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Jason S. 09-01-2012 05:32:41 174.254.113.205 Report to Moderator	I think I found the answer. According to federal mogul a TO20 piston compression height is 1.980 and a TO30 is 1.875 which is .105 difference....that"s quite a bit. The reason I was asking is my TO20 runs great but it doesn"t have the pulling power that the TO30 I grew up with had. I"ve got a set of 3 5/16 sleeves...so all I need is a TO30 crank and I guess the pistons would have to be custom made with a 3 5/16 diameter and the 1.875 compression height....which would get me close to the power of a TO35 but still use theTO20 block. I know the valve sizes and combustion chamber is different between the two engines but that is a pretty easy fix. Does this sound like a plan? [Reply]   [No Email]
David G 09-03-2012 19:20:57 205.215.206.18 Report to Moderator	Re: Piston compression height differences in reply to Jason S., 09-01-2012 05:32:41   I got custom pistons made for my MH 44, it started out at $600 and ended up at $1200. You really want to make sure that is the path before starting.   [Reply]  [No Email]
Duner Wi 09-01-2012 19:48:17 216.226.80.242 Report to Moderator	Re: Piston compression height differences in reply to Jason S., 09-01-2012 05:32:41   Don't know if this would work. Never tried it. Z129 has 1/8 inch more stroke than Z120 so compression height should be .125 less, but Z129 has 6.6 compression versus 6.1 for Z120 maybe the .020 difference accounts for compression increase. So if you took off .025 off the top of Z120 pistons you might have 8.1 compression. That might work with good gas. If you run into squish or quench problems I would want not much less than .032 . I have heard of down to .022 quench/ squish but never tried it . I think you will have to flycut the head and I don't know how much you can take out. The only other thing i can think of is cut the top top off Z120 pistons .105. Hope the piston has enough material to cut off. I have no idea if this would work but something to think about. Or make your custom pistons and be done with it.   [Reply]  [No Email]