Technical Sbc overheating need help

Fan is on right. Engine turns clockwise when looking at it, so that fan will pull air through the radiator

 

Good point/catch. Maybe OP has a weak starter that doesn’t spin engine over well and retarded timing to assist it?

 

Retarded the timing to keep it from rattling to pieces !

 

That too!

 

Brain fart on my part - thanks for straightening me out!

Chris

 

Years ago I did a valve job on my dad‘s 76 F150. Apparently when I took the heads off the scale broke loose and got in the radiator. Ran fine around town for a week. My brother took at the college and it ran hot and overheated at highway speed‘s all the way to South Carolina. Replace the radiator and problems solved. I have the opposite problem with my model a small block. Runs cool at speed gets warm at lights. Needs a fan shroud. Winter project.


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Make sure you get a hi -flow thermostat ... there is really a big difference in restriction with them fully open...

 

A lot of cooling issues result from the fact that the shroud and other "tins" that were original to the vehicle are now missing. First thing I would do is install a shroud.

 

Total timing (static plus mechanical) should be about 34-36 degrees. This will help it run cooler. Also at highway speeds a correctly working distributor vacuum advance will lower engine temp a few more degrees.

 

I'd scrounge the bone yards for a genuine Chevy clutch fan..... And a shroud...

 

Non of my tri-five pickups every had a shroud. The fan was 1/2-3/4” from the radiator. The shrouds I’ve made today start from Speedway Circle Track catalog and are made from aluminum. Some I mount vertical and others horizontal. The last one was painted semigloss black and works great on a 10-1 engine with a 15” 4 blade fan.

 

It never went over above about 165 without the thermostat going down the highway on a hot day,

It's on correct it's blowing towards the engine

I ran bigger engines with that much time and never had a problem before

I'm looking into some aluminum radiators now I might switch it out too

 

It ain’t air flow at 60 mph!


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Bingo. Try both sides of the radiator when it gets hot and the truck is off.

 

Radiators hot all across doesn't seem to have any cold spots

 

That sucks, check the t-stat and make sure it's opening all the way or isn't partially stuck open. Last would be to check it again without the t-stat and if it's the same as before (running cool at all times) maybe cut the t-stat up and just use the flat piece as a restrictor.

 

Yeah, it looks like there is not enough air flow through radiator at highway speed.

 

It has a spring in the lower hose it doesn't seem to be collapsing,

I just picked up a new thermostat housing that's supposed to be higher flow, I mean from the looks of it it looks pretty high flow compared to a stock one, I'm also installing the heater tonight so those hoses will be hooked up as well even though I still had a bypass hose going from one of the other

 

I put a new mister gasket thermostat in it and it's supposed to flow twice as much and changed the rad cap and the thermostat housing, I also hooked up the heater core, I took it for a spirited drive around town but we will see tonight what happens when I hit the highway

 

So ..what happened ?

 

Plugged radiator either inside or out and possible air flowing around the radiator rather than through it.

 

Sorry for the late reply on this I've been busy after doing that stuff I talked about it hasn't once overheated again even sitting in traffic it does good I have a 180 thermostat in it and it never goes above 180

 

I wonder if there is a lot of oil sludge build up from not using a thermostat..

I would use a Stant SuperStat in 160..

 

Did anyone mention a water pump is possibly on the way out?

 

I the pictures of the moter i see were the temp gauge goes in at the manifold ,but there is nothing hooked to it,were is your sender for your gauge?