my car has about 61,000 miles on it, I was just planning out doing the heads and cam with a 150 shot and when the heads came off I found out that 2 of the cylinders had rings that were starting to go bad (showing excessive blowby), so I went ahead and got everything to refresh the short block (rings, bearings, main bolts, etc) and then when the main caps were coming off one of them literally came off in 2 peices. I have NEVER seen main caps come off in 2 peices with everything else being just fine, seen a few cranks broke, but not the caps. Has anyone else experienced anything like this? kinda pissing me off that so much stuff is wrong on a motor with 61,000 miles... almost like I bought a ford... Looks like there was a air pocket in the cap when is was made causing it to crack. Anyone else experiece anything like this with their car? What can I do at this point.. aside of buying a 4 bolt main kit and having expensive machine work done to drill the holes for the new bolts. From what I know GM doesn't sell just main caps, you have to get a whole new block to get the caps (cuz generally if the caps broke while the motor was running the whole thing is f()cked) so is there anywhere else I might be able to just get 1 main cap, or even al new 2 bolt main caps for a LT1? Are the main caps the same for Gen 1 chevy small block 350s and Gen 2 small block 350s, cuz I did find some for a gen 1 350s for around a $100??

 

The fact that your cap broke should not surprise you as much as a couple of bad cylinders. In 61k if you have 2 bad holes, you must have had other issues that you haven't told us about. I question how you know the rings in only 2 cylinders is bad causing blowby? Is it actually the cylinder walls that are scarred or do you see something else that leads you to believe the rings are bad?

If only 2 of 8 are actually bad, more than likely it was caused by "souping" from having dead cylinders. The fuel washed the oil down off the cylinder walls.

BTW first and second generation main caps have the same registration. So you can purchase 14011052 from a place like gmpartsdirect.com for $49.73.

Even if you get just 1 main cap, you will probably still have to have it align bored anyway. Even though the note with the cap says it will have to be align bored when the front location is replaced. The process of drilling and tapping for splayed caps is not the hard part. Milodon makes them in a kit with a drill bushing so you can do it yourself. You must be sure not to go too deep and drill into the water jacket.

I think you beat on it too much. Now you want to spray it, you're only asking for problems.

 

honestly, I think the rings just started to go bad cuz the car just sits a lot. since I got the car 3 years ago I have only driven the car 4,000 miles... well 4,000 hard miles. The car pretty much was garaged 7 months and was driven every now and then in the summers since I got it (which is why it still looks like its brand new, and is mistaken by everyone as a much newer car). Still doesn't explain what the problem with the main caps tho, i really beleive it is a manufacturing defect just cuz I wouldve figured a rod, piston or crank would've broke before the cap. Thanks for the part # on the main cap. Got any idea of how much a align bore will cost?

 

Its not the first time i've seen the main cap issue. It happened on my car. I pulled the old motor for a rebuild and found 1 of my main caps were cracked in too. I also did a search and found another guy that posted he had the same thing happen on a stock car.