Raising compression in a 400?

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Something to ponder- the costs to machine the block and heads are not cheap. With my smogger 360 the cost of new KB107s at under $200 a set is cheaper than all the machining of a block and 2 head surfaces. I dont know what a set of 400 B pistons costs but a psiton change is better than milling to get comp.

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Milling the block and the heads to raise compression in this particular case is just silly. it's going to cost more to do all that machining and in the end you end up with parts that will fit nothing else .

Just throw it together and run it till you have the money and equipment to do it RIGHT ...

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Milling the block and the heads to raise compression in this particular case is just silly. it's going to cost more to do all that machining and in the end you end up with parts that will fit nothing else .

Just throw it together and run it till you have the money and equipment to do it RIGHT ...

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Machining the heads the right way does not make them parts that will fit nothing else. Done right they are interchangable between engines. I agree that the gain will be minimal and that pistons is the right way to go but as I stated but would you put pistons in a marginal or high mileage block without boring & fitting?? I wouldn't. Nor would I put new pistons and a bore job into the engine without having the heads reconditioned and the crankshaft checked out and trued if needed. But what do I know I am just a shadetree mechanic. Right Johnahah??

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516 might spec at 74cc but unless it's already been milled they typically measure 84cc....

And that 8.5 C/R estimate is pretty optimistic as well...

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i just milled my 906 heads 40 and there are now 74cc and those are open chambers, 516 are same chamber as 915 closed there 74-5 ccs now unmilled. you can have a 8.2 to 1 400 seen many with taller than factory deck like plus 20-25 thou. got my 906 head soo tight by also putting in 2.14/1.88 monster farera nontulup valves

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Doesn't the low compression 440 pistons in a 400 bring it up to 10.1? You may have to cut valve reliefs but.....

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you cant put 440 pistons in 400, 440 has 4.32 bore 400 has 4.34 bore and 440 has 6.76 long rod for raised block 400 is low deck with monster bore

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https://board.moparts.org/ubbthreads/showflat.php?Number=5153974&page=0

http://www.moparchat.com/forums/showthread.php?t=90139

http://valiantlord.com/engine.html

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Doesn't the low compression 440 pistons in a 400 bring it up to 10.1? You may have to cut valve reliefs but.....

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you cant put 440 pistons in 400, 440 has 4.32 bore 400 has 4.34 bore and 440 has 6.76 long rod for raised block 400 is low deck with monster bore

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516 might spec at 74cc but unless it's already been milled they typically measure 84cc....

And that 8.5 C/R estimate is pretty optimistic as well...

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i just milled my 906 heads 40 and there are now 74cc and those are open chambers, 516 are same chamber as 915 closed there 74-5 ccs now unmilled.

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I'm sure a head change will yield some increase in compression, but with worn bores and rings I gotta think blowby is going to be increased greatly. So, how much additional compression is he really going to get?

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Judging by where and how this is bouncing all over the place you are just adding more facts that are confusing the issue and I don't think it really matters, if I'm reading this right getting any work done outside of just bolting on parts to the shortblock as is is the only course of action ?

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Yeah, that's why I was trying to stay out of it. But it's like a train wreck...

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One thing that is been glossed over is no 440 piston is going to fit a standard bore 400 because the standard bore of a 400 is 4.342 , thats .022 oversize .

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Nothing that a piston stretcher or some aggressive knurling won't fix...

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Don't buy new pistons to put in an old, worn block. You're gonna spend $200-300 on pistons and rings but what kinda ring seal will you have???

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Exactly what I said way back when. But nobody seemed to agree and kept on with the new piston thing.

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Rings just plain aren't going to make up for an out of round cylinder but do what you want. If you go with the tight clearance KB pistons be prepared for some piston slap too. If you are going to spend the money for new pistons do it right. For about 125 bucks you can have it bored and the pistons fit right.

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Putting rings in this engine as is is just silly , the cylinder needs the proper hone finish to get the rings to seal, I don't think gapless rings come in plain cast iron as that's probably the only thing that will even remotely seal , plus now people are expecting him to breakdown the short block while it's still in the vehicle ?

Don , I wish I could get a V8 bored and honed for that cheap, around here is $300 ...

Train wreck , that's what this has been for me ....

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Typically changing pistons will require the engine to balanced as well. Otherwise its going to shake itself apart. Also the factory head gaskets were .020 and felpros are typically .042 so milling .040 off the heads only nets a .020 gain.

I think your money would be better spent on a performer intake, carb and camshaft.

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You use the "Lighten up Francis" ALMOST as much as you use the "Outside the box thing" Think up some new ones or crawl back under your rock PLEASE!!!!!!!

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Do you actually have anything constructive to add , if not go back under your BRIDGE ... PLEASE ...

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I really have to laugh at this, 'constructive to add'. Funny thing is, when I said the same thing your response was something along the lines of 'people not blowing sunshine and rainbows up your backside'.

Pot meet kettle x2.

This was an interesting thread that I didn't mind reading through. So what if someone brought it back from 2009? What's your point?

Mike.