Timing n temps
 

Can someone explain how timing can impact engine temperature? The car hasn't been on the road yet, but it overheated quickly in the garage after running mostly on fast idle. Also seems to be missing a bit and maybe a little backfire through the carb. I'm really new at this... are these symptoms related? Thoughts on how to approach? Hoping to get her running smoothly before moving on to body, paint, etc. Thanks!

Re: Timing n temps
 

It could be severly retarded or advanced. Retime your motor and see if that improves your situation.

Re: Timing n temps
 

the vast majority of As that end up in this shop are timed late (retarded) by the owners.
Late timing will lead to very rapid overheating.

Re: Timing n temps
 

Thanks. I'll retime tomorrow. What's the reasoning for it? How does the timing affect the temp? Also, what's a good running temp and where should I measure the temp without a probe? can I use an infrared?

Re: Timing n temps
 

When the timing is retarded the burn produces more heat than power.

Re: Timing n temps
 

How timing affects engine temp: First, fuel doesn't 'explode' in the cylinder, it burns. There is an actual 'flame front' that progresses across the combustion chamber from the spark plug after the plug fires. If the 'fire' is started at the proper time, the burn is completed by the time the exhaust valve opens and just hot exhaust gasses flow out through the exhaust port and manifold. But if the fire is started late due to retarded timing, the fire is still burning when the exhaust valve opens and now there is a live flame blowing out past the valve, adding a lot of excess het to the valve, port, and exhaust manifold. The extra heat in the valve and port is transferred to the cooling system, possibly overtaxing it. The excess heat in the exhaust manifold turns it red and warps it.

Re: Timing n temps
 

What 40 says. Depends on how much the retard is, but more of the block is exposed to the heat as the piston is further down in the cylinder.
Actually retard at idle on initial start up can help heat up the engine quicker which is good. But that is not the way to run it.
First get the timing right. Then start adjusting the carb, which if too lean will raise temps and back fire.
Timing, mixture really are interrelated.
Of course, maybe your radiator is partially constricted which will also raise temps. (Put in some radiator cleaner but only as a last resort.)

Re: Timing n temps
 

Just to go along with what the others have said, there is a specific amount of fuel to be burned within a specific amount of time. The full force of the burn is used to push the piston down, allowing the hot gases to be "cooled" off by the cylinder walls. If the timimg is off and the burn starts late, "the fire is still burning when the exhaust valve opens and now there is a live flame blowing out past the valve, adding a lot of excess heat to the valve, port, and exhaust manifold." as well as the less time the heat is exposed to the cylinder walls.

Now early timing can also produce excessive heat but you usually get other symptoms before that happens like hard starting, starting pinging.

Re: Timing n temps
 

I think that was the exact problem. I retimed and my temps are about 180 at the rear of the head measured with an infrared. Exhaust manifold is around 200 and much higher below the exhaust clamp. Small oil leak at the inspection plug and a little near the back of the oil pan, but I'll get to those. Thanks for the help and insight on the reasoning!

Re: Timing n temps
 

A fat mixture can also cause high temps or is it lean. Now for the debate to begin!!!

Re: Timing n temps
 

You should also check the timing after the manual setting procedure. Put #1 on top dead center. Make a mark with white paint on the crank pulley and somewhere on the timing chain cover nearby. Turn on the ignition and hand crank with spark plugs out. Turn until the #1 fires. It should fire where the two marks meet. You are then assured your timing is correct.

Re: Timing n temps
 

A slightly rich mixture will burn a little cooler than a slightly lean one. A really rich mixture will not run well and will blacken the plugs. A really lean mixture can cause spark knock (pinging) and could burn a hole in a piston. Ron W