desoto hemi question

Does anybody know what the combustion chamber volume on a 276 desoto hemi is, and what the combustion chamber volume is on a 345 desoto hemi is?

 

Although I don't have the actual numbers, the chamber volume is easy to do - but I don't think that's what you want.
Just for the chamber volume:
Chamber volume = cylinder volume ÷ (compression ratio - 1)
Example: 276" engine at 7.5:1 ratio:
276 ÷ 8 = 34.5" per cylinder, ÷ 6.5 = 5.31" or 87.0cc

You're looking for the volume in the head, only - right? To see what happens to CR if you swap heads? Total volume won't work because most of these have some domes, and the dome volume isn't easy to find.

 

Your assuming that you have 0 deck height and flat top pistons

 

Your assuming that you have 0 deck height and flat top pistons

???????????

 

Thanks panic. Good info.

 

Sorry Panic, but the math doesn't work. By your example a 392 would go like this; 392/8= 49; 10:1 then becomes 9 and 49/9 = 5.4 or 89cc. I have cc'd many but have never seen a Chrysler head smaller than 105 cc. The formulae does not accout for pos or neg dome.
The only way to know the cc is to measure the chamber.


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the math doesn't work

The math does work, you have to actually r e a d what I wrote.

Your turn.

 

Yep panic is right

Anyone got the size??

 

Why is it so difficult to actually answer a concern with examples or perhaps expand on the theory with a few more words? I maintain that the example does not work unless you have a zero dec height and flat-top pistons just like BearingBurner suggested. The formulae may provide the total combustion volume but not the combustion chamber size because it has no means of accounting for dome volume, positive or negative. Yes, you may have alluded to this but the formulae was presented and an example given which was in error.

If you have a proof, please present it, if not, this conversation is over.


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I'd explain what I said... wait, I already did that.
No, nothing wrong with it, example not in error.

this conversation is over

OK!

 

Sounds to me this question is only going to be answered the old fashion way....stick a couple of valves in the cylinder head and fill the chamber with fluid from a Barrett and measure how much it takes to fill it. I've looked through all my manuals and articles on the early hemi heads and I can tell you valve sizes, physical size differences and what will interchange between them but not one piece of info refers to combustion chamber size in ccs. Dealing with 392s I know they run from 105-110 ccs and the later 426 runs 168 to 172 ccs.

 

They should be the same at around 79 cc. This will depend on how much the valves are sunk into the head. My 352 (341 + .060") has a compression ratio of 10-1 with a steel shim head gasket ( .025" thick compressed height )and the piston domes protrudes above the deck by .050". At 8.5-1 the 330 has the top of the piston .045" below the deck and uses a composite gasket .045" thick. After careful computation, the 330 is actually only about 8.1 to 1. To get some decent compression on that motor you're going to need some serious domes. How far down the hole are your slugs? Bill

 

Hey Hemi Bill (or anyone else for that matter),

Anyone know what the stock chamber cc's are for a stock 330 Desoto Hemi head? Also I believe the "Best" head gaskets crush down to .040"...can anyone confirm?

Thanx

Rat

 

I have found them all to be about 79cc. Bill

 

im using chevy 202 intake and ford 351 cleve 1.75 exhaust valves and after milling off 5 thou they were 73 cc's. these are 56 341 heads