Dale Schendel wrote:
should have tried a 20r block machined to fit 22 r low prfile pistons and a 22r crank. (more compression) the draw back is it has to be just right to keep the pistons from slapping the valves.
Why use a 20R block at all? You can weaken it by boring it to 92mm, or you can just use a 22R block (like I did) and weaken it less by boring to 94mm. I'm using Forged 94mm high compression pistons in a 22R block with a 20R head. 20R and 22R cranks are identical.
The only thing I'd change if I did it again would be the age of the block. I compromised with a "tall deck" (1981-84) motor, I got a deal on a few of the parts. I should have held out for a newer "short deck" (1985-95) That would have meant different pistons (still high compression, still 94mm), but they would have been flat top instead of domes (more efficient combustion that way), and more importantly, they would have been about 75 grams lighter per piston. That makes them rev a lot easier. The added bonus is a lighter engine, I'm not sure how much, but I'd guess 30 lbs.
I'd still use the 20R head, but it would have been milled about 1cm to work with the late type timing chain (2 links shorter), I actually did buy a 20R head already to go, but sold it when I started the tall deck motor.
The only problem with the short deck motor would have been the compression, about 12 to 13:1. My motor will run on pump gas... (I'm guessing that mine is about 10.5:1).
The other motor is also a single row chain (unless you buy a $500 conversion kit), and mine is a double roller.
As for the parts from circle track folks... I'm always looking for nice spares. I actually bought most of my stuff from the circle track guys, and sold a lot of my unwanted spares to them (stock intakes, holley carb adapters, etc).
Scott
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