Overheating BBC 468 Pro Street Willy's Coupe

[topradman]

Hi all, have a seriously distressing overheat issue. Car is a 41 pro-street Willy's coupe, 468 BBC, turbo 400 A/T, don't have a lot of info on the engine but the entire build only has about 400 miles, chassis and all, very nice car. Ok, car takes about 15 minutes to get to about 205F but if left running, will slowly continue to climb and I shut it down at around 225-230F. Ambient is 95F today but it will do the same on 85F day but just takes a little longer. Car had a 4 row cu/br radiator and a cheesy 12v fan when it came to me. I built a 3 row, 1" tube double pass radiator with core measuring 20.5" tube length (25" overall width) x 18.5" height x 3 1/2" thick cross flow. I added a Vintage Air Monster fan ( claim is 3800 CFM+ ) and I believe it as it uses about 65 amp to start and about 45 amp continuous ( like a Lincoln MK IV fan ). The water pump was a Proflow electric and I upgraded to a Meziere advertised 55 GPM pump. Timing is set at base 14btd, mechanical all in 34btd, with vacuum and mechanical all in 46btd. Radiator/fan/shroud assembly is angled back about 10 degrees to help direct the air back and down from under the car. Carb is Quick Fuel with sight glass bowls and am getting enough fuel. After mentioned upgrades, car takes a little longer to heat but still will. After a discussion with Stewart Components & Meziere, I decided to reduce and possible flow restrictions since it is an electric pump rather than belt driven, so.... I took everything apart again, cut open the radiator and made to a single pass, upsized the bottom and top hoses both to 1 3/4", made a new water outlet upsized to 1 3/4", put it all back together ( 1 gallon coolant + 2 1/2 gallons distilled H2O ). Ran it again and does the same. Replaced gauge with Autometer full sweep manual gauge for more accuracy. Car behaves the same. The more throttle I give it, the more it will heat whether driving or setting still! .... I disconnected the hoses, set up an aluminum/plastic fan for a 454 1 ton chevy van in front of the car and piped hoses & tubes to it ( about 2 ft in front of the car ), mounted a Derale fans/shroud assembly to it and the car cooled fine for about an hour. Keep in mind that with this test set up, I could not close the hood, could not run the AC and of course, set up was outside the engine bay. The fans come on at about 195F and shut off at about 180F. Fan cycles did start to get a little farther apart so don't know if I had run it longer if it would have eventually gained more heat but it didn't seem like there were any problems. The radiator out of the van has more frontal ( 560 sq. in. versus radiator I built 379 sq. in. ) but van radiator cubic inches of heat sink is less ( van radiator 1120 cu. in. versus radiator I built 1327 cu. in. ). I realize frontal is more important than thickness and I also realize test is not fair as the outside unit is removed from the car but at least I now know the engine can be cooled ( at least for an hour mounted outside the car, LOL. Cars not gonna look very "Cool" with that arrangement ). Soooo.... any ideas?? If the head gaskets were wrong for the cylinder heads/block ( i.e. parallel flow versus series flow ), is it possible that the test radiator outside the car could still do the job but the one in the car not do the job based on the more stressful environment? Does anyone know if you can run a bioscope into the water pump ports in the block and look up inside and see any of the water port/head passages or has anyone ever tried? Any solid info would be helpful before I pull the heads to find everything is as it should be.

Thank you in advance for your input!

[topradman]

Sorry, put and "aluminum/ plastic" RADIATOR out of a 1 ton gm van

[fdicrasto]

I don't see mentioned a t-stat.

[topradman]

No thermostat under the advice of Stewart and Meziere so T-stat bypass hose is not on this car. I have built a number of cooling systems for really big motors with similar recipe and have not had problems. That is what is stumping me. I am going to break down and put a restrictor in tomorrow but I am pretty sure it will not help, probably make it worse.

[cpmotors]

Yes ,wrong head gaskets/ or coolant holes not drilled. The FP 1037 requires the two lowers to be drilled, the FP1027 doesn't. I just finished a 496 that had the same problem, would build heat but never cool down at cruise, he tried bigger radiator and pump etc. I would also put more initial timing into it too.

[steve cowan]

i would use alot more initial timing as well,i lock my distributors because i believe they idle cleaner,people say they can kick back on the starter motor but the only time i see that is if the engine has a bit of compression 12to 1 or more.
i am using a 55 gph mezzire pump as well on my 383 streeter
4 core alloy EBAY radiator,i do not use a thermostate with an electric pump i cut the guts out of the thermostate and use it as a restrictor only
10.9:1 comp,500hp
runs low 11s @ 121mph
185-190deg cruise
205deg traffic
if you dont have any mechanical problems like head gaskets arse about it should not be to hard to fix i dont think
good luck and keep us informed how you go

[Geoff2]

Yup, if the overheating is at idle, it may need more idle timing. If it overheats at all speeds, you have other issues. Keep in mind that 400 miles may not be enough 'loosen up' time if the parts were assembled with tolerances on the tight side [ tight piston to bore, tight brgs etc ].

[Newold1]

I am with CPmotors on this one. To many times I have seen this same problem on a big block where the head gaskets are either wrong for Mark type and the water is going into the block at the pump and straight up and out the front of the head and back to radiator thus not cooling head. Use a point and shoot thermometer to scan the head temps front and rear and I think you might find the problem. the bummer is you've got to tear down the heads and re-gasket.

[stealth]

I've chased these overheating problems many times...I started experimenting with a few things and found out most of what you hear is not true..

The thing I found out was water flow....not claimed water flow and I think it's good...but actual water flow. I ended up running my water pumps faster that crank speed. Quite a bit faster.........

This worked in almost every case to eliminate overheating issues...

I've never had good luck with electric pumps unless it was a very low hp engine...

[Racerrick]

not a fan of electric pumps n the street. The restriction at t-housing in cooling system is a must. Built wrong, holes not drilled, wrong head gaskets, bored to tight. rule of thumb is 1sq inch of radiator /hp 20x20 good for 400hp.

[engineguyBill]

Just for the heck of it, why don't you install a thermostat and see what happens. Use a 160 degree unit and drill some small holes in the unit for coolant circulation when closed. Results could very well surprise you.

[user-17438]

How about start at the basics.. Base idle timing, cruise timing, air fuel mixture. Vacuum advance?..... Waterpump bypass functioning? Or how about oil pan size.. Check oil temps. Could just need an oil cooler.

I see people all the time running around with 4 quarts of oil in their 600hp big blocks with 3 core radiators saying their stuff is overheating because it gets to 200°f.

These are the same guys that have 10 degrees of base timing with vacuum advance plugged off. And a Carb spitting out a 10:1 Afr.

Figure out why it's making so much heat before you band aid any problem.

[Baprace]

Yes ,wrong head gaskets/ or coolant holes not drilled. The FP 1037 requires the two lowers to be drilled, the FP1027 doesn't. I just finished a 496 that had the same problem, would build heat but never cool down at cruise, he tried bigger radiator and pump etc. I would also put more initial timing into it too.

I agree with cpmotors that the solution is the coolant holes/head gasket and a little more base timming. JMO

[topradman]

Ok, just put a phenolic spacer & heat shield for the carb. I know this will not cure my overheating problem but after I posted last, I went back to the Willy's and fuel was running over into the carb so engine had heat synced and fuel was boiling over so that would have needed fixed regardless. Funny how you could not see the fuel boil in the sight glass? Hmmm.... So now, I pulled a valve cover and confirmed another "possible" indicator that the head gaskets "could" indeed be mismatched. The heads are casted as #14092359, 86-89 427 ( tall deck motor ) which I think will be a gen-IV cylinder head, I believe, and the block is a casted #10114182, 91-95 4 bolt gen-V block. This doesn't mean the builder didn't do the right head gasket but it does mean that it is more of a possibility that there was a mistake made. Again, "Hero" 2 pass radiator 3 row x 1" tube core ( in desperation, converted back to single pass now ), "Hero" fan 18" x 45 amp, very professionally shrouded and sealed to radiator, 1 3/4" inlet and outlet hoses & all ( was 1 1/2" upper & 1 3/4" lower, desperation again ), Meziere 55 gpm electric pump, no thermostat, no thermostat bypass hose, has heater valve shut off so no looping coolant without being cooled in radiator, no combustion leaks, plenty of fuel, carb is well tuned. I am also going to replace the alternator tomorrow with a 140 amp as it only has a 90 amp. The 90 amp tests out fine but may be just short of what all the electrics needs to make the fuel pump, fan, water pump, compressor & hvac motor work. I know it's boarder line for sure. For the "heck" of it, I am putting in a restrictor in the thermostat housing but all my cooling experience ( over 200 custom builds ) tells me this will not help at all but I will do it just to see. I will post my results before changing the alternator. Any other experienced cure info is very, very welcome! Thanks guys!

[Keith Morganstein]

I post this from time to time, but I'm not sure anyone wants to listen...
With cooling systems. People start guessing and start changing things. Some time you hit it, some times you don't. Guesswork gets expensive and time consuming. I can't guess any better than anyone else

There is some science to diagnose cooling system problems.

Start with checking temps in at least four spots. I prefer to use thermistor probes into the coolant, an IR gun can be used to an extent.

Place probes, take reading in at least four spots.
Radiator inlet and outlet. Before the thermostat and after the water pump.

A good working cooling system will have a 12-15 degree delta T. ( across the radiator in and out, and also engine in and out.

Watch the reading as the engine is running and cooling system is working.

Temps Closer together than that indicate a cooling Capacity problem. (Insufficient cooling)

Temps Farther apart indicate a coolant Flow problem. (Restriction of coolant flow)

Closer = Capacity. Farther = Flow

For example, If a capacity problem look at airflow and radiator size/capacity

If a flow problem look for plugged (internally)radiator, water pump issue, thermostat, collapsing hose, other flow issue.

If having trouble finding a flow problem, pressure gauges can help locate the restriction.

For the OP, ( and. Not criticizing) if you did this, you would be able to find out if you had to rework the radiator or airflow before you went ahead and did.