My Willys 3A and 3B Community

3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: stony on February 22, 2014, 09:24:50 PM

Title: How much to shave
Post by: stony on February 22, 2014, 09:24:50 PM

Getting ready to try to get the "49" on the road this summer.  Extensive engine work needed.  Trying to get a little more HP.  I may be mistaken but it appears that the Supersonic head is basically a shaved standard head.  Two Q's:  approximately what is the compression ratio of the Supersonic, and how much would need to be shaved from a stock head to be equivalent.  Am assuming valve clearance will not be a problem.  Thanks!

Title: Re: How much to shave
Post by: garage gnome on February 22, 2014, 10:49:11 PM

The stock head is about 6.5:1 and the supersonic head is about 7:1 to keep the numbers simple. But the horsepower comes from the word Supersonic!  ;)

Title: Re: How much to shave
Post by: Mike S on February 23, 2014, 12:31:02 AM

I shaved my stock head until the CC's were 73cc's. I think we are at about 7.3 - 7.5 to 1. Just a guess, and the thickness of the head gasket effects the final CR.

Title: Re: How much to shave
Post by: Bruce_W on February 23, 2014, 03:57:42 PM

  The Supersonic head is obviously a completely different casting - just look at the top side of it - it's not just "a shaved standard head". The thing that worries me about planning a lot off of these heads is that it will reduce the thickness of the head directly over the cylinder/piston. How far can we go here?
 " Am assuming valve clearance will not be a problem."  I would not assume anything in this area either.     BW