Quote:
Originally Posted by Tony H
I would be cautious about changing port profiles-they are sized for the valves. Flow may be lost if the valve size/port size ratio is changed. No easy solution really. JMO but I think it will be lots of work for small gain. I would try the 3.5 heads with some 4.5 solid cams-the 3.5 and 4.5 used the same cams so there should be plenty out there. You will gain some compression-the 4.5 heads are 45cc and the 3.5 heads are 39cc so you could do the math.
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I might be a to concerned about messing with ports on a street engine with an automatic but with a manual and mostly at high rpm it's not an issue I dont think. Regardless of that I used a comp calculator. I thought that there was more than a 6cc difference. Sure looks like alot of matierial missing around the plug and face of the deck surface. You are talking about a d jet 3.5 (39cc) and a k jet 4.5(45cc) correct? I've got 3 figures here
1. Stock 4.5 k jet. Used it to get compression at 8.000-1 cr by messing with dish volume
2. With 39cc chamber and 1.905mm 4.5 head gasket 8.563-1 cr
3.with 39cc and alloy 1.2446mm gasket 9.049-1 cr
See any thing wrong here? I was really hoping to get up closer to 10-1 cr
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