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Author Topic: How much to shave  (Read 982 times)

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Offline stony

How much to shave
« 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!
1949 CJ3A 11159 body 11225 engine 11140
On preservation vs. restoration:Roscoe Lee Brown "the Cowboys" when he met the whores on the trail:"Well, I have the inclination, but not the time”.

Offline garage gnome

Re: How much to shave
« Reply #1 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!  ;)
Nate in Western MA 1953 3A #3268, The Jalopy, '47 2A Wheelin' rig, '49 3A, #37071, unmolested, bone stock named Ted

Offline Mike S

Re: How much to shave
« Reply #2 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.
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Offline Bruce_W

Re: How much to shave
« Reply #3 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
Until We Jeep Again...........