454 cooling issues

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prairiehotrodder
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454 cooling issues

Post by prairiehotrodder »

454 in a 78 malibu street / strip car. Very basic combo that wants to get hot at cruise speeds. Its 9.7 CR with a big aluminum aftermarket radiator, mezier electric water pump, gutted thermostat, and a small electric fan. From when you start it cold it warms up really fast and goes all the way up to 180 after a mile of driving and keeps on going up to 200*F. If you stop driving the temp falls down pretty quick with the fan on. Its acting like it has a 200* thermostat. I'm used to cars that get warm when you sit still and cool off as your cruise but this one is the opposite. There is no bumper on the car and the rad is almost completely exposed to the air except for a trans cooler in front of it. I checked and the water pump seems to be turning in the right direction. Any suggestions ?
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Re: 454 cooling issues

Post by barnym17 »

suspect waterpump not flowing enough.
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Re: 454 cooling issues

Post by mag2555 »

One of the most common reasons for this at part throttle running times is not having a added 8 to 10 degrees of vacuum advance taking place.

Somewhat lean mixtures at part throttle need more time to burn completely when making power counts as the piston is driven down the bore.

The later the burn starts the more heat there is to try and pump out at BDC since it did not get used earlier.
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Re: 454 cooling issues

Post by prairiehotrodder »

A couple things to adress the above mentioned suggestions :

I wondered if it was running lean, the carb is an 'out of the box" 850 QFT double pumper. I richened up the primaries from 76 to 81. That seemed to gain some power at WOT and the plugs look nice a light brown. But it still gets hot. I don't have an O2 gage on this car.

I checked the voltage to the pump and it was 12.8 with the engine idling. Voltage at the alternator was 14.3. I wired in a relay for the water pump and now i'm getting 13.4 at the pump. I haven't driven it yet but perhaps that will help a little ?

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Re: 454 cooling issues

Post by rp930 »

Not enough airflow
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Re: 454 cooling issues

Post by Tom Walker »

Has already been mentioned, but what is the ingnition timing?
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Re: 454 cooling issues

Post by rebelyell »

too much sludge-sediment-scale in block-heads-rad-heater.
After a good flush, then Clean the entire system with a strong acid followed by a neutralizer.
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Re: 454 cooling issues

Post by BillK »

First of all is it really getting to 200 ? What kind of gauge and where is the sending unit ? 200 actually is not that terrible if it stops at that point.

I think those cars had a spoiler / air dam didn't they ? Is it still there ? I pulled my hair out on a mid 80's Trans Am that did the same thing and it turned out the air dam was missing and as soon as we put one on it stopped all of the overheating at speed.
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Re: 454 cooling issues

Post by mag2555 »

Agreed with the above!

It helps the cooling in any car or truck to not have so much air thats moving under it pressurize the engine compartment.

If you want to try a cool experiment ( no pun intended) I did years ago, get longer hood bolts and stack up about a inch of washers on the hood hinges to raise up the ass end of the hood .

This 45 minute long experiment can produce a drop of 12 degrees in running temp from what I recall.
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Re: 454 cooling issues

Post by Tom68 »

Lean or rich at cruise is a slow water jacket heating burn.

Cooling it with a rich mixture is high speed stuff.

Timings been mentioned several times, what's your cruise timing advance ?
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Re: 454 cooling issues

Post by RDY4WAR »

Advance the spark timing.

...since it hasn't been mentioned yet. :P
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Re: 454 cooling issues

Post by mag2555 »

It has, I did with my including vacuum advance comment.

His gutted T stat could be the problem all on its own since he says the temp comes up fast which sounds to me like the coolant is just moving thru the rad too fast .

Other issues could be no spring in the lower hose and it’s getting sucked closed, once again due to no stat.

While on the subject of rad hoses, ribbed types are a bad restriction if your running such .
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Re: 454 cooling issues

Post by af2 »

Gutted Tstat?
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Re: 454 cooling issues

Post by prairiehotrodder »

timing is 37 locked. This motor has 300 hp less than my 555 with the same cooling system and the 555 doesn't get hot. I will look at the air dam.
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Re: 454 cooling issues

Post by Tom68 »

Add 12 degrees of vac to the 37.

You're probably pulling more vac at cruise with this motor, more manifold vac is more fuel getting burned to create it.

Same cooling system but your going to add an air dam now ?
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