Thread: Race engine cooling concerns....

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Over the winter I built a 439 c.i. 18 degree sbc for my Vega. Well...really, I had a professional assemble it with the parts I provided. It dyno'd at 755 @ 7000 r.p.m. I was very pleased with those results, however my first quarter mile pass was disappointing....10.01 @ 142 mph in a 2600 lb. car. Heck....my 550 h.p. 421 went 9.70's! The motor was falling on it's face at full throttle immediately after leaving the line. Upon inspection, I found that the fuel regulater adjuster had come loose, and my fuel pressure was in the 4 lb. range. No problem...fixed it. Also....it ran extremely hot....like 220 - 230 on the return road. I know an engine will run hot, when running too lean on fuel, but I'm concerned even with the problem corrected, after running the engine for 15 minutes, and watching the temp. creep up to 195. I'm using an electric water pump, 3" radiator w/ fan, no thermostat. Any suggestions on how to get the water temp down without going to alcohol? For comparison....my last motor was a well built 421 c.i. sbc, 23 degree, and always ran around 170 -180. Never got any hotter. The c.r. on the new motor is 14.7:1.

A thermostat will keep the water in the block longer and help cool the engine down. that's what I have always been told, that without one the water is moving to fast to absorb the heat.

If you don't run the T-stat you'll need to run a restrictor, something like Amazon.com: Mr. Gasket 6126 Water Outlet Restrictor 90 Degree Plate Kit: Automotive to get the flow rate right.

Originally Posted by green34ford

A thermostat will keep the water in the block longer and help cool the engine down. that's what I have always been told, that without one the water is moving to fast to absorb the heat.

I agree, and I also believe this is why a good sleeve type thermostat is better that a disc with a hole in it or even a poppet type thermostat. As the load changes on the engine, the temperature in the coolant will vary, certainly not a one size fits all situation.

Also, with a new motor, one that hasn't fully "broken in", the friction factor is a bit higher. Other things to check would be fuel/air mixture (to lean equals heat) and timing not set properly and verify the centrifugal advance works properly.

Of course the above is my opinion, ymmv... yada yada yada... hope it helps

What temp did it get to on the dyno? Has the timing been retarded since being on the dyno? Same waterpump etc that the 421 had? Anything other than the engine changed since the 421? Is it the same block as the 421? basically just a head change is different?
I would bet you have trapped air in the back of a head, you can drill & tap for a little popet valve into the water passage right at the back of each head - moroso sells them. When filling the engine you push the valve and hold it to release the trapped air - they look like the pressure valve on the front gearcase of a blower.
Have you done any other changes to the front sheetmetal? like opening the inner fenders etc so that air can go around the radiator instead of thru it? you don't have wire pump wireing reversed do you? so the pump is running backwards - don't laugh, i did it once.
Thats about all i can think of. Good luck, oj

Lots of things---but first---what kind/type of electric pump?? what type fan??electric?? amps drawn??(relates to cfm)
14.7 cr???????what fuel??timing???? how hot when you went to starting line????? Pressure cap?????????recovery system????

First....thanks for all the replies. I will try to answer all the related questions: the pump is a new CSR...on the old motor, I used an Edelbrock mechanical water pump....this may be a factor. This is a completely different engine...BFM heads....new Dart little M block....2 piece intake....alum. 3" radiator w/ overflow tank....the wiring to the pump may be reversed....never thought of that. I've had a few cooling fans run the wrong direction, though. The timing is exactly where it was, when dyno'd....which is not to say that it is exactly where it should be, due to the factors changing.......it was set at 35 degrees, but will probably be increased to 37 -38 for the next test / tune. I'm running 114+ gasoline......the water temp. was about 180 at the line. No other changes to the body of the car....it has open fenders / no inner fenders. I know this engine will run hotter than the other one, just due to c.r.....but is 195 - 200 too hot, if I can get it to stay in that area? Thanks again. Dave.

what is a CSR pump??need gallons/minute flow---
Electric fan????? what kind, how many amps, how much cfm rating--were the pump and fan on??? why did you get it ti 180 before starting line???

Was the engine dynoed and run with same fuel system and same fuel????

Ya' know one thing that comes to mind for me is your sending unit location. The sender that inputs to my ECU is right at the head while the one that inputs to my dash gauge is on the water neck, just downstream of the T-stat looking at the combined water flow. They show between 15F and 25F difference, with the dash at 180F the temp at the heads, shown on the ECU calibrator will vary from 195 to 205 depending on load and driving conditions. With a 195 t-stat I was seeing temps up to 225 to 230F at the ECU, so I dropped back to a 180 stat. What temps (location) are you looking at? Also, have you shot it with an infra-red temp gun while at temp? That can give you an idea of water flow, and might show you an air pocket that's turning to steam?

Most puter controlled engines nowdays (1996-up) don't fire the fans till 226 degrees. I don't think I'd have any concerns till she hit the 225 mark as long as I was sure it doesn't have any air pockets and I was positive the pump is running the correct direction.

Antifreeze get hot and stays hotter longer than water too.

I don't think you can run antifreeze on the drag strip because of spillage 1gary. it's dangerously slick when spilled.

Originally Posted by green34ford

I don't think you can run antifreeze on the drag strip because of spillage 1gary. it's dangerously slick when spilled.

Bracket E.T. cars do all the time.Well the ones driven to the track that is.Over the yrs our 9.90 cars had water in them of course.

Your post led me to what was most likely the problem. The water pump was working intermittently....actually would come on, but shut off within a few seconds, then start again. I checked to see if it was working...and it was...initially, but never even considered it again, until you suggested the backwards thing. I traced the wiring, but found no problems with it. Only when I ran a different 12v power source to the pump, was I able to see that it was stopping / starting for no reason. Thanks for not trying to "re invent the wheel". This is the reason I use this forum....not to have some "genius" ask me questions like..."did I have the switch on?'....or "why did you let it get to 180 degrees?". Thanks again.

Glad you solved it so easily.
One thing we do is similiar to GM where we drill and tap a hole in the thermo housing and another in the waterpump and run a piece of that teflon tube (airshifter tube) with a couple yorlok fittings from the pump to the thermo housing to help with the blocked air.