Spark Advance versus Overheat

drolston

drolston

Well-known member
From 30 to 50 mph, my flathead is happy as a clam. On a warm day, it overheats badly in slow traffic and if I push it up in speed or up a long grade. Block was boiled out for recent overhaul; new aluminum radiator; new Carpenter water pumps; 170 degree high flow thermostats, fastened in place. Bored and stroked to 284", mild Schneider 248f cam.

It is commonly noted in the threads I reviewed that having the spark retarded can contribute to overheating. I advanced the spark one tick mark (2 degrees, I think). The engine likes that setting; starts easy; no pinging. In searching the threads, one comment suggested that having the spark too advanced could also cause overheating. I guess I should try retarding, but I hate to disturb such a sweet running engine.

Suggestions?
Take the thermostats out?
Spend a small fortune on a Brassworks radiator?
 
Have you tried measuring temp at top of radiator and again at the bottom after the t/stats have opened??
My 40 drops 30* top to bottom with NO stats, new pumps.
Paul in CT
 
1931 flamingo said:
Have you tried measuring temp at top of radiator and again at the bottom after the t/stats have opened??
My 40 drops 30* top to bottom with NO stats, new pumps.
Paul in CT
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I have checked with the IR gun and don't get that much drop.
Why did you decide tor run without thermostats? Also have overheat issues?
My next move is to remove the thermostats and see if it makes a difference.
 
I have a '36 lb engine with a Potvin 3/4 cam. 2 97's on high rise Eddie Meyer manifold, Eddie Meyer heads, stock distributor rebuilt by Bubba. Bubba sets the timing when he ships them back and marks "where it should be". My engine puked coolant out the radiator at highway speed at that advance. Read all I could find about different timing with different cams. I ended up advancing the distributor to the max-with thermostats it runs cool all day long--sit in line at Back to the 50's for 45 minutes and it gets to about 190. Sarts instantly and keeps pulling as long as I keep my foot in it. Hope this helps. Rod
 
What engine engine and distributor do you have? I doubt you have advanced it enough to cause any overheating. Any way to check spark advance?
 
flatjack9 said:
What engine engine and distributor do you have? I doubt you have advanced it enough to cause any overheating. Any way to check spark advance?
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Engine is 59A/B with Pertronix in the crab distributor. I have no electronic way to check timing. I have always done it by ear. The engine was broken in with the timing mark on the side of the distributor at the center mark. I ran fine there. I advanced the timing one mark and it ran fine there also. So I left it there on the theory that the more advance you can run without pinging, the better. I will try advancing another two degrees to see if it starts easily and runs without pinging there. And if it makes overheating better or worse.
 
My guess is that you could use more advance. I run a Vertex Magneto on my 284 cube engine and run about 24 degrees total advance. I'd move the advance up some more - and keep doing so until you have a pinging issue. How did you setup your vacuum brake?
 
Bored&Stroked said:
My guess is that you could use more advance. I run a Vertex Magneto on my 284 cube engine and run about 24 degrees total advance. I'd move the advance up some more - and keep doing so until you have a pinging issue. How did you setup your vacuum brake?
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The brake has was initially set with a light touch. Maybe I should give it half a turn in to be sure it is still making enough friction to stabilize the breaker plate?

How would you do it?
 
I am one who does not believe that the disc is there to stabilize the plate. Most of the time the vacuum is keeping the disc off the plate, so how can it stabilize?
 
Here's $.02 worth more to think about. I ran 160 stats in my 8ba & changed to 180 stats. It runs cooler over all with the 180s .
 
mfirth said:
Here's $.02 worth more to think about. I ran 160 stats in my 8ba & changed to 180 stats. It runs cooler over all with the 180s .
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The thermostats should not have much of an impact on the maximum operation temperature. They increase the rate the engine warms up and maintains a minimum operating temperature.
 
G.M. said:
You need to fill the radiator with the required 22 quarts
to get a true reading. G.M.
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The core on that Champion aluminum radiator is 19" tall, which is almost 2" shorter than stock, and the tank is also about 2" shorter. So that is maybe 3 quarts less total capacity. The smaller radiator core size surely makes a difference in cooling capability, but I do not believe the total volume of water in the system makes much difference, as long as the core is covered and not sucking air into the tubes.

When I got the car it had a 22" tall, 21" wide radiator part #01T (from a 122" wheelbase truck, 39 -41, I think) wedged into it. It leaked a little but never overheated. If that solves the problem, I will probably spring for the Brassworks or Walker. Ouch!
 
Cooling capacity does make a difference. Not to say reduced would not work.


Put two pots of water on the stove at the same heat and time. One is 1 cup of water, One is a 2 cups of water. Which to boil first.


Same if...If you put two 55 gal drums plumbed on the front of your car, you'd be highly unlikely to ever overheat. Maybe timing, block restrictions, over bore,...etc. Certainly a radiator that is restricted would not help.



No matter the temp sensor, even if they can be restrictive in summer or high heat ambient temps.
 
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"If that solves the problem, I will probably spring for the Brassworks or Walker. Ouch!"

Check to see if you have a local radiator shop that is familiar with circle track racing radiators. They can usually make you a radiator cheaper and better than the popular hot rod shops. They will also know how to baffle it to stop aereation. Aluminum is not the way to go for a street driver. Copper cools better. Aluminum is lighter. It lightens your wallet better also.

"Boiling out" a block generally refers to hot tanking. this will NOT remove rust/scale, especially in the bottom of the water jackets.
A block that has been acid stripped will never overheat if the cooling system is working right.

As for spark advance on a mildly modified flathead, lots of numbers have been published but the end result is usually a seat of the pants setting assuming the distributor has been set on a machine. You also have to have a positive way of determining top dead center and have a degreed pulley. If you power time on a chassis dyno, from maximum horsepower, you will need to retard the distributor about 2 degrees for normal street driving.
Total advance should be about 24 to 28 degrees and all in at 2000 rpm.
You do not need the vacuum brake on a modified engine. The weights will take care of the advance curve.
 
Pete, maybe a circle track guy can do it for street. Most circles ran 20min at max everything. Drag flatheads could be plumbed from pump to head or less.

Circle track guys would have the skills to make it right.

I do run recored rads from a local. Did a nice job retaining upper and lower tanks. Not cheap but everything fit, important on with early fords.
.
 
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I checked a local old-school radiator shop regarding re-core of the truck radiator I have. The new core is over $700, which, with labor, puts that approach in the same price range as Walker and Brassworks.

Regarding water capacity: If more heat is going in than the radiator can take out, the thing is eventually going to boil, regardless of how much water the system holds.

Also, I checked back with the local shop that built the engine; they know flatheads and swear that the inside of the block was pristine. The engine did not overheat before the overhaul and radiator change, so I believe that the block is okay. But bored and stroked means burning more fuel and creating more heat with each cylinder firing. The cam is pretty mild, but exhaust valve timing could also be dumping more fire through that block.

I will report back after the radiator swap.
 
drolston said:
Regarding water capacity: If more heat is going in than the radiator can take out, the thing is eventually going to boil, regardless of how much water the system holds.
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I will disagree here. It'd be like inner coolers are pointless, if normal air flow is fine. But we can disagree.

It's just volume and heat increments. Cool Volume is always better. But maybe the exhaust should be piped to the intake too, as there is hot fuel charged air there. But we want that out the engine.

drop a gallon of boiling water in a bucket contenting 1 cup of cool water or a 5 gallon bucket of cool water. Which one are you going to stick your hand in right away.

But as you say if your radiator is too small too undersized in volume and can't handle the take out and interchange, it won't discharge heat.


Never heard a bad word about Brassworks or Walker. Pertaining to fit of sheet metal or other. Guess when building a hp motor there is some things to do.




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