[64speed]

It gets up to about 220 and I have never tried to see if it goes past that, the temp light comes on so I shut it off. The temp sending unit is in the head so I know its getting way hotter back there.

[64speed]

My initial is 10. The bushing in the distributor with vacuum is giving me way too much advance. Like 41 all in. Since putting the electric fans on it is even slower to get to 220 but it still does. It is a lot slower though. I also think the compressor is undercharged which may be contributing I’m told. When the air is on the clutch should be engaged all the time right? Right now it’s not, it is cycling a lot. More damn wires under the hood but it does stay cooler longer. I think I can get it there but it’s gonna take tuning. I refuse to believe there is a 40 degree difference in idle just from the air.

[Singleton]

41 degrees total with vacuum advance is not too much. What is the total timing without vacuum advance?
Also, the factory overheat light came on a 246-248 degrees. Is the engine getting that hot??, or do you have a non-stock sending unit?

[lust4speed]

Forgive me for not going back and sorting through 21 pages, but is your AC system an aftermarket like Vintage Air? If so, all aftermarket systems cycle the clutch. For that matter the POA replacement tube sold by Old Air and others also cycle the compressor. Only a stock GM system runs the clutch all the time when the AC is on.

[64speed]

Originally Posted by lust4speed

Forgive me for not going back and sorting through 21 pages, but is your AC system an aftermarket like Vintage Air? If so, all aftermarket systems cycle the clutch. For that matter the POA replacement tube sold by Old Air and others also cycle the compressor. Only a stock GM system runs the clutch all the time when the AC is on.

It’s classic auto air

[68WarDog]

Originally Posted by 64speed

It’s classic auto air

I don't recall, but have you tried advancing the timing? Try 2 degrees at a time and see how the engine behaves.

[grivera]

What is your initial timing + vacuum advance at idle? This is where it gets hot correct?

[64speed]

Originally Posted by grivera

What is your initial timing + vacuum advance at idle? This is where it gets hot correct?

My initial is 10 with 10 added by vacuum

[25stevem]

If your initial is 10 at idle then by 3500 rpm you should have at least another 20 showing up from mechanical advance, and then the 10 from vacuum advance coming in on top of that when you plug that in.

If this is not the case then you will never end your overheating issue!

[grivera]

Originally Posted by 64speed

My initial is 10 with 10 added by vacuum

Adjust your initial to 14-15 so you have 25 with VA

[64speed]

See this is where I run into trouble. I have a bag of bushings and springs and charts. I do not know where to begin and I CANNOT replace this engine.

[25stevem]

If you have a compression tester then please if you have not done so yet do a test on 2 cylinders in each bank the proper way and report back please.

[NeighborsComplaint]

If you balancer isn't marked or is too hard to read, order a timing tape to install on the balancer. The sell them based on the balance diameter. 5-1/4" is for Pontiac assuming you have an OEM style balancer. It makes verifying your timing a lot easier.

If the tuning kit that came with your distributor is the same as the Moroso (3 sets of springs (black/heavy, copper/medium, silver/light), 2 sets of bushings, 2 weights and a center bar, here is all you need to do. Install the bushings (pivots) in the weights and install the weights and center bar. There are 2 sets of different size bushings, one for the new weights and the other oversized to compensate for worn original weights if you are reusing them. Just use the bushings that best fit the weights. There are no stop bushings to limit total advance. Use the middle weight (copper) springs. The weights and springs will alter how fast the timing advances. The light-weight springs (silver) are typically too soft and will not pull the weights back in at idle. You can try one light (silver) and one medium (copper) but that combo is typically too light for reliable timing also. If your color code is different, you can just look at the gauge of the wire used for the spring and see which is light, medium or heavy.

Set your initial (no vacuum) timing between 10 and 12 BTDC and run the RPM up to check your total mechanical advance. It should fall between 23 and 26 Degrees. Connect your vacuum advance and your total timing should be around 32-36 Degrees. If the engine doesn't ping and accelerates smoothly, you're done. If you have an adjustable vacuum advance, you can fine tune with it. The typically provide an allen wrench to adjust. You pull the vacuum hose off and adjust through the vacuum port.

It's either this or calling your builder to see what he will charge to sort out the distributor tuning. Then you can work on the cooling if the problem persists. If your total timing is around 45 Degrees like you say, that is likely the cause of your overheating.

[grivera]

His overheating is at idle - not at cruise - which is why I suggested more idle timing + vacuum advance. Right now he is at 20 (10+10) which is pretty conservative. Of course he needs to work on total as well - something like 15 initial, 20 mechanical, 10 VA. It’ll let him know if the extra initial timing will help cool at a standstill.

[64speed]

I added 3 degrees and my oil pressure jumped 15 psi and my vacuum went from 12 to 15. It’s still getting hot but I have a hot spot because the thermostat reads 220 but the light comes on.

[Bill Hanlon]

If your idle RPM didn't change too something really weird is going on.

[Sirrotica]

From my past experience, this could be a seeping head gasket, or a pin hole in a casting just putting enough gas into the cooling system to cause OH at idle. It isn't a common occurrence, but it does happen. Enough gas surrounds the thermostat and because it doesn't have water touching it it will heat up way higher than normal because the gas insulates the coil spring in the thermostat. Once this gas gets vented out the pressure cap it will act normal while driving, then at idle it will again build a gas bubble, and cause the thermostat to not open.

Easiest way to check for this is leave the car idle, take the overflow hose, and submerge it in a clear bottle of water, check for bubbling. Depending upon how small the leak is it may take 15-20 minutes for it to build enough pressure to force the gas out the pressure cap, so be patient when watching for the bubbles.

It may not be this, but it surely mimics a minute leak into from the combustion part of the engine into the cooling system, won't cost anything to check it, then you know for certain.

[tom s]

Long thread,have you got a lazer temp gun?If not get one so you can see temps of the water going into and out of the radiator.You should have a 30 degree drop if the radiator is efficient.You can also look for hot spots in the cooling system,like the thermostat housing,water going into the head at the intake crossover,they are invaluable when we have a engine on the dyno for looking for issues before they go into a car.Tom

[64speed]

I am putting the Clutch fan back on it and sending the fans back. They do not cool as good as the mechanical fan. Soliciting information from various sources gave me conflicting opinions so I figured I would try them. Now it goes up in temp even with the air off so the clutch is the best of the 3 I tried. I am pretty much disgusted at this point. I borrowed a temp gun and the back of the heads are hotter than the rest but the mechanical gauge in the car is almost spot on at the crossover. It is not a radiator issue because as soon as I start moving it goes down again. If I turn the heat on it stops and goes down too, I guess the heater core fan is acting as another radiator.

[25stevem]

Here is a issue that may be a big part of your problem and forgive me that it just came back into my mind.

If your running a Edelbrock intake they have a big potential problem with the water crossover.

That being the opening in each side of the cross over is at least 1/4” smaller all around( circumference) then the outlet in each head!

This makes for a massive restriction and when I gasket match a Edelbrock intake it’s the first thing that I go after and gasket match!
I would be willing to bet that if you address this your hot running issue is reduced by 75%, if not completely.