjustable rockers on peanut port heads, deal with a machine shop that you can trust and ask lots of questions, match the components to the application and don,t assume you get what you asked for CHECK THE WORKS BEEN DONE CORRECTLY, IF YOUR NOT SURE RESEARCH WHATS BEEN DONE AND VERIFY ITS BEEN DONE CORRECTLY, don,t assume a damn thing!and DON.T BOLT THINGS ON YOUR ENGINE WITHOUT CLEANING AND CHECKING CLEARANCES

youll need the decent valve springs
what you really should do is order these
Dart 27001230-4 - Dart Pushrod Guideplates
heads+dart_pushrods.jpg (and yes having a machine shop clearance the heads and do a mild port and bowl clean up to be sure the works done and clearanced correctly when swapping to the adjustable rocker arm and better valve springs is a really good idea as is a 3 angle valve job and new valve seals and having the valve guide clearance checked and then verify rocker geometry.
ROLLER rockers cost more but reduce friction and are usually good for a 20-25 hp gain on a big block



301-27001230-4.jpg ... 0/Item/208 (crower cam)
keep in mind the peanut port heads will frequently benefit,in mid and upper rpm power, in many cases from a good high flow single plane intake even at engine speeds under the 5000 rpm lower limit many engines require before that engine component design is generally effective at boosting power, as air flow rates are fairly high even at mid rpm ranges.



yes , you can use the standard oval port intake manifolds on the peanut port cylinder heads, it will bolt up and work, its certainly not a perfect match but they work fine, and if you want to take the time and effort you can get an exact match with some epoxy and a die grinder used in the intake manifold ports


If your intention was to maximize lower rpm torque in a 396-454 with peanut port heads , for use in towing a heavy load, at lower speeds,
they are certainly designed to do that, I.d say peanut port heads and a mild cam (similar too but certainly not limited to this one, obviously check clearances and dynamic compression)

and ideally about 9:1 compression would be about ideal for your intended application.
long tube 1.5"-1.75" headers similar to these, and a low restriction exhaust would help.{adtype}&gclid=CICK9qnA-dUCFQ2DMgodaWwCcQ&gclsrc=ds

wieand makes a specific intake to maximize peanut port head flow, in the lower and mid rpm ranges

346236 1975-87 454 Open 113cc . combustion chamber PEANUT port

dynamic compression should ideally be in the 8:1-8.1:1 range

try to get the quench distance in the .040-.044 range
with the 113 combustion chamber a 15 cc-17 cc dome gets you near 9:1
hyper-eutectic pistons would be fine here.
I would try to find a 4.20-4.3 diameter head gasket

obviously ask the manufacturers tech dept, if they have any suggestions and if they have had and clearance issues using your part number cylinder heads with the pistons your about too order, just to reduce any potential problems, yes youll want to manually verify piston to valve and piston to combustion chamber clearances

related info

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Staff member
I got a call from FRANK last night to tell me an engine block he had picked up, at a bargain price locally, and expected to have machined for use as a back-up engine was not going to work out , he took my advice rather grudgingly to have the block sonic tested BEFORE he invested a good deal of time and cash into machine work,
Frank considered it a totally un warranted expense, ...well .. that was until his machine shop called and informed him that three cylinder walls would BE LESS THAT .100 thick in places,
AT A .060 over bore, so he has decided to leave that particular block at its current bore diameter IF it will hone to a standard smaller bore size.
thus he saved him self a good deal of time and wasted cash by checking BEFORE spending several hundred dollars in cash for machine work that would have been wasted
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The Grumpy Grease Monkey mechanical engineer.
Staff member
QUOTE=""] 467 Peanut Port Dyno Test
Finished up a 467 Peanut port build today. 4.310 X 4.00, ported 236 peanut port heads 2.190 1.880 valves, Edelbrock performer RPM intake, carb was a vacuum secondary holley 770, with a 1 inch 4 hole spacer, compression was set at 9.4 using a custom CNC dome Mahle piston, cam was a custom ground 228 @ .050 Hyd flattappet, lobe separation was 112 installed @ a 108, GM stamped LS6 rocker arms were used, factory 4 quart GM pan, M77 oil pump.




a bit of match strongly suggests limiting the engine rpms of a 10:1 compression 496 BBC with its 4.25" stroke and 6.385" connecting rods to 6000 rpm, and limiting the cam duration to about 235-240@ .050 duration and perhaps .600 lift.
a 2800 rpm- 3000 rpm stall converter. 2.125" primairy headers about 24" long with a 3.5" diam. collector 24" long
cams similar too these



think about this, engine combo in a average muscle car with a decent 4l80E transmission, and some 3.54:1 rear gears, it would certainly keep up with traffic!
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It would be the best way to make a C4 Corvette fast on the Street Grumpy.
BBC With Peanut port heads.


Too powerful of a Torque curve and ypu can not hookup no matter what on the street.
Poncho 455 shines.
BBC Peanut port could too.


The Grumpy Grease Monkey mechanical engineer.
Staff member
Oval Port Big-Block Chevy Cylinder Heads - The Big O
The best way to illustrate the power potential of performance cylinder heads is on the dyno.
By Richard Holdener
Super Chevy May 18, 2012
Click image below to view image gallery

Ask a big-block enthusiast what they need to make 600 hp and chances are they will point to some sort of rectangular-port head. No one in their right mind would select an oval-port head to make that kind of power, let alone one with a diminutive 265cc intake port, right? Well, big-block fans, times have changed and so has that well-defined line between the pedestrian oval-port and rectangular-port performance heads.

Back in the day, all the factory high-performance Rat motors were sporting rectangular-port heads and the street/strip crowd followed suit. But that was then and this is now. The aftermarket has stepped up in a big way and produced oval-port heads that not only out-flow any factory rectangular-port version, but do so while dramatically reducing port volume. The combination of more flow and less port volume makes these oval-port heads a much better choice for your street/strip motor than their rectangular-port counterparts. For motors up to and even beyond 600 hp, especially small-displacement big-blocks (under 500 inches), the hot setup today is more than likely an aftermarket oval-port.

With oval-port heads taking the street/strip market by storm, we decided it was a good idea to take a long hard look at them and thoroughly check out the performance potential. This meant gathering a number of different oval-port cylinder heads and putting them through their paces, both on the flow bench and the engine dyno.

First up, we needed a suitable test motor. We decided on a 0.060-over 454 equipped with a forged crank and forged rods from Procomp Electronics matched to a set of forged pistons from Probe Racing. The pistons feature an 18cc dome to help provide a streetable static compression over 10.0:1 with the 110cc chambers employed on a couple of the oval-port heads.

Many of these heads offered combustion chamber volumes below the 120cc range used on most rectangular-port heads. The smaller chamber (relative to factory rec-port heads) improved power by increasing the static compression--always a plus. The test motor also featured a healthy hydraulic roller cam in the form of an XR300HR from Comp Cams. It a 0.560/0.580 lift split, a 248/254 duration split, and a 110-degree LSA. All testing was run with an Edelbrock Victor Jr. intake fed by a Holley 950 HP carb.

Before being run on the engine dyno, each of the heads had to be mocked up to determine not only the appropriate pushrod length, but also the correct head bolt/stud combination. Our 2.25-inch dyno headers presented a problem for the heads equipped with stock port locations and required use of head bolts in the lower holes to provide adequate clearance. A few of the heads required different middle stud lengths, but ARP helped cure the situation. All we had to do was juggle the necessary bolts and studs to properly secure the heads. Thanks also goes out to Fel Pro for supplying the necessary head and intake gaskets for our test.

The test Rat was finished using a set of hydraulic roller lifters, timing chain, and a couple of different sets of pushrods from Comp Cams. Comp also supplied the aluminum roller rockers (1.7 ratio) for our head shootout.

The finishing touches included a Milodon oiling system, an electric water pump, and balancer from Procomp Electronics. Prior to their time on the test mill, each head was given the once over on the flow bench, then set up to measure port and chamber volumes.

The heads supplied for the test shared the oval-port configuration, but that doesn't mean they were all the same. We started with a factory oval-port head to establish a baseline, in this case the peanut-port variety. We hoped to include a traditional oval-port head as well, but it fell through at the last minute.

The heads from Dart and Procomp Electronics were as-cast with no additional machining of any kind. Heads supplied by Brodix and Trick Flow Specialties both featured port matching, but the Brodix head carried it one step further with CNC work on the combustion chamber. The AFR, Edelbrock, and 049 heads from Dr. Js all combined full porting and chamber work.

As expected, the level of work applied to the heads resulted in differences in flow and power. Take note that the combustion chamber volumes varied from 110 cc to 121 cc, resulting in a difference in static compression of 1 full point. This alone was worth 3-4 percent in power, so bear this in mind when reviewing the results.

The one upgrade we would like to see on many of the heads is more valve spring pressure. At the top of the power curve, some suffered slightly due to inadequate spring pressure.

Power and price usually go hand in hand, but check out the retail prices to determine how your favorite does in the all-important bang-for-the-buck category. Next month, we'll be testing some popular rectangular port heads on a larger-displacement Rat.

Test 1: Chevy Peanut-Port Heads


Our intention was to run a set of stock peanut-port heads and a set of stock oval-port heads, but our oval-port heads fell through. The stock peanut-port heads featured a 2.06/1.72 valve combination with 118cc combustion chambers. Closer inspection revealed that even our "stock" peanut-port heads had been milled sometime in their long life. The small valves, port volume, and flow numbers made them less than ideal with this healthy hydraulic roller cam, but they surprised us by exceeding 500 hp with peak numbers of 512 hp and 514 lb-ft of torque. Looking at the graphs, the peanut-port heads actually ran neck and neck with the aftermarket heads up to 4,500 rpm, which makes them ideal for intended low-speed truck applications. With a little porting, they make good heads for a mild street BBC, especially a small-displacement 396.

  • Notes: Out-of-the box 360 castings
  • Retail Price- N/A
  • Intake Valve Size-2.06
  • Exhaust Valve Size-1.72
  • Intake port vol-253 cc
  • Chamber Volume-117 cc [milled]
  • Peak Power-512 @ 5,800 rpm
  • Peak Torque-514 lb-ft @ 4,800 rpm
  • Avg HP [3,500-6,300]-453.4 hp
  • Avg TQ [3,000-6,500]-489.9 lb-ft
  • Tq @ 4,000 RPM-508.5 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 33 24
.100 57 51
.200 117 94
.300 185 128
.400 233 158
.500 247 179
.600 250 297
.700 250 211

Test 2: Airflow Research 265


The AFR 265 heads didnt produce the highest peak power and torque numbers of the test because of peak flow numbers. In fact, every aftermarket head we tested actually offered better flow number numbers at 0.700 lift (and many at 0.600 lift) than the AFRs. Even the ported 049 heads outflowed the AFRs at 0.700 lift, but our 0.580-lift cam never made it to 0.700 lift. Besides, power doesnt come from peak flow, it comes from maximizing flow in the usable lift range. Since the valve must open up to the maximum lift value, then close down, it spends twice as much time in the rest of the lift range as it does at the peak. Using the additional mid-lift flow offered by the AFR 265s, the 468 BBC produced 613 hp and 559 lb-ft of torque. The spring package provided by AFR allowed the hydraulic roller motor to rev cleanly to 6,500 rpm. In terms of average power production from 3,500 rpm to 6,300 rpm, the AFR 265s produced 501 hp and 536 lb-ft of torque, while knocking down 520 lb-ft at 4,000 rpm.

  • Notes: Fully ported, chambers worked
  • Retail Price- $2,238
  • Intake Valve Size-2.19
  • Exhaust Valve Size-1.88
  • Intake port vol-266 cc
  • Chamber Volume-112 cc
  • Peak Power-612 hp @ 6,400 rpm
  • Peak Torque-559 lb-ft @ 5,300 rpm
  • Avg HP [3,500-6,500]-501 hp
  • Avg TQ [3,500-6,500]-536 lb-ft
  • Tq @ 4,000 RPM-520.3 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 37 30
.100 73 63
.200 164 141
.300 241 196
.400 298 239
.500 332 260
.600 331 273
.700 316 280

Test 3: Brodix Race Rite Oval 270


The Brodix Race Rite oval-port heads featured 270cc intake ports that flowed just shy of 340 cfm--enough to support nearly 700 hp on the right application. Obviously, our mild combination could not take full advantage of what the Brodix heads had to offer, but they performed exceptionally well on the 468 nonetheless. Unlike the AFR or Edelbrock offerings, the Brodix Race Rite heads relied on CNC porting only in the combustion chamber. The intake ports received a minor gasket match, but the cutter was not allowed to do any serious work. The lack of CNC porting didnt seem to hurt the flow rates, as the intake and exhaust ports of the Brodix heads flowed 336 cfm and 270 cfm, respectively. This allowed the Brodix-headed 468 to produce 591 hp and 553 lb-ft of torque. The BBC averaged 492 hp and 528 lb-ft of torque while thumping out 512.8 lb-ft at 4,000 rpm.

  • Notes: CNC'd comb. chambers, intake ports
  • Retail Price- $2,796
  • Intake Valve Size-2.25
  • Exhaust Valve Size-1.88
  • Intake port vol-269 cc
  • Chamber Volume-111 cc
  • Peak Power-591 hp @ 6,100 rpm
  • Peak Torque-553 lb-ft @ 5,100 rpm
  • Avg HP [3,500-6,500]-492.7 hp
  • Avg TQ [3,500-6,500]-528 lb-ft
  • Tq @ 4,000 RPM-512.8 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 34 30
.100 69 64
.200 149 127
.300 220 163
.400 275 193
.500 315 225
.600 336 254
.700 333 270

Test 4: Dart Pro 1 270 Oval-Port


The Pro 1 name from Dart has always meant power and this new 270 oval port cast was no exception. The Pro 1 was one of only two full as-cast heads to be tested. All others featured some sort of CNC porting, chamber work, or port matching. Obviously the designers were earning their money, as despite the virgin aluminum, the as-cast Dart Pro 1 offered impressive flow numbers. It's always easier to improve the flow with porting, but getting the results from a casting takes real talent. With enough airflow to easily support our test motor, the Dart-headed BBC produced 593 hp and 554 lb-ft of torque. The 111cc combustion chamber makes the Dart Pro 1 a perfect candidate for head swapping on a 7.4L truck motor. Yank a wrecking yard mule, stuff in a cam, and ditch the peanut ports in favor of a set of Dart oval ports and you have one serious street motor. The smaller chambers on the Dart head (compared to a typical 119cc chamber on peanut-ports) add both flow and compression to further increase power. The Dart Pro 1s showed the power of oval ports by averaging 494 hp and 529 lb-ft of torque and offering 509 lb-ft of torque at 4,000 rpm.

  • Notes: Totally unported, as-cast
  • Retail Price- $2,995
  • Intake Valve Size-2.25
  • Exhaust Valve Size-1.88
  • Intake port vol-274 cc
  • Chamber Volume-111 cc
  • Peak Power-593 hp @ 6,100 rpm
  • Peak Torque-554 lb-ft @ 5,300 rpm
  • Avg HP [3,500-6,500]-494.0 hp
  • Avg TQ [3,500-6,500]-529.0 lb-ft
  • Tq @ 4,000 RPM-509.8 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 36 34
.100 71 69
.200 158 117
.300 235 159
.400 290 204
.500 323 234
.600 324 252
.700 325 267

Test 5: Dr. J's Ported 049 Oval


Popularity, availability, and cost all make a factory oval-port head appealing. Because so many enthusiasts not only have heads, but decided to massage them, we opted to include a set of ported 049s in this test. The factory 049 heads came from Dr. J's and were treated to their typical valve upgrade, full porting, and even a slight milling to get the chamber volume down to 118 cc. It is all but impossible to get the chamber size down to the 110cc range offered by the aftermarket heads, but the flow numbers were certainly right in the ballpark. The drop in compression caused by the larger chamber volume hurt power slightly through the entire rev range, but the ported 049s demonstrated why so many BBC owners insist on porting the stock stuff.

Equipped with the Dr. J heads, the 468 produced 576 hp and 538 lb-ft of torque. Torque production exceeded 515 lb-ft from 4,500 rpm to 5,800 rpm, while the BBC averaged 481 hp and 515.8 lb-ft of torque. Down at 4,000 rpm, the iron-headed big-block produced 504.7 lb-ft of torque. The one problem with iron heads is obviously the weight.

  • Notes: Reworked factory heads
  • Retail Price- $1,599 (porting customer-supplied castings)
  • Intake Valve Size-2.25
  • Exhaust Valve Size-1.88
  • Intake port vol-267 cc
  • Chamber Volume-118 cc
  • Peak Power-576 hp @ 6,000 rpm
  • Peak Torque-538 lb-ft @ 5,100 rpm
  • Avg HP [3,500-6,500]-481.4 hp
  • Avg TQ [3,500-6,500]-515.8 lb-ft
  • Tq @ 4,000 RPM-504.7 lb-ft

Lift In EX
.050 33 34
.100 73 71
.200 152 120
.300 228 162
.400 282 188
.500 320 215
.600 336 238
.700 329 246

Test 6: Edelbrock RPM Xtreme


The name Edelbrock has been around since the dawn of hot rodding, but it still has a few tricks up its collective sleeve. Case in point: Its RPM Xtreme heads, which offered the highest peak airflow of any of the heads we tested. Unfortunately, our test Rat, or more specifically our cam choice, was not able to capitalize on the available airflow, as it occurred at 0.700 lift, though the RPM Xtreme heads flowed nearly as much at 0.600 lift. These heads featured CNC porting through the intake, exhaust, and combustion chamber, and the power numbers reflected the extra work. Only the Edelbrock and AFR heads allowed the 468 to exceed 600 hp, as the Edelbrock-headed BBC produced 601 hp and 552 lb-ft of torque. The average power numbers also reflected the port work, with average horsepower and torque checking in at 498.2 hp and 524.1 lb-ft, respectively. Down at 4,000 rpm, the Edelbrock heads managed 514.9 lb-ft of torque and averaged over 515 lb-ft from 4,100 rpm to 6,100 rpm.

  • Notes: CNC porting throughout
  • Retail Price- $2,597 (porting customer-supplied castings)
  • Intake Valve Size-2.25
  • Exhaust Valve Size-1.88
  • Intake port vol-303 cc
  • Chamber Volume-111 cc
  • Peak Power-601 hp @ 6,200 rpm
  • Peak Torque-552 lb-ft @ 5,300 rpm
  • Avg HP [3,500-6,500]-498.2 hp
  • Avg TQ [3,500-6,500]-524.1 lb-ft
  • Tq @ 4,000 RPM-514.9 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 35 29
.100 63 61
.200 133 125
.300 210 186
.400 280 225
.500 327 257
.600 351 277
.700 353 285

Test 7: Procomp Electronics


Procomp Electronics has made its name by providing affordable performance. Its BBC oval-port heads qualify on both counts, as the as-cast aluminum heads maximized airflow and minimized cost. The second of the true as-cast heads, the oval-ports from Procomp Electronics featured no porting or CNC chambers and instead relied on the as-cast port shape to maximize flow. With a peak flow number of 346 cfm, the Procomp Electronics casts had plenty of potential, but they were hampered by the largest combustion chamber of the group. The 121cc chambers dropped the static compression 1 full point compared to the other competitors. If each point is indeed worth an extra 3-4 percent in power, a comparable compression ratio would put these heads right in the hunt in terms of power. But equipped with the 121cc heads, the 468 produced 555 hp and 527 lb-ft of torque. Since compression hurts power everywhere, the average numbers dropped to 471.1 hp and 506.1 lb-ft of torque. Though down on power, Procomp Electronics should have no trouble selling these at a retail price of just over $1,000 a pair.

  • Notes: As cast, no porting
  • Retail Price- $1,095 (with spring upgrade)
  • Intake Valve Size-2.25
  • Exhaust Valve Size-1.88
  • Intake port vol-311 cc
  • Chamber Volume-121 cc
  • Peak Power-555 hp @ 6,200 rpm
  • Peak Torque-557 lb-ft @ 5,200 rpm
  • Avg HP [3,000-6,500]-471.1 hp
  • Avg TQ [3,000-6,500]-506.2 lb-ft
  • Tq @ 4,000 RPM-507.6 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 36 29
.100 77 61
.200 140 126
.300 214 174
.400 276 210
.500 314 241
.600 331 264
.700 346 284

Test 8: Trick Flow Specialities 280


When talk turns to performance cylinder heads, naturally Trick Flow Specialties has to be included. It stepped up for this test with a set of its PowerOval 280s. As indicated by the name, the PowerOvals combined 280cc intake ports with a 2.19/1.88 valve combination. Despite choosing the smaller intake valve (2.19 vs. 2.25), the PowerOval heads offered plenty of flow. Though the heads featured as-cast ports and chambers, the intake port did receive a minor port match. Even without the aide of CNC porting, the PowerOval heads offered flow numbers of 337 cfm on the intake and 261 cfm on the exhaust. These flow numbers translated into a peak power output of 576 hp and 544 lb-ft. The PowerOval heads offered a broad torque curve, bettering 515 lb-ft from 3,800 rpm to 5,700 rpm. In terms of average numbers, the TFS heads produced 485.7 hp and 521.7 lb-ft of torque and managed 517.8 lb-ft of torque at 4,000 rpm. The PowerOvals are affordably priced at under $2,000 assembled and ready to run.

  • Notes: As cast no ports and chambers
  • Retail Price- $1,849 (with spring upgrade)
  • Intake Valve Size-2.19
  • Exhaust Valve Size-1.88
  • Intake port vol-279 cc
  • Chamber Volume-113 cc
  • Peak Power-576 hp @ 6,100 rpm
  • Peak Torque-544 lb-ft @ 5,200 rpm
  • Avg HP [3,500-6,500]-485.7 hp
  • Avg TQ [3,500-6,500]-521.7 lb-ft
  • Tq @ 4,000 RPM-517.8 lb-ft

Flow Data: CFM @ 28-ins

Lift In EX
.050 32 30
.100 67 62
.200 143 122
.300 212 160
.400 266 189
.500 302 221
.600 328 244
.700 337 261

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The Grumpy Grease Monkey mechanical engineer.
Staff member

10.68 @ 122 mph in a chevelle with a 468 bbc peanut port head combo with under 10:1 compression and a 228 duration at .050 lift cam

9.3 comp
228 @ .050 hyd cam, smooth idle, on the limiter @ 1100 feet 6500 RPM
Peanut port heads 236 casting
Stamped steel rocker arms LS6
Stock GM 4 quart oil pan
Performer RPM intake
850 Carb
A real 3700 plus pounds
3253 DA 27.80s baro

So far 10.68 @ 122 on the rev limiter, if I can fix the hesitation on the launch look for 10.50s, then take 2 tenths off for the correction factor and there you have it. And will be working on that today.

Dart Big Block Chevy Big M Engine Block

  • Siamesed Extra-Thick Cylinder Walls: Resists cracking and improves ring seal (minimum .300'' thick with 4.625'' bore).
  • Scalloped Outer Water Jacket Walls: Improves coolant flow around the cylinder barrels to equalize temperatures.
  • Four-Bolt Main Bearing Caps: In steel or ductile iron have splayed outer bolts for extra strength.
  • Crankshaft Tunnel: Has clearance for a 4.500'' stroke crank with steel rods without grinding.
  • True ''Priority Main'' Oil System: Lubricates the main bearings before the lifters.
  • Oil Filter Pad: Drilled and tapped for an external oil pump.
  • Rear Four-Bolt Cap: Uses standard oil pump and two-piece seal - no adapter required!
  • Lifter Valley Head Stud Bosses: Prevent blown head gaskets between head bolts.
  • External Block Machining: Reduces weight without sacrificing strength.
  • Simplified Install : Fuel pump boss, clutch linkage mounts and side & front motor mounts simplfy installation on any chassis.
  • Dual Oil Pan Bolt Patterns: Fits standard and notched oil pans.
  • Bellhousing Flange and Rear Main Bearing: Reinforced with ribs to resist cracks.
  • Note: Does not include cam bearings, freeze plugs, or dowels
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There is no question of the Big Block Chevies power potential Grumpy.I am still driving my 87 C4 Vert daily.
Want more HP Of course.
Near factory stock it cruises at 90-100 mph effortless to Chicago & back home effortlessly for hours.
It must be mild cammed.
Traffic Jams happen too.
Have that Huge 800 HP rated Griffin Race radiator in as you recall from DC Last year.

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