350 running hot

[harold45]

I am new to forum and have a problem. I have a 4 bolt main 350 from a 1974 corvette in my street rod. Rod is a 1940 Ford 4 door pickup i built on a truck frame.When first built there was no problem with heating. I have heating problems in the last 5 years that have gotten worse. When i check temp of exhaust header tubes, #3 and #6 are 100 degrees hotter than the rest of the tubes. 400 degrees or more. I have had radiator flushed. It was OK. Engine flushed, OK. Checked water pump, also OK. Last year i removed heads suspecting wrong head gaskets, and found 400 head gaskets on engine, no center water passage holes in gaskets. Replaced with correct gaskets and still #3 & #6 hotter. It is has Edlebrock cam & lifters and carb. Put new Accel Distributor on this summer. I think if i can fix the problem with #3 & #6 exhaust i might fix overheating problem. Any suggestions would be appreciated.

[harold45]

Has 160 thermostat. vacuum advance. Twin electric fans with shroud. Not sure of timing, all done by ear. The 2 hot exhaust tubes concern me more than anything else and I feel that may be the root of the problem. Thinking I may need new heads. My step-son is a former chevy mechanic. 20 + years and keeps telling me to drop in a crate engine. I will check timing later, as per your questions.

[harold45]

I understand now. Will quit looking at exhaust temps and concentrate on timing and carb.

[firebird77clone]

WHEN FIRST BUILT no heating trouble.

First rule of troubleshooting: what changed.

With the wrong head gaskets it was running cool. With the old distributor it was running cool.

Changing these and flushing the radiator and block didn't fix it.

Something changed. Did you loose a lower air dam? How about some pixels? We might see something.

BTW welcome to the forum!

[Ryanjoseph]

I am new to forum and have a problem. I have a 4 bolt main 350 from a 1974 corvette in my street rod. Rod is a 1940 Ford 4 door pickup i built on a truck frame.When first built there was no problem with heating. I have heating problems in the last 5 years that have gotten worse. When i check temp of exhaust header tubes, #3 and #6 are 100 degrees hotter than the rest of the tubes. 400 degrees or more. I have had radiator flushed. It was OK. Engine flushed, OK. Checked water pump, also OK. Last year i removed heads suspecting wrong head gaskets, and found 400 head gaskets on engine, no center water passage holes in gaskets. Replaced with correct gaskets and still #3 & #6 hotter. It is has Edlebrock cam & lifters and carb. Put new Accel Distributor on this summer. I think if i can fix the problem with #3 & #6 exhaust i might fix overheating problem. Any suggestions would be appreciated.

Sounds like possible cracked head or block maybe did you have the heads or block ever magnifluxed?

[techinspector1]

The 160 thermostat is the first thing wrong. Replace with a 190/195. Warm the motor up like it should be and stop worrying about exhaust gas temps. If the cooling water temp exceeds 195, check back here.

And for the rest of you fellows, stop using these fosdick AFTERMARKET fans and shrouds. Generally speaking, they're junk compared to factory electric systems. If you're building a car from scratch, use an engine-driven fan and shroud, they're bulletproof.


.

[jerry clayton]

Tech-your just a Fosdick hater--------I'll bet that Bernie and that new congressgirl from New York and maybe Nancy are too---------
I like the Ford Taurus or Lincoln fans plus the Viper units-----

[jerry clayton]

On an 180* intake manifold-the 3 & 6 cylinders feed from the same crossover----------An 1/8 turn on an idle mixture screw can cause that kind of exhaust temp at idle-

[firebird77clone]

Ah great point, nearly escaped me.

Is your over temp trouble at idle or at cruise?
Unless I overlooked it, you didn't specify what temps you have.

Is it boiling over?

Have you confirmed your guages?

If it is not boiling over, then you might not actually have an over temp problem or maybe you do have over temp, but it isn't a problem per se.

We need more details please.

Welcome to the site.

[jerry clayton]

Another common cause of a couple of cylinders running higher EGT is that they are on the cross over port that the power brake vacume is hooked into----------

Back several years ago there was one of the ford engines that had hose going to a fitting with a smaller hole into two ports-caused burnt valves after a few years consistly in those cylinders

and this guy's not been back since september???????????