Join Date: Mar 2001
Location: Calgary, Alberta, Canada
Hi all. I have finally saved up some cash to complete the rotating assembly in the 406 sbc, but I came across an issue when I went to the part store to get some pistons. The guy at the speedshop was concerned about piston-to-wall clearance issues depending on how the machinist oversized the block and what grain of honer was used. He mentioned that cast, hypereutectic, and forged pistons all have different clearance specs, and putting a hypereutectic into a bore milled for stock pistons might cause bind-up. Also, the coarseness of the honing will determine whether moly rings are to be used or not. Here is where my problem gets worse: the block was machined a year ago, and naturally the machinist can't remember my exact block and what he did to it. I DO, however, recall telling him I planned on using hypereutectic pistons in there (he actually asked) but I don't recall any talk about rings. Now, what might you suggest I do to go about determining what pistons/rings to put into my bore? I don't really feel like paying a machinist again, heh. Is there some way of measuring the bores with a vernier caliper or something and matching up the result to the desired piston? Also, is there a visible difference in coarse grain honing and fine grain honing?
I most certainly would appreciate any advice or help offered, as the parts man obviously isn't too keen on selling me pistons blindly.
Thanks a ton in advance,