8BA Flathead overheating on highway

[SonicRaT]

Looking for a bit of help trying to diagnose my heating issues. This is installed in a 1930 Model AA with a C4 transmission and an explorer rear (3.27). The engine was installed by the previous owner, so I don't know much at all about it. It was rebuilt about 4-5 years ago and then dropped into the ModelAA. It has less than 500 miles on it as they couldn't drive it due to major steering issues.

Here's what I do know:

- 8BA Block, heads, and intake
- 4" crank, unsure of cam -- supposedly an original merc cam
- Edelbrock 94, 53 jets, leaks quite a bit on shutdown
-- Requires 4 turns out on the idle screws, otherwise it'll stumble/stall -- everyone seems to say these should be around 1 1/2 turn, does this indicate something?
- Summit electric fuel pump (was gravity fed previously, switched to electric pump to see if it was a fuel issue)
- Summit 1-4psi regulator, set at 3psi
- Distributor connected to venturi signal
- Speedway water pumps
- Griffin aluminum radiator w/ electric fan (new with engine)
- 15lb cap
- 180* Thermostats (originally had none installed)
- Timing on the stock mark

The backstory:
The previous owner had the engine built by a machine shop out in Washington that was apparently well versed in flatheads. They were never able to drive it after dropping it into the Model AA due to major steering issues. They had installed an EZ Steer box and put the tie rod ahead of the axle without fixing the ackerman angles -- needless to say, it wasn't safe.

I've since fixed the steering and have started taking it for longer drives at higher speeds, and thus the issues have appeared.

The problems start when trying to maintain speeds over 50mph. At 50mph, the temperature will slowly begin to creep up to around 210 -- it takes around 10 miles or so of driving at this speed for it to creep from 185 to 210 -- however, it will typically stay at 210. Anything faster than that, though, and the temperature continually creeps. At 60mph, within 10 miles of driving it'll rise from 185mph to 220 and continue to climb. Hills or load of any kind contribute even further to the problem -- it seems to even struggle on hills a bit.

I did a lot of lurking and reading and checking all of the common things -- first, I checked the vacuum advance and found the diaphragm had failed, so I was getting no advance at all. I replaced the vacuum can and have verified I'm getting advance now -- however, it made no difference at all in the temperature creep. Also, it really didn't seem that it made much of a difference in drivability either. I had expected there to be a rather significant difference in power, but didn't notice much.

So, I thought maybe I had a faulty thermostat or something of the sort -- I pulled the outlets and found there were no thermostats installed. I installed some 180 degree thermostats and it made no difference at all other than stabilizing the temperature at idle and low speeds right at about 185*.

From there, I suspected maybe it was an issue from gravity feeding from the stock Model A tank. I installed a summit electronic fuel pump and regulator (3psi) -- it feels like my low RPM torque is slightly better, but still, the overheating remains. No difference of any kind.

All of my plugs look fairly decent -- a light amber coloring on the porcelain, no fouling or rich cylinders. Cylinder 1 was rather clean by comparison to the others though.

The truck will idle all day and not overheat -- it'll either cycle with the fan settings or it just sits at around 185* since I installed the thermostats. It idles steadily at 550rpm -- i can go lower, but it seems to get a little unstable under 500. I connected a vacuum gauge to the manifold and it is rapidly bouncing between about 17-21". I've also got a slight ticking noise coming from what sounds like the passenger head area that I've not yet been able to identify.

If I run the car without the radiator cap, I don't get any geyser effects -- the water stays fairly stable for a while. As the engine warms up, the level starts to rise quite a bit until it'll begin to overflow -- though if I increase the RPMs the water level tends to drop back down again. A combustion gas check on the fluid returned negative.

I checked the head bolts torque and found that about 4 of the bolts along the bottom of the head between the middle cylinders on each side were about 10lbs behind the rest of the bolts. I tightened them all to 65lbs, but still no difference.

I'm not really sure what to do next -- do I pull the heads and looks for cracks/gasket issues? Dig further into the timing? Issue with the Edelbrock 94? I'm running out of ideas and any advice would be greatly appreciated!

[Tinker]

Whats your block like? What you know about it. How big is your radiator?

[SonicRaT]

Originally Posted by Tinker

Whats your block like? What you know about it. How big is your radiator?

I unfortunately don't know much about it other than what I've posted -- it was allegedly tanked/magnafluxed at the shop the previous owner had it built at. I don't know much about the radiator either, other than it being a custom ordered griffin -- the core itself is 17.5"x19"x3" with some rather large tanks, not sure how many rows. It has an electric fan and a full shroud with blow through flaps to allow excess air to blow through the shroud if it creates any sort of resistance.

I've drained/filled the coolant out a few times in the process of installing the thermostats and such and it always came out perfectly clean -- no rust or any contamination that I could see.

[Tinker]

The problems start when trying to maintain speeds over 50mph. At 50mph, the temperature will slowly begin to creep up to around 210 -- it takes around 10 miles or so of driving at this speed for it to creep from 185 to 210 -- however, it will typically stay at 210. Anything faster than that, though, and the temperature continually creeps. At 60mph, within 10 miles of driving it'll rise from 185mph to 220 and continue to climb. Hills or load of any kind contribute even further to the problem -- it seems to even struggle on hills a bit.


Typical suggestions:

Lean condition. Check plugs
Retarded spark, timing
Small radiator or flow.
casting sand. Does a hot tank remove all the casting sand without shaking?
exhaust gases in the coolant.

[SonicRaT]

Originally Posted by Tinker

Typical suggestions:

Lean condition. Check plugs
Retarded spark, timing
Small radiator or flow.
casting sand. Does a hot tank remove all the casting sand without shaking?
exhaust gases in the coolant.

The plugs look OK so far, but they've been in there a while. I figured it might be fuel as well, which is why I switched to the electric fuel pump/regulator over the gravity feed. That didn't make a difference, so I pulled the carb apart to check the jets and it has 53's installed, which everyone suggests should run a little toward the rich side already. I am going to order some 55s and 57s just to swap in and see if anything changes.

As for the timing -- I know the advance wasn't working previously, as the diaphragm was torn. I've since replaced it and know that the mechanics at least work and I've seen it advance with the timing light -- not sure if the curve is correct or not. I thought for sure the timing was going to fix it, but it hasn't made even the slightest of changes.

The core size of the radiator does look a little smaller by comparison to most of the Model A flathead radiators I see -- it seems to have a much larger bottom tank than others, but it still seems like a decent size core compared to what the engines originally used.

I'm not sure about the casting sand -- wouldn't I see some sort of debris coming out of it when flushing?

The exhaust gas test came up negative.

[Tinker]

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If plugs were fouling you'd know right away. lightly lean might take a bit more.



Model A radiator size would be a bit small.


Would think a hot tank would get most out even if some of that stuff is baked in like a old pizza pan.



check out http://www.bubbasignition.com/49-53.html



just some thoughts...

[Brian]

have you re-torqued the heads?

[SonicRaT]

Originally Posted by Tinker

If plugs were fouling you'd know right away. lightly lean might take a bit more.

Model A radiator size would be a bit small.

Would think a hot tank would get most out even if some of that stuff is baked in like a old pizza pan.

check out http://www.bubbasignition.com/49-53.html

just some thoughts...

The plugs have looked OK so far -- but they've been in there a while. I'm certainly no expert on reading them, so I can try to get some pictures up and I'll pick up another set to do a run or two on a fresh set to see where I stand.

As for the radiator, I was referring to the aftermarket Model A flathead radiators, such as what Walker makes and a few other companies. My core size seems to be about 2-3" shorter than most of those, as they went with a larger tank on the bottom, but I've seen a few low boys running a similar sized core without issues -- so I'm not quite sure if the radiator is the culprit or not yet.

I sent an e-mail to Bubba -- might pick one of his units up just to eliminate that possibility, as it seemed odd to me that there was almost no difference between no vacuum advance and when I fixed it.

I called the shop where the work was done and they confirmed they tanked and magnafluxed it, but he couldn't track down the order sheet since it was from a few years back so I'm not quite sure all of the work that was done. I've found nothing at all in the coolant when draining it -- so I don't quite think it's plugged up, but who knows. If all else fails, I'll be pulling the motor and stripping it all down to try to figure out what I'm working with.

Originally Posted by Brian

have you re-torqued the heads?

Yes -- as I mentioned in the original post, I have checked all the torque on the heads -- I found a couple of them that were around 50ft-lbs on each side -- the bolts right around the center cylinders on the bottom row of bolts. They're all at 65ft-lbs currently -- same issue.

[Bill OH]

AA Ford has a headlight bar - is your license plate fastened to that bar in front of the radiator? Try blocking open the flaps on the shroud and remove the hood for a trial. I had an 8ba in a 53 Ford and had similar issues. After 8 years I traded for a 61 Ford 352. Have you checked the float level in the carb? Four turns out on the idle screws is a red flag. What is going on in that carb? And the vacuum is not steady.

[chap52]

You could lower that fuel pressure to 1 1/2-2 # should be plenty.
#1 plug cleaner that the others?
Is there any signs of water in the oil? milkyness...
Have you done a compression test? How close are the results?

I leaning towards water flow. If, as you reported it gets to 210 and won't cool back down I would check radiator flow before I did an engine removal and tear down. Also check those thermostats in a pan of boiling water and see if they open. Some "lesser mechanics" than us have been known to put them in backwards. lol

May be looking for an elephant when it is just a mouse in the house.

Keep us posted, Chap

[19Fordy]

Is your radiator the same size as the one used with an 8BA. Might be too small.
Radiator hose collapse? Use a puller fan instead of a pusher style. Have you tried water pumps with curved impellers? Are you using a shroud? Blown head gasket?

[rotorwrench]

I agree with others on the idle circuit screws being turned so far open. That is compensating for some kind of blockage in the fuel delivery system. It indicates a lean condition. The power valve may not be functioning as it should either.


The load-o-matic vacuum circuit on the 8BA carb is relatively simple. A person just has to make certain there are no leaks and that the venturi vacuum source is functioning as it should.


On an overhaul of an 8BA family engine a person needs to look down into the water jacket as best they can to check for signs of core wire or sand. I took an 8BA block to a ready-strip shop back in the 80s and had the operator tank it. The process filters the solution during the cleaning process. The operator took a coffee can full of core wire and sand out of that block. When he finished with it, it looked like new on the outside and the water jackets were visible all the way to the bottom where ever I looked in there.


Aside from proper ignition timing and fuel delivery, blockage or air leakage into the system is the major cause of overheating so all unknowns need to be checked to insure proper function. Pressure the system up and make sure it holds at least the amount of pressure that the system can take and hold it.


I know that this Model AA is modified a good bit but it is still a truck so it's heavier than the average Model A. The heavier weight vehicle usually has standard shift. The C4 requires vacuum to operate the modulator so make sure that that system is sealed up. Vacuum leaks can be a problem. Also, the automatic transmission requires cooling as much as the engine and even more so in some cases. Make sure the transmission cooling system is adequate for the job.

[Mike in AZ]

Do you have a pressure gauge to verify pressure setting? Mike

[19Fordy]

I think rotorwrench is on to something re: c-4 cooling. Are you running a transmission cooler?

[SonicRaT]

Originally Posted by Bill OH

AA Ford has a headlight bar - is your license plate fastened to that bar in front of the radiator? Try blocking open the flaps on the shroud and remove the hood for a trial. I had an 8ba in a 53 Ford and had similar issues. After 8 years I traded for a 61 Ford 352. Have you checked the float level in the carb? Four turns out on the idle screws is a red flag. What is going on in that carb? And the vacuum is not steady.

No license plate on the front bar -- nothing at all to impede radiator flow in the front. I don't have side panels on the hood and have tried without the hood entirely as well -- i could see the flaps working at speed.

The carb certainly has me baffled -- I'm not sure whats up with that idle circuit. I'm also not sure what causes a rapid bounce on the vacuum -- it's not a float, it's a violent bounce between 17-20".

Originally Posted by chap52

You could lower that fuel pressure to 1 1/2-2 # should be plenty.
#1 plug cleaner that the others?
Is there any signs of water in the oil? milkyness...
Have you done a compression test? How close are the results?

I leaning towards water flow. If, as you reported it gets to 210 and won't cool back down I would check radiator flow before I did an engine removal and tear down. Also check those thermostats in a pan of boiling water and see if they open. Some "lesser mechanics" than us have been known to put them in backwards. lol

May be looking for an elephant when it is just a mouse in the house.

Keep us posted, Chap

I figured that since I don't seem to be running rich and it seemed to make no difference from the gravity feed setup, that leaving it at 3psi would be fine -- I can try lowering it though.

Yes, the #1 plug is cleaner than the others, but just barely. No water in the oil. Need to get a compression tool and run the numbers -- used to have one but seem to have lost it when I moved a while back.

The thermostat are new and are working -- otherwise I'd have issues in other places than just highway speeds. Also, it previously didn't even have them and did the same.

It's running a modified version of this radiator that was ordered directly from Griffin -- the only difference is it's using a single, larger fan, and it has a larger bottom tank.

https://www.jegs.com/i/Griffin-Radia...70085/10002/-1

Originally Posted by 19Fordy

Is your radiator the same size as the one used with an 8BA. Might be too small.
Radiator hose collapse? Use a puller fan instead of a pusher style. Have you tried water pumps with curved impellers? Are you using a shroud? Blown head gasket?

See the radiator link above -- it's "supposed" to be made specifically for a later flathead in a Model A. I haven't visually seen a hose collapse while driving with the hood off on the upper hoses -- would I be able to test that more by just revving in neutral? It's already using a puller, so it's not blocking the fins in the front. It does have a full shroud -- you can see how it's designed in the link above -- just a larger big fan instead of two fans. Haven't seen any exhaust gases in the coolant yet, but it could be something weird with the head gaskets -- I have new ones and have been thinking of pulling the heads to search for the ticking noise and the bouncing vacuum. Haven't done anything to the water pumps -- they're new speedway units that came installed already.

Originally Posted by rotorwrench

I agree with others on the idle circuit screws being turned so far open. That is compensating for some kind of blockage in the fuel delivery system. It indicates a lean condition. The power valve may not be functioning as it should either.


The load-o-matic vacuum circuit on the 8BA carb is relatively simple. A person just has to make certain there are no leaks and that the venturi vacuum source is functioning as it should.


On an overhaul of an 8BA family engine a person needs to look down into the water jacket as best they can to check for signs of core wire or sand. I took an 8BA block to a ready-strip shop back in the 80s and had the operator tank it. The process filters the solution during the cleaning process. The operator took a coffee can full of core wire and sand out of that block. When he finished with it, it looked like new on the outside and the water jackets were visible all the way to the bottom where ever I looked in there.


Aside from proper ignition timing and fuel delivery, blockage or air leakage into the system is the major cause of overheating so all unknowns need to be checked to insure proper function. Pressure the system up and make sure it holds at least the amount of pressure that the system can take and hold it.


I know that this Model AA is modified a good bit but it is still a truck so it's heavier than the average Model A. The heavier weight vehicle usually has standard shift. The C4 requires vacuum to operate the modulator so make sure that that system is sealed up. Vacuum leaks can be a problem. Also, the automatic transmission requires cooling as much as the engine and even more so in some cases. Make sure the transmission cooling system is adequate for the job.

I thought the same with the carb issues -- which was why I went from gravity fed to the electric pump, but it made no difference at all -- even with the screws. It felt like my lowend torque might have picked up a little bit, so I think it helped with the accelerator pump (if they have them -- not sure on the 94's, but the two jets that'll spray when you pump the throttle).

For the distributor, I thought for sure that was the culprit with the vacuum diaphragm broken, but replacing it hasn't made a difference. I have tested it with a mityvac and it holds vacuum and looks to advance correctly. I haven't hooked a gauge to the venturi signal though as I only have the mityvac gauge and can't get it inside the vehicle -- would I be able to see any significant vacuum show up on it while parked and revving?

I have pressurized the coolant system to 12lbs and it held pressure for about 20 minutes.

The C4 has manifold vacuum hooked up -- I'm not sure if it has a slight leak, but if I pull the line to it the vehicle will stumble massively and just about stall until I hook it back up. The transmission has two coolers installed -- a heatsink style mounted underneath the bed to the rear and the radiator cooler. The transmission seems to operate well until the engine overheats -- when the engine gets to 220-230, it seems the radiator is actually heating the transmission fluid to the point where the transmission will start leaking fluid from the pump seal. I believe the C4 is supposed to stay around 175? I've considered just moving it to a standalone multipass cooler to avoid the engine heat all together. The trucks weighs about 3100lbs -- so I wouldn't think it'd be stressing the transmission out that much. My cruising RPM should be about 2200 RPM at 60mph with the gearing/tire combination (32" diameter tires).

Originally Posted by Mike in AZ

Do you have a pressure gauge to verify pressure setting? Mike

The fuel side? Yes -- I've verified it's at 3psi currently.

Originally Posted by 19Fordy

I think rotorwrench is on to something re: c-4 cooling. Are you running a transmission cooler?

As I mentioned above, it has a standalone, heatsink cooler and a transmission cooler in the radiator itself. There doesn't appear to be any issues with the transmission at all except when the engine temperatures exceed 220-230, then everything goes to hell. The transmission will start puking fluid out of the bellhousing, and the fluid temp will be around 220+ which I've heard is god awful for those transmissions. I don't have a temp gauge on the transmission side, so I've had to use infrared to get values from that. It only ever has issues when the engine has gone past 215+ -- anywhere else and it's completely fine.

[SonicRaT]

Here's a picture (if photobucket works for today) showing the radiator and the basic setup with no side panels.

[JSeery]

Are you sure the engine (radiator) is heating the transmission or is the transmission heating the coolant? I would de-couple them and see what happens. May well be the radiator creating the transmission issues, but it would be a fairly easy check.

[Kurt in NJ]

looks like 20% less radiator than a stock model a

[SonicRaT]

It's possible the transmission is the source of the excess heat. It was supposedly a rebuilt unit when it was dropped in. It shifts very well while driving and has done nothing to stand out with the exception of puking fluid when it gets hot. I was planning on getting a separate bar and plate unit to run them separately just to see if it made a difference. I wasn't sure if I could get by running just the heatsink style cooler on the transmission or if I should wait until I have a better unit as the primary.

Also, there's no brake dragging or anything of the sort -- the truck rolls extremely easily and nothing hangs up after hitting the brakes.

Originally Posted by Kurt in NJ

looks like 20% less radiator than a stock model a

With that giant lower tank, it reduces the front core size by about 14% over the standard griffin radiator, though it's about 1/2" thicker than the standard core. It was ordered directly from Griffin this way, so I'm hoping they wouldn't have knowingly sold it too undersized for the application, but who knows. I'd thought about picking up another radiator just to see, but they're not exactly on the cheap side of life. I have come across quite a few hot rods in the region running flatties on a smaller core than that with no issue, so I was giving the radiator a soft pass for the moment while I looked elsewhere.

For example, I met a local running this radiator with an 8BA with no issues -- and this core is about 3" shorter than mine:

https://www.coldcaseradiators.com/st...adiator/#tab-2



Forgot to mention -- I have checked the float levels and they're within spec. The needle was clean and looks to be one of the rubber tipped style. I believe the carb was new when installed on the engine as well. Is there anything specific to the Edelbrock 94 that would be different from the Holley? I haven't found a rebuild doc for the edelbrock 94 yet, so I'm not sure what to look for if I tear it down.

[Ronnieroadster]

Adding the C-4 transmission heat to the radiator is the first thing you should eliminate when i use the C-4 behind any Flathead an external cooler is used so no heat is added to the engine cooling system. Also another area many builders fall short on is the head gaskets used some head gaskets have very small water holes located in five critical areas. These small water holes reduce the amount of coolant that will flow from the block to the head this reduced flow allows the coolant to be super heated by the exhaust ports.
This lack of coolant flow especially when driving at highway speeds only gets worse since the exhaust ports are now getting hotter since the engine is turning higher RPM"S.
One thing you can do if your not already doing it is just run straight water not any mixture containing antifreeze. Straight water will dissipate heat better than anything else During my experience dealing with poor radiator core issue the only change i was able to make was adding just water doing that lowered the temp 10 degrees its not a fix for other issues but its a little something non the less.
Looking at the picture the lower tank seems large it would be better if the radiator core was longer to help cool. A thick radiator core is great however the thicker it gets the less those inner tubes can drop temp. Since heat from the front tubes is making it hard for cool air to reach those rear tubes.
All the above is from my actual experience dealing with similar heat issues seems to me no one thing is going to help its going to be a number of things to help you get the engine running cooler at highway speeds.
Ronnieroadster