New Build 440 overheating

[DaveInDenver]

I have two Challengers that have undergone the same engine change-up, build design & overheating redults.

I recently changed out a 318 CID/904 Auto for a 440 CID/727 Auto. Installed a Holly Sniper fuel injection system.

The engine was built by a highly respected machine shop that focuses on race engines. We used standard heads, factory high performance exhaust manifolds, 15° advance, 4-core champion radiator with electric fans, new factory style water pump and 160° thermostat. Coolant is 50/50 water mix.

The Sniper's water temp reading runs about 195° to 202° in mixed driving. If I spend too much time at traffic lights, temps reach 225° or even higher.

I attempted to work any Trapped air out of the heads by raising the front of the car while the thermostat was open but no difference in results.

 

[scar426]

Factory thermostat is 190 i believe. Your 160 may be too cold and not letting the radiator do its job (i.e. water moving through the radiator too fast). other issue could be the actual width of the radiator, small block cars were mostly 22" whereas big block cars were 26" core width. My 528" stroker 440-6 barrel runs fine at 180-205 ish in 100+degree south Texas heat. (26" radiator, factory 190 thermostat, clutch fan plus electric pushers in front of add-on a/c condenser)

 

[DaveInDenver]

I have two Challengers that have undergone the same engine change-up, build design & overheating redults.

I recently changed out a 318 CID/904 Auto for a 440 CID/727 Auto. Installed a Holly Sniper fuel injection system.

The engine was built by a highly respected machine shop that focuses on race engines. We used standard heads, factory high performance exhaust manifolds, 15° advance, 4-core champion radiator with electric fans, new factory style water pump and 160° thermostat. Coolant is 50/50 water mix.

The Sniper's water temp reading runs about 195° to 202° in mixed driving. If I spend too much time at traffic lights, temps reach 225° or even higher.

I attempted to work any Trapped air out of the heads by raising the front of the car while the thermostat was open but no difference in results.

I apologize for not giving all the facts. Both aluminum radiators are new Big Block radiators.

 

[Chryco Psycho]

What type of fan are you using , sitting in traffic & having the temps rise means the fans are not doing their job adequately . I recommend a 18" clutch fan with a shroud for best results .
I agree with above I would be using a 180* or 195 Tstat

 

[BriceRoad]

Is your A/F ratio correct?

 

[DaveInDenver]

The Holly Sniper auto adjusts A/F Ratio. It is around 13.5. I am at 6300 ft altitude.

 

[BriceRoad]

Ok cool. I had a very similar problem and after years of troubleshooting the only thing I could come up with was my carb was too big for the cam. I assume your pulleys are correct?

 

[DaveInDenver]

Ok cool. I had a very similar problem and after years of troubleshooting the only thing I could come up with was my carb was too big for the cam. I assume your pulleys are correct?

I am using electric fans. They are set to activate at 160°. They seem to have good air flow.

 

[Steve340]

Is the engine able to bypass water? Some engines are not happy if you block off the heater.

 

[DaveInDenver]

Is the engine able to bypass water? Some engines are not happy if you block off the heater.

The heater core is still functional and in use.

 

[Steve340]

You could remove the thermostat completely to eliminate it being any part of the problem for a test.
If it still gets up to 225 or more you know the problem is elsewhere.
It will take longer to heat up but if there is a problem it will still get too hot.

 

[BriceRoad]

By pulleys I meant the pulley on the water pump and crankshaft. If they are incorrect the water pump could turn too slow or too fast.

You said the timing is 15 degrees advanced. Is this the timing at idle? I always got my engine up to 3K RPM and set it at 34 degrees (with vacuum advance disconnected). I am not sure what my timing was at idle.

 

[Chryco Psycho]

Removing the Tstat will cause overheating not help ,
Electric fans will not pull air through the whole core of the rad as it it needs a shroud covering the whole core to pull air through the whole core , I have seen a few rads with a full shroud & 2 fans cut into the shroud , most electric fans are not even close to the efficiency of of a engine driven fan & shroud

 

[One of few]

While the wrong thermostat will create the same symptoms, I’m wondering if the engine builder used the wrong head gasket twice? Gasket material blocking the cooling ports will generate those run away temps.

I have a fresh built 383, that I bumped up to a 496, with a little help from 440 source, and it has the same Holley sniper FI system. I’m a long way from firing that one up - I just hope the engine builder got this one right.

 

[Challenger RTA]

So are you a mile high?

 

[Challenger RTA]

Try the simple thing first.Pull thermostat,boil water and put it in see if it opens and closes when pulled out.do it a couple of times. New ones do go bad too! If it's stuck open the motor will over heat.coolant doesn't stay in radiator long enough to cool. stuck shut wont cool at all. Sometimes it works if you just throw it out of site and get an other one!

 

[BriceRoad]

Just posting this information in the hopes someday it helps someone. I had my engine built in 2001. I only assume my problem was the A/F ratio because I thought I had tried everything else in the 16 years I had it. (in 2017 I tried changing the camshaft and have been having problems with that ever since. Hopefully I am on the last rebuild.) Some background information: My car is Barracuda Gran Coupe which originally came with a 318/auto. So, just like the OP I have the 22" radiator support. I don't know how to change sheet metal (but I definitely want to learn) so I kept the 22" opening. I wish I could have switched it to the 26" opening. My engine is a 440 with cast iron heads. I have recently found out that my compression ratio with the head gaskets I have always used is 9.65:1. The engine builder told me to use a "509" cam but I didn't because I was worried about the car being streetable. Definitely I wish I had listened to him but I digress.

In 2001 I bought a radiator from a company called US Radiator. It is a copper 3 core radiator but it has 3 sections in it so the coolant gets cooled 3 times before going back into the engine. IIRC I did have a shroud when I fiirst started out. As long as I was moving the car stayed at around 180 to 185 degrees. Most of it's life I either had 2.94 or 3.23 gears so it wasn't revving high. I took it 500 miles to Ohio for the Nats on 4 occasions. No issues with overheating although one of those times on the way back there was an accident with a fatality. The Police closed the road and I was doing a lot of idling. The temperature got up to about 230 degrees and then I had to pull over and let it cool down but it didn't boil over. In fact in those 16 years it never boiled over. I tried all different kinds of Tstats. I tried using a stock one with a 1/8" hole drilled in it. Last I stuck with a 180 degree high flow Tstat. At one point a I spent $700 on a 26" aluminum Be Cool radiator but no shroud. I used adapter brackets to fit it in my car. I tried all kinds of timing settings and I did have the incorrect pulleys on my engine and I replaced them with the correct pulleys. I bought a book called "Cooling Your Mopar" which led me to try a lot of the stuff I have mentioned. A friend said to try Water Wetter but I never did. None of those things made any difference with overheating while not moving problem. The last thing I was going to try was a pusher elctric fan but someone told me the engine fans pull a lot more air so I never go to it. Don't know if that is true or not. After the last rebuild I decided to go back to the radiator from US Rad because it looks more original. I want my car to look original but perform well like I had recently purchased it new. I couldn't find the shroud so because I suffer from CRS I really don't remember if I started out with a shroud or not. I bought a new shroud for 22" radiator at last years Nats so I will be using a shroud when I get this thing together.

Anyway with my engine I had two problems. The overheating and a pinging problem at WOT. I fixed the pinging by setting the the timing and installing a restrictor plate in the distributor and by getting the vacuum advance set correctly. Now the reason why I am saying all of this: I had a friend come over recently to look at my engine. One of the things he looked at was the head gasket. The head gasket I use it Fel-Pro part number 1039. I picked it because I had mistakenly thought that my compression ratio was higher than it actually was and I wanted the thickest head gasket I could find to help with the pinging problem. He noticed that there is a slit in the head gasket that covers where the coolant flows. He was wondering about this and now I am too. This slit would seem to restrict the flow of coolant. Does anyone know if this matters or not? Is it possible that at idle the slit just doesn't allow enough coolant to flow through the engine? I have included a picture. "A" is the factory hole that flows the coolant and "B" is the slit on the headgasket that covers it. Is it possible that I have used the incorrect head gasket all along?

 

[BriceRoad]

This is a different Fel-Pro head gasket. While it does have the slits where mine does the other holes for the coolant next to the head bolts on the exhaust side seem larger.

 

[Steve340]

I think you are Ok. The slits are designed to limit water flow but still line up if the holes in the heads are in different places.
There main job is to allow steam pockets to disperse.

 

[One of few]

Bingo - allowing full flow will cool much better. I’ve seen this problem before - if both engines have the same symptom, I believe you’ve found the root cause.