Question on piston clearance

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So i just received newly bored cylinders back from machine shop. Went to measure clearances with new pistons just to double check before i start re-assembly. I am getting clearances of closer to .0016-.0017in. Manual i believe calls for a standard clearance of .0020-.0022in. Any advice on this? Should I worry about potential seizing at this clearance?
 
Bought from Cruzinimage. Cast...i think.
 
Couple questions:

did the machine shop have the pistons? They need to, in order to get the clearance correct.

How are you measuring this? My experience has been that when using feeler gauges in this manner, they tend to read a few thousandths low. So your .0016 might be .0018 or .0019 (I'm guessing due to the non-curved nature, and not taking a single point reading).

I've gotten away with being significantly too-tight clearance on a few builds, using high quality OEM pistons and a very gentle break-in using leaded race fuel (burns cooler, so less expansion during break-in).
 
Yes, machine shop had pistons. I measured using telescopic gauge and micrometer. I bought pistons from cruzinimage (ships from Japan) and previously had good performance with them. Also has good reviews from others. I can always ask the machine shop to double check my measurements and hone a bit further if needed....
 
I learned from the best by watching your video, Jim! I'll admit my telescopic gauges probably aren't up to the highest of standards. So i took several measurements top, mid and bottom more than once and carefully tried to follow same technique as in vid. Any single measurement that came out different by more than .0002, I went back a third time. Assuming my measurements are accurate, will I risk seizure if I break in slow?
 
Assuming my measurements are accurate, will I risk seizure if I break in slow?
Well, if you follow Delagem's technique above I'd guess you'd be OK, but..... that kinda misses the point. I'll bet you paid a pretty penny to that machine shop. I think I'd take 'em back and make 'em do the job right..... .002" to .0022".
 
Thanks, Jim. Thought thatbwas your vid, sorry. I sent machine shop a message outlining my concern. He charged $100, which i thought was very reasonable. He's done other work for me in the past and am sure he'll take care of me.
 
IIRC pistons aren't really round but are carefully machined ovals to compensate for expansion and the rocking forces involved. There is a proper place on the piston to measure, check the clearance but it slips my feeble mind where that is.
 

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So first with piston at top of cyl. I inserted the gauge until it hit resistance and wouldn't go any further. It was like this on all four "sides" at the top. Gauge would go down about halfway the length of the gauge or a bit further, but not much. Consistent all around. I then moved the piston to the bottom of cyl. Gauge would barely squeeze into the sides where piston pin goes and then would get "stuck" with very little of the gauge inserted. There was no way that gauge was going in under the skirts perpendicular to piston pins (second pic). Maybe due to the flatness of gauge, so I tried sneaking it in on a corner of the gauge. No luck on either side. Heard from my machinist this morning and he said he "thought" he left at least .002 clearance. At this point I'm inclined to take the cylinders/pistons back for a bit more honing. I could attempt the honing on my own, but since he did the job to begin with I am inclined to have him finish it up. Won't take much to take a few more off. LMK your thoughts - and thanks for your time and help on this.
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Sorry...still getting a hang on how posting pics work on this site. Cut and Paste doesn't seem to work, though they showed up when I tried it. Here they are:
 

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Yeah... second pic is how. If a .002" won't fit, I'd guess your measurements are accurate. Have you read the top end buildup thread in the Tech section?

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