Head Temperature

[Karl]

I've been playing with my new infra red thermometer Its very interesting . The exhaust manifold gets to 450F but what is more interesting is that when running the head temperature between plugs 1 and 2 is 40F cooler than the temperature between 3 and 4. Same on both my Model A's -one standard ther other with B motor, head and water pump I suspect it is influenced by proximity to the water pump.When you stop the car within a couple of minutes all of head is the same temperature. Karl

[PC/SR]

That is interesting. I would have thought that the deflector inside the side inlet would direct more radiator water to the rear of the block and up into the head.

[Mike V. Florida]

Originally Posted by PC/SR

That is interesting. I would have thought that the deflector inside the side inlet would direct more radiator water to the rear of the block and up into the head.

It does, inmagine the temps if it did not!

[skip]

First radiator cooled water flows between #1 and #2. After cooling those cylinders and warmed the water continues to #3 and #4 and becomes heated up some more? Just a guess. So that would be normal?

So what is the temperature difference between the top'O radiator and the bottom of the radiator? That's maybe more then 40 deg F. I can't touch and keep my hand on the top [160 deg F +] but I can hold my hand at the bottom [140 deg F].

I was told that exhaust manifolds glow red hot at night under some running conditions. No wounder these warp-up very often. And the reason? Pulling the hot unburned exhaust through the block instead of the head. A major engineering flaw with anyflat head. Includes V-8's. The heat stays in the block.

skip.

[40 Deluxe]

Usual cause for a red manifold is retarded timing. Combustion should be completed by the time the exhaust valve opens so just hot gasses are going out, not flame from a still-burning mixture. Only time to have the spark lever all the way up is for starting so it doesn't kick back. Nothing more annoying than to hear an engine struggling because some clown is trying to drive with the spark lever up!

[Old182]

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FWIW: Keep in mind the IR thermometers read surface temperatures and they can be quite different than internal temps, particularly during a hot soak after a hard run. The exhaust side of my cylinder head was 100* higher than the generator side after a run from heat rejected from the manifold. Didn't check front to back though...

[Model A Speedster]

A couple of ideas here ... First, the water in the block will take the shortest route to the radiator, aided by the water pump or not. Therefore, the back two cylinders will not get as much cooling effect as the front two. Henry might have placed the water inlet (the "cold" water, as heat rises) closer to the back of the block rather than in the middle. That would have helped. Second, the back of the exhaust manifold is getting ALL of the hot gases - from all four cylinders. The cumulative effect, so to speak. The front of the exhaust manifold is only "collecting" half of the heat. Yes, sometimes the back of the exhaust manifold will get red hot; if so, you're running either too lean or with a spark that is not advanced enough. A Model A is a pretty tough car. It can withstand a lot of abuse, but there's no sense in pushing your luck.