dprestridge

Looking for options for bringing the temperature down on my 1980 l48. I have made several engine upgrades to the L48 block; Flat top pistons, SCAT Crank, Performance Cam, 1.5 Roller Rockers, Aluminum performance intake, 600Cfm Carb, Aluminum Radiator, Block Hugger Headers, true dual exhaust with Magnaflow mufflers, High flow water pump and a high flow 160 degree Thermostat.

The car is running about 218 to 225 degrees and I do not know what else to do to get the temp down on the car.

MelWff

What is your initial ignition timing and the total mechanical?

Gerry80

First what type of fan are you using. A stock fan with a termostaticly controlled clutch will work the best. If you have this set up make sure your clutch is working correctly. Spin the fan by hand, if it spins without resistance, the clutch is shot.

Next, make sure your fan shroud is installed and all the foam inserts are installed. Your goal is to make sure the fan can't pull in any air that could bypass the radiator. Same thing with the foam between the radiator shroud and the hood. You want the air coming in to either go in the engine or through the radiator.

You should need or use such a low termostat. If the cooling system is working correctly, the 180 or 190 would work fine.

If all the above fail, it may be the radiator. I have a similar engine setup as you and while I was rebuilding the engine swapped the radiator for a Griffin that I got from DeWitts. I later learned that it was probably overkill and I should have started with replacing the flexfan I had with a stock configuration.

falconview

does it run hot always, or more so at a stop or highway..etc.

dprestridge

I have a new stock Fan with a new Clutch on it. I have all the seals on the shroud to keep air flowing through the radiator.

dprestridge

More so in stop and go traffic. At a stop the temp actually drops and then when you take off it goes up. the highest it has gotten is right at the Red mark but it has never boiled over.

dprestridge

The Timing is at 8 degrees and I am not sure what you mean by total mechanical. I had the timing set to manage the "Camming" and it runs well

falconview

are you running a catalytic...if so one or 2? make sure they arn't causing any restriction, but then again you say the car runs well, is the new rad to factory spec or speced to your upgrades?

Goody

What brands for the water pump and radiator? Some alum rad's are not built all that well and do a worse job of cooling than the original brass units.
Same with the water pump. A high flow water pump may pull the coolant through the cooling side of the system so fast it doesn't dissapate all the heat that is can.

falconview

Goody

He is asking how much total timing that you have. Does all timing come in very fast (all at once at a low RPM) and what RPM range is it all in at? Maybe the advance springs are toast and you get 38* advance by 1500RPM which would likely be bad. Or the vacuum advance is a possible cause. Need to know how much total advance.

Something else to consider: a vacuum leak which allows the engine to run extremely lean and therefore really hot. Any chance you can get a wideband o2 unit on the exhaust to see what the air fuel mix is doing?

dprestridge

Hmm. I do not know the total on it. I am not that skilled on that. I did have a professional mechanic who builds custom high performance engines for Nascar set my timing and adjust the Carb and vacuum.

dprestridge

I am not running Cats on it nor the AIR pump. All of that stuff has been removed

dprestridge

The Water Pump is a Summit Racing and the Radiator is a Harrison

Project80

"More so in stop and go traffic. At a stop the temp actually drops and then when you take off it goes up. the highest it has gotten is right at the Red mark but it has never boiled over."

If your temp drops while at an idle, the water has a chance to stay and cool in the radiator just a little while longer.

Did it run hot before the mod's?
Does the lower radiator hose have a spring insert inside it?
Are you running a 50/50 mix of coolant?

dprestridge

no it did not run as hot before the mods. I do not know if the lower hose has a spring in it but I will check. I am running the Good Green antifreeze with a 50/50 mix. Sounds like the water may be moving too quick. I have a new 180 degree thermostat I am planning on putting back in it and removing the 160 degree. Do you think that will help?

Project80

To check the lower hose spring, when it's cool just squeeze it to see if it has the reinforcing spring. If it doesn't, it may be collapsing with the higher rpm.
The 180 thermostat will just change the temp that it starts to open. It's the radiators job to shed that unwanted heat.
You stated that the timing was set at 8 degrees, did it change from before the mods?
From the other post, you stated that a mechanic set the vacuum. If the vacuum is not within spec's, as stated before a lean condition will also make it run hot. A hose may have come off.
Have you considered bolting the stock pump back on?
You could also try calling Harrison and see what they say. I had a new radiator flow tested by a shop just to eliminate it with an overheating problem. It wasn't the problem, it flowed 100%
The overheating may not be just one thing, it could be a combination of problems.

MN80Vette

The radiator in my '80 was leaking when I bought the car. I replaced it with a HD aluminum rad with one row in the core more than the original rad. I have an electric fan-only (no mechanical fan), and the temp never goes over 200 degrees, even while idling around Car Craft Summer Nationals for 30 min in 90+ degrees after autocrossing for a while.

DRIVESHAFT

Dont assume that you have a proper timing curve for the street just because a guy that works on race cars set it up. Guys that only work on race engines dont have to make them run in stop and go traffic conditions. Part throttle timing requirements are different from full throttle requirements. If your engine doesnt have enough advance for the situation its running in, it will generate more heat. If you read the timing sticky at the top of the page you will get a better feel for whats required.

John Dingman

In most cases the stock copper radiator will do just fine but with all the mods you have made you might have to improve the performance of the radiator to keep up. You should be able to drop that 30-40 degrees by simply changing to an aluminum radiator alone.