[NeighborsComplaint]

My sincerest condolences. You can source a block, have it machined and transfer the usable parts assuming metal shavings didn't get into your main and rod bearings scoring the crank.

[64speed]

I’m on the fence on what to do from here. To be totally honest that engine had great street manners but it was too much for a daily driver. I don’t think the BBC rockers had anything to do with it.I just looked the others and they still have perfect contact patterns. I don’t know if I will use this cam grind again. It’s a little much. Whatever I do it’ll have MSD

[NeighborsComplaint]

Originally Posted by Skip Fix

In looking for a higher ratio rocker years ago(1.75-1.8) I checked about every other engine family . A BBC rocker is roughly 0.120 longer stud to roller tip center than ANY Pontiac rocker. Comp's SS BBF are their BBC with a 0.045 offset trunnion to shorten the distance. Crower has a BBC with a 0.090 offset I used WITH a lash cap and a 0.200 shorter pushrod. It took that to get a decent pattern.

Paragraph 3, Post 1226-1227 (duplicate post). My thoughts exactly.

[P@blo]

Sorry to hear 64. Just be sure to keep moving forward with your goals in mind. Problems that can be easily solved with a cheque are not really problems.

Did you let the builder know?

[64speed]

No, going down there Monday, not his fault

[Gach]

Hate to see this, I will say tho over the years I’ve found two blocks after being mag that those very lifters bores had hair line cranks. Can I ask what cam you used, cam specs?

[Lemans64]

Well that really sucks, I thought maybe you lost a camshaft to cause this, but this is crazy.
Sorry to hear about this.

[OCMDGTO]

Yikes horrible news sorry to see that. How about find a stocker/iron heads, etc to run in the meantime?

[tom s]

Hyd rollers usually don’t cause lifter bore failure.Just not enough spring pressure.I suspect something broke and might have got caught and jammed the lifter in someway?Tom

[Gach]

64 speed. I’m on the fence on what to do from here. To be totally honest that engine had great street manners but it was too much for a daily driver.

.

That’s reason I was asking for cam spec’s

[Gach]

I’m just saying it’s a good possibility that the very front lifter bore which just hangs out in mid air, was weak or my of had a hair line crack, that wasn’t detected. It finally let go taking the adjacent one out also. No fault of the builder or cam. Seen this in more then a few times. In that case not even installing lifter bored brace could prevent it.

[64speed]

Wayne has another block he is pretty sure. If so I will be transferring all useable parts and rocking on in a few months

[Gach]

Originally Posted by 64speed

Wayne has another block he is pretty sure. If so I will be transferring all useable parts and rocking on in a few months

Nice! Glad to hear you haven’t given up.

[geeteeohguy]

Originally Posted by 64speed

I’m on the fence on what to do from here. To be totally honest that engine had great street manners but it was too much for a daily driver. I don’t think the BBC rockers had anything to do with it.I just looked the others and they still have perfect contact patterns. I don’t know if I will use this cam grind again. It’s a little much. Whatever I do it’ll have MSD

Very sorry to see this. If it wasn't for bad luck, I think you sometimes would have no luck at all.

As a crotchety older guy, I prefer building my engines as drivers, not racers. I use factory parts and go pretty mild. So far so good....the 389 in my '65 is running strong 41 years after the rebuild and still leak free (plenty of seeps!) and the 400 in my '67 has about 90,000 miles on the rebuild I did for less than 2k 34 years ago. Still does not use oil, runs great. O68 cam, USA lifters, Forged pistons, iron Pontiac heads. Just get in and drive, no drama. These things get expensive and frustrating when you tweak them for as much power as you can get. You need to ask yourself if it's really practical.

[64speed]

Well I have the heads and the forged rotating assembly. The cam is screwed. Paul Carter picked that cam specifically for my gear,trans,tire height, it was perfect….but it was rowdy. I think a rev limiter and this never would have happened unless it’s was a crack that would have eventually failed regardless. The car is/was outstanding and will be again. Isky is fixing the cam and Wayne will do his thing. Good thing we are friends and I can make payments

[64speed]

This failure didn’t involve fire like my last Chevrolet so I’m still ahead of the game.

[geeteeohguy]

Originally Posted by 64speed

Well I have the heads and the forged rotating assembly. The cam is screwed. Paul Carter picked that cam specifically for my gear,trans,tire height, it was perfect….but it was rowdy. I think a rev limiter and this never would have happened unless it’s was a crack that would have eventually failed regardless. The car is/was outstanding and will be again. Isky is fixing the cam and Wayne will do his thing. Good thing we are friends and I can make payments

Have never seen lifter bosses break off of a block on a stock Pontiac in 45 years of playing with them and other engines. Have never seen a cracked boss on a stock block either.

What about the rest of you guys? My gut tells me that the aftermarket parts are the cause of this failure.

When I was in the auto industry, 99% of the time when something failed, it was the 'upgraded' aftermarket part that caused the failure, not the factory engineered and designed part. This was just as evident when I was in the Model T club as it is here and on the Corvette and Tundra forums.
I see a lot of money being spent on engines and running gear that doesn't even make 1000 miles before it explodes....usually due to poor quality parts.

[tom s]

Bores do break when solid roller cam get to 200 lift at 200 duration with out a lifter bore brace.Tom

[grivera]

Are you keeping the BB Chevy rockers for the new build?

[64speed]

Originally Posted by geeteeohguy

Have never seen lifter bosses break off of a block on a stock Pontiac in 45 years of playing with them and other engines. Have never seen a cracked boss on a stock block either.

What about the rest of you guys? My gut tells me that the aftermarket parts are the cause of this failure.

When I was in the auto industry, 99% of the time when something failed, it was the 'upgraded' aftermarket part that caused the failure, not the factory engineered and designed part. This was just as evident when I was in the Model T club as it is here and on the Corvette and Tundra forums.
I see a lot of money being spent on engines and running gear that doesn't even make 1000 miles before it explodes....usually due to poor quality parts.

My first Pontiac was a 64 Lemans with a 66 389 and Muncie. The only thing I ever did was put oil and gas in it. I drove it as my only means of conveyance for 4 years. I agree, mild stock parts probably don’t fail as often, but find OE quality stuff now. It’s pillar or post. You can buy 500 roller lifters and hope for the best or you can buy 1200 buck Crowers and still hope for the best. The Chevrolet fire I mentioned was a stock 89 Jimmy that windowed the block for no apparent reason and severed the fuel line onto the exhaust. Freak accident I agree and I was able to save it from total loss but there are no guarantees is my point I guess. I could build it back milder but what’s the fun in that?