[alanmay0]

OK I have to make one major correction in my narrative. I bought the car in Florida in December on 2021. It was in ugly shape and needed major restoration work. It had a aluminum intake manifold and a elderblock carb on it. It had an aluminum radiator with one 12 inch cooling fan. The engine was horrible looking so that is why I decided to take it out and have it rebuilt, repainted and then we sanded and repainted the engine compartment. I did drive this car from Florida To Texas, about 750 miles with no over heading issues that I was aware of. At this time the temp gauge was not working so it always read all the way to the cool side. turned out it was the sending unit was bad. So taking this into consideration something must have changed during the rebuild that is now causing the engine to run really hot. I will change this info in my first post. sorry for this.

really hope someone can help me figure this out so that I can drive the car.
thanks again.

[25stevem]

The picture in your post 20 is of a 69 and up timing cover with the two gray metal sleeves and the o-rings in the face of those sleeves.
The 64 thru 68 water pumps / timing covers do not use those.

[Cliff R]

So you don't know what pistons in it or the specs of the camshaft.

IF it was rebuilt at some point with those 8 valve relief POS pistons that are often .030-.050" in the holes at TDC, and a cam that's not degree'd correctly, that may be all of or a MAJOR part of the issues you are seeing.

1967 waterpump and pump speed (pulley diameters) systems aren't that great right to start with, which can also contribute to running hot.

I've ran into several 400's over the years of working on these cars that ran really hot. They would heat up very quickly, go right past 200 degrees and peg the gauge minutes later.

I cured one of them (1967) by retarding the cam 4 degrees AFTER doing everything possible in every other area to get it to run cool. This included a HUGE 4 row radiator, 7 blade HD clutch fan, later timing cover/pulley/waterpumt set-up, etc, etc. NONE of those moves cured it, helped superficially, but it still ran WAY too hot for my liking.

While the timing cover was off I noticed one of those POS 3 keyway roller timing chains, but didn't pay it much mind at the time. I went back into it, and discovered someone had advanced the cam 4 degrees. I put it back to zero (dot to dot) and from there on we had trouble getting the engine to heat up. It wouldn't go past 180 degrees no matter what you did or how you ran it.

Got involved with another 400 a few years later where someone had installed those 8 valve relief pistons in it. They were over .035" in the holes at TDC combined with a thick head gasket. Removed them, went to flat tops, zero decked the block, .039" head gaskets and that cured all the issues. Like the other 400 we had trouble getting it to heat up vs the gauge going right past 200 and headed for 250 degrees.......

[alanmay0]

wish you were my neighbor. thanks

[25stevem]

i Know you posted that you tested the cooling system for combustion gases, but at 135 and with the motor at a idle when you remove the cap it should not have pressure like that to release.
Like stated in post 26 you may have a air pocket up in the heads where no coolant is getting to.

The cure is to fill the Cooling system with the rad cap off as the motor warms .
Once the stat opens let the coolant rise until it just about over flows and then put the cap on.

[prostreet64]

Have you inspected the plugs? If you have one that is really 'clean' compared to the others then you probably have a head gasket leak and water is getting into that cylinder and exhaust gas is getting into the coolant. Had this happen on the Bird recently and had a hard time tracking it down because none of the classic symptoms of a head gasket leak were evident. May not be the issue but really easy to check out.

[alanmay0]

I will check this out tomorrow when the engine is cold. thanks for the suggestion

[alanmay0]

will do this when the engine cools down again.. thanks

[25stevem]

I would bet that the bank of the motor who’s center exh ports read 295 has the bad head gasket , but I would replace both gaskets along with the normal things like Checking the head and deck surface for straightness of .002 or less, , replace the head bolts and clean out all the head bolt holes so that a bolt can be threaded in with light finger force.

[alanmay0]

spark plugs from driver side

[Joe's Garage]

That way, when you run the engine, any air will bleed of fairly quickly.

There should not be ANY bubbles circulating in the system when the water is full and it is at operating temperature. None.

Any bubbles, particularly a steady stream of little tiny bubbles indicate a leaking gasket. Not blown, just leaking.

I think your spark plug for #5 looks a little too clean compared to the others. That would be where I would look first.

Good luck!

[alanmay0]

would this cause the engine temp to go up to and past 250 degrees

[prostreet64]

you bet, super heated exhaust gas will heat up the coolant very fast, of course depending on how compromised the gasket turns out to be.

[Joe's Garage]

We had a 'leaker' that would fluctuate between 230 and 250* steadily up and down. Never overheated, just ran hot and fluctuated.

And there was always a steady stream of tiny bubbles in the coolant.

Gasoline's ignition/burn temp is 495*, and the temp inside the combustion chamber, with the gases burning under pressure, is around 2800* and can approach 4000* under certain circumstances.

So, YES, even a small amount of combustion gas will heat the coolant up really quickly.

["QUICK-SILVER"]

Originally Posted by 25stevem

I would bet that the bank of the motor who’s center exh ports read 295 has the bad head gasket ,

I would have to compare end exhaust port temps on opposite head to rule out carb adjustment or a vacuum leak.

Clay

[alanmay0]

what temp would you be looking for at the rear exhaust ports to determine if things were ok?

[Half-Inch Stud]

Crud for thought:

Just maybe, if there is 1-hot CYL, then there is an exhaust valve not opening enough, meaning bad cam lobe and loose Rocker arm if PolyLocks were used. Rocker may show tight for factory rocker nut and Lifters that were not pumped up when tightened.

[alanmay0]

I will take temp of spark plugs when I run it again. thanks

[alanmay0]

here is a picture of the spark plugs on the drivers side that hat the 290 degree temp on center exhaust ports. also a short video of the water in the radiator as it is running. Let me know if the bubbles you see could be a bad head gasket. thanks. Is there a way to upload a very small mp4 file?

[rtp]

I had one brought to me heating on occasion...owner tried everything.
Recent rebuild on a 4.181 bore 428 with 6x heads purchased somewhere.
I decided to pull the heads and found a soft plug in the water passage at the front of the head on one side...opps. Runs a lot cooler with that head flowing water now.
Also upgraded to 17 inch core support and the ac radiator with stock shroud and clutch fan and an edelbrock pump. Cam is on 109 center and 32 total...runs 180 all day long