heads for 302 sbc

Grumpy · Aug 8, 2015

pdq67 said:
Back again..

Guys,

Are 200 cc intake port, 2.02"/1.60" valve cast-iron heads with 49 cc chambers OK here.

I am thinking about installing 2.02"/1.60" valves in my rebuildable 305HO, -601 heads vs buying the 200 cc intake port heads..

I measured my -601's and my set stock cc at 53 and 55 cc's chamber-wise and have right at 160 cc intake ports.

Is 200 cc intake ports too big for an 8,000 rpm 301??

Please advise..

Thanks..

pdq67

I does not matter if your building a 283 sbc or a 632 BBC, the math is readily available to calculate the correct matching components to your intended power,rpm and fuel/air requirements, all factors that match the intended rpm range, power curve and air and fuel requirements,header design, cam, lift and duration and lobe separation angles are easily calculated, it just takes a bit of research and reading links.
the physics of air flow,compression, quench, cam acceleration rates, header scavenging , don,t magically change if the cars built by FORD,BUICK,CHEVY,DODGE,or PONTIAC, the factors can be calculated

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

Calculating the valve curtain area
The following equation mathematically defines the available flow area for any given valve diameter and lift value:
Area = valve diameter x 0.98 x 3.14 x valve lift
Where 3.14 = pi (π)
For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches

here's a chart FROM THE BOOK,HOW TO BUILD BIG-INCH CHEVY SMALL BLOCKS with some common cross sectional port sizes
(measured at the smallest part of the ports)
...........................sq inches........port cc
edelbrock performer rpm ....1.43.............170
vortec......................1.66.............170
tfs195......................1.93.............195
afr 180.....................1.93.............180
afr 195.....................1.98.............195
afr 210.....................2.05.............210
dart pro 200................2.06.............200
dart pro 215................2.14.............215
brodix track 1 .............2.30.............221
dart pro 1 230..............2.40.............230
edelbrock 23 high port .....2.53.............238
edelbrock 18 deg............2.71.............266
tfs 18 deg..................2.80.............250
I'm rather AMAZED that when ever I mention the fact theres actual tests, and well known math calculations for ideal fuel /air ratio, exhaust back pressure in the exhaust system,and intake plenum vacuum , fuel distribution, bearing surface speeds, rpm limitations , and ignition timing , valve float, air flow rates in the intake ports , port stall and they look at you like you are 9 feet tall and just stepped of a flying saucer

COMMON SBC INTAKE PORTS
felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches
http://users.erols.com/srweiss/calccsa.htm

USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations , don,t guess ask questions!
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://www.circletrack.com/enginetech/1 ... ch_engine/

http://www.wallaceracing.com/Calculators.htm

http://users.erols.com/srweiss/

http://www.csgnetwork.com/automotiveconverters.html

http://www.bgsoflex.com/auto.html

SOFTWARES AVAILABLE
http://www.virtualengine2000.com/products.htm

http://performancetrends.com/Engine-Analyzer.htm

http://www.camquest.com/

http://www.virtualengine2000.com/calculator.htm

http://www.proracingsim.com/desktopdyno.htm

http://www.land-and-sea.com/dyno-max-data-acquisition-software/demo.htm

Loves302Chevy · Aug 10, 2015

On my 302 Chevy, I used Edelbrock Aluminum 6073 Performer RPM 2.02/1.6. They have 185 cc/70cc chambers. Be very careful if you are going to gasket match or port these heads. The pushrod "pinch" area gets thin very fast and I broke through in a couple of places and had to use epoxy to repair. Then I found out that the pushrods rubbed the walls in this area. Since I was already too thin, I could grind to add clearance, I was forced to use offset rockers. If I knew all of this beforehand, I would have ordered these heads bare or used different heads, because I had to replace everything anyway.
I don't want to ever know how much money I had to put into these to make them work.

yes a 302 SBC engine sounds damn impressive , and yes it can be quick, butit can be built even quicker if the correct components and a bit more displacements used in the build!

heres a bit of a comparison between common stock chevy heads vs a mild iron dart head, and yes DART and other manufacturers have much better heads available
Chevy 882 Iron in stock form flow 206 int/145 ex
-these are thin casting and very common cylinder heads
http://purplesagetradingpost.com/sumner/techinfo/heads1.html

Grumpy · Aug 10, 2015

thats an all too common story! almost everyone who builds a serious engine and builds it correctly finds that money "SAVED" by purchasing "BARGAIN PRICED" heads eventually finds out that the final true price , with the machine work, and porting done easily exceeds the price of more expensive, brand name heads that could have been purchased with much of that work already completed.

at roughtly $1400 for two 185cc aluminum heads those edelbrocks were hardly CHEAP heads, and while they are commonly used, and will work, if the engines going to be used for racing, as a street/strip toy, its not ideal on a race engine, design, a larger port size and a matching intake manifold design, matched to a solid roller cam, matching springs, roller rockers, building the engine with about 12.7:1 compression and use of high octane race gas as fuel might be strongly considered an option.
building a 302 SBC that will power a street/strip toy is a far different goal from building an all out race engine,
where your goal is usually maximizing the power per cubic inch and lower rpm performance considerations are basically meaningless.
a properly built RACE 302 SBC , will use a solid roller cam valve train, all forged rotating assembly , and probably 6.125" titanium connecting rods, it will be used far differently than a street cars engine, gear it correctly, use it in a car with a manual transmission that weights as much under 3000 lbs as the rules allow,and youll use that engine where it will spend most of its time in the 5000 rpm-7800 rpm power band, making it all but useless on a street car, but remember most race engines get torn down, inspected and rebuilt every few months, thats one reason Ive suggested building a 383 for a weekend toy, because the extra displacement and lower average rpms tends to aid durability.

throw a similar engine, with proper tires and drive train, gearing, etc. in a 2600 lb race car , that probably can put 520 hp to the pavement, well you do the calculations
http://www.wallaceracing.com/et-hp-mph.php
yeah! your probably thinking that looks like a kick ass engine! heres where reality, kicks you in the nuts! getting a street driven car to weigh under 3000 lbs is going to take a great deal of work and cash unless you build a t-bucket or A.C.cobra replica, or similar car, and chaning that engine to have a 3.875" stroker crank, to boost displacement to 396sbc allows the engine to make noticeably more torque at a far less stressful lower rpm range,

and yeah! that extra 110 ft lbs of torque at 4000 rpm, and considerably reduced valve train , and rod bolt,etc. stress, has advantages

http://www.summitracing.com/parts/edl-60895/overview/

example
http://www.airflowresearch.com/index.php?cPath=24_33

http://www.summitracing.com/parts/bro-1321003

related info
http://www.superchevy.com/how-to/en...wer-with-your-350-chevy-engine/#ixzz3SD8JjB7n

http://garage.grumpysperformance.com/index.php?threads/the-new-215cc-vortec-heads.266/#post-35948

http://www.hotrod.com/how-to/engine/ccrp-1209-eight-budget-sbc-head-shootout/

http://garage.grumpysperformance.co...good-street-combo-your-after.5078/#post-30795

http://garage.grumpysperformance.co...u-buy-bare-or-assembled-heads.534/#post-29038

heads for 302 sbc

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Loves302Chevy

"One test is worth a thousand expert opinions."

Grumpy

The Grumpy Grease Monkey mechanical engineer.