Hot engine after rebuild

[Fireguyfire]

I had some matching done on the 440 out of my 70 300 convertible.
I’ve spent the week assembling it, painting it and reinstalling it, and today I was able to fire it up and do the cam and lifter break in.
I idled the car at 2000 rpm for 20 minutes or so, and then I noticed that it was getting very hot, including the manifolds and even the radiator was radiating excessive heat.
The good news is that the cam break in is done, but I need to figure out the overheating issue.
The thermostat is new.
The car did give a small backfire when I shut it off and I’m wondering if I had the timing off too much.
I set initial at 12 degrees BTDC but I realize that I didn’t disconnect the vacuum from the distributor before setting initial timing.

Could the timing being put on the break in at 2000 rpm cause excessive heating?

Also, what else would it be wise to check?
I will pull the thermostat and boil it to be sure it’s working.

I did leave the rad cap off to see if the thermostat opened and coolant started to flow, but I did get some coolant burp out of the top.

Any suggestions on trouble shooting the heating issue would be appreciated! I’m

 

['66 Fury I]

Why do you say it was too hot? Temp gauge? Gut feeling? Or.... If the rad cap was off, the "burp" was probably some trapped air finding tis way out. What is in it for coolant? If it is water alone, it would boil at 212F with the cap off. Anti freeze mix depends on concentration, but can be checked with a hydrometer.
An infrared thermometer might help diagnose the situation. But if coolant is flowing, that is good. You do have a fan?
If the vac advance is connected to ported vacuum, and the timing was set at curb idle speed, the timing is probably not too far off.
When I fire an engine for the first time, I must admit that I am a little paranoid.
Lindsay

 

[Fireguyfire]

The engine was extremely hot to be near, and I’ve got or restored more than 20 over tge year.
The rad basically started to steam on its exterior.
I always run 50/50 coolant and water and I’m not 100% sure the coolant was circulating as after it burped i put the rad cap on.
When I shut it off you could hear the coolant gurgling in the top of the engine.
Definitely not something I’ve seen before but running it at 2000 rpm for 20 plus minutes with the timing out might be the explanation?
I’m going to pull the thermostat and make sure it’s working for sure.

 

[Fireguyfire]

I’m wondering if the burp that happens that belched out a fair bit of coolant might indicate an air pocket in the cooling system?
If that’s the case, how does a guy get rid of it?

 

[CBODY67]

Did you run the car in a garage with no dedicated air circulating into the grille from an electric fan? Or just with the cooling fan pulling available air into the grille during the cam break-in period?

IF, per chance, the dist vac advance was hooked to a "manifold vac source", setting the timing at 12 degrees would have resulted in a retarded timing setting (12 degrees BTDC + approx 12 degrees of timing from a functioning vac advance at full advance), by something like 12 degrees BTDC. As the full vac advance was in there, but you set the timing as if there was no additional timing from the vac advance being hooked up. In that case, a hot running engine would result from the retarded timing. But in that case, the exhaust manifolds could be glowing red, too, I suspect. Otherwise, if the vac advance is hooked to "ported" (as it should be), then there usually is less vac at that vac port at base idle to actuate the vac advance unit. So, ensure which port the vac advance line is hooked to, just to make sure.

Point of curiosity . . . what did the coolant temp gauge inside the car read through all of this? Or did the HOT light come on, if so equipped?

I concur on the use of the IR heat gun to check things with. After things cool down all the way, recheck the coolant level (leaving about an inch of space between the bottom of the filler neck and the coolant. Then recheck the base timing with the vac advance line unplugged. Then you can use the IR heat gun to monitor heat at several engine locations (i.e., upper hose, lower hose, water pump housing, cyl heads, r & l sides of the block, thermostat housing).

Please keep us posted on what you discover,
CBODY67

 

[Fireguyfire]

Thanks for the inputs gents.
Out of curiosity, what are you guys running as initial timing with vacuum disconnected?
I’m on the edge of the Rockies so at higher altitude than a lot of places.

 

[darth_linux]

Thanks for the inputs gents.
Out of curiosity, what are you guys running as initial timing with vacuum disconnected?
I’m on the edge of the Rockies so at higher altitude than a lot of places.

I'm at 1500 feet and my 383 2bbl really likes 15* BTDC @ 500rpm.

 

[Fireguyfire]

Also, my 300 doesn’t have a temp gauge, only idiot lights. I was under the hood monitoring things when it became clear the engine was too hot so I jumped in and quickly shut it off.
I don’t think the “hot” light was on but I can’t be sure.

 

[CBODY67]

The spec timing on our '66 Newport 383 is 12.5 degrees BTDC. It works well there, but when I moved to Lubbock TX for my last two years of college, I asked the local Chrysler dealer's service manager if I should advance the timing. He had relatives in New Mexico (higher altitude) and a similar '67 Newport 383 2bbl. He said he added another 2 degrees to the initial for those trips. So I put our Newport at 15 degrees and it worked great (we also used premium fuel in it, as that is what it liked, even with 12.5 degrees BTDC). In general, 15 degrees BTDC might be the limit, at any altitude with whatever octane of fuel the engine likes, up there.

Chrysler also specified leaner main jets for the higher altitudes, but the additional spark timing might compensate for those, a bit, apparently.

CBODY67

 

[HWYCRZR]

I am pretty sure at 2000 rpm the engineers expected some additional airflow through the radiator from the vehicle movement. Above and beyond what the fan moves through. Also with the hood up you are recycling hot air through your radiator. Remember when the hood is closed the cool side (front) of the radiator is isolated from the hot (engine side of the radiator. When the air flows the the front of the radiator when the hood is closed, it forces the air wash past the engine helping cool the outside of the block and exhaust heat. When your hood is up, the radiator pulls the air through, but since the cold side is no longer sealed from the hot side the hot air gets recirculated through the radiator. Also you lose the air wash over the engine so your exhaust and engine heat has no way to go except up past the block and then back through the radiator. I believe even in the service manual (at least by ‘68, they recommend that if you are running the engine with the car stationary that you should use another fan in front of the car to up the air flow and cut down on air recirculation.

 

[Justin Plant]

I've always heard (from old timers) that a mechanical fan is worthless above 30 mph. You can't draw any more air than you can force through the radiator. it make perfect sense to me. I put my high velocity shop fan in front of my car whenever it's running stationary.

 

['66 Fury I]

Testing your thermostat in a pot on the stove is a good idea. I have always drilled an air bleed hole in thermostats. A 1/8 inch hole should let any trapped air escape yet not "short circuit" the 'stat. Just a thought. Lindsay

 

[rags]

I've always heard (from old timers) that a mechanical fan is worthless above 30 mph. You can't draw any more air than you can force through the radiator. it make perfect sense to me.

that's a fact. alt/wp belt broke on my newport. drove it home that way without overheating. air moving through the radiator spun the mechanical fan and water pump to circulate the coolant and cool it.

 

[rags]

how does a guy get rid of it?

I have always drilled an air bleed hole in thermostats. A 1/8 inch hole should let any trapped air escape yet not "short circuit" the 'stat.

that's how.

 

[Fireguyfire]

Out of curiosity, what is the normal working temperature you would expect to see from an engine using an infra red temp sensor?

 

[Mudeblue]

that's a fact. alt/wp belt broke on my newport. drove it home that way without overheating. air moving through the radiator spun the mechanical fan and water pump to circulate the coolant and cool in it true

I've always heard (from old timers) that a mechanical fan is worthless above 30 mph. You can't draw any more air than you can force through the radiator. it make perfect sense to me. I put my high velocity shop fan in front of my car whenever it's running stationary.

Not true! Broke an alternator/fan belt when the alternator locked up on my previous 65 SF back in 69, qualifies me as “an old timer, in Minneapolis when it was -20- and it overheated very quickly. It was a Saturday afternoon and no place for repairs. I watched the temperature gauge and my roommate watched for a bar so we could let it cool down. Many stops and it took all afternoon to get back to the apartment but had a good time.

 

[CBODY67]

Out of curiosity, what is the normal working temperature you would expect to see from an engine using an infra red temp sensor?

Basically, thermostat temps at the t/stat housing, upper radiator hose, and engine block. Possibly similar at the lower hose and water pump housing. The heat gun is also handy to see which parts, if not all, of the radiator core are hot, too. The exhaust manifold runners will be over 500 degrees F, so the area on the cyl head might have some bleed-over from the exh flow, as the inside of the head would not. Similar with the exh heat in the head crossover under the plenum area of the intake manifold.

Hope this might help,
CBODY67

 

[Gerald Morris]

I'm at 1500 feet and my 383 2bbl really likes 15* BTDC @ 500rpm.

I used that for some months, then went back to 12.5 BTDC, running a Stromberg WWC, which is what I suspect you have. I dialed it back after noticing too much pinging when goosing the engine at WOT.

 

[Gerald Morris]

Out of curiosity, what is the normal working temperature you would expect to see from an engine using an infra red temp sensor?

If reading w the IR gun at the water neck (thermostat housing) I see between 175-190 F, usually the lower end of that spectrum. I'd worry if I saw much over 200 there.

 

[Gerald Morris]

Not true! Broke an alternator/fan belt when the alternator locked up on my previous 65 SF back in 69, qualifies me as “an old timer, in Minneapolis when it was -20- and it overheated very quickly. It was a Saturday afternoon and no place for repairs. I watched the temperature gauge and my roommate watched for a bar so we could let it cool down. Many stops and it took all afternoon to get back to the apartment but had a good time.

I've found that having PLENTY FAN, even at Interstate speeds (75-90 mph) during these infernal summers here is THE THING, even if under more clement circumstances one has saturated the radiator with wind. WHY? Total surface area exposure. While the amount of air passing through the cooling vanes in a radiator might saturate at 30-35 mph, the front of that box, and even portions of your engine will continue to benefit from plenty air flowing AROUND it and such.

Whatever the complex real aerodynamics may be when cooling a B/RB rolling down a gasping hot southwestern highway, I've lived to see that not only does a mech fan help cool the engine. but so does a pusher running on top of that at times. I very seldom run the electric pusher on the highway at speed, but I've had a few times when it helped, odd and counter-intuitive as that may be.

Having just flushed the coolant, and put my summer mix of 33% glycol, 66% pure H20 into Gertrude's cooling system, I see her running along at thermostat temperature most of the time, this month. I use the Mr. Gasket RobertShaw 370-180 clone, which works VERY well, thank you. I tested this stat after the flush, found it still right on, so will use it until otherwise. I now have about half a dozen RobertShaw 370-180s hoarded up, which should do us for a good long time. That's an EXCELLENT thermostat folks. One needn't drill it either.