I had a buddy stop by the shop to have me weld up a bellhousing. He told me he'd blown his engine (sbc) and said it was caused by another friend turning the distributor while trying to help with a hard start issue. After a short drive with a lot of poppin' and snappin' he took it back and had him put it back... never with a timing light. A few days later, the engine let go. Bent valves and pushrods, a rod through the block... the whole shebang. He believes that it blew up because of the timing, but I don't know. My question is this... Can simply having the ignition timing off by a few degrees cause catastrophic failure? To my understanding, valve timing and ignition timing are related, but one can't change the other. Right? Turning the distributor won't bring any moving parts into contact with one another. The engine in question has some miles on it and probably some pretty hard miles at that. So, is there something that might have been worn to the point that the faulty timing caused it to finally give up...? JOE
No,turning the distributor won't crash parts together.Turning the distributor will advance or retard the timing. Turned too much either way and it won't run. Too slow and it'll lose it's power & overheat some,,too advanced and it will be hard to impossible to start and/or ping and rattle resulting in pistons/ring lands damaged. However,, Maybe the timing chain was already letting go and the erratic timing helped it jump teeth and break,, locking the whole thing up.
Sounds like this thing was ready to blow up. Dont think changeing the timeing had anything to do with it.
Usually, too much timing in an engine will cause pre-ignition, also called detonation. Most of teh time, detonation will make a hole in a piston top before it scatters the engine, but detonation is also very hard on the upper rod bearings, which is not good for teh long term future of the engine. It can also dick up the piston ring lands, which can sieze or break the top compression ring. Sometimes, it can pop a headgasket, possibly resulting in anti-freeze entering the oil, not good for bearings.. So the question is, did timing lead to kicking a rod out of teh block? Probably not, but maybe... Good luck, -Abone.
Blowers like a lot of initial - like 18 to 20. Did he have the advance in the distributor limited so it would only give a total timing of 32 to 34? If it was stock it probably had 24 degrees of advnace. That on top of 18 initial is a shit load of advance at it would detonate like Flamedabone says.
I'm pretty much thinking when he said "blown" and mentions rods and shit hanging out, he doesnt mean he's installed a huffer.
Tudor, blown up engine, not an engine with a blower.... I agree that while it may have played a small part in it's demise if overadvanced, it sounds like the motor was ready to let go anyway. It also sounds like the typical clueless owner, where whatever happens is blamed on whoever worked on it last.
"My question is this... Can simply having the ignition timing off by a few degrees cause catastrophic failure?" Not very likely at all, especially around the block a few times Sounds to me like the sbc was ready to go, heres why Why did it become hard to start? What had gave up at that point in time? IMO = I would guess a timing chain or related problem threw some ignithion timing related symptoms, Continued romping on it put her to rest for good.
sounds like the engine was weak to begin with, and probably on its last leg..did changing the timing genade the engine?..I dont think so..I think it was bound to happen because it was worn the fuck out..could it had hurried the break down..possibly..but it wasnt the root cause
Bingo! Worn timing chain skippped around,valve timing went to shit,pistons wacked the valves,bent pushrods,one or more pistons failed and jammed in the bore and Mr Rod exited through the block.
yeah..you tuned up my engine now the radio dont work, and the rear spring broke..its yer fault and i want you to make it right
Back in the early 90's I wrenched at Monkey Wards auto,( holdjercomments) and we married every clown whoever had a battery installed in their car. It was miserable. I just work on my own junk now for that reason alone.
More likely he had crank bearings worn out which caused the hard start problem. Advancing the timing could help overcome the drag allowing the engine to start. Or like trucked up said a worn timing chain - too much slop so no accurate timing. What flamedabone says has some merit but I seriously doubt it would cause catastrophic damage unless driven long and hard that way.
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