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OP here, had a very well known cam company recommend a cam that made all the intake valves hit the pistons. After 100 miles one of the valves decided it had enough and broke off. I was only driving about 40 miles an hour and boom. Left a trail on the road. That was back in May and now I have a forged, supercharged, cammed, methanol spraying engine, life is good. Rest in pieces old LS2
Startup keeper failure, took out a Scat H beam and scored the block pretty good. I keep it in the cupholder of my truck for now to remind me that when I want something done right I have to do it myself. Not a corvette but still up there.
OP here, had a very well known cam company recommend a cam that made all the intake valves hit the pistons. After 100 miles one of the valves decided it had enough and broke off. I was only driving about 40 miles an hour and boom. Left a trail on the road. That was back in May and now I have a forged, supercharged, cammed, methanol spraying engine, life is good. Rest in pieces old LS2
Cam specs were 231 256 650+lift lsa 115 I still have the same specs. T
Those marks arent valve reliefs, those pistons are flat top stock
he cam company was nice enough to give me a free cam after they said it was all my fault. God bless em. Instill have the same specs but I bought dished pistons (-11cc)
Patsgarage, well done sir, your pic is worthy of this thread. If there was ever a memorial for blown engines that block should be interred there slowly spinning in a glass case with sad violin music playing.
Patsgarage, well done sir, your pic is worthy of this thread. If there was ever a memorial for blown engines that block should be interred there slowly spinning in a glass case with sad violin music playing.
He called me when he did it, I did not believe that it was as bad as he said until I saw it in person. He has gone through two more since then, but not nearly as bad. He has gotten his 95 Camaro into the low 12's on that engine before it let go. I think he dialed up the boost to 24#s when it grenade.
Cam specs were 231 256 650+lift lsa 115 I still have the same specs. T
Those marks arent valve reliefs, those pistons are flat top stock
he cam company was nice enough to give me a free cam after they said it was all my fault. God bless em. Instill have the same specs but I bought dished pistons (-11cc)
its the builder/assembler's responseability to check for clearence when installing cam.sorry to see these results
Irok, You are absolutely right, it is the responsibility of the builder to check clearances. I called the cam company to order a cam with different specs, slightly smaller. The guy said I could go bigger. He suggested the 235 251 but he said "I wouldn't go bigger" that' when my full on stupid kicked in and didn't check. I thought the guy would know exactly what he was talking about. It was an expensive lesson, but I wanted a forged motor anyway, wanted to turn things up a lot.
Fox guys have been doing that pretty regularly since the 80s. I have a few buddies with flow pot blocks in their rose gardens.
Yep... 2-bolt main 5.0 motors + gobs of boost/power do not last too long. Mine didn't ever do this^^^, but only because I built a 4-bolt R302 before too much failure could occur. I've pulled out a block or two with hairline cracks forming in the mains.
Fox guys have been doing that pretty regularly since the 80s. I have a few buddies with flow pot blocks in their rose gardens.
Was automatically thinking of SBCs out of habit and didn't think of the stock 5.0 blocks but you are correct. Very weak main webbing, most don't attempt to run them beyond 500 flywheel or so on the stock block even with girdles and fills - the block will still break just the same, it just might stay in one broken piece instead of two lol.
To compare, an LT1 SBC from the same time period can safely handle 1000hp on the stock block. No crazy issues with the block itself until ~1200 where the core starts shifting and it gets hard to keep the cylinders round. ~1600 is the record AFAIK...not bad for a factory block.
Yep... 2-bolt main 5.0 motors + gobs of boost/power do not last too long. Mine didn't ever do this^^^, but only because I built a 4-bolt R302 before too much failure could occur. I've pulled out a block or two with hairline cracks forming in the mains.
I did the same with the latest production Boss block, if I wasn't running that block when the valve dropped it would probably not been ok to run anymore. It cracked the cylinder lightly and just to be save I sleeved it. It didn't go into the jacket or anything but it was taken 4.30 to get the sleeve in there and still didn't hit water, amazing how strong the FRPP blocks are.
Originally Posted by PuckDracon
Was automatically thinking of SBCs out of habit and didn't think of the stock 5.0 blocks but you are correct. Very weak main webbing, most don't attempt to run them beyond 500 flywheel or so on the stock block even with girdles and fills - the block will still break just the same, it just might stay in one broken piece instead of two lol.
To compare, an LT1 SBC from the same time period can safely handle 1000hp on the stock block. No crazy issues with the block itself until ~1200 where the core starts shifting and it gets hard to keep the cylinders round. ~1600 is the record AFAIK...not bad for a factory block.
The 351w block will do ~1000 too the 302 block was a bastard child. However mine did hold up to 630rwhp for a while, until I hit a massive pot hole that shifted the radiator and the blower pulley wore through the hose and melted a cylinder down. Block showed no signs of wear though which was surprising, put GT40 heads on it and it went into my buddies 64.
My pops has a 383 with a one off Banks TT on it and he managed to crack the block after launching it out of the water. He said it was "less than a second" to which I giggled and said I bet it was longer than a second.
03-10-2018, 11:00 PM
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