VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1931 Overheating 194

I finally got back to this project of getting this car to run. I rechecked and set the valves @ .006 for intake and .008 for exhaust. My dwell is at 0.012, my timing is at 18 degrees BTDC, AC plugs set at 0.040. This engine persists to overheat within 10-15 minutes. The ambient temp in my garage is 50-60 degrees F. I had the radiator re-cored to a vertical tubes, had a thermostat installed and removed that. Bypassed my heater core and this engine still overheats. The fan is a 4 blade. Before I got this far, the block and head had been at a machine shop where is was boiled and cleaned. I have the new style water pump from the Filling Station and had installed the brass baffle plate in the cylinder head. I have been taking exhaust temps with an infrared gun. The inward cylinders are significant hotter. Particularly, cylinders 2 & 3 and 4 & 5. This does have a cylinder head from a 1929, if that would make any difference. I had to shim the valve train mounts up with washers to make any valve adjustments. No bubbles in the coolant and had consistent compression across all cylinders last time I checked. Any suggestions?

I forgot to add that I replaced the water temp gauge and sending unit with new. There is a 50/50 mix of conventional coolant & water.

I know there are those that will not agree with me but I had better results running straight water in our '31 and '40.

Check the temp at the radiator top and bottom . Have you tried it on the road? I had a similar problem and it was timing related. It ran fine down the road but overheated at idle or in traffic. I know you posted the timing was at 18 BTDC but you could try advancing a couple more to see if it helps. FYI I also checked the exhaust temps and had the same results regarding inner cylinder temps so that may be normal.

Typically # 6 cylinder is hotter than any others for three reasons. It is next to the firewall so gets less air flow than the others. It is further from the water pump and cooler coolant. It runs leaner fuel mixture then the middle cylinders. That suggests something is causing the middle cylinders to heat. I would get a test kit for exhaust gas in the coolant. Yes there can be a crack that does not result in visible bubbles in the radiator. BTW # 1 is the coolest as it gets more air and cool coolant.

Should the dwell be more?

I haven't moved it on the road yet, much less around my alley way. I cannot get it to idle with the choke off. Needs tires as well. It starts nice, idles fine.I am wondering, do I need to static time the distributor for 18 degrees? The delta between the top and bottom tank of the radiator , I have not recorded, but at a glance, I recall a 20-30 delta.

That is not your dwell....that is the distributor point gap. The correct point gap should be .018" with a dwell of 36 degrees.

From what you describe, it sounds like you have a cracked cylinder head and the exhaust gases are causing the excessive temperature. You might want to pull the cylinder head and have it checked for cracks. Also, you would be better off with the correct 1931 cylinder head instead of the 1929 cylinder head.

Looks like your carburetor needs rebuilding as well.

I already rebuilt the carb. What did I do wrong there?

If I decide to spend more money, where can I get the correct cylinder head for a 1931?

Your carburetor probably has dirt in the jets from the gas tank.

Finding a good cylinder head is extremely difficult and usually very expensive if you do find one. You will have to call around to various obsolete part suppliers to see if you can locate one. A "Parts Wanted" ad in the G&D would help as well.

I'm a complete noobie on these old Chevys, but if it were me I'd want to square away the idling issue first. Here's why:

Diesel engines, which do not throttle air flow, cool down at idle. Spark ignition engines tend to run hot at idle, at least in part due to the reduced air flow through them. With the choke engaged on our carburetors, air flow is reduced below that normal for an idle condition, so it doesn't seem abnormal to me that the OP is having difficulty with temperature control under extended choked idling conditions.

There are a few 1931 Chevys listed at Rocky Mountain Relics ( http://rockymountainrelics.net/ ). Maybe they have a good head to sell you.

Cheers, Dean

I have a head but I am in the Atlanta area. If you are coming through sometime and still need one you can take a look. I had it tested and a little work done but I am not shipping it.

Dave

With your dwell set properly, just for giggles, before you pull head or anything else major, set your timing to the book. 12 deg instead of 18. Takes a little time, but try it.



Best to ya.

Jim.

Just a stab in the dark, but could the holes in the head gasket not line up with the 29 head and cause circulation problems?

1929 thru 1932 used the same head gasket.

Funny, I thought of that possibility also but knew what JYD said to be true. Still, makes you wonder if some sort of blockage is going on.

MOST LIKELY THERE IS BLOCKAGE INSIDE THE BLOCK OR THE CYLINDER HEAD OR THE RADIATOR.

COUNTLESS THREADS IN THE 29--32 SECTION AND THE 33--36 SECTION CAN BE FOUND WITH WHAT PEOPLE HAVE FOUND OUT IN TRYING TO SOLVE THE OVERHEATING PROBLEM.

INCLUDING REPLACING THE FAN WITH A 34-36 STOCK FAN WITH A DIFFERENT PITCH TO THE BLADES.

SPEND SOME TIME SEARCHING THE THREADS IN THE SECTIONS.

MIKE LYNCH

Press the third key up on the left.

CAPS IS NO LONGER YELLING, ITS JUST THAT US OLDEN GEEZERS PREFER THE LARGER TYPE ON THE SCREEN, MAKES IT EASIER TO READ THE POST WITHOUT SQUINTING.

MIKE LYNCH

FYI, you can make the text larger on the screen by pressing ctrl and plus (+).

On the flip side, you can make the text smaller by pressing ctrl and minus (-).

Cheers, Dean

unless you are an Engineer, then all i see is all caps, hard for me to read and WRITE lowercase letters anymore !!

I think we resolved this problem. I was contacted by John Kemkes of the Packerland VCCA Club. After talking with him for awhile, he suggested I remove my carb and ship it to Chip Sweet in Texas to inspect or rebuild. Chip found two issues: 1. The low speed jet was broken. Had to take the special puller to get the small broken piece out. That is why it wouldn’t idle correctly. 2. The standpipe was loose. It was running too lean which resulted in the engine overheating. I installed the carb yesterday and was able to get the engine to idle around 400-450 RPM, steady vacuum around 16 in hg. I can now idle this in 40F ambient for a half hour now before the temp gauge reaches hot. I still have the thermostat removed. Is that normal?

Hello GreenBayPacker14,
When I read your original post about the engine not able to idle without choke, I thought about how without the choke that the engine could not run due to the lean condition. With enough choke, the engine would run but still with a lean condition. Extended idling with little cooling airflow at the radiator adds to the temperature rise. I agree with the post by "Swampledge". You had a lean machine. With the rebuilt carburetor, the lean condition is eliminated, but still, for extended idling, airflow is at minimum. I don't think that these cars were meant for extended idling as much as the modern cars can. Try aiming a leaf blower or box fan at the radiator to see if that extends your idling time with normal temperature readings. Be sure to vent your exhaust gases safely outdoors.