I've read a lot of posts regarding overheating problems (guess why), and one thing that comes up is timing. How does timing effect overheating and why?

Retarded engine timing will heat one up quick

The mixture starts burning a bit before TDC & is still burning for a bit after TDC. When it's retarded the fire is started later (closer to TDC) so it's still burning as the piston has moved further down on the power stroke which exposes more of the cyl walls to the combustion heat which heats up the nearby coolant as opposed to that window being up close to TDC. I understand that the time a given mixture takes to burn is pretty much the same (so the total timing stays the same) no matter when you start the burning (the initial timing) so that when the piston is moving faster (higher RPM) that you have to start the burn earlier so it will end (peak psi) at the right (after TDC) sweet spot & that for max power you want the peak psi to be at a certain # of degrees past TDC for max push on the pistons which happens from correct timing. From what I understand that's the simplified version. I've always wondered where the heat is going (using correct timing) if the amount of heat produced is the same if it ain't going (disproportionally) into the cyl walls which takes place if the timing is retarded. More of it would be closer to TDC with the time window taking place up top & maybe more of it is carried out the exhaust (hotter ex temps). If the same or nearly the same amount of heat is being produced it has to be going somewhere

Out the exhaust, where you want it?
Joe

Timing either too retarded or too advanced can cause overheating...


Just my $0.02...

Makes sense. I just reset the initial using the vacuum gauge method, wound up bringing the initial down 2 degrees. Couldn't keep it under 200; before the reset it sat at 180 all day.

Thanks, that's kinda what I thought but nice to hear it from someone with more experience. I alwyas like to know the why, instead of just the "trust me, do it".

Out the exhaust, where you want it?


no, you want it burning in the combustion chamber. worst case of retarded timing I ever saw was on an AMX- the exhaust manifolds were glowing!

http://www.google.com/url?sa=t&rct=j...bvm=bv.53217764,d.aWM

Lots of good info in here.

That's because unignited FUEL was burning there.

Joe

My best case would be to have the flame front meet the piston at the top of the cylinder then continue expanding to the bottom. The more fuel and air the larger the flame(porting-cam-carb-intake-turbo). You want the water in the block too be hot, 200 or more, so the heat that is made stays in the cylinder,more pressure.I turn my water pump and fans off before the run to build heat, the engine will use that heat down the track,turn on the pumps at the end of run. HEAT=POWER. That is why cast iron head always makes more power then aluminum,all things equal,aluminum absorbs heat faster. The residual heat then goes out the exhaust. roundabout way of saying timing should be adjusted for each combo for the driving you do, i like as much advance as will allow