Track Car Overheating, small block Ford
A friend of mine has asked I submit the following overheating problem. It has been a VERY frustrating year and hope you all can help. The message is lengthy but want to provide all the details in chronological order for your analysis. Thank you in advance for your help!!! r
Four years ago I purchased a "strap on" race car, namely a 1967 Cougar set up as a TransAm car. My car has had virtually the same set up for several years and served me well, without significant problems, through 3 racing seasons or about 2200 miles.
In the winter of 2002-03, I redid the motor since it seemed time and for no other reason. Block, heads, crank retained -- New pistons, rods, valves, etc. Original engine produced 300 rwhp. Rebuilt engine was bored 40 over and stroke was lengthened, do not know rwhp of current set up but undoubtedly more.
On the track it did OK in Feb and Mar when the ambient temps were in the 40's and 50's up at Willow Springs, but it must be realized that no true race temps were ever achieved.
Conditions changed in April and we experienced very erratic swings in the water temp. 220 - 260+ and back in space of 1 or 2 sec. when racing hot and heavy. We asked you folks for help and it was your conclusion that the coolant level was down and there was "cavitation."
I accepted that, brought coolant level up (it was down) and raced again in Jun at Willow Springs. The same wide/rapid swings in coolant temperature were noted. In addition we found coolant level falling by about 1 gal each 15-20 min race. A small amount of white foam was found in the oil which was considered, by most, to be insignificant. At the shop, a small crack in the head gasket at # 8 was found and thought to be due to inadequate / improper torquing of head bolts, some were "loose."
With "problems" "fixed," returned to track. This time we were on the long course at Fontana on a very hot day, track ambient approx. 110. I was able to make only 3 or 4 laps before the same wide/rapid swings in coolant temp would recur. Again I found coolant level down about 1 gal and slight foam in oil. Brought coolant level up and tried it once more with the same result. Back home a crack in the block was found which was said to be "only evident at race temps."
With block replaced, same inerds, returned to track convinced we now had the problem/s solved. You guessed it, NOT! Exactly the same temps were noted again; that is to say, coolant over 250 and oil over 260 whenever engine exceeded 4500 rpm and believe me you are not racing or having fun at that speed. This time it was felt that my Griffin radiator was plugged up with "crap" from the Ford small block/s.
Reverse flushed the radiator and put car on chassis dyno with similar results.
As you may be aware, this is not a radiator which can be rodded out with ease, so it was replaced and in addition a Gano filter was installed in the top hose. Again the car was placed upon chassis dyno and run up to 6000 - 6500 rpm with the same overheating of coolant and water.
Needless to say, I am very frustrated and would like any help or suggestions that you might have.
Thanks, George :sweat:
Collapsed lower hose or warped manifold or bad t- stat or slipping belt or wrong pulley ratio. These are all I can think of right now.
What pressure cap are you running? Measure the distance down to the cap sealing surface in the rad to make sure it is parallel to the top, I've seen a couple where this surface was warped and caused the cap to release into the overflow and not completely close after the initial opening. I found it by putting a rubber gasket cut out of sheet rubber under the cap which effectively raised the pressure where it would release and added a softer seal.
The cap itself needs at least 0.050" compression on the rubber seal ring or it will release early, any compression grooving caused by set on this ring reduces the pressure it will release at. I sounds like you have the rad puke it's guts into the overflow and then suck it back in and the cap is not closing to keep the system sealed. If the seal area in the rad is not parallel it will open and not close properly and you end up with a pulsing pressure release which explains your temp swings.
When it happened to me it was a bugger to diagnose since a new cap didn't solve the problem even though running with the hood off the car allowed a passenger to witness the reservoir alternate between full and empty. Of course this only happened at race loads and rpm. I recommend at least a 16 pounder on your system, I ran a 24 pound cap to maintain good pressure in the system and prevent the dump to reservoir that we were having (a rotary engine turning at 8500 can generate 20 pounds easily just in coolant flow pressure). I would rather overpressure the system than have it puke during a yellow flag and then be out of coolant when the green drops again. Race rpm subjects the rad and coolant system to very high pressures and rads when new can handle 50 psi and higher before they blow out, usually it's the rad hose that goes first anyway. Seal it up tight and then try it under load and see if it solves your problem.
Hope this helps.;)
Possible water pump cavitation?
It still sound like low coolant problem because of the erratic and rapid temp fluctuations. Possible air pockets in the cooling system.
You have a new block, but what about cracked heads? The small amount of white foam may be ok, but with significant loss of coolant (1 Gal) that seems to be problem that needs to be addressed a little more closely.
Do you have access to an infrared emission tester to put in the radiator? How about a block tester kit to see if the test fluid changes color.
Thank you all for taking the time to help. This problem has been a real stinker. I will pass along and report back how it is finally resolved.
I think the radiator cap is going to get a real close scrutiny!!!! I'm sure it was changed once but not with the attention you detailed.
Thank you, r
I had a 68 cougar, I used a alumin radiator out of a newer Chyrsler mini van, it's really wide and some modifications will be made to fit it in there, but It cured my cooling problems and Id think itd cure yours also...
I just thought of another reason why this might be part of your problem RAW, if the cap releases all the pressure not only do you lose half the cooling capacity and efficiency from the pressurization of the system but the areas that are really hot turn the coolant instantly to steam, certainly would explain the cracked iron your seeing. We never had this problem with the rotary's because there's no head to crack, it just wipes out the rotor seals after 10 races and flakes off a chunk which wipes out the rotor and cases too.
Yeah, I really loved that one.:rolleyes: :(
If I get a chance Ill go out next weekend and take a pic of the radiator Im speaking of, My cousin bought the car from me and he has installed a 12.0:1 351C (with Iron 4v heads) with no cooling problems..
2Wilds right, the VW Scirocco ones work well too but are getting hard to find. A bigger rad never hurt anybody!:) If your still using the original downflow rad you need a cross flow upgrade.;)
Thx gang for responding. The owner is chasing the issues presented on this thread.
4 Jaw -
I got a message from the owner "...dropped down to 16# since couldn't find 24#" and is now looking for another race cap. Also, the car has a new cross flow radiator. The new radiator replaced the previous cross flow as the theory was down to a clogged radiator.
I got your e-mail, replied thru HotRodders and forwarded on to the cars owner. They are sure the timing is correct but the builder is checking the car again.
Also, we sure hope prohibition does not return until this issue is addressed! Could you pass that bottle...
Thx again and I will report back the progress or new problem signatures, r
Update to cooling issue!
I received a call last night from the owner, George, about the status of the track car we have been discussing. George is at Willowsprings Calif. for a meet this weekend with expected ambient temperature highs of 60 degrees. This should give us a final test. This is what we know to date.
The car has been on the dyno twice since my last entry. The radiator cap in the past had been replaced with a 16# but now is a 24#, thank you 4-Jaw. Also, the engine builder put a hose from the top of the thermostat gooseneck back into the engine and sorry, I do not know exactly where. It is supposed to reduce or eliminate cavitations. Also, for information, the 302 is putting 360 hp to the rear wheels.
The first dyno run improved the situation by allowing the engine to run at higher rpms (before remember it topped out at 4500 rpms) and ran longer but eventually started the same problem.
George was told Felpro had re-engineered the Ford head gasket to address passenger side coolant flow problems. So, a new head gasket was installed, right side only, and the car ran ok (6500 rpm range) on the dyno. So now at Willowsprings, we shall see.
I asked specifically to find out, part number, about this “new” head gasket design Felpro has engineered. George was told that there was no new part number. This is because Felpro’s “new” design will be part of all new stock thereby we will all get the new design after the old stuff is sold off the shelves.
What do you think? Thx, r
Is this a SBF? Cleveland? What kind of heads? I heard of some problems with the early Ford Motorsport aluminum heads before?
Sounds like a cool car your running and Willow Springs has got to be my favorite track. Too bad I'll probably only get to drive it playing Nascar on the computer. Hmmm I wonder if I can download a early Cougar car mod for the game.:D
A few more ideas, have you checked the advance timing to make sure it's working, the old Ford style distributors with a set of Mr. Gasket advance springs would sometimes stick advanced if the stop was set too far. Make sure they are free and loose and don't stick with the springs off. No worries if your electronic.
Keep us up to date.
P.S. Some in car video of a sliding Vintage TransAm Cougar coming through the corkscrew hard on the gas just might give me a heart attack.:)
Heating problem resolved!!
Looks like the problem is resolved and a great weekend at the track!!! Thank you for the help!! Here are few parts of messages I received.
"...It was colder than in Sept., however, oil temp hit 260 in the peak of action and water remained at 220 without fan and on ram air alone..."
and especially for 4-Jaw:
"...Wish I could give 4JAW a palpitation with a view of the start of the Flag race when 42 cars entered Turn One 3 & 4 wide !"
thx again, r
Craig was nice enough to send me some pics of the car, she's a beaut.:)
Did I ever mention that I am a big time Cougar fan?:thumbup:
Even factory valve covers! Sniff...brings a tear to my eye...sniff. Notice the correct Ford Blue on the engine! Oh ya baby...thats what I'm talkin bout!:)
Great stuff Craig, thats is certainly a mans car to muscle around Willow Springs!:thumbup:
Thx for posting the picts. The cooling problem has been a challenge. roger
|All times are GMT -6. The time now is 03:54 AM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.