318 compression ratio

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39moparman

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I recently acquired a 73 318 with fast burn heads that were 0 decked. It has standard pistons and the block was not bored over. Can anyone tell me what kind of compression ratio I am running? Also, I was told it has an RV towing cam. Exactly what does that mean?
Thanks,
39MM
 
Compretion 8.6:1 and the rv cam will give you better performance and breath better,
 
I hate to sound like the newbie I am but doesn't 0 decking the fast burn heads raise the compression?
 
You can't zero deck heads. The piston can come up to the top of the block and that would be called a zero deck piston. Milling the heads is a way to increase the compression ratio and it is a math equasion dealing with the amount of cc's in the head.

MoPar has a "Engines" book that tells how to do this and how many cc's for the head to mill for a point raise in ratio. Which would probably be just great so long as it's actual ratio is 9.5-1 and not just working off the advertised ratio which is high for what it is actuallly.
 
You are correct (not that you needed me to tell you that). The guy told me that indeed the heads were milled to achieve a zero deck piston. How much exactly was milled he didn't know because he bought the engine in a Coronet and swapped out engines. So the guy before him had the work done. Between the fast burn heads and the mill work done on them, I'm assuming the compression ratio wouild be substantially greater then the factory 8.6 to 1. But without knowing how much was milled, I guess we can't know for certain.
 
The only thing that comes to my feeble mind is to have the heads cc'd.
 
In that case, exit feeble mind for one that works.

After you cc the head, measure how far down the hold the piston is, if the piston has valve reliefs, cc them, find out head gasket thickness and bore.
Come back with these values and I (we'll) add in the bnore and stroke of the engine to find out what the ratio is.

OH! Is this engine overbored? Let us know.
 
You cant set piston height by milling heads. So he's already confused. So, I'll toss out somewhere between 7.5 and 8.8:1 depending. You really cant tell without measuring the head chamber volume, and seeing how far down the pistons are in the bore.
 
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