Hello Everyone,

First time posting and need some advice. I have a 1978 C3 with a new 383 Stroker at 500 hp. I am running 2 electric fans on a 3 core radiator. All is well until I'm in stop and go traffic then she starts getting hot. It has has shot up to 265 on one occasion. I've tried different fans and none did the trick. Should I add fans to the front of the rad where they push and the others pull? Maybe a Switch so I only use when needed? Has anyone done this or should I look at different solution?

 

Welcome to the forum
Copper or aluminum radiator?
What size fans?
What temperature do the fans first come on?

 

check CFM rating of fans.. you need minimum 3500 -4000 CFM

 

Shrouds? Lower spoiler in place?

Buy an IR temp gun and measure radiator inlet and outlet temps at idle. Is there a temp drop at idle?

Where do you live? What the current ambient air temp?

 

Make sure you have at least a 180-195 T stat and that the rad cap is new as well.

 

What's your spark timing at, particularly when you're at the stop portion of the stop and go traffic?

 

I agree with the post on the IR temp gun. I battled overheating with my 383 relying on my temp gauge. I'm running a DeWitt's aluminum radiator and dual electric SPAL fans. The IR Temp gun showed how way off it was. When the gauge was hitting 220, the thermostat housing was only hitting 180. As it turns out at least in my case it was the temperature sending unit. I installed a replacment and followed the advice of fellow members of NOT putting any teflon tape or pipe sealer so it wouldnt interfere with the gauge readings. Now all is good.

 

No you don't

 

 

Thermostat, timing, and buy you a GOOD fan controller.

Craig

 

 

As stated by a couple of other members in this thread....I cannot stress the importance of correct timing on overall engine performance which includes cooling. I would hope your mechanic would start here. The reason you SHOULD start here is because for one thing it is free/cheap.....the other is once it is right, then you can go determine if chasing fans and radiators will be beneficial. A good mechanic would go here first and if your mechanic scoffs at it, find another. Also, if the mechanics claims to be able to set timing by ear, lose his/her number.
After timing is set, have them perform the idle screw adjustment just for the hell of it. The two go hand in hand.
Do you have any pics of the engine compartment?
Good luck to you and post your results!

Jebby

 

The thermostat will not really lower temps unless it is a bad thermostat. The difference from a 180 to 195 is just when it opens. Once you are open a 160 180 or 195 will not cool it down anymore. It does sound like you have a timing issue or your radiator is blocked up or your fans are not up to doing the job. I run 2 higher Hp cars. The Vette runs an LS3 with 500+ HP with a 195 thermostat. The fuel injection systems like the motor to run a little warmer. It never exceeds 205 even when sitting in traffic on 90+ degree days. I have a Dewitts radiator with dual Spal fans and it is controlled by a simple switch in the cooling system that kicks on at around 200 degrees. The other car is a Cobra with a 540HP, dare I say Ford motor. It runs a big aluminum radiator with dual Spal fans. It runs a 180 thermostat. The computer for the fuel injection controls each fan individually. Again it has never exceeded 210 in the hottest traffic days. Most of the time just one fan kicks on and keeps it cool. Both cars are tuned right and the timing is set correctly. Actually timing is controlled by the computer.
It sounds like your "mechanic" is throwing parts at it hoping something will work instead of diagnosing what is wrong and fixing it.

 

I would guess the issue has more to do with a cooling system flaw-radiator capacity, water pump, thermostat, etc. If there was a dramatic timing issue at idle causing the temps to soar when the 500 Gross HP 383 is putting out very low hp, then the engine would quickly overheat under load moving at speed as well if the timing was that far off in my experience, but I could always be wrong. Retarded timing on my personal cars over the years has been more of an issue at speed than at idle when the engine is producing extremely low power and a proper cooling system can absorb the additional heat from the incorrect timing. I would carefully check the timing as a first step that is free, though. My money is on the cooling system or fans.

Severely retarded timing was the issue with the 78/79/80 L-82's which ran very hot from the factory for emissions. When brand new, my 78 L-82, 4 speed no less, routinely ran 225-245 on the highway, not stop and go traffic. The temps would actually go down in traffic versus being on the highway from the severely retarded timing.

 

You are getting great advice here.
My car is modified with the dual Stahl fan and a Dewitt aluminum radiator. I'm using a 195 degree thermostat. She runs at 180 all day.

I'm using a fan controller from the Auto Cool Guy.

The radiator made the biggest improvement in my cooling issues. Hands down.

 

If the fans are mounted to the rad and you have open areas on the rad I had the same issue. Stock system requires ALL foam to seal air leaks in place.

I now run a dewitts aluminum rad but the ticket was their shroud that includes 2 fans. No dead areas as it draws over the entire rad.

 

 

There is no shrouding around those fans. Also no seals around the core support to the radiator. To much area for air to slip by and not cool the radiator

Not related to the cooling issue but get rid of that glass fuel filter. It will crack and break at some point and spew fuel all over and set te front end of the car on fire. I never will understand why anyone would put one of them in there. Its not like you need to see the fuel filter.

 

Those twin electrics have their own shrouds. Any more than that would actually hinder air flow. You can't block the back of the fan units.

 

Nope there is no shroud at all other than the fans. This setup has the proper shrouding. Plus as I said above no seals so the air will go everywhere but through the radiator.

https://www.dewitts.com/collections/...l-dual-fan-kit