Thread: Failed LS7 4 times

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I am on my way to a new 540, but still do not know the reason the old ls7 failed. This motor was rebuilt 3 times since I have owned it, each time with oiling problems. First it dropped pressure, on the dyno, and spun mains. Second it lost pressure, nearly seized and the strip down reviled jammed lifters. OK, block is not indexed and that must be the prob. Third time after 20 mins first start up, system 1 filter shows bearing metal. Strip down shows slight ware on mains again and crank scraped. Each rebuild done thoroughly, cleaned, and put together with basically all new parts except crank and block. What the hell is going on. Three engine builders can not find the problem. I only hope it disappears with the block and the crank

If the block was properly honed and mic'd and the crank was cleaned up, polished and mic'd I cannot see a reason for the failures other than shoddy parts or shoddy workmanship. Maybe the previous builders were to lazy to spec everything out for themselves and used the previous builders specifications. If this is the case, and the original builders specs were faulty, then the rest of the rebuilds would follow suit. Amazing what a .010" difference in clearances can make.

could be many things and one would be the wrong lifters and lack of oil i have built many big blocks at see 7500 and they are not indexed lifters bores how did you get a 540 out of a ls7 block they will not take a bore that big?

thats what happenes when you buy crate motors??????????

Each rebuild was mic'd correctly by guys who know. Last builder was fully aware of this oiling prob and went to great effort to find the problem with the parts. Only the block, crank and bare alloy heads were reused. Everything else new and expensive. Block was decked, honed, aligned and the bores cleaned up. Crank crack tested, ground, check for straight. Pat, I was after your advice earlier, but eric has steered me to a World 9.8, 4.25 x 4.5. We'll do 8.4 comp and run an 871. Hopefully this will bring back the smile

Originally Posted by gassersrule_196

thats what happenes when you buy crate motors??????????

Uh. But aint that what goes into new cars???????

Originally Posted by Flatblack 57

Each rebuild was mic'd correctly by guys who know. Last builder was fully aware of this oiling prob and went to great effort to find the problem with the parts. Only the block, crank and bare alloy heads were reused. Everything else new and expensive. Block was decked, honed, aligned and the bores cleaned up. Crank crack tested, ground, check for straight. Pat, I was after your advice earlier, but eric has steered me to a World 9.8, 4.25 x 4.5. We'll do 8.4 comp and run an 871. Hopefully this will bring back the smile

what is it ? are you asking whats wrong with the block you have. is it to 4.500 bore ? or are you buying a new engine from eric ? if so why ask the old block you have could have two things that are wrong with it 1 is when they bore it they cut in to the main oiling galleys if it a mark 4 block or the lifters are not rigth and the oil hole is up past the lifter bore at full lifte. but i would say some one did not know what they were doing ? and it could be a over look thing like the distributor if it has a slip coller not set up right and not driving the oil pump. but you would of never had oil psi but if you did have it and lost it i would say it was set up to tight if your burning the bearings out of it .big blocks really do not have oil problems

Originally Posted by Corvette64

Uh. But aint that what goes into new cars???????

which is why new cars suck??????????

I would like to buy a motor from Eric, but it would cost about 35k to get on my front door. I live on the other side of the world from most of you guys. The old LS7 is going to make a nice coffee table for my living room. Only has 30 thou over bore, standard MSD dizzy and mains were down to 30 thou under size, due to the 3 rebuilds.It always had 65 to 70 psi untill the bearings got chopped out. I dont know if it was to tight by feel. I used to turn it over with a breaker bar alright. I was only curious as to why it kept failing. Im thinking maybe a casting problem in one of the galleries.