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400 question

hooks2u

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hi everyone
I'm building a handicap capable drag car for myself out of a 72 duster, here is a link to FABO http://www.forabodiesonly.com/mopar/showthread.php?goto=newpost&t=181162 anyway I wanted to ask a couple questions about my 400, the pistons are sitting .080 down at TDC and theres no valve reliefs just flat top pistons, would that be stock??
here are some pics
 

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They kind of look to like "replacement cast pistons", but it's hard to tell from a photo, you could pull the oil pan see if they are cast or forged pistons, if they have a thick parting/forging line they are more than likely forged probably, if the have a thin parting/casting line they are more than likely cast, cast pistons in a race engine "aren't a real good idea" if your planning on revving over 5000 RPM, they tend to break piston skirts, also 0.080" down in the hole is usually "pretty low compression" for a performance/race engine, if you run a larger camshaft than like 0.520"+, make sure to check for valve clearances, with no valve reliefs, what heads are you planning on running ??, what camshaft are you planning on running ??, what class are you planning on running in ??, you could always run some aftermarket, lower CC "closed combustion chamber" heads, to bring the static compression up some, quality cylinder heads can make up for allot... There is a site that has a bunch of racing formulas/calculators for engine combos, rear axles, tires, etc., it's handy to know exactly what your dealing with or just experiment on what combo does what... www.WallaceRacing.com/Calculator.htm , good luck with your A-Body 400 BB 72 Duster race car project, I wish you well...
 
hey thanks for the info, I had gotten the 400 just to use the block for a 451 build but saw the pistons and it has a 509 cam in it so I was curious, thought about maybe running this motor like it was if it was special and do the stroker this winter.
 
.080 in the hole is most likely pretty close to stock for a low compression engine....and is pretty worthless for high performance. You could use a cam that produces high cylinder pressures but then since the engine won't have any quench, it'll most likely ping on pump gas. And back in the 60's a neighbor killed himself by using cinder blocks for getting his car up in the air.....good luck.
 
Yes cinder blocks expload...danger wil robinson...! Now onto the 400..they look like stocker 8.2:1 cast jobbies..& the .484/282* hemi grind purple shaft works great with that set up + stock 906's & a RPM intake with a good thermoquad...its what I have in my dads duster & it boogies + is decent on gas mpg's
 
Old Hooks aint as think as yall stupid he is. Pay attention to HOW he has the cinder blocks placed. He has them positioned they way they are DESIGNED to hold a load. In that way, they are quite strong indeed.
 
Those are stock low compression slugs in there and I'm with Cranky about using them for anything more than a driver. Not because they are weak, but your off the shelf cam choices are limited. If you want to build for performance, and have a few bucks for pistons and balancing, get some zero deck forged replacements. Unfortunately there are no cast high compression replacements for the 400 so you will need to go aftermarket. If you are on a budget and want to run the short block as is, then don't put too much cam in it, and/or find a set of factory closed chamber 915 heads (or even 516's) and use a steel shim head gasket.

The cinder blocks are placed properly as Rusty said but I'd feel better if you had a 2x6 between the block and tire to distribute the load a bit more.
 
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