61 Overheating - Radiator?

[John H.]

Re: 61 Overheating - Radiator?

The original radiator was the original to the car, without the surge tank on top. The aftermarket looks a little smaller. It came from Cal West. It looks like the original in appearance. I'm wondering if the small holes in the head gaskets they make today are large enough.

Jerry -

Regardless of what appears to be the original radiator, that car came originally with a Harrison stacked-plate aluminum radiator, which is distinctively different than a conventional copper/brass radiator, and a copper/brass radiator has significantly less cooling capacity. Can you post a photo of the "original" radiator and one of the Cal West aftermarket radiator? It's not the head gaskets - they all have smaller coolant holes than the holes in the block and heads, as designed-in flow restrictors to balance coolant flow front-to-rear.

[Doug F.]

Re: 61 Overheating - Radiator?

The radiator cap has no effect on operating temperature - it only determines the point at which the coolant will boil.

Exactly. He reported that the engine boils over, not just overheating.
At this point, he has made no mention of how hot the engine is when it boils over. He may not have an overheating problem, but rather a weak or faulty radiator cap.

[Jerry G.]

Re: 61 Overheating - Radiator?

The new radiator is still in the car right now. It fits in the support like it should, but you can tell that it doesn't have the rows of cooling channels and fins that the original has. I think he's going to bite the bullet and buy the DeWitts unit. The Cal West is brass and copper. He took the old one to two shops today, but they both said it's not repairable. The temp gauge will peg when it's hot.

[Joe C.]

Re: 61 Overheating - Radiator?

The new radiator is still in the car right now. It fits in the support like it should, but you can tell that it doesn't have the rows of cooling channels and fins that the original has. I think he's going to bite the bullet and buy the DeWitts unit. The Cal West is brass and copper. He took the old one to two shops today, but they both said it's not repairable. The temp gauge will peg when it's hot.

Jerry,

Tell your friend to install the old rad, and run it with the cap turned to the 1st detent, so as to not pressurize the system. It shouldn't leak too badly when used that way. Provided the "original" radiator was cooling sufficiently, I recommend trying that test first, just to verify that it is , indeed the radiator capacity that's at fault.
It is probable that that is the cause, but so much was done, including an engine rebuild......................so let's establish a "baseline" before he shells out the big bucks for the DeWitts replacement Harrison.
There is one very unlikely scenario that might be contributing to the phenomenon, and that is an exhaust leak into the cooling system via a leaky head gasket. Highly unlikely, but worth considering since the engine was rebuilt. If the engine continues to overtemp with the old radiator temporarily installed, then your buddy has a more severe problem, such as a leaky head gasket.

Joe

[Joe C.]

Re: 61 Overheating - Radiator?

Exactly. He reported that the engine boils over, not just overheating.
At this point, he has made no mention of how hot the engine is when it boils over. He may not have an overheating problem, but rather a weak or faulty radiator cap.

Doug,

The coolant shouldn't get hot enough to boil.
If it was 100% water, without a radiator cap (atmospheric), then it will boil @ 212 degrees.
It shouldn't reach that temperature under normal conditions.
Assuming he has a 50/50 mix of antifreeze/water, and also assuming that the cap is "bad", then the 50/50 mix shouldn't boil until about 240 degrees, anyway. If the system is pressurized to 13 psi, then boilover protection reaches closer to 260 degrees.
(Don't hold me to exact numbers here, as I don't have a jug of antifreeze handy.......but you get the idea.)

Joe

[Clem Z.]

Re: 61 Overheating - Radiator?

Jerry,

Tell your friend to install the old rad, and run it with the cap turned to the 1st detent, so as to not pressurize the system. It shouldn't leak too badly when used that way. Provided the "original" radiator was cooling sufficiently, I recommend trying that test first, just to verify that it is , indeed the radiator capacity that's at fault.
It is probable that that is the cause, but so much was done, including an engine rebuild......................so let's establish a "baseline" before he shells out the big bucks for the DeWitts replacement Harrison.
There is one very unlikely scenario that might be contributing to the phenomenon, and that is an exhaust leak into the cooling system via a leaky head gasket. Highly unlikely, but worth considering since the engine was rebuilt. If the engine continues to overtemp with the old radiator temporarily installed, then your buddy has a more severe problem, such as a leaky head gasket.

Joe

i have found that that corrosion between the "fins" which are a press fit and the tubes causes the rad not to cool because there is no thermal contact and the fins are what do the cooling

[Doug F.]

Re: 61 Overheating - Radiator?

I have run an old copper brass radiator on my '61 270 hp motor for the past 15 years without immediate boil over problems. It is unlikely that my radiator in the best condition. I have JB weld slathered on some of the leaking seams. It does run a bit on the warm side. But in my opinion, he should not have immediate boil over problems with a new copper brass radiator in place unless it is grossly smaller than the original size. Granted, the DeWitt's would cool better, but I don't think that is the problem in this case.

Was the balancer replaced with the engine? Maybe the balancer has disbonded and the timing mark has slipped. The ignition timing could be off due to the timing mark being off.

You might also flush the coolant and open the block drains. There might be crud in the water jacket that is preventing adequate debris. I have heard of some unfortunate folks ending up with plugged up radiator tubes after installing an engine that had junk in water jackets which went to the straight to the radiator.

Lest you think I do not believe in the DeWitts radiator, I have purchased one, but like Joe Lucia's spare parts inventory, it currently is sitting on a shelf.

[Jim D.]

Re: 61 Overheating - Radiator?

It will idle and stay cool until driven, then immediately overheat.

A buddy of mine had the same thing happen. He took it to a well known car guy. New thermostat, hoses, water pump, radiator flush than a new radiator. Cost him over $3000. Still had the problem.
I fixed it with a shot of WD40. The weights in the dizzy were stuck and he had no advance above an idle. Check to make sure your timing is advancing. Retarded timing while driving will heat it up in a hurry.

Jim

[Jerry G.]

Re: 61 Overheating - Radiator?

Thanks Jim. The distributor is a single point. Nothing was changed on it after the rebuild. The car never ran hot until the rebuild. The vacuum advance is the same unit and the weights were free.

[Jerry G.]

Re: 61 Overheating - Radiator?

Today I set the timing again at 4 degrees BTDC. When hooking the vacuum line back up, there's no jump in the timing. We thought maybe there was a vacuum leak, so we pulled the intake and replaced intake gaskets and new carburetor base gasket. Replaced the vacuum advance. Put it back together, same thing. Advance is not working upon hooking up the hose. The hose is good. The carb is an aftermarket edelbrock which was on the engine before rebuild. I can move the breaker plate by hand, but maybe it's stuck to the bearing. I don't think it's the radiator now. It's the exact same size as the original, although it's brass and copper. Any ideas other than the distributor? We don't have another one to try right now. Thanks

[Clem Z.]

Re: 61 Overheating - Radiator?

Today I set the timing again at 4 degrees BTDC. When hooking the vacuum line back up, there's no jump in the timing. We thought maybe there was a vacuum leak, so we pulled the intake and replaced intake gaskets and new carburetor base gasket. Replaced the vacuum advance. Put it back together, same thing. Advance is not working upon hooking up the hose. The hose is good. The carb is an aftermarket edelbrock which was on the engine before rebuild. I can move the breaker plate by hand, but maybe it's stuck to the bearing. I don't think it's the radiator now. It's the exact same size as the original, although it's brass and copper. Any ideas other than the distributor? We don't have another one to try right now. Thanks

the carb most likely has ported vacuum,no vacuum till you crack the throttle.

[Doug F.]

Re: 61 Overheating - Radiator?

Take the cap off the distributor and suck on the hose to the distributor vacuum motor. Can you see the plates move at all?

What is the vacuum reading on the line to the distributor?

The back of the Edlebrock has a large port at the base that you can tie in manifold vac if desired. As Jim mentioned and Duke has pointed out before, if you disconnect the vac advance, you can watch the temp shoot up quickly in a matter of minutes.
Doug

[Jerry G.]

Re: 61 Overheating - Radiator?

Today we checked the new advance, and it will move the timing when hitting the throttle. It doesn't move as much with the hose disconnected. Vacuum at the two small ports on the front of the carb is at 2 inches at idle. There's a larger port on the front also that has 7 inches of vacuum. No difference in timing at idle on that port either. We'll have to get an adapter for the rear port to see if that makes a difference. The vacuum will rise to where it should be a higher rpm's to around 17-18 inches off the small ports. If the rear port doesn't help, we're back to the radiator I guess.

[Doug F.]

Re: 61 Overheating - Radiator?

If it is a engine with a mild cam, it sounds like you have a low vacuum problem. The port with 2" of vacuum is probably the ported vacuum port. I think the larger port that gave you 7" of vac is a manifold port. If the port on the back of the carb is only running 7" too, then you have low engine vac. The distributor vac advance may not be advancing the timing because of the low vac and the cannister may be rated to start advancing at a range above 8" of vac.
A couple of things to help check:

Since it sounds like you have a vac guage, disconnect the hose to the engine and plug the vac port at the carb. Tee the gauge into the vac line and with the engine running suck on the open of the hose noting the vacuum reading. Increase the suction until the vacuum cannister starts advancing the timing as noted by an increase in engine rpm.
or
You might disconnect the vacuum line and try advancing the initial timing to 10 deg, 15 or 20 deg or so and see if the engine vac picks up. After you adjust the idle speed back down to the proper range, take a manifold vacuum reading. That should tell you if the engine can generate the proper vacuum at idle.

If the vacuum at idle is still low, you might want to do a compression test or leak down test to make sure it is not a mechanical problem with the engine.

Also the valves could be adjusted improperly so that you are not getting full closure and not developing proper vacuum.

Finally, you might want to verify that the balancer has not slipped. Set the # 1 cylinder to TDC of the compression stroke and look at the timing mark on the balancer and pull the cap of the distributor to see if it is pointing at/near the #1 terminal of the cap. If the timing mark on the balancer is not at TDC and the distributor is not pointing to the proper wire, then the balancer ring may have slipped. This happened on my '66 Mustang. If the reference mark is incorrect, then your timing will be off and that could be the cause of your overheating and low engine vacuum problem.
Doug

[Duke W.]

Re: 61 Overheating - Radiator?

Assuming the carb is the original WCFB, I don't think it has "ported" vacuum advance.

Total idle timing should be initial plus full vacuum advance of about 16 degrees, so it should read about 20 deg. total idle advance and the idle condition should be about 500 @ 18" if a manual trans.

If it's a PG a different VAC may be required to achieve full vacuum advance idling in Drive.

You should use a vacuum pump and dial back timing light to determine the entire spark advance map and compare it to OE specs. What is the VAC ID?

Also, most base engines up to '66 can benefit from more initial timing. The total WOT timing (initial plus full centrifugal) for 327s should be in the range of 34-38 - maybe a couple of degrees less for 283s because of the smaller bores and chambers, but some of the OE specs I've seen show only about 30.

I think about half the "overheating problems" even with a marginal radiator are due to spark advance map issues.

Duke