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MoparManiac117

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I've got a 383 with the 906 heads going into my '72 Duster and I'm trying to get as much compression as I can out of it without using domed pistons. First question I have is this: I've heard you can 'zero' the deck relative to the pistons to up compression. can someone clarify? Also, does anyone know how much can be milled off the stock heads to reduce the combustion chamber volume? My third issue is this: how much cam can I get away with and avoid having valve/piston clearance issues? or is there an easy way to calculate the interference?

for reference my plan is to use the flat top speed power forged pistons bored 0.060" over, forged rods (not sure which kind yet), a Mopar Performance single plane M1 4bbl intake manifold, either the Schumacher or TTI A-Body headers, and would like to shoot for 450 crank hp.
 
Sure, I'll take this on 1 at a time. Please stand by;
 
I've got a 383 with the 906 heads going into my '72 Duster and I'm trying to get as much compression as I can out of it without using domed pistons. First question I have is this: I've heard you can 'zero' the deck relative to the pistons to up compression. can someone clarify?
Click to expand...

What your asking actually, as I see it, is how much can the deck be milled. That itself I do not know. But, the pistons can be purchased in tall heights. With this in mind, you can get to or pretty close to a position of "Zero Deck " height. That is where the piston sits. Flush or zero with the deck.

Any material difference can be milled from the block, or piston if need be.


Also, does anyone know how much can be milled off the
stock heads to reduce the combustion chamber volume?
Click to expand...

Sorry, I do not know that exact amopunt. I remember reading .060, but leave that to the actual build and machinest. Don't do it right away.
 
My third issue is this: how much cam can I get away with and avoid having valve/piston clearance issues? or is there an easy way to calculate the interference?

for reference my plan is to use the flat top speed power forged pistons bored 0.060" over, forged rods (not sure which kind yet), a Mopar Performance single plane M1 4bbl intake manifold, either the Schumacher or TTI A-Body headers, and would like to shoot for 450 crank hp.
Click to expand...

Most aftermarket piston have enuff clearance built into them for some serious cam lift and durations. The cam required for 450 HP is nothing in lift and duration for the power level sought.

In fact, a modest cam could be used.
 
Lots of good info...Thanks alot. I'm going to be talking to my machinist this week and probably taking the block and heads in early next week. I've already got it torn down and the only things I'm reusing are the block and heads so everything's still up in the air. This is my first build so I'm not going with anything to crazy.
 
When you take the block in and have it cleaned up, sonic checked and know it's exact dimentions. (Height) From there, choose a piston that will fit the biull for zero deck. Do not get stuck on one piston. Keep an open mind.

Stock heads can make the power you seek.
 
rumblefish360 said:
Stock heads can make the power you seek.
Click to expand...
That's what I was hoping to hear. I know the closed chamber 915 casting is a better head for higher compression but for my mild build, I figured I could make the 906s work. Thanks for the help. I'm sure it's not the last question I'll have about this build. I'll keep you updated.
 
Good, please do keep posting about this!
 
I think for every .0040 you take off a head is like 1 cc reduction...so like a
-.040 on 906's is like a 10cc reduction in combustin chamber volume...so you go from a 81cc(?) to 71 cc.....which (depending on the year should bring you close to 9:6-1 /9:8-1
 
And you have to mill the intake side of the heads also or mill the intake...Not sure of those #'s
(that all sound right?)
 
Yes, mill the heads deck and you'll need to mill the ntakle side. There is an amount that you can get away with before the intake face has to be milled, but I do not know how much that is.
 
here's some pics
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Woooooooo, greasy sucker huh?!
Degrease'em and glass beed'em!
YUmmmmmmmm
 
I was thinkin the same thing when I tore it down. The cylinders were filled with oil when I took the heads off but that turned out to be a good thing.
 
There is another option to consider. If you're going to be buying new rods, pistons, crank and of course bearings and the like you may want to consider talking to these guys. http://www.440source.com/strokerkits.htm
You can stroke that 383 to 438 with all new internals and using a 440 crank with cut down journals, at least that way you know what you're getting. If my 383 in the Demon ever calves that's what I'm going to do.

Terry
 
Know anyone with a forged 440 crank laying around. You could always turn down the 440 mains to fit in your 383 to give ya 438ci
Since your talking about buying aftermarket forged rods and still need pistons it's not going to cost ya a ton more and you end up with 55 more cubes.
440 source and a few other companys sell the whole kit and just individual parts for a stroker 438ci and even bigger if you really want to go crazy, just make sure you have a machine shop check out everything before assembly.
I really wish I had done this to my 383. The 400 block I have is getting a stroker crank for sure.
 
The closest you will come to zero deck pistons is around .014 in the hole which can be easily taken to zero deck, BUT most flattop pistons for 383's do not have valve reliefs. If you zero deck a 284-.484 might not even fit. Find a piston with valve reliefs. try KB. The motor presently in my duster has pistons .014 in the hole, a .020 steel shim head gasket, and uncut iron heads and the compression works out to 9.2:1. A good pump gas ratio with a small cam.
 
I had thought about going with a 440Source stroker too...I need to sit down and look at the cost vs. what I'll gain of both rotating assemblies side by side.

Longgone: Thanks for the link to those articles...I'd read them a while back but had forgotten how good they were.

Dusterdon: Thanks for the advice on the setup...I really like what you've got going there. I also found some valve relieved pistons from diamond racing...anybody know anything about their stuff?
 
I'll add something... The blueprint deck height of a package is 1/2 the stroke, the rod center to center length, and the compression height of the piston, all added up. Just my opinion here... You are much better off choosing a package, and then fitting the block to it, then measuring the block, and then choosing the package. Reason being, when you have the thing square decked, your shop can set that dimension where ever you want. And you're having it square decked anyway. 383s are notorious for being taller than they were supposed to be. No 383 was ever even close to "10.5:1" because of this fact, and other quality control issues with mopar. I like the KB162 flat top, and I have the deck cut down to get the top flush with the deck. That's just as Rumble said.."zero deck". Domed pistons are not measured from the top of the dome, but rather from the top flat around the perimiter. So a zero deck dome will pop up the height of the dome from the block's deck. In any case, the KB162 needs a deck height of 9.956, and most blocks are in the 9.98 area. Tallest I ran accross was over 10.00. How that one ran without ticking I have no idea.
 
You`re welcome MoparManiac117. A lot depends on which way you`re going with your build, if you`re simply looking for some hp on the cheap, then bolt -ons and combining stock pieces that complement each other should get you the power you seek without breaking the bank. I`ve read that `68 pistons installed in say a `67 block will protrude about .030 above the block which should bump the compression nicely. That combined with a `67 440 head (915) will also step up the compression. Even the cheapest rotating assemblies complete will set you back a couple grand.
 
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