Do you have a big fan you can put in front of the radiator ? And is there any coolant seepage from any of the head bolts I've found the ones between 3 and 4 are susceptible but then it can happen anywhere and you said its rebuilt so did the block and heads get the water passages cleared out well ? and what is the engine bored out to ?
We’re your plug readings normal?? A lean condition can easily cause this. I’d still suggest a good vinegar bath before making any other changes. If anything, it just may indicate you have “bed full”of core springs holding a whole crap load in your passages. I’ve seen plenty of those springs in the jackets. If one of them moved and started blocking flow. You may have to consider a tear down. Before I’d do that I’d come up with a makeshift system to check your coolant pressure coming off the top hoses.
Do you have access to a heat gunthisbis a good troubleshooting tool . It pains me to see your efforts without results so let's see if the heat gun can tell you where to look . The heat gun will tell you where not what but we need this now have you installed thermostats with a small hole drilled in it for flow relief ? If your coolant is running thru the radiator too fast it does not have time to cool so get on a welding glove a start it up and squeeze a radiator hose and see what happens if that alleviates then get some thermostats
125 miles is not enough to get everything worn in, especially rings where the friction will be greatest until they are well seated. I highly recommend a 4-row radiator on these things. I would let it run at 1K RPM for some hours and see if it loosens up. If the ring gaps are set too close it will take some time.
Did you check your hoses? There was a overheating / cooked motor thread recently that had the root cause as a old thermostat stuck in one of the return hoses. Could be a restriction of some sort.
A couple of thoughts first the nose opening of the car is extremally small definitely cool looking but a big problem for actual air flow needed to cool an engine especially a flathead. Second the fan shroud design is not allowing air to pass threw and into the engine compartment around its perimeter. The completely closed shroud other than the area that's open for the fan is actually causing the air coming in from the front to reverse direction since it has no place to go once it hits the inner shroud surface around the outer surfaces of the fan opening. Air needs to be able to not only pass threw the fan it should also pass threw the outer radiator tubes as well thus the air flowing into the engine compartment this helps pull heat off the core tubes as well. The closed off fan shroud design will not allow all the air possible to flow threw the core of the radiator. Ronnieroadster
MBC , Your temp readings don’t sound terrible really . Do you think the fluid from the C4 could be causing the temp to get up there a little bit ? But,,,,I completely agree with Ronnie’s post above as well . Tommy
I agree with Ronnie 100% on this. That kind of fan shroud does more harm than good. Good airflow needs a smooth transition to change direction, not a flat blockage. You'd be better off cutting away most of that shroud.
Drive it to Ronnie's house. It will either be broken in and running fine, or if not I'd bet he could tune it up for you.
eyeballing the plugs - 7 of 8 very rich one (#1 lean) induction one 4 bbl (used both holley and edelbrock) on a sharp manifold. right now zenith 2 bbl on french manifold thanks
Look at most higher-end shrouds.... they have any number of rubber flaps down low on the side that faces the engine. The purpose of these flaps is to allow air to flow through (bypassing the area of the fan) when you are moving, but when the fan kicks on (as in.. stopped in traffic) the fan in the center of the radiator provides enough suction to pull the flaps against the shroud, sealing off that flow path. I added flaps to the bottom of my 'flat' shroud and it helped a fair bit.
I had the same issue with a V12 water pumps from.skip and the issue was the shims on the block where the water pumps connect to the block
Engine fresh maybe 12 hours on it. Timing checked good with 2 diff dist. Im going t o do a radiator experiment today I hope thanks for your input
Been running with the nose off - I had the same problem with no shroud just fan - I'm going to try a radiator experiment in the next few days. I'll post results thanks to all for input
Think that's a good idea its looking like there's not enough radiator core to help shed off the heat. Ronnieroadster
I read through the thread, and I can't see if you changed your points and condenser. My distributor was rebuilt by Bubba several years ago, and was not overheating with a newly cored radiator. A couple of months ago, it started getting hot, even on cool days. DiFalco recommended changing the points and condenser. I did, set the gap and found TDC to set the timing. Overheating has been resolved. YMMV.
A flathead with a 1/8” overbore does need a large good radiator. Check plugs , possibly lean Check exhaust for no blockage Check each side of the flahead , remember each side is independent UNTIL it reaches the radiator. Did you use the correct head gaskets and install on correct side with the gasket notch in the correct spot ? I tried a flathead in a T bucket, I needed a 4 core radiator and extra homemade radiators along the framerails . I used older style water heaters for home baseboards. Its copper tube with aluminum fins . Not sure its still available.
Did that car originally have hand controls? If so, I knew the builder. It raced with the Golden Wheels club. It was a fairly good B main car. Ran with almost no weekly maintanence though. The first thing at the top of your list should be, check the water jackets for rust and MAINLY scale. The ONLY thing that will remove scale is stripping. The car ran cool when first built.
Like many others have said about the small grill opening and the timing are the first place to start. I have a couple of other things to add. 1. Run a 50/50 distilled water/coolant mix 2. Run two 180 deg thermostats (not 160 deg) with a hole drilled in the flange. The water is often moving through the system too fast and not getting a chance to cool in the rad. The 180 deg thermostat will fix that. This is are real flathead issue a lot of people just don't understand. A couple of things to note: 1. While running a higher pressure cap will increase the boiling point of the water in the rad you've got to be careful with this in a flathead. I think their coolant system was designed to run at 12 lbs. You may have other issues come up if you go higher. 2. The stock pumps are ok but if you compare the impeller design on the original compared to some modern aftermarket ones you will find the new ones have an angled blade design for moving more water. I'm not saying that's your problem.
All my shrouds are built like the one shown and work fine. It appears to be about 1” away from the core and will suck air by all the fins and tubes. Since it cools at idle I would agree with the thread that at the corners should have rubber covered holes that will open at speed adding more air flow past the tubes and fins. I believe todays fuel blend has to take some of the blame. Cars that were bought in the 50’s had no cooling problems and do today. Those in the know about flatheads and their cooling needs today are here and willing to help. The opening and radiator size in this instance seem to be contributing to the over heating a speed.
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