My mechanic that is putting my pistons in seems to think that the bore is too big for the pistons. I think he just doesnt know about forged pistons expanding since he is used to NA V8's. Anyway, I called JE up and the tech guy Rick told me that the clearance for the piston to the cylinder wall should be .004 larger than the measurement taken from a half inch up from the bottom of the skirt. I have been told it was .0035. I guess thats about the same number anyway. So tomorrow they are going to measure the bore and see if it is correct. I tried to explain to the mechanic that it is a littel loose because they expand under high temperatures. He is used to big blocks and NA cars so he thinks the piston shouldnt have any play when in the bore.

no, thats the correct bore

.004 is the correct one right?

My 8.5 JE's said .0035 I had a problem with Howell shipping me the wrong rings (standard bore rings) so it seemed initially that the bore was way too huge (big ring gap). dunno man, call up howell or HRC or whoever you bought the pistons from, they should send you a detailed spec sheet.

My forged pistons definitely have play in the bore... I can make them clunk up against the cylinder wall. I've checked all my clearances several times and they're all right. A couple people on here assured me that some play is ok.

Thats what I thought but my mechanic swears that it isnt supposed to be like that. I wish I lived near HRC or Howell or even Dino. There isnt anyone around here who has any kind of knowledge about the 420a. And I do have the spec sheet but its at the shop in the car. I have to take a look at it tomorrow.