Anybody wanna take a guess on my 8BA overheating situation

Sorry for the long read but this is bugging the crap out of me.
My 51 8ba has just recently started to overheat its all stock except for a Bubbas converted distributor timing is set at the dot and seems to be advancing with rpms correctly.
Here is what its doing I (up til now its always ran 180-190) I went on a trip staying on all 2 lanes made it about 150 miles all was good until I came to a 4 way stop, I then noticed it jumped to 200 and then stayed there for a bit then all at once went to 230.
I pulled over let it cool topped it back off . Then it would only go 20 to 30 miles then repeat. I limped it home replaced T stats with new 165* T stats made sure waterpump intakes were clean of debris and replaced Rad cap (7PSI) then it went about 25 miles at 50-55 MPH and did it again. I let it cool topped it off and then it ran190-200* for the rest of the trip 75 miles each way I drove it around town several times it was fine.
This weekend I left to go on a 200 mile each way trip thinking it was good but after about 25 miles it did it again same deal top it off after it cooled down a bit and continued on at 50 mph repeating this process every 30 - 50 miles this morning at the hotel I reverse flushed the motor thru the heater hoses for about 5 mins a side then flushed the radiator backwards thru the heater hoses letting the water come out the radiator cap for several minutes it ran pretty clean the entire time and I didnt notice any big chunks of debris. We then drove around Indy traffic in the show and made it about 140 miles running at 180 -190* then all of a sudden it jumps up to 210 and starts the same deal all over again it always seems to do it at highway speeds and today it would definately cool down if I slowed from 55 to 50 ( 2450 rpms at 55) but in the past it didnt always do that. Also even after just stopping for a few minutes adding usually about 3/4 of a gallon to top it off it would be fine for another 30-50 miles???
The radiator was boiled out last year and looks to be not plugged up at all. I'm thinking it must have rust or debris of some type moving around in there and restricting flow some how anybody have any thoughts Please?

PS Friday after the first incident I made it to a parts store and put a pressure tester on it, it held at 12 PSI. I then started the engine and even revving it a bit the pressure stayed stable so that should eliminate a head gasket Im thinking.
Thanks In advance Mike

 

First thing that came to my mind was head gasket. The pressure test may not show it until the motor is under load.

Neal

 

Even though you got a official bubba distributor, make sure the timing isn't moving around, check it with a light confirming all rpm ranges .
Let me know if it's doing anything weird.
Timing will cause lots of heat problems.
How many miles on the distributor .?

 

Is there any chance your pressure cap is not holding pressure all of the time. You asked for guesses and this is probably a bad guess.

 

First get a good timing light one that you can check total advance with and find out exactly where you are with the timing, total advance and when it comes in, you might have to take a few degrees of timing out of it, or add a few...........

 

Fill up the radiator to about a inch below the filler neck and run the engine until the temp comes up to operating temp. While holding the idle to about a 1000 rpm watch the coolant in the radiator and look for bubbles. If you have a compression leak you should see tiny bubbles in the coolant as it flows through the radiator. A even better was is to buy a HC detector that you put on the top of the radiator and if you have any hydro carbon in the system the fluid in the tester will turn blue.

 

When it starts running hot..and your stopped, try running a water hose over the radiator and see what the temp does.

 

Hi Jim, I donno if you remembered I talked to you briefly about the advance at your party the other nite. Its probably got a few thousand miles on it maybe 4 thousand. I've replaced the points and condensor once. I just checked and reset the dwell at 30* timing is at the dot and seems to advance well and seems pretty stable at a given rpm. I did try advancing it a bit it didnt seem to change temp any so I put it back to the dot.
It runs like a top BTW other than the overheating deal.

I replaced the cap already it made no difference That was one of my first guesses too

 

What water pumps do ya have? Straight water or a mix?

 

Thanks for the replies already
Pete Im not sure what pumps they are they were on there when I bought the car (this is my shoebox) and just straight water now until I get this figured out I dont want to be puking antifreeze all over it. It is really weird though, today it went a steady 3 hours at 53 MPH and was locked on 185* then all of a sudden it just jumps up to 210. Now I just shut it off before it gets much hotter and it usually takes less than a gallon to completely top it back off to the neck.
I can stop, carefully remove the cap, usually a bit of steam will release with the cap. Then top it off and take back off in less than 5 minutes and it will go another 25 miles or more sometimes before it gets hot again.

 

belt stretched, slipping?

 

If the motor is hot, it is surprising that you can open the radiator and not have the water boil out.

My experience with bad gasket/cracked block was that the motor did not get that hot, just blew the water out to where it was low on water and then the motor got hot.

I don't know if it is ignition or gasket that is your problem but still leaning toward head gasket.

Neal

 

Ive watched for bubbles or the coolant level rising /pushing out wuth the cap off doesnt seem to be any. Flatheadfan its a 2 belt set up both seem reasonably tight I can slip the fan a bit but I think thats still ok or normal.

 

Yep. New belts. Tighten them good. If the water pumps leak, change them out. I used Speedway pumps. Lots of hard, fast miles on them. No problems. But, a sudden change like that kinda indicates a blockage somewhere.....

 

is it possible you have a funky gauge giving you some wierd readings.

the reason I ask...you can open the radiator cap without it spewing coolant.

maybe it really isn't running hot, but the gauge is telling you it is?

 

Thanks Neil, It did boil over yesterday but I try not to let it get over much over 210 before I stop now to avoid the cap removal geiser.
At first I thought it must be a head gasket too, but with a pressure tester on there for a couple minutes under fast idle it didnt increase pressure or it wont push any out with the cap off at fast idle, and then today ran all over Indy traffic then 3 solid hours on the road before acting up? wouldnt a bad head gasket be more consistant? and It usually takes less than a gallon to top it off and sometimes its still full even.

 

Many years ago I had an engine that would overheat on long trips. After many parts, teardowns and shoptime. It worked down to bad distributor centrifugal advance bushings. Until everything got hot the advance would work just fine. When hot it would lock down the timing.

 

I am gonna swap out the gauge but it will boil over. I just now try to stop before it gets that hot 210 to 220, at 230 it starts puking. We watch the guage and you can tell when it does it, it will be steady 185-190 then in a matter of a couple minutes or less just start climbing up pretty fast. Also no sign of water in oil or exhaust.

 

Shubox fords had a problem with air flow circling around through the area between the top of the radiator and bottom of the hood..Ford made up a cute little filler piece with a rubber gasket at the top to fit against the bottom of the the hood, side to side...is that piece still in place?

 

Remember that the coolant in the two sides of the motor are seperate. One side can be heating and the other may not. Maybe that is why it isn't that hot when you stop it and open up the radiator.

At 210 degrees with a pressurized system, it should not be blowing water out.

Just throwing out some random thoughts.

Neal

 

Thats interesting, at this point I'd be glad to swap a new Bubba distributor in it if that would fix it.

 

"Rocky"....had a point - are the factory panels present?....this from a former '50 Club Cpe owner...

 

That piece is NOT on there I know it should be. Im gonna try to make a filler panel for that The reason I thought that wasnt it was I drove the car alot in the past with no problems, today it went 3 hours @ 180 yesterday it wouldnt go 20 minutes. Also its never done it in town or in traffic I think an air flow problem would be less likely at highway speeds wouldnt it?

 

Bump for day shift any other ideas for me to check. I really hate the tought of just throwing parts at it.

 

Sounds like maybe it's not always getting proper advance. Have you had a look at the weight mechanism to see if there is any sign of sticking or wear? Sorry if this has already been covered...

 

have you tryed what I suggested? wont cost anything but time

 

no motor i havent got to try that usually it has overheated out on highway and not where ive been able to have access to a garden hose to try that

 

Pull the distrubutor, place it in an oven at 250 till it's fully heated.

Use gloves, hold the gear and try the centrifugal advance by hand.

 

How old are your hoses? Any chance they're coming apart inside and blocking/restricting your coolant flow?

Flatman

 

My car is like what you discribed, my 8ba in a 35 ford will start to run hot and then over heat, If i run it at around 2500 rpms then go up a hill or suddenly slow down and stop. if i keep it moving and lower the rpms it will stay cool. If i run up a hill too slow at low rpm with lots of throttle it will run hotter as well. But i think 2500 rpms cruising is what does it to mine. maybe the water flows to fast, or makes an airpocket, i dont know. But i can run up the same hill at 2000 rpms and not overheat, But 1500 or 2500 it will.