First of all what are claimer pistons or sportsman pistons? I understand forged, hypereutectic and cast as far as quality goes. I put some domed pistons in during the summer (never run) but I'm thinking flat top is better. Lower compression. The block 3858180 has been decked seems like he said .020 not sure. The heads 3917291, 64cc are fresh not sure they have been milled so all in all a little vague to say the least. What I want is 10-1 or close. So I think I'm in the market for some flat top forged or hypereutectic pistons although I have no worries about adding a little octane to the fuel. Also looking for a cam. Pretty much a street motor with a side order of taking it to the track. Will have four two barrels and a five speed, 355 rear.
In dirt track racing, claimer pistons mean that if someone else thinks you are cheating they can claim your motor for a fee. Do you know how large the dome is in CC's? You can calculate roughly, if you do.
The chamber is listed at .64 and I see pistons from +5.0cc to -5.0cc The bore is 4.030, stroke 3.25, original deck height 9.025 (before cut)
The dome volume is what you need to figure out. Here are a few calculators. https://www.summitracing.com/expertadviceandnews/calcsandtools/compression-calculator https://speedmaster79.com/tools/engine-compression-ratio/ http://www.csgnetwork.com/compcalc.html
The engine in my avatar is a .060 over 327 with TRW domed forged pistons 10.5's. Fuelie 202 heads. Comp Cam XE262H cam and valve springs. Headers. Balanced and a Holley Street Avenger 670 CFM carburetor. I couldn't be happier with this combination. Ground pounding idle and pulls hard through all four gears with a 3:73 post rear. Gary
Claimer pistons are just low cost pistons to make building a motor a little more affordable for the dirt track guys. If they race and win, someone can "claim" the motor for a fee.... around $300-400.... so you don't want to have a lot of money tied up in a build that has a ton of money in it. Most are just plain cast pistons, KB sells hypereutectic claimer pistons which are pretty decent especially for the price.
Polish and CC your combustion chambers to increase chamber volume and lower compression. Also will eleminate hot spots and carbon buildup.
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