[footjoy]

I was reviewing some things on my 400 x.040 build I have come to the conclusion I might have made some mistakes. Not sure

pontac 406 block
flat top pistons with 4 reliefs
Crower 40240 cam straight up
pontiac #15 heads small valve 90cc
performer intake
Quickfuel carb 735 cfm
stock exhaust manifolds
HEI
2004r with 3.73:1 = 2.55 final gear

Looking at the cam information it is recomended to have 9.5:1 compression.
I don't think I have that much compression probably more like 8.75.

according to Wallaces charts the block and heads are rated for 290 horse engine that does not take into consideration cam and carb.

Questions
1. do the heads and cam work well together?
2. what would it take to get 350 horse power from this block?

The car runs OK but gas mileage is 10 mpg. If I am going to get that kind of mpg I think I'll look at more horse power.

Any constructive thoughts?

Thanks greg

[pastry_chef]

Originally Posted by footjoy

Crower 40240 cam straight up

This cam?

https://www.summitracing.com/int/par...0240/overview/

[steve25]

Your heads flow 182 Intake cfm @ .450" lift, that's enough for 360 hp in a well tuned motor with the needed compression for the Cam its running, that being said I have not run the numbers , but I do not think your even at 9 to one comp with your set up now.

To save your combo if it lacks snap with your rear gears you might concider running a Vari duration lifter , or advancing the Cam 4 degrees.

[tooski]

I couldn't find a 40240 cam. Maybe 60240. I have a similar cam, only on a 110 lsa. I had a thread on CR for that cam. Smaller cam, good cylinder filling. Was told to use not much more than 9:1 for it. I think others will say the performer intake is not ideal. A stock intake would be better but the QF will need an adapter and still not be ideal. Mine is an RPM with 750 VS. I like the power but I couldn't say if it is 350. My mpg is likely in the high teens as a guess ( my RA4 , 10:1, 4.11 gears engine got 11 mpg city driving - calculated. This one is much better.)

[ponyakr]

Assume you mean 60240. That cam might do OK, especially in the lower rpm range. . But, a Voodoo 262 cam should get you closer to that 350hp number.

https://www.lunatipower.com/voodoo-h...8-262-268.html

A '71 400 with 96cc #96 heads was rated at 300hp, with only an 067 cam.

A '70 400 with 72cc #13 heads was rated at 350hp, with that same 067 cam. So, the CR does make a difference. A '69 RA3 400 with a 744 cam was rated at 366hp.

Therefore, I'd guess that your 90cc heads, with a 262 Voodoo cam, should make somewhere near 350hp.

Obviously, the exact specs of the build, as well as state of ignition & carb tune will help determine max hp number.

Len Williams estimates aprox 385hp for this 9.25 CR 400.

http://lenwilliamsautomachine.com/400_Long_Block.html

Cam specs are not listed. But Rhoads lifters are on the list. Rhoads lifters can allow you to run a larger cam, but still have a decent idle, good vac, and good low rpm torque. This might help you reach that 350hp number you mentioned, but still have a very streetable cam. Some love Rhoads lifters. Some hate 'em, & badmouth 'em every chance they get. A Voodoo cam does not need Rhoads lifters.

It has been posted here many times that there have been lots of guys very disappointed with an 041 clone cam, in a street 400. So, I think it is safe to say that less than 230° intake duration @ .050 lift will be better suited for a street 400.

If trying to get anywhere near 350hp, I don't see any reason to use a cam smaller than an 068 clone. The 2801 Summit is similar, with more lift.

Besides the 262 Voodoo I mentioned, here are a few more that might work.

Howards 410021-12

https://www.summitracing.com/parts/h...w/make/pontiac

Lunati 10510312

https://www.lunatipower.com/street-m...8-276-286.html

Howards 410141-12

https://www.summitracing.com/parts/hrs-410141-12

Crane 283951. This cam, with Rhoads lifters, should have a broad power range, getting you to, or very near that 350hp range, but maintaining decent low rpm manners.

https://www.summitracing.com/parts/c...IaAusEEALw_wcB

[footjoy]

What compression is what we shoot for Static or Dynamic


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[Steve C.]

From the Crower 60240 cam card.....

"4 degrees of advance have been ground into this Camshaft"


.

[Steve C.]

2004R Gear Ratios:

First- 2.74:1
Second- 1.57:1
Third- 1:1
Fourth- .67:1

3.73 rear gear x .67 = 2.499 final gear


.

[STEELCITYFIREBIRD]

Originally Posted by Steve C.

2004R Gear Ratios:

First- 2.74:1
Second- 1.57:1
Third- 1:1
Fourth- .67:1

3.73 rear gear x .67 = 2.499 final gear


.

I believe first gear calculation is where you want to look for adequate torque multiplication for a given cam/displacement/CR.

You got a pretty deep first gear!

[Steve C.]

Correcting the first post...

2004r with 3.73:1 = 2.55 final gear


.

[footjoy]

Well thats a bummer. I don't think I have it in me to pull the front off of that motor.

Cliff is that your guess to?

Greg

[footjoy]

Originally Posted by footjoy

Well thats a bummer. I don't think I have it in me to pull the front off of that motor.



Cliff is that your guess to?



Greg

This motor runs 180 degrees on a 95 degree day it has snap and will turn the tires, it cruises 75 at 2300 rpm. Runs A/C and doesnt get hot.
How can you tell the cam is installed wrong with out pulling the timing cover off.

I think I am in denial. Thanks



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[gtofreek]

Originally Posted by footjoy

What compression is what we shoot for Static or Dynamic


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Always, ALWAYS, base cam choices off of static compression, NOT dynamic. Dynamic compression can be deceiving. Two cams with the same intake closing point will show the same dynamic compression, but one may be better at cylinder filling than the other[say a roller cam compared to a flat tappet cam] thus raising the dynamic compression of the engine even though the valve is still closing at the same point. Plus I have cured detonation problems in engines by advancing the cam, NOT retarding it. So the dynamic compression thing can be real deceiving, and shouldn't be used for cam determination, IMO.

[77 TRASHCAN]

Are you going to, or can you zero deck the block? IT would help with any type of a build.

I assume stock type .039 head gaskets?

I get 8.6:1 with pistons .020 in hole, 8.92:1 with zero deck

[footjoy]

Would I get any help from these heads if I put bigger valves in?

Would it be worth it to Mill these heads?

What would be a good set of heads to get me to 350 hp but still have street manners?

Thanks

[STEELCITYFIREBIRD]

So I see you have been working on this a lot lately after searching your other threads.
What is unclear is what camshaft you have in it.
In another thread the 60243 Crower was listed, then a 60240? In this thread.

[STEELCITYFIREBIRD]

Originally Posted by STEELCITYFIREBIRD

So I see you have been working on this a lot lately after searching your other threads.
What is unclear is what camshaft you have in it.
In another thread the 60243 Crower was listed, then a 60240? In this thread.

Disregard, found clarification.
60240.

[STEELCITYFIREBIRD]

Is this a fresh bore, ball and ring job, etc?
What pistons?
Dual exhaust?
What year make and model is it in?

Holley carbs are notorious for heavy fuel consumption if not tuned well or in a good state of tune.

You may gain some performance and fuel economy by tweeking your dizzy and carb.
Vacuum advance operational?

A heavy FOOT will kill MPG in any vehicle.

I'd look at the tune, cranking compression before changing out any major components.

[PunchT37]

It might not be the best cam for your app but, it will work fine. I ran one of those in a stock W72 400. No problems.

[steve25]

In terms of your # 15 heads I know that installing a larger Exh valve will pick you up flow nicely, but I am not sure about the Intake valve.

The thing you can count on by installing larger valves is a increase in compression .

For instance a easy .030" mill on the Deck ( no need to mill the Intake flange at .030" ) knocks you off 5 CCs of chamber volume and the bigger valves like 4 CCs , so right there your down to near a 80 CC chamber

Every .006" milled off gets rid of 1 CC of chamber volume.
If you where to mill .045" of the head I would want to see you mill that same amount off of the Intake so that all bolts back together nice & happy!


If you can hold off on making a decision until the weekend, I have a # 15 casting and I will stuff in a 2.11" valve and then flow test it to see what gives for you if you like?

Also since we are taking about maybe pulling your heads for a workover, I would like to know what valve springs are on them because if they can take up to .500" lift ( stock ones can't) you can add higher ratio rockers now or down the road to that Cam and pick up more over the nose duration ( will not effect idle really) and close to .040" in lift which in itself is worth atleast 10 hp .