#3 main cap
Thread Starter
Heel & Toe
Joined: Nov 2013
Posts: 18
Likes: 1
From: Chilliwack BC
#3 main cap
I just got my block back from the machine shop on my L82 rebuild. I was bored .030 over and had the mains line honed. The machinist showed me that after line honing the #3 main cap had an issue. The cap needs to be tapped in but it pulls out of the register easily. It does not move laterally. He said that the engine will be ok for a cruising, hotrodding around but not for beating on. Anyone like to comment on this? Anyone seen this before?
Brent
Brent
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Yep. Insufficient cap register increases the risk of galling &/or spinning a main bearing (BTDT). If you plan on making a good bit of power &/or revving it very high, I'd change out that cap and re bore/hone the mains.
Thread Starter
Heel & Toe
Joined: Nov 2013
Posts: 18
Likes: 1
From: Chilliwack BC
Yes torqued to the correct value with the stock bolts, I was planning on upgrading to ARP bolts. The HP will be around the 375 range and rev to 5500.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I just got my block back from the machine shop on my L82 rebuild. I was bored .030 over and had the mains line honed. The machinist showed me that after line honing the #3 main cap had an issue. The cap needs to be tapped in but it pulls out of the register easily. It does not move laterally. He said that the engine will be ok for a cruising, hotrodding around but not for beating on. Anyone like to comment on this? Anyone seen this before?
Brent
Brent
When the bolts are torqued the cap can easily spread apart slightly. During the 19 years that I was a professional engine builder and the 28 years since I found many main caps had to be knocked loose with a hammer and many simply lifted off without effort. It's not a problem as long as its a zero clearance.
Thread Starter
Heel & Toe
Joined: Nov 2013
Posts: 18
Likes: 1
From: Chilliwack BC
I can't really blame the machinist, for not bringing it to my attention first thing. He normally does the bottom first, for this very reason, then bores the cylinders. In this case the #4 cylinder had a rust mark and I wanted to see if it would clean up at .030 before ordering pistons. Hence when he got to the bottom most of the engine was done. He advised me that the fact it is in the middle of the crank, four bolt main, and It may have been that way from GM it should be ok because of the end use. It not being a tire shredding, nitros monster.
Thread Starter
Heel & Toe
Joined: Nov 2013
Posts: 18
Likes: 1
From: Chilliwack BC
When the bolts are torqued the cap can easily spread apart slightly. During the 19 years that I was a professional engine builder and the 28 years since I found many main caps had to be knocked loose with a hammer and many simply lifted off without effort. It's not a problem as long as its a zero clearance.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Tho the number of mills I've done over the years may pale by comparison with those turned out by a "professional", IMOE cap register related issues are a very real concern the higher up the performance scale one aims. Anyway, however different may have been my own experiences, our debating that fact doesn't speak directly to your specific inquiry. Here's my short take...
Should your machinist have brought it to your attention?
Yes.
Will you be safe without doing anything further?
At your intended power level, probably.
What would I do?
Asked and answered, my having done so based on performance levels nearer those at which I'm somewhat more familiar. YMMV
Should your machinist have brought it to your attention?
Yes.
Will you be safe without doing anything further?
At your intended power level, probably.
What would I do?
Asked and answered, my having done so based on performance levels nearer those at which I'm somewhat more familiar. YMMV
Thread Starter
Heel & Toe
Joined: Nov 2013
Posts: 18
Likes: 1
From: Chilliwack BC
Tho the number of mills I've done over the years may pale by comparison with those turned out by a "professional", IMOE cap register related issues are a very real concern the higher up the performance scale one aims. Anyway, however different may have been my own experiences, our debating that fact doesn't speak directly to your specific inquiry. Here's my short take...
Should your machinist have brought it to your attention?
Yes.
Will you be safe without doing anything further?
At your intended power level, probably.
What would I do?
Asked and answered, my having done so based on performance levels nearer those at which I'm somewhat more familiar. YMMV
Should your machinist have brought it to your attention?
Yes.
Will you be safe without doing anything further?
At your intended power level, probably.
What would I do?
Asked and answered, my having done so based on performance levels nearer those at which I'm somewhat more familiar. YMMV
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