Compression height and hemi pistons

[kmc3420]

I got my "208" piston yesterday, pin fit is good in both piston and rod. The rings are the wide pattern or old style. Ring groove clearance good. I will mock up case, rod piston and cam tonite, check the "in hole" and skirt clearance. If OK the rotating stuff and head are going to the machine shop for a balance and a shave.
Make sure you get the right rings.
Louie

Did you end up using your stock wristpin? I got my piston, the 2.756 Flat top, .570 Compression. I pulled the head and carb, haven't opened up the case yet to pull the crank, cam and rod. I like what you have found, its promising at least that I can get what I need if my piston doesn't work.

Can you explain why you chose the 208 over the one listed above, because of the larger wrist pin? Not questioning your purchase, rather questioning mine.

 

[Louie]

I used the pin that came with the piston, it appears that clones share the same pin dimensions but the predators run about 10 g lighter. Pin clearance is 0.002" at both rod and piston. (ARC 0.040 over rod for predators) The rod crank clearance is 0.002" by direct measurement and will be confirmed with plastigage on final assembly. The piston-bore clearance is snug at 0.002" direct at 90 degrees to pin but a 0.0015" feeler gauge will not pass. I will need to hone the cylinder some to suit me.
I chose the "208" piston because the predator piston was shown "out of stock" when I was looking for answers. I see no difference, even the weight is the same, except the "208" has 1.5mm rings and I think the predator has 1mm rings. Am I correct? When you said you were going your route I decided to stay with the "208" and we could compare notes. If you have the narrow rings you my have the better deal, although I've been running an old clone with wide rings and it does fine. (10 races, no smoke).
I ended up 0.026" in the hole with the +0.040" rod. I'm ready to send this puppy off to the machine shop for balancing and a head shave of 0.050".
Thanks, all of ye.

 

[kmc3420]

I used the pin that came with the piston, it appears that clones share the same pin dimensions but the predators run about 10 g lighter. Pin clearance is 0.002" at both rod and piston. (ARC 0.040 over rod for predators) The rod crank clearance is 0.002" by direct measurement and will be confirmed with plastigage on final assembly. The piston-bore clearance is snug at 0.002" direct at 90 degrees to pin but a 0.0015" feeler gauge will not pass. I will need to hone the cylinder some to suit me.
I chose the "208" piston because the predator piston was shown "out of stock" when I was looking for answers. I see no difference, even the weight is the same, except the "208" has 1.5mm rings and I think the predator has 1mm rings. Am I correct? When you said you were going your route I decided to stay with the "208" and we could compare notes. If you have the narrow rings you my have the better deal, although I've been running an old clone with wide rings and it does fine. (10 races, no smoke).
I ended up 0.026" in the hole with the +0.040" rod. I'm ready to send this puppy off to the machine shop for balancing and a head shave of 0.050".
Thanks, all of ye.

I plan on using my stock wristpin(From Predator) as well with the flat top piston. I did not gauge any clearance's last night as I was tearing the block apart. I think you are good to go the way your response reads. I will have to do some measuring on my rings, crank, and rod just to make sure all parts are within spec. I don't have my rod yet, but will report back once I get some #'s. Thanks for your help Louie, in your search for help, you helped me. It looks like Ring Size is the only difference in the pistons.