Thread: Big Block overheat

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hey guys im new to the forum .ive also had this problem in two different cars the first was a 1979 malibu and mind you this motor was 1979 454 bone stock with performer intake/holley 750 only and i couldnt keep temps below 200 if the car wasnt moving.so i dont believe its got any thing to do with any mods.the cooling system had a 3 core rad/17 flex/stock WP/160 thermo.TODAY IVE GOT A 454 WITH ABOUT 10:1 /268XE CAM/RPM INTAKE/160 THERMO/17 FLEX/4 CORE RAD/AND ONLY 14 DEG INITIAL ADV AND IM HAVING THE SAME PROBLEM.I THOUGHT IT MIGHT BE AMBIENT TEMPS UNDERHOOD SO I ADDED A COWLHOOD LIKE THE FIRST CAR,BY THE WAY THIS IS A 1986 MONTE.SOMETIME TOMMOROW IM GOING TO GET A HIGHER PRESSURE CAP(22)TO SEE IF I CAN SOLVE THIS PROBLEM.IM ALSO THINKING ABOUT A HP PUMP.BUT THE ALUMINUM RAD IS THE LAST ON MY LIST.ANYMORE IDEAS???THESE CARS ARE TIGHT WITH BBC UNDREHOOD.TODAY IVE TRIED THE BIG ELECTRIC APROACH BUT IT SEEMED THE FLEX WAS PULLING HARDER AT IDLE.IVE ALSO GOT THE BECOOL DUAL 11 INCH SETUP WHICH ILL TRY ALSO.

Cab, try this site out. it's pretty good stuff about overheating.
www.inccn.net/techforum.htm

after trying the dual fans they kinda kept the the engine around 200 ,but today i bought a VICTOR PUMP and now my fans bring the temps under 180 WOW! VELOCITY IS WHERE ITS AT MAN.SPEND THE MONEY ITS WORTH IT......JEDI1

HEY CAB THE VICTOR PUMP HELPED BUT THIS WAS ONLY WITH THE HOOD OPEN AND THE CAR IN PARK.BUT ONCE THE HOOD WAS CLOSED AND IN DRIVE OOOOH BOY IT STILKL GETS HOTAND WOULDNT GET COOL WHILE IT WAS IN MOTION WITH THE DUAL FANS BLOWING.SO LIKE I SAID THE BE COOL DUAL CORE UNIT WOULD BE THE LAST THING ID TRY BECAUSE IT COST THE MOST BUT AFTER SEEING ITS PERFORMANCE FIRST HAND I THINK THIS SHOULD HAVE BEEN MY FIRST OPTION.NOT ONLY DOES IT COOL WHILE IN TRAFFIC BUT COOLS DOWN VERY QUICKLY WHEN IN MOTION.FORGET ANYTHING ELSE IVE PUT IN MY THREADS SOFAR,AND GET A RADIATOR OF THIS TYPE AND CHASE THOSE GREMLINS AWAY.

My opinion of your heating problem is a fuel/air issue. You need to make sure you have the right sized carburetor for the engine.
If engine runs lean it runs hotter. If carb. is correct, next you need to make sure the fuel/air adjustments at all four corners are set correctly. This is done by placing engine on diagnostic analyzer. Adjust air/fuel screws one at a time to obtain maximum vacuum, then go to next screw. This may take a few rounds to get them set identical. make sure you do not have any vacuum leaks on engine. Also, is carb. vacuum or mechanical secondary's. A big block with high HP, depending on cam shaft, will not have sufficient vacuum to open secondary's, that will again cause lean condition. A Dominator or Holley is the best carb. to use.
This is from experience!

Good luck,
catsasswiring

My opinion of your heating problem is a fuel/air issue. You need to make sure you have the right sized carburetor for the engine.
If engine runs lean it runs hotter. If carb. is correct, next you need to make sure the fuel/air adjustments at all four corners are set correctly. This is done by placing engine on diagnostic analyzer. Adjust air/fuel screws one at a time to obtain maximum vacuum, then go to next screw. This may take a few rounds to get them set identical. make sure you do not have any vacuum leaks on engine. Also, is carb. vacuum or mechanical secondary's. A big block with high HP, depending on cam shaft, will not have sufficient vacuum to open secondary's, that will again cause lean condition. A Dominator or Holley is the best carb. to use.
This is from experience!

Good luck,
catsasswiring

160 thermastat doesnt sound good either ,for that thermostat to work the operating temp of the car would b 140 to 180 ,that themostat is never gunna close on ur car!!!

Are you running a vacuum advance distributor?

If not, you should be.

Source the vacuum advance line to full time vacuum - any source below the throttle blades.

Shoot the timing and make sure you're getting some advance from the vac advance unit.

Most times, GM engines with centrifugal advance only or the vacuum source selected to ported vacuum - above the throttle blades - will overheat.

Originally posted by catsasswiring
My opinion of your heating problem is a fuel/air issue. You need to make sure you have the right sized carburetor for the engine.
If engine runs lean it runs hotter. If carb. is correct, next you need to make sure the fuel/air adjustments at all four corners are set correctly. This is done by placing engine on diagnostic analyzer. Adjust air/fuel screws one at a time to obtain maximum vacuum, then go to next screw. This may take a few rounds to get them set identical. make sure you do not have any vacuum leaks on engine. Also, is carb. vacuum or mechanical secondary's. A big block with high HP, depending on cam shaft, will not have sufficient vacuum to open secondary's, that will again cause lean condition. A Dominator or Holley is the best carb. to use.
This is from experience!

Good luck,
catsasswiring

Your point about running the right size carb is correct, but an undersized or oversized carb doesn't mean the engine will run lean or rich.
It just means you need a larger or smaller carburetor.

A high horsepower engine in correct tune will pull a little more vacuum than a stocker.
To the tune of 1" or so of vacuum which is plenty to open the secondaries on a Holley that's functioning properly.

Even if the secondaries didn't open, the fuel/air ratio would still be ok.

The majority of the time overheating can be attributed to airflow problems with the radiator or timing issues.

timing you if not under a load you want as much timing as you can get 45 at lest . check water speed make sure it is not runing to slow or to fast you may have to play with the pulleys to get it rigth make sure you do not have a air lock in the rad . try a stewart water pump and royalpurple purple ice have done all them and they work on much bigger engines . on the fans. you have you to make over 2500 cfm to cool this engine. a fixed fan may work much better

I had a similar situation when I built my 427. I started out with a 3300cfm electric fan with stock radiator and water pump engine did exactly what yours is doing. Switched to high flow aluminum water pump and things got hotter switched to aluminum radiator no help. Well the only thing that did work and works very well is a steel 7 blade fan no clutch & no flex

Originally posted by jedi 1
HEY CAB THE VICTOR PUMP HELPED BUT THIS WAS ONLY WITH THE HOOD OPEN AND THE CAR IN PARK.BUT ONCE THE HOOD WAS CLOSED AND IN DRIVE OOOOH BOY IT STILKL GETS HOTAND WOULDNT GET COOL WHILE IT WAS IN MOTION WITH THE DUAL FANS BLOWING.SO LIKE I SAID THE BE COOL DUAL CORE UNIT WOULD BE THE LAST THING ID TRY BECAUSE IT COST THE MOST BUT AFTER SEEING ITS PERFORMANCE FIRST HAND I THINK THIS SHOULD HAVE BEEN MY FIRST OPTION.NOT ONLY DOES IT COOL WHILE IN TRAFFIC BUT COOLS DOWN VERY QUICKLY WHEN IN MOTION.FORGET ANYTHING ELSE IVE PUT IN MY THREADS SOFAR,AND GET A RADIATOR OF THIS TYPE AND CHASE THOSE GREMLINS AWAY.

Glad to hear the Be Cool dual is working great, I have been reading all the post and a lot of good ways to approch the over heating problem. I have a bbf with bore 30 over and 13 to 1 comp, and I also have Be Cool rad with two 13" pusher fans. Havn't turn it over yet or broken it in. But will keep everyone inform on how it goes as soon as I do.

i know the becool guys and they are still trying to figure out how i keep my cars cool with out there rads in them ?like i said water speed is very critical factor and a fan that moves lots of air

Pat, thats what helps make this site so nice, we have the pleasure of people who have been their and done that to help us trouble shoot our rides. We use cirruit setters or flow valves in heating and cooling to control the flow of water so heat transfer can take place.