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Discussion Starter · #1 ·
Can anyone tell me what timing has to do with the overheating of an engine? How they are related to one another.

Does over advanced timing cause overheating? Or is it retarded timing?

I am trying to study up on this before I crank up my engine for the first time.
Thanks
 

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timing

Retarded timing will cause a engine to run hot.

We you say cranking it up for the first time,Are you talking about breaking in a flat tappet cam???


Keith
 

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Discussion Starter · #3 ·
Thanks Keith,

No, hydraulic roller. Completely rebuilt motor.

Retarded timing huh? I know that to be true now but just don't understand the mechanics or logic to it. Isn't overly advanced timing the one that melts pistons?

I do appreciate your input. As everyone knows, screwing up your timing is very expensive $$.
 

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Besides timing being retarded causing heat to build, so will a lean carb. If you are firing the motor for the first time, make sure the carb is on the fat side so as not to lean the motor out in the RPM range.
 

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Timing

Over advanced timing will cause Detonation, that is what melts holes in pistons and lifts ring lands. Not really the timing it self that is the problem.

Not sure i can explain in scientific detail why late timing causes a engine to run hot.

I'll have to think on that one a bit.

Your not going to have any problems during start up. A engine with a roller cam is almost fool proof. As long as it was assembled corect and the oil system primed before you fire it.


Keith
 

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hgufrin said:
Can anyone tell me what timing has to do with the overheating of an engine? How they are related to one another.

Does over advanced timing cause overheating? Or is it retarded timing?

I am trying to study up on this before I crank up my engine for the first time.
Thanks
Retarded will over heat it most quickly. The burn occurs over about 80 degrees of crank rotation, when started late, there isn't time for the the flame temps to be reduced by work against the crank. This combined with the reaction still occurring when the exhaust valve opens conspires to dump really hot gases into the exhaust passages. This greatly increases the valve temp and the amount of heat picked up by the cooling system thru the structure of the head and exhaust port. The exhaust manifold/headers also become very hot, enough to glow. With retarded timing, the temps come up very quickly.

Too much advance will eventually result in overheating but it's much slower to build compared to retarded timing. Usually before anything bad happens one usually notices that the engine is hard to start, tends to explode thru the carb, and if it runs at all it's with no power and tends to detonate from the extreme pressures formed before TDC. So you usually head this problem off before the temps get very high.

Bogie
 

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hgufrin said:
I know that to be true now but just don't understand the mechanics or logic to it.
Late timing will allow the fuel/air mixture to continue to burn while the piston travels away from TDC. This causes a lot of heat to be absorbed into the cylinder wall that wouldn't ordinarily be there. If extreme enough, exhaust gasses will still be carrying a lot of heat w/it. This heats up the exhaust valve, seat, port and the surrounding water jacket has to try to absorb all this additional heat. The result of it all can be an overheating condition.

Isn't overly advanced timing the one that melts pistons?
Over advanced timing will damage pistons due to detonation as well as increased heat. Detonation can pinch the rings in the lands so they won't be able to do their job. This can allow flame erosion to occur. At the worst, detonation can cause pistons to crack, scuff bores along w/bearing damage and if bad enough crank failure. At the least, power will be down. In any event, accelerated wear will happen.

EDIT- Messed around typing this long enough for the question to already be answered (a couple times) while I was still typing. :embarrass Oh well.
 

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Bad cam timing

I recently changed the heads off my 97 mustang gt and now it runs like ****, loss of power, backfiring once i let off the throttle and just sounds horrible. will running it like this for a bit mess anything up? and does this sound like retarded timing.
 
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