overheating?

85 403cutlass · May 29th, 2005

i have a olds 403 with 330 heads two eletric fans 10&16" 3 core raidiator
no t-stat 600 holley timing is at 16 btc engine has .040 overbore and runs hot
210-230 heads & block have been magnafluxed.

Code:

please help

imported_Oldsmaniac · May 29th, 2005

I have heard that running with no T stat can sometimes cause overheating because the coolant moves so quickly thru the system that it doesnt get a chance to give up its heat. Maybe try a 160 stat and retard the timing some to like 10 degrees BTDC at 900 RPM. The trans also gives up heat to the radiator.....maybe a trans cooler will help.....Just my thoughts....Good Luck.

85 403cutlass · May 30th, 2005

at first i had a 180 t-stat and i put a 5spd in it and i checked the heat from the hedder with a raytec and it will max out the gun [888 degrees] I think its running lean i have tried to ritchen the idle it dident seem to change i think i need a 750 carb?

imported_Sgt Art · May 30th, 2005

Oldsmaniac is right about the lack of T'stat not allowing the coolant to flow correctly it allows it to move too fast and not properly dissapate heat through the radiator. The temp of the headers seems high, but I'd be more concerned about the temp of the coolant. Use your temp gauge on the radiator top. Don't throw parts at a problem. If you suspect the fuel mix to be too lean, check the plugs. A blistered white electrode would possibly indicate too lean a mixture. Check your timing, too retarded or too advanced will cause temp problems. Also have them pressure check the system to ensure it is properly sealing. If not, the boiling temp of the coolant goes down allowing overheating. A 50/50 mix of antifreeze and water with a 15 psi radiator cap should raise the boiling temp to about 270. If your engine is hitting 220 or so when running or stopped, that's not really overheating. When you cut the engine off, it will go up some, but then come down as it cools off. Timing, proper flow and no leaks of pressurizing problems are the things to look for. If temp rises when it's running while sitting that's pretty normal. What happens when you're driving.

403's came stock with 750 Quadrajets (in fact I think most Quads are 750) what type car are you using now? I ran a 600 cfm Edelbrock on an Olds 455 for quite awhile with no issues. I also have a 600 cfm Holley on a 460 Ford and it runs great. No race car car engine, but it hauls around a 72 Lincoln that weighs in over 5200 lbs.

texasred · May 31st, 2005

Quote:

i checked the heat from the hedder with a raytec and it will max out the gun [888 degrees]

I thought exhaust gas temp is normally somewhere in the 1200-1300 degree range and header temp was normally 800-1000?

C.J.

imported_Oldsmaniac · June 8th, 2005

Have a couple of more thoughts....the 403 cylinders are siameesed in that there are no cooling passages in between cylinders. I believe the 403 heads have extra cooling holes drilled into them and when swapping to earlier heads more holes need to be drilled.....I dont think a lean mixture is the bulk of the problem...Its probably a combination of things adding up.....I still would try to retard the timing some....