Bbc overheating

Have a 540 BBC 700hp in my custom truck. Alum. high perf. radiator, 24 lb. rad. cap, 160 deg. thermostat (two 1/4" & two 1/8" holes), no water pump bypass line, Fast fuel injection. running straight water with Prestone Super Anti Rust and a little antifreeze (checks to +20 degrees). Can't cool it even long enough to get it out on the highway to see if it will cool at high speed. Need all the help I can get, so please don't hesitate to give any suggestion no matter how trivial you may think it is. Thanks

This is the first time I have posted any thing her so excuse me if I make a mistake. I'm not sure I even know how to find any answers you may suggest.

Do you have serpentine or V belt accessory drive? They each require a different water pump due to the opposite direction of rotation. Just a thought.

i ran many bbc smaller 396to 632. on the street it could be many things one as simple is a air lock in you radiator . what fans are you using if so did you check rotation like willy said make sure pump is the right rotation as well as if a mechanical fan thats picth the right way if the water pump is REV rotation get a starting point and work from there could be timing and many small thing s adding up as well

Eleven of us emptied our brains into the contents of this tutorial. Read and heed......
http://www.crankshaftcoalition.com/w...cooling_system
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Is this a fresh motor?
Is the cooling system purged of air?
While watching the lower rad hose, bring the RPMs up a bit & watch for signs of collapse.
Purge // recovery tank
If you are using electric fan(s) where-- in front as pusher or behind as puller-- make sure airflow is as intended.
Manual fan-- shroud?

Serpentine belt? Is the fan spinning correctly to pull air?

Thanks for all the responses. A few things I didn't mention. Running two 15" electric fans with 10 blades each. Custom built shroud to ensure no air passes around the shroud. Both are pullers. Running March pulley setup with serpentine belt. Water pump is turning clockwise. Going to pull water pump and check rotation and refill and burp engine to get all air out. Also going to tap intake manifold and install bypass hose.Thanks again, and keep sending any suggestions you think might help. Charles

A 1/16" hole drilled in the tstat base is a trick I recently learned: it helps the motor burp out air bubbles.

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Originally Posted by 50s rodder

Have a 540 BBC 700hp in my custom truck. Alum. high perf. radiator, 24 lb. rad. cap, 160 deg. thermostat (two 1/4" & two 1/8" holes), no water pump bypass line, Fast fuel injection. running straight water with Prestone Super Anti Rust and a little antifreeze (checks to +20 degrees). Can't cool it even long enough to get it out on the highway to see if it will cool at high speed. Need all the help I can get, so please don't hesitate to give any suggestion no matter how trivial you may think it is. Thanks

This is the first time I have posted any thing her so excuse me if I make a mistake. I'm not sure I even know how to find any answers you may suggest.

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I see you've drilled holes in your thermostat, but why did you do away with the bypass and how did you do it.?.? Also, you never say how hot it gets. Does it get over 200 degrees? And lastly, what makes you radiator high performance?

Can you post a pic of the serp system? Some aftermarket "serpentine" is nothing more than wide belts on wide pullies.
A true serp belt will "snake" its way around all engine accesories & use a tensioner pulley.
If its a true serp like a stock one, the water pump turns left ( counter clock wise )
After market wide belts use standard clockwise pumps....This would be for crank & water pump, with another wide belt for alternator.

Speaking of pullies, are they stock size, overdrive, or underdrive?

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Originally Posted by 50s rodder

Thanks for all the responses. A few things I didn't mention. Running two 15" electric fans with 10 blades each. Custom built shroud to ensure no air passes around the shroud. Both are pullers. Running March pulley setup with serpentine belt. Water pump is turning clockwise. Going to pull water pump and check rotation and refill and burp engine to get all air out. Also going to tap intake manifold and install bypass hose.Thanks again, and keep sending any suggestions you think might help. Charles

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do not worry about the by pass if you drilled the stat but if you have a old stat cut out the center and try it as a shim after you burp it. just see what happens i ran many bbc with out the by pass and many with. it just comes in to play if you do run the the stat, with a 160 it really is not in play if engine is warm. you may want to check the water pump and take back cover off and check pump if burping fails look for any thing blocking the water ports out of pump seen one with casting flash plug one water port and pump impeller could be slipping on hub whos water pump are you using ?

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Originally Posted by pat mccarthy

pump impeller could be slipping on hub

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I've told the story of this happening to me. Took days to find the culprit. Subsequent water pump R&R included grabbing the impeller with one hand and the drive hub with the other hand and giving the works a good twist in opposite directions. TRUST NOBODY.
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Excellent recap and analysis of what it takes to have an effective cooling system. Just Great and Thanks for the work that went into the analysis. Once 50's rodder checks his system, and still has problems, Something like Evans NPG+ may help, keeping in mind the cooling system basics still must be up to par!

Up date? Still working on it?

Called water pump mfg. and confirmed it is std. (clockwise) rotation. Installing bypass hose from water pump to intake manifold. Will find someone who can verify timing and air/fuel mixture and reevaluate where things are and hope the problem is cured.