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Discussion Starter · #1 ·
Hey guys, new member here with an interesting challenge. Any input/advice would be awesome.

Heres the rundown

I've got a 69 block #3955272 396 that has been bored .30 over already from the previous owner and has the heads #3931063 on them right now. I will be ripping the block bare and selling the stuff to fund my build so nothing stock will be in it. I've been told no i cannot achieve 500-550hp NA from a 402 block nor run 10s in the 1/4 mile. I've got a "oh yeah i'll prove you wrong" attitude so i've been talking with some old school racers where i work and got some advice and stuff and researched blah blah and my goal is to have a 500-550hp motor and to run 10s in the 1/4mile. I'll be shoving this motor into a 76 camaro. Yes i already know the trans, suspension and rear need to be modded but those are future plans as i'm focused on this one at the moment. So far the build i've come up with is this (with the help of a big block builder)

AFR 265cc heads AFR 265cc Oval Port Magnum BBC Cylinder Heads 3610-1 - SummitRacing.com
Single plane intake manifold
850cfm carb
he suggested a cam close to these specs (solid roller around @050 268/272 660/660 108)

454 Crank, (scat, eagle, or callies) steel crank
I beam rods 6.135
KB361 pistons

any thoughts or suggests on how to get 500 out of what i have? I'd get a 454 but people want too much for them and theres non within reasonable driving range
 

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454 crank into 402 build 550 hp goal

I haven't heard of anyone building a 434 stroker from a 396. You will need to zero deck the block, may as well get the pistons up as far in the hole as you can. This bottom end with the heads you have listed will only have a 9.5 compression ratio with the aluminum heads I would rather have about 10.5 compression ratio. I have a cam suggestion for you, it's a solid roller from Crower. Chevrolet Mechanical Roller Camshaft - Camshafts . Talk it over with the old school racers and your machinist to see what they think. Try Mr. Gasket MLS .040 thick head gaskets. This way your quench will be on the money.
 

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With those heads and that cam you could make your hp goals without the 454 crank. Use a 4000-4500 stall, 4.11-4.56 gears, 26x10" slicks , and build the engine for 10.5 -11:1 cr.

If you use the 454 crank then you also need to use the 454 flywheel and balancer (externally balanced).

Better to build a 496. 100 more cubic inches for the same money.
 

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Discussion Starter · #10 ·
So I should stick the stock sized crank in there? What bottom end should I go with to get that compression ratio? I'm open to opinions and advice. This build isn't set and stone. I'm just wanting at least 500+ hp out of this thing
 

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550 hp from a 454 is as mild as 420 hp from a 350. the heads you are talking about will support 600 plus hp.the short block just needs the CR and camshaft to match the power you want to extract from the heads. 396 to 496 doesnt matter it can be done.The bigger engine wont have to rev as high. I would never want a small bore long stroke for a race car,bigger bore engines make more power from the same heads.
If you want to squeeze more torque and fuel economy,or build lower power boat motor,or 4x4 engine then thats when a long stroke small bore might be the answer
If you do not have a big bore block and want one,sell what you have and build a 540 around 335 heads.a very mild 540 will make 650 hp and 700 pounds torque. up to 900 hp 598s that are pump gas friendly,,,costs a lot though.
figure your budget first
 

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Try and use a little taller tire.. 26" tire with 411 or 456 ratio you will probably run out of gear in the 1/4. You should be able to fit a 28" tire and it will look much better.

With the Camshaft your looking at you might as well build it with some compression.. 12.1 or better. Get your 4k stall and take a little weight off the car and go racing :)
 

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That's just a cam he suggested for the 454 crank build. If you guys have a better option with the stock size crank I'm all ears
That actually looks like a pretty good cam to go racing with.. When I built my car I actually went a little larger. But just remember..

The bigger the camshaft.. The more money it's gonna take to make it work :)
 

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With those pistons at 17cc dome, the heads at 112cc chambers, you'll be in the area of 9.55:1 static compression ratio. This will leave you short at least 3 full points of SCR to deal with that cam. It needs 12.55:1.
Sorry, I'm late on my answer. Looks like everyone else picked up on it also.:thumbup:
 

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As mentioned the biggest thing against you with the small bore long stroke is the lack of compression. Not many off the shelf pistons are available, most are for 108cc chambers and with custom pistons $$ the dome is so big, with the 115 cc head, that the flame travel suffers..

I would sell the 396 block. Or have it sonic checked and if good bore it to 4.250" and use standard bore pistons for 427-489 depending on stroke. Some 396 blocks also will have to be clearanced for 454+ cubes.

Budget build would be 427 bore, 396/427 crank with old L-88 style pistons. This combination works well with a .660" cam, not hard on internal parts. Revs like a small block.

I built one last june for one of the guys that works in my shop. He had a lot of fun $$ breaking the 7.5" Camaro drivetrain stuff..
Next year he will have better parts underneath..
 
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