a high torque 406


The Grumpy Grease Monkey mechanical engineer.
Staff member
Hey Grumpy,

I just sent you an email regarding getting a cam recommendation for my 406 build. Not sure if it'll come through or not as gmail may not recognize my comcast.net email as legit.

So I'll repeat myself here, I was just wondering if I could give you all the pertinents regarding my build and you'd be able to give me a cam recommendation?

- Zach

list as much info about the car, drive train tires gearing and all the engine components, heads, intake, compression,headers exhaust system, ignition, rotating assembly ETC. what do you intend to do with the car?
what work can you do vs need to farm out to have done?and Ill ask questions if I need more details, to figure out what you need
many guys ignore proven combos, because it may cost more than they want to spend, and either insist on using components they own currently or think they can buy far less expensively than the components, I know from experience will actually work.

This is a v2.0 of the 406 I built as my first build back in 1997. It originally had a 750 Holley, Holley Contender intake, 461 double-humps, 9.4 CR, and a pretty tame Comp 268XE flat tappet. But she was fairly strong for being so simple and the car being so heavy.

For v2.0, the goal is 12.5s (ideally lower 12s after a year or more of tuning and parts upgrades) and very reliable road manners so I can drive 2-3-4 hours at a time to out-of-state car shows or events without worry.

Here's the details:

- 68 Biscayne
- Right at 4,000 with me in it
- 75% Street/25% Strip (Read: pretty aggressive street car to most. Though probably not that aggressive in your world
- 406 SBC (stock block)
- 750 Holley (but will likely need to move to an 850 or even a "mild" 950HP down the road if budget allows)
- Holley Contender dual plane intake (mildly ported and port-matched to heads)
- Dart Iron Eagle Platinum 200cc heads with "medium" port job (I've opened the intake runners at the "pushrod pinch", but probably won't work the bowls, cleaned up the combustion chambers and smoothed the exhaust runners.)
- 1.6 intake and 1.5 exhaust roller rockers
- 10.5 CR
- 6" Scat rods (thus requiring reduced base circle cam, which I didn't know till after I got the internally-balanced Scat rotating assy.)
- 1 5/8" Hedman headers/2.5" Pypes mandrel-bent exhaust with their RacePro (least restrictive) mufflers. I realize I'm a bit small on the headers, but 1 3/4" or even 1 7/8" just really aren't in the cards at this time. The heads are square-port and the headers are round, so I'll be welding up the headers and grinding them out so there's no step.
- TH200-4R/3200 stall/3.42 12 bolt (will probably bump up to a 3.73 after the engine's in and running)

I'd like to run it out to somewhere around 6200-6400 if possible.

I'm going to do a hydraulic (retro-fit) roller.

I will be running an old-fashioned clutch fan as I don't have the electrical system (still 1968-fresh) to handle electric fans. And I'll be starting her up on a stock HEI dizzy. But I plan to upgrade to a DUI HEI in the months after the engine's running.

I probably missed something, so just let me know if you need any other details. I look forward to your input.

if your putting the emphasis, on peak hp rather than street-ability the cams below will work ok, with your 200 cc port heads and 3200 rpm stall converter, but will work best if matched to the correct drive train gearing, and a 3.42:1 is marginal

or a bit milder, and a better match to the 3.42:1 rear gear


(why not check with both crane and CROWER for their ideas?)

a rocker stud girdle for increased valve train rigidity,might help,and while a 3.73:1 would help, a 3.90:1-4.11:1 rear gear would help more, the 3.42:1 will not be ideal with this cam, and I would not be overly concerned with the 750 cfm carb restricting power, Id be far more concerned with a restrictive exhaust system past the headers, and getting the tuning right

I've heard of both Crane and Crower many times, but for some reason, just hadn't considered them. I think my impression of Crane is that they're past their prime or they're basically just Comp with the Crane label. But my impression of Crower is that they're still a high-quality, very revered brand more suited to race cars than street cars. I guess I can give them both a call and see what they'd recommend.

So both of these are off-the-shelf cams which is interesting. I see Crane's is a reduced-base circle, but can't find whether or not Crower's is.

Minimum operating rpm is interesting. (None of the other guys gave me that figure and I never thought to ask.) I was hoping with my overdrive and lock-up converter to be loping down the highway at 70mph at around 2200-2400. But their specs say 2800. Yikes. Guess I can't have everything - well, with a carbureted GEN 1 SBC combo anyway.

The stud girdle was mentioned. I'll be running 7/16" screw-in studs which will help a bit. But yes, a girdle may be another part that comes along after she's up and running and I can filter some funds back into my "fun budget".

I think the headers need to be a bit bigger myself. The exhaust could stand to be 3", but b/c it's mandrel-bent and the muffs are a straight-thru design, I'm okay with that compromise. I may ditch the tailpipes and run turn-downs. But that's all the more I'm willing to do on the exhaust. It's not as restrictive as most guy's 2 1/2" kink-bent, poorly run exhaust systems.

Thanks for digging into this Grumpy! Gave me some more food for thought.

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The Grumpy Grease Monkey mechanical engineer.
Staff member
you might want to consider roller rocker arms as the reduced friction and much more precise and accurate ratio due to the roller bearings reduces heat and those factors are easily worth 15 hp or more.
the crower , or comp cams steel roller rockers units will have a longer fatigue life and the bearing trunions are replaceable so they can be rebuilt after 60K-80K

,Fatigue limit, endurance limit, and fatigue strength are all expressions used to describe a property of materials: the amplitude (or range) of cyclic stress that can be applied to the material without causing fatigue failure.[1] Ferrous alloys and titanium alloys[2] have a distinct limit, an amplitude below which there appears to be no number of cycles that will cause failure. Other structural metals such as aluminium and copper, do not have a distinct limit and will eventually fail even from small stress amplitudes. In these cases, a number of cycles (usually 107) is chosen to represent the fatigue life of the material.

youll want to take the time to do the math and compare components, lets for a second assume your,debating these two heads,
if you compare the 195cc vs 210cc AFR heads, all the way
theres a significant improvement in flow and a negligible decrease in port flow speed
theres always a compromise made between cost and potential power,
and obviously you want to match components to the intended power and rpm range,
but having seen a bunch of 383 builds use both AFR heads,
I think the 210cc choice here, is a no brainer if you can afford the price.

heres 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)


Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow

if we compare the head air flow rates between a 195cc and 210cc head on a 383-406 SBC and assuming a decent roller cam with the lift and duration,required, and intake that allows the heads to flow at their full potential,
195cc Street Head Flow Chart
.200 .300 .400 .500 .550
Int 146 201 247 275 280
Exh 119 166 197 213 218

210cc Race Ready Head Flow Chart
.200 .300 .400 .500 .550 .600 .650
Int 145 199 255 292 301 309 311
Exh 110 158 192 210 214 220 222

if you compare peak intake rated flow at .550 lift
280 cfm vs 301 cfm (about a 9% increase) youll see why
thats in theory potentially a 43 hp gain


[color:red]READ THE LINKS[/color]













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Hi Grumpy,
I am in a similar circumstance to Zach,
1949 chevy pickup, 3600lbs , mustang 2 front end, jag rear irs with 3.54 gear set.
Dart shp block, 4.125 x 3.75
Dart shp 200/64cc aluminium heads.
Srp forged pistons , compression is 10.4
Dart Dual Plane intake.
Holley ultra street avenger 770 carb.
Scat cast steel 9000 crank and 5.7' rods.
The gearbox is a T700r with a 3000 stall convertor.
My current cam is the lunati voodoo 60104 276/284 233/241 @.050 .510/.525 lift 110lsa.
I want to convert to a hydraulic roller and have been looking seriously at the crower cam 00471 you suggest.
I can get another gearset for the jag rear which is a 4.09, which is high for my needs but i would be interested to see what the rpm at 65mph in lockup would be. I do some 100miles trips every now and then so highway gearing needs to be factored in.
What would the maximum duration that a 3.54 rear would suit and would the 4.09 rev on the highway .
The car is mostly saturday night cruise car with frequent spirited driving, some highway driving is also a must.
Two other cams i am looking at is the Comp 286hr 230/230 @ .050 286/286 110lsa .560 lift , Lunati Voodoo 231/239@.050 282/290 .535/.550 110lsa
My ideal rev range would be from 2000-6000 with killer mid range.
Any advice would be greatly appreciated
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The Grumpy Grease Monkey mechanical engineer.
Staff member
every choice you make is a compromise in some area, since you will be taking longer drives and not primarily racing as a primary goal,
Ill point out what I did in a similar build,
that cam you suggested.. Lunati Voodoo 231/239@.050 282/290 .535/.550 110 lsa
sounds like, it would match your application and run fairly well,
with the current 3.54:1 rear gear
matched to the current T700r with a 3000 stall convertor.
AS would the crower 00471

if you read through ricks engine build thread (link below)
that cam produces decent mid rpm torque,
but ID go with the slightly milder
crane 119661 like I have in my corvette
due to the major weight difference, between Ricks t-bucket and your truck and my corvette which are rather similar in weight, and minimal difference in rear gear ratio (your 3.54:1 and Rick and I's 3.73:1)


I ran the crower 00471 in my corvette that weights close to what your truck weights with a 700r4 trans and while it produces kick butt, peak power, in my opinion, its not ideal in a car/truck that weights nearly 3500 lbs,
especially when the engines cruising at 1500 or so rpm.
now in a light car like Ricks t-bucket he could have gone a bit more radical, jumping up to a cam like a crane 119651,


was something he could have easily done, due to the t-buckets light weight, but its generally best to be a bit conservative in cam duration on a car used mostly for transportation, and where getting good long term durability is a better goal than a couple extra peak hp.
a cam like the 119651 would be a total P.I.T.A. to drive below about 4000 rpm in a heavy car with your gearing and stall speed,
youll rarely use,the peak power levels a more radical cams longer duration potentially provides,and the milder cams a much more street driveable selection, especially if you realize that you can get ten times as much peak power on demand with a wet nitrous system, over what the slightly milder cam cost you in peak power compared to the more radical cam, and the better driveability is the more reasonable choice, knowing that a wet nitrous system, can be ignored 90% of the time and only used if needed!
now the crane cam, is also not ideal but its a damn good compromise in my opinion in that is sacrificed a bit of peak power for a bit more friendly and manageable low rpm street manors, which I personally found in my corvette to be the sweet spot for what I felt was required.
if you read the corvette engine build thread you'll notice I have a wet nitrous system, this produces, almost scary power with the crane cam. but of course its there when you want it and not used when you don,t need it!
keep in mind the cam choice is only one factor here, and several other factors like a decent set of long tube headers and a low restriction exhaust helps the engine breath, and the use of a single plane intake with a nitrous plate, or indexing the cam a bit advanced or retarded,your ignition advance curve, jetting etc. could also change the power curve




Hi guys, I am looking at purchasing the 508HP Blueprint Engines 400 Long Block. This engine comes with Blueprint aluminum heads which have a 220cc intake port and a 64cc combustion chamber which puts compression at 10.3:1

I have a new set of AFR 195 Eliminator heads with a 65cc combustion chamber. Below are the flow numbers for the blueprint heads that come on the motor vs my AFR 195's.

The AFR's seem to outflow the blueprint heads by a fair bit and use a smaller intake runner. Given this information if everything else was left the same do you think I would make a lot more power with the AFR heads?

Cam Specs for the Engine
Cam Specs:

Cam Type: Roller
.555 Intake .576 Exhaust
236 Intake / 242 Exhaust duration
@ .050 - 110° lobe separation
With 1.6 Roller Rockers


Intake Runner Volume (cc): 220cc
Intake Port Location: Standard
Intake Valves Included: Yes
Intake Valve Diameter (in): 2.08 in.
CFM Port Flow Average @ 28"
.100" - 76
.200" - 137
.300" - 189
.400" - 228
.500" - 254
.600" - 258


Runner Volume (cc): CNC- 65cc
Exhaust Valve Diameter (in): 1.600 in.
Exhaust Valves Included: Yes
Port Shape: Square-Port
Exhaust Port Location: Standard
CFM Port Flow Average @ 28"
.100" - 112
.200" - 155
.300" - 186
.400" - 203
.500" - 208
.600" - 216


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Thanks for the insight and information, its always good to hear first hand experience.
The heart says crower, mind says lunati/crane!
I might look at the lunati/crane with 1.6 rockers .
I need to get rid of my 1 5/8 block huggers and put my money into freeing up the exhaust flow first before a cam swap.
Thanks for your reply


The Grumpy Grease Monkey mechanical engineer.
Staff member
Id suspect well over 90% of us older guys went through the process of selecting and installing a cam,
that was a bit more radical that the car and application really called for, most of us were damn reluctant,
to admit the result sounded a good deal better to us than in fact the car ran.
Especially if we were honest enough to actually get both an honest assessment of the cars street driveability,
and bothered to get the cars 1/4 mile e.t. and top speed, recorded.

heres a brief related 100% true personal story,
I well remember my 1967 pontiac firebird ,400 , I installed a radical isky solid lifter cam, a dual quad intake with twin 500 AFB carbs
hooker headers , did some porting, swapped in a 4.88:1 rear gear , and used a hurst shifter etc.
the car sounded like a funny car , it ran decent but eventually I got tired of the car requiring you to drive with the engine rpms above about 3700 rpm
I swapped to a slightly milder crane solid lifter cam and the car was both noticeably easier to drive and almost 3 tenths and 4 mph faster in the 1/4 mile.
it eventually dawned on me and I was forced to admit the isky cam was too radical for the application.
the result was that I learned like most guys eventually do,that a good combo will rarely result from randomly selected bargain priced parts ,
ans simply selecting a cam that is a bit more radical that some buddy is using is seldom a good idea, my only defense was I was 20 at the time!

Strictly Attitude

solid fixture here in the forum
I did the math and it worked well will do the same again with the new engine will my old cam work yes but not ideal so time to pic a new one out. I have a home for the old one to go to.


"One test is worth a thousand expert opinions."
I can get another gearset for the jag rear which is a 4.09, which is high for my needs but i would be interested to see what the rpm at 65mph in lockup would be. I do some 100miles trips every now and then so highway gearing needs to be factored in.
What would the maximum duration that a 3.54 rear would suit and would the 4.09 rev on the highway .
My 84 Trans Am has 4.10 rear gears with the TH700R4 transmission and 28" tall tires. I have been told that the car could weigh as much as 4000#, and I know that the ultra low trans 1st gear combined with the 4.10 gears is not ideal, but it certainly helps get the car off the line.
If I remember correctly, I think I was revving 2300 rpm in OD at 65 on the highway. It's not as bad as you might think.
My new cam has a range of 2000-5800 and the new converter is 3400 rpm stall. Hopefully I can see how it all works out this summer.


The Grumpy Grease Monkey mechanical engineer.
Staff member






Using Transmission Gear Ratio:
.70 gives these RPM data:

Engine Speed (RPM) MPH 4.09 Gear MPH
8000 RPM 232.76 MPH
7500 RPM 218.22 MPH
7000 RPM 203.67 MPH
6500 RPM 189.12 MPH
6000 RPM 174.57 MPH
5500 RPM 160.02 MPH
5000 RPM 145.48 MPH
4500 RPM 130.93 MPH
4000 RPM 116.38 MPH
3500 RPM 101.83 MPH
3000 RPM 87.29 MPH
2500 RPM 72.74 MPH
2000 RPM 58.19 MPH
1500 RPM 43.64 MPH
1000 RPM 29.10 MPH


"One test is worth a thousand expert opinions."
Yes, I was correct, 2300 rpm. I was starting to question myself about that.
BTW, with that combination, you could hardly tell when the torque converter locked -
only about 100 rpm drop.
Thanks for the insight, they did make a 3.77 for a jaguar rear, but everyone I spoke to here in australia said the are very rare and virtually impossible to source. Well I got on the internet myself after this newer information in this forum and actually found a company that sells new 3.77 gearsets in England (which is where I should of checked first seeing that's where there made) not cheap but may work better with the existing cam to get the performance I am chasing, 450/450hp tq, without going to a roller, I will order it and keep you posted


The Grumpy Grease Monkey mechanical engineer.
Staff member
Hey guys, I was just wondering what factory, cast iron heads, you guys would use for this build.

I've got a bone stock 400 that I'm going to build for my 1972 Impala. I plan on giving it around 9.75 - 10:1 compression with a set of flat top pistons. When I first build it, I'm going to put in a Comp 260H hydraulic flat tappet cam with 212 degrees at .050" and .440" valve lift to begin with, but plan on upgrading it later to a Comp 270 Magnum with 224 degrees at .050" and .470" valve lift. I want it to be a mild performer with about 300 - 325 horsepower, and I want it to be perfectly daily drivable.

The car weighs 4400lbs with me inside, has a th350 trans, and either 3.23:1 or 3.42:1 gears. I plan on making it a daily driver street/strip car that runs around the mid 15's.

The heads that I plan on using right now is a mismatched set of 350 heads that have been rebuilt to be a pair. One head is a 993, and the other is a 487. I plan on doing a little port work to these heads, a little bowl blending, and drill the steam holes for the 400. I believe they have been milled, but I don't know how much.

So, the question is, should I go ahead and use these heads for this build, or should I go for another set?

the answer has much more to do with your budget limitations ,
than much else,given your stated modest goals,
than mis- matched heads with different flow and compression,
a new set of VORTEC heads with a matched intake,
would be noticeably better, than a mis-matched set of those current sbc heads
most of us are on budgets that severely restrict our options, and yes decent parts cost more money than most of us can easily afford.
but Id point out that youll be leaving at least 30-40 hp untapped if you use those mis matched heads, compared to just the vortec heads I linked too, and you could rather easily gain an additional 30-40 hp with even better heads matched to a cam upgrade.

3876487 350 71-73 1.94/1.50 76cc
3998993 307/350 68-79 1.71/1.50 1.94/1.50 76cc


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The Grumpy Grease Monkey mechanical engineer.
Staff member









  • Comp Height 5.565" Rod - 1.561
  • Comp Height 5.7" Rod - 1.433
  • Comp Height 6.0" Rod - 1.13
  • Pin Diameter - 0.9272

if you change to much cheaper and much stronger 5.7" connecting rods the less common compression height pistons are not an issue
youll have dozens of choices in a 4.125-4.165 bore diam. with a 5.7" rod
keep in mind the old O.E.M. rods have already been through millions of stress cycles and they are a weak design
resizing, , refurbishing the original 400 connecting rods, and replacing
just the connecting rod bolts will cost far more than the SCAT 5.7" aftermarket rods that are at least TWICE as strong



5.565 rods


5.7" rods


piston for 5.7 rod

piston for 5.565 rods




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