Technical Running hot at idle

I am with Mike.

Ben

 

I couldn't get my blown flathead to start the first time after****embly. It took a while to find but the brand new (to me) 471 had been disassembled for polishing and someone (not me this time) forgot to bolt the pulley snout to the impellers. ***** happens. Check everything, especially new stuff and new people!

 

With limited initial advance, you have to be sure the vacuum advance is working at idle.

If you pull vacuum line off distributor and immediately put your finger over the vacuum leak, does the idle rpm decrease?
Yes-vac advance and idle circuit are both working.
No-one of the above, or both, are not working.

Please report back for more info.

 

First, all too many guys get their hands on an old car and***** their pants because the engine runs warmer than they think it should although the engine is happy runnning at that temp. Get that heat gun out and make sure that the engine temp is what the gauge reads and the gauge isn't wrong. Wrong temp sending unit in my 71 GMC with a 350 had the gauge about 40 degrees off. Rembering back when my buddy Ron Moore had his 29 roadster with a 350 and at a rod trot we went to he thought his car was running hot as the gauge red 265. It had Walker radiator and the Walker rep was there and he asked him to look at it and with no shirt on undid the radiator cap with it reading 265 and no steam, no hot water no nothing as it wasn't running even close to hot. The Walker rep didn't have a thermometer to stick in the radiator but the SnapOn man I did business was there and he had one on the truck and sold it to him and the temp read just over what the thermostat was rated at.
A decent thermometer doesn't cost all that much and can often be found at a parts house or a candy thermometer will work if you don't get caught.

Still temp goes up at an idle and drops back down with road speed is most often air flow through the radiator. If you have a big fan that you can stick in front of the car when it sits and idles that helps with checking the air flow thing. I've got an old squirrel cage fan out of an old oil furnace that will blow a cat off the table from 4 feet away that I set up in front of rigs when they are sitting there while I have the engine running working on them. The ricky racer fan in my 48 doesn't move enough air to blow a good fart and the temp goes up in a hurry at a stop light.

 

got a video of that? sounds like fun

 

Could your exhaust be partially blocked?

 

So far, the advice has been pretty good. Going forward? Verify the radiator is not partially plugged with rust, the actual temperature is correct vs. the gauge reading, the timing is correct, and the fan/shroud is adequate. Other things that can be done-
Carburation- 500 CFM is borderline for a 364. Will be hard to read the plugs without going on the highway, but still, it may indicate a lean condition.
Water Pump- Buick went from a 3-vane impeller to a 5-vane impeller in 61 for the A/C cars and reduced the pulley size to overdrive the pump. That change would require the last version of the timing cover. The clearance between the impeller and the timing cover may be excessive. The impeller should just touch the cover without the gasket, and the cover should be free of cavitation pits.
Radiator- go to a larger or thicker one.

 

I can find nowhere in all of this discussion where anyone has asked or verified the following.
With a 13 lb pressure radiator cap and a 50/50 mix of coolant and water, the boiling point will be raised by approximately 39°F (13 lbs x 3°F/lb) above the coolant's boiling point at atmospheric pressure. For pure water, this would be 212°F + 39°F = 251°F, and for a 50/50 mixture, it would be around 220°F + 39°F = 259°F.

So the question is with the radiator cap on has it ever spewed water out of your burp tank? If not you don't have a problem at all.

 

So, i been back on the car, used an infa red temp gun pointed in the water at the top of the rad, it seems to be lower than what the gauge is reading..i also tried it in various places on the front of the radiator, it was reading around 10 degree hotter at the top compared with the bottom, the water isnt boiling or anything..i un hooked the top hose from the radiator side , left it connected to thermostat housing, started it up and tons of water was pumping out, so I think its all working ok, i took the temp gauge sender unit out, no water at first then when I took the rad cap off it came gushing out. So I figured it had a lot of air in the system from when I changed the heater hoses..i ran the engine for a good 20 mins with the rad cap off, watching all the air bubbles popping out the top, I kept squesing the top hose and heater hoses. It seems to be somewhat better..i think it was a combination of air in the system and the gauge reading slightly higher than the actual temprature. I have the sender unit mounted in the drivers side head at the rear. The passenger side front location has a plug that I am unable to remove.

Gauge I am using is a cheapo chinese electric ebay jobby, i bought a mechanical gauge with a long curly wire going to a long bulb type end, and tried to fit that, but it leaks up the centre, the flange around the top of the bulb isnt big enough so isnt seating in the hole properly, i think its dropping right down into the head, so even tightening up the nut as tight as it will go does nothing because the bulb is able to move up and down in the hole, alowing water past and up the centre of the nut. Think It needs a washer of some sort to widen the flange on the bulb so it seats against the step inside.

 

No, not had it do that . The only time it did boil was on its first drive after the rebuild, and the reason being was the heat diversion plate in the passenger side exhaust was stuck closed. Plus it was one of the hottest days of the year.

 

@hot4hotrods
Just thinking out side box
Sounds like probably over tightened,
so try using a copper washer,
In the fitting , then instal the probe/tube

Or low temp solder, Build Probe/tube

Or take like a strain of # 4 ga wire
Wrap around few times between
Nut & probe / bubble & maybe add
Little light coat former gasket /silicone
Snug it up , let dry for a few Hrs , then refill coolant.
The other plug you cannot get out drill a small hole in it step up close to size
Take a hacksaw blade cut it 180° each cut 2 cuts , then you should be able to remove what's left just sneak up on it so you do not cut into the threads on the head, if hacksaw blade is too tall grind it down so it's half the height the times you're done your fingers will be sore unless you have a air saw which takes like a jigsaw blade

 

Not over tightened, it was leaking the whole time I was screwing it in, tightening it didnt help..i looked online and lots of people have the same problem with them. Again it was a chinese cheapo ebay one. So what people seem to be doing is using a washer, one good idea i saw involved slicing the top off a nut, the type that goes on a copper fuel line, then rounding the hexagonal sides off, the reason this is a good washer is that its got that concave bevel on the inside that fits perfectly against the shape of the flared part of the sender bulb.

As for the plug thats in the passenger side head, its sitting flush against the head, doesnt protrude, and its got like a screw type head with a single slot. So it could be undone with a large flat blade screwdriver. Its seized in there solid though..i even tried welding a nut on it, through the centre of the nut, i cranked on it with a torque wrench but the nut just broke off. I might try welding a larger nut but around the outside of the nut this time. Screwing a bolt into it, and then welding that, and see if I can then undo it that way.

 

If a mechanical gauge with a bulb and threaded nut at the end, they need a brass adapter that screws into the head and the bulb seats in the adapter, the nut squishes the bulb into the adapter to seal it.

 

So this weekend I took one of these and cut the threat part off, just leaving the nut, then rounded the corners off the nut turning it into a washer. This seemed to work, I ran the engine up to operating temp..i managed to remove the plug from the front passenger side head and installed it here, close to the thermostat. I still kept my electrical gauge which takes from the sender unit plugged into the drivers side head at the rear. The elcgrical gauge is reading a good 20 degree higher at the back, than the mechanical gauge at the front .

 

Just as it should, the back of the motor is hottest part. Water flows through the block and exits up through the heads, the farther back in the block, the bigger the holes in the heads to let water out. My 250 inline six read 20 degrees hotter between cylinder 1 and 2 then it does with the sender right under the thermostat.

 

Yay. Sounds like you might have narrowed down the problem.

But if nothing else works...
... change your screen name.

Hahaha I so funny.