Head Combustion Chamber Volume ?

[Anonymous]

Here's one for the experts...

If I have a stock '66 Mustang 200 and I put a '79 200 head on it will the compression ratio drop? Basically, what I'm wondering is what is the difference in volume between a '66 head and '79 head and how much needs to be plained off in order to make them equal?

 

[Anonymous]

Hi Burnerlief,

The short answer is yes. And maybe for more than one reason.

First, If you engine is original, or has not been rebuilt in the last few years, it will have the original "thin" head gasket (about .025 - .030 installed). These gaskets are very difficult to source these days and, frankly, they aren't as good. The current gen head gasket has an installed height of .045 - .050. So, this alone will lower your CR unless you mill the head .020 -.030.

Second, the stock 66 head has a chamber volume of 52cc - 55cc. The 79 head will have a chamber volume of 58cc - 62cc. As a rule of thumb, milling the head .010 will reduce the chamber size by about 2cc.

Having said that, one really should measure the chamber size and the deck height of the engine before milling as there is no way to know what has been done to the head, or the block, prior to your ownership. So, take the time to calculate the CR in advance.

Enjoy the trip - Steve

P.S. If youdon'town a copy of the Falcon Performance Handbook you should consider it. http://falconperformance.sundog.net

 

[Anonymous]

Thanks for the info., I appreciate it.