Cracked piston in fresh engine

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J

Joseph24251_200

The Mopar Kid
Joined
Oct 23, 2006
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Fayetteville
Oh here we go I just recently rebuild a 360 using KB 107 .040 over after gettin the engine running for the first time i found that the engine had a blowed head gasket on the passenger side. I replaced the head gasket and all was fine except a exhaust leak. Then one day the car started smoking badly and had way to much pressure under the valve cover so i pulled the engine thinking i may have had a bad ring only to find i had a small peace of my piston missing and a crack. What could of caused this it was only on #4 cylinder. I wanna know what the deal could be before putting this thing back together. Thanks to any one who reads or replys.
 
it just cracked down to the top ring and that was it. I could of sore I had the ring gap right i just checked it and it was a lil big thou should of been .032 and it was .039 on this one ring but that was what i was thinkin the problem was also. This was the first time i tried file to fit rings. Expensive learing experience huh!!! Just when the ridin' got fun! I imagin that would explain the light smoke i would get every now and then untill it started smokin all the time. Any suggestions for a first time filer?
 
The KB's are a good piston, but due to their high top ring placement, a bit more sensitive to top ring gap. The old ".004 per inch of bore" is too tight for these slugs. If your gap was to the loose side of Kieth Black's specs hpwever, they owe you a piston and gasket set.
 
Well i just double checked the ring gap on that piston and it was .039 again. I'm a go back to there site and see if the .032 was the gap i was required to use but i'm pretty sure that was it. I'ma send them a email in am min, and see what they say.
 
.039 should have been more than enough. I put together mine and I only gapped mine at .030 and I've put about 700 miles on it (pretty hard miles too) and had no problems.
 
could coolant have gotten into that cylinder during to
head gasket leak?
 
Well in that case, better make doubel sure block and head faces are flat.

Fayetteville where? Fayetteville, AR or Fayettenam, NC.?
 
I lived there myself Yadkin & Gruber and then Raeford Rd & Bingham Drive. Spent a few days at Pope a year or so back and was amazed at the changes since I moved away in 93. Too bad Rick's Lounge is gone, is the Flaming Mug still there?
 
When I was stationed at seymour johnson afb I made a run to Pope I had a good time in your fair city but that was in 78.

What was the piston to cylinder clearance? It may well have been from the head gasket but I have to ask how bad was the exhaust leak?
 
I actually never heard of Flaming Mug, and it is a shame Ricks Lounge is gone. But the exhaust leak actually got pretty bad on the way home the day it started smokin. when i removed the head I noticed it was leakin on the header gasket.
 
Detonation damage. I dont think at .039 that it had a ring issue. Can you post pictures of the tops of the pistons on the cylinders that didnt have a head gasket issue?
 
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