CC's of rocket heads Question

What are they?? i have a '49 303 that could use some head work, but is practically new otherwise including .060 over flattops, what are the CC's of 55 or '56 heads compaired to them? I'm wondering where it would put me compressionwise if i went the newer better breathing heads.

Also what is a safe mill job without causing bolt up or valvetrain issues?

 

1954 and 1955 324s' have smaller intake ports and valves than the 1956 engines. 1957 and later cylinder heads will physically bolt on to 1949 to 1956 engines, but the port matchup on intake maniflolds will be off because different cylinder deck heights are used. 1957 and later cylinder heads have larger coumbustion chambers and valves.
I think all 303 engines are stock with flat tops.

Here is a thread that is a good read.http://www.jalopyjournal.com/forum/archive/index.php/t-47584.html

 

Be aware that if you bolt 324 heads on your 303, you'll also need a 324 intake and exhaust manifolds. I think that the factory c.r. rating for your engine was 7.25:1, and the rating for my '56 324 is 9.25:1. If you find a pair of 303 heads with a big 3 cast on one of the exhaust ports, you'll gain about one full point of compression over the '49 heads.

 

1954 and 1955 324s' have smaller intake ports and valves than the 1956 engines. 1957 and later cylinder heads will physically bolt on to 1949 to 1956 engines, but the port matchup on intake maniflolds will be off because different cylinder deck heights are used. 1957 and later cylinder heads have larger coumbustion chambers and valves.
I think all 303 engines are stock with flat tops.

Here is a thread that is a good read.http://www.jalopyjournal.com/forum/archive/index.php/t-47584.html

 

You're stuttering.

 

Okay thanks, i must have misread something, so i can only go later 303 heads then?

 

don't take everything you read on the internet as gospel
do some research and form an educated conclusion

 

That's what i'm doing, the little mags have a lot of info, but dont quite cover this stuff

 

you could consider talking to a local Automotive Machinest and find out what he thinks. Reality is, there are many things you can do to a valve train to increase performance. The "one-off" theory is fine, but doing more with what you have is probably cheaper in the long run.