Technical Cadillac 331 cylinder head upgrade

Hello all,

I hope this is the right place to post this.

I have searched on this forum and on the internet in general but have not really come across a definite answer to my specific requirement.

I'm rebuilding the engine from a 1952 Cadillac.

I understand that in stock form it has a low compression ratio.. somewhere around 7.5:1 or something like that.

Some time back before my engine needed a rebuild, I read somewhere online that a later model Cadillac cylinder head can be used to raise the compression ratio.

I would like to keep every thing or most other things stock.. like the exhaust manifolds, valve covers, intake, Rochester 4 JET carb. etc.

What is the cylinder head that I can use on this 331, that will bring the compression ratio up ?

Is it the 1955 331 head or 365 heads ? I read online about someone who built a 331 with 390 heads but he had a whole lot of other performance bits on it as well.

Thanks

 

I'm sure someone here has the answers you seek....

 

The '55 Cadillac 331 had 9.0:1 compression and the later 365 engines were higher yet I think. I'm not sure if these increases were the result of cylinder head changes or piston design. There are some knowledgeable Caddy guys on here however that will hopefully chime in. I'm building a '55 and 9.0:1 is perfect for my driver.

 

From what I have read, the higher compression was gained only from the cylinder head, untill 1955. After that the pistons also may have changed.

Can you please let me know the casting numbers on your 1955 heads ?

Thanks

 

What ever you buy make sure they are not cracked. If the old Cads were over heated they were prone to cracking the heads.

 

Thank you for the advice. Yes I will make sure the heads are checked for cracks before I pay for them.
Am yet to find a pair of heads for sale though. Still looking for casting numbers for 55 heads

 

I can give you a number for 1956 heads, which are reportedly notorious for cracking. 1465406-7 is the number I have found, and I believe that is for the right hand head, and also may have been used in 1957.

 

Found these numbers here on the HAMB, posted by @mgtstumpy for 1955 heads. 3630582 right, and 3630583 left.

 

Thank you... However those are part numbers as listed in the parts catalog. NOT casting numbers which are cast into the heads.
The part number is not on the head anywhere so we can not look at a head and say what part number it is. Casting number is visible.

 

Ah, that explains the huge difference in the '55 to '56 numbers. Those '55 numbers were in a publication in the cylinder head section. Maybe he will see that I tagged him, and perhaps have the casting numbers.

 

I know this has the part numbers listed, but has useful info on the swap..with thanks to the original poster of this info..

 

Casting numbers on my '55 heads is 1462611 with a "4" cast in on both heads. Same on both.

 

OHhhh !!! Thank you so much for this !!! This is exactly what I need to see !! The chamber volume !!

 

Thank you very much !! Now I can search for heads !