Advance or Retard timeing for cooler running
- Thread starter Jemelton#
- Start date
BRENT in 10-uh-C
Well-known member
Help me understand, which will help in cooler running, advance or retard timing? I have heard both, what is your feelings on the question.
Generally speaking, by advancing ignition timing helps cool the engine temps because the engine is operating more efficiently. When an engine is laboring, it is generating heat. Too far advanced (-by a lot!!) could cause it to run hotter, but predominately it is a retarded ignition timing that causes engine temps to rise.
Big hammer
Well-known member
Don’t forget about the GAV ! Opening it a little more can help with your over heating
Mulletwagon
Well-known member
Definitely advance !
Patrick L.
Well-known member
Kind of a double edge sword.
Retard really causes heat !
Advance is a good thing to a point, too much advance can have its issues [ detonation].
But to help keep the engine cooler advance is your friend.
Retard really causes heat !
Advance is a good thing to a point, too much advance can have its issues [ detonation].
But to help keep the engine cooler advance is your friend.
BRENT in 10-uh-C
Well-known member
Ummm, definitely not Advance.
Don't believe me, ...start your Model-A engine and advance the spark lever all the way. Now drive for 5 miles. Then while maintaining the same driving speed, retard the spark lever all the way and continue driving and maintaining the same speed. Tell us how long it takes before the radiator starts spewing water due to overheating!!
Patrick L.
Well-known member
What Brent is saying, I think, [ I really don't want to speak for him and get him upset] is that there is a happy medium as I tried to say [ apparently not well]. Too little advance [ retard] really makes an engine over heat. Too much advance can/could also do the same to some extent. These engines do not need 40* of advance. The happy medium is about 30*.
Drive down a nice smooth level road at a smooth 30 mph and play with the lever. You'll find/feel a happy spot. Usually about 9:00.
As soon as I start mine [ or used to start it] thats where I set the lever until I shut it off.
Synchro909
Well-known member
Both running the engine too advanced or too retarded will cause damage.
Too advanced, it will run hot and rough. The bottom end will be damaged, likely breaking the crank shaft. It will be down on power and economy.
Too retarded, it will be sluggish (won't rev), run hot and drink fuel. A hot engine is likely to crack the block in an extreme case.
Right in the middle is "Just Right". If the driver has any mechanical aptitude, he will feel it when the engine is "happy".
Too advanced, it will run hot and rough. The bottom end will be damaged, likely breaking the crank shaft. It will be down on power and economy.
Too retarded, it will be sluggish (won't rev), run hot and drink fuel. A hot engine is likely to crack the block in an extreme case.
Right in the middle is "Just Right". If the driver has any mechanical aptitude, he will feel it when the engine is "happy".
BillCNC
Well-known member
I found a post by a guy named Andrew Mackey from 2010 that explains it pretty well:
When timing is retarded, peak pressure and heat is delayed, and is not confined to the combustion chamber. Delayed ignition causes the peak heat and pressure to occur in the cylinder body itself. The flame actually burns the lubricating oil off the cylinder walls, causing more friction. As the combusting mixture is not under high compression, it is less dense, again causing further delays in the burn. When the exhaust valve opens, extremely hot, still burning gasses are blown out the exhaust port. past the valve. This flame heats the valve red hot, and superheats the head and manifold. Running an engine retarded for any length of time, under load, will cause valve burn out, and excess wear to the rings, piston, and cylinder.
Running a 2 stroke engine retarded can have severe consequences as well. Again, it allows the main flame and pressure to build within the cylinder instead of the combustion chamber. The excess heat in the cylinder burns off the lubricating oil, overheats and distorts the cylinder body, and when the exhaust port opens, allows direct flame impingement on the face of the port and piston surface to occur. A severely retarded 2 stroke, under load will melt the piston and damage the exhaust port in short order! I have seen engines with the pistons actually blow molten aluminum out the exhaust port, to the point that the rings also get burned off by the flow of burning exhaust out the ports.
An engine, with no load, running retarded may not give symptoms of retarded overheating until it is too late, and damage has been done. This may show up as burned head gaskets, warped or burned valves, poor ring seal, and severe power loss, especially when loaded for a length of time. With the piston removed, a sure sign of retarded timing is a brownish or blued cylinder wall, and a severely varnished, or galled piston skirt. This is directly the result of an over heated piston, and the fact that oil has been burned off the cylinder.
Ignition Timing is not the only reason for retarded timing! Setting the mixture too lean, and or an intake leak (worn throttle shaft, leaking gaskets, broken hoses) will also cause heating due to the lower density of fuel to air within the cylinder. The lower fuel/air density causes the mixture to burn longer, with a similar result in damage.
Andrew
Regards
Bill
When timing is retarded, peak pressure and heat is delayed, and is not confined to the combustion chamber. Delayed ignition causes the peak heat and pressure to occur in the cylinder body itself. The flame actually burns the lubricating oil off the cylinder walls, causing more friction. As the combusting mixture is not under high compression, it is less dense, again causing further delays in the burn. When the exhaust valve opens, extremely hot, still burning gasses are blown out the exhaust port. past the valve. This flame heats the valve red hot, and superheats the head and manifold. Running an engine retarded for any length of time, under load, will cause valve burn out, and excess wear to the rings, piston, and cylinder.
Running a 2 stroke engine retarded can have severe consequences as well. Again, it allows the main flame and pressure to build within the cylinder instead of the combustion chamber. The excess heat in the cylinder burns off the lubricating oil, overheats and distorts the cylinder body, and when the exhaust port opens, allows direct flame impingement on the face of the port and piston surface to occur. A severely retarded 2 stroke, under load will melt the piston and damage the exhaust port in short order!
I have seen engines with the pistons actually blow molten aluminum out the exhaust port, to the point that the rings also get burned off by the flow of burning exhaust out the ports.An engine, with no load, running retarded may not give symptoms of retarded overheating until it is too late, and damage has been done. This may show up as burned head gaskets, warped or burned valves, poor ring seal, and severe power loss, especially when loaded for a length of time. With the piston removed, a sure sign of retarded timing is a brownish or blued cylinder wall, and a severely varnished, or galled piston skirt. This is directly the result of an over heated piston, and the fact that oil has been burned off the cylinder.
Ignition Timing is not the only reason for retarded timing! Setting the mixture too lean, and or an intake leak (worn throttle shaft, leaking gaskets, broken hoses) will also cause heating due to the lower density of fuel to air within the cylinder. The lower fuel/air density causes the mixture to burn longer, with a similar result in damage.
Andrew
Regards
Bill
David in San Antonio
Well-known member
JEMelton# - Thanks for asking this question. I had it too! The only thing I could remember was an article from probably 50 years ago in which a Harley Davidson rider said he forgot to advance the timing after kick starting his motorcycle. After some time onlookers were pointing at the bike with some alarm. He pulled over and saw the exhaust area of the cylinders were glowing red hot!
Jemelton#
Senior Member
What prompted my original question regarding timing of a model a was an experience I had on a 1966 Pontiac OHC 6. After a hard 8 hour drive in the middle of an Iowa summer I had a exhaust valve burn. The mechanic who did the repairs explained that my timing was way off but I could not remember if it was advanced or retarded. now I know, thanks for the information.
Synchro909
Well-known member
Retarded. A lean mixture will do the same thing.
Up till the 1960s, we had a lot of English cars on our roads. They were geared the same as they were in England and although they were told many times, the manufacturers didn't change anything forth every different driving conditions. Travelling long distances with a low ratio diff meant the engines were revving too high for too long. Even with the ignition set according to their specs, English cars, especially the smaller ones were notorious for burning valves or worse.
It was only when the Japanese cars started arriving that we got a decent car even though the basic design was often a copy of an English car
rotorwrench
Well-known member
I just say both. The engine runs the coolest when the operator properly adjusts the spark control for best operation during conditions of both load and no load. Retard a bit under the load of climbing a hill then advance when going down the other side. On the flats, it can remain advanced unless the vehicle is overloaded but it will get hot anyway if it's overloaded.