Engine trouble

Where are the spark plug washers??? Are you using them??? #2 cyl. is partially fouled. #6 & 8 cyl. look a little lean compared to the drivers(left) side #1-3-5-7

 

I'd be looking at the radiator and hoses. Squeeze the bottom hose to see if it collapses.
You haven't said but I assume the radiator water is clean/clear. Should always have some antifreeze it there, not just clean water.
Mine is an odd green colour but otherwise clean. When you fitted the new water pump did you fit the same type? There are different fin counts for AC and non AC cars.

My Nailhead overheated for a while, traced it to an inlet manifold leak, my mistake on assembly. Also found several small inlet leaks in manifold and carb. Fixing all those helped but wouldn't cause your issue I would think.

What was the car/engine/driving history BEFORE it overheated? Had it been well behaved?

 

Plugs look decent to me, I'd go with sticky thermostat (not opening all the way) or plugged radiator.

 

check the basic timing mark on the viberation damper.... I have found some to be off center.... install a piston stop in no 1 cyl and GENTLY, BY HAND ROTATE THE ENGINE BOTH WAYS UNTILL IT STOPS AND MARK THE LOCATIONS... then measure half way between those marks and that is your actual TDC .... then figure your timing from there....
also has the engine ever been rebuilt without replacing the cam bearings ???? if so , that is your source of low oil pressure....

 

"Where are the spark plug washers??? Are you using them???"
- None of those installed, didn't know they were standard, I'll get some on there.

"#1 cause of high speed overheating is a plugged up radiator."
- Yeah, probably not a bad idea, I just need to be on top of the cause, so I don't band aid it, and it only seems fixed.

"Squeeze the bottom hose to see if it collapses"
I'll take a look.

"When you fitted the new water pump did you fit the same type? There are different fin counts for AC and non AC cars."
Not sure on that, I believe there was only one version available when I ordered, and the car doesn't have A/C any longer.

"What was the car/engine/driving history BEFORE it overheated? Had it been well behaved?"
It's been a while, but I think it was pretty well behaved, and stayed pretty consistent on flat surfaces. On a hot day, when going uphill, it would heat up a bit, so it wasn't flawless for sure.

"I'd go with sticky thermostat (not opening all the way)"
Installed one in Phoenix, there wasn't one in there. It would probably help a bit to remove it, but it doesn't solve the cause.

"has the engine ever been rebuilt without replacing the cam bearings ???? if so , that is your source of low oil pressure...."
I think the oil is compromised, I'll try some new oil first

"check the basic timing mark on the viberation damper.... I have found some to be off center"
I need to get the dial back light so I can get a handle on that part first, I'll keep this in mind though.

 

Overheating a motor a few times, especially if it's a old stock motor can take the temper out of the rings and make for oil burning and loss of power of course!

 

You need to do a couple of tests before you do anything else or start spending money... first run a good basic compression test on all cyls... that will tell you if you have popped head gaskets, or cracked block or head that is causing the heat problem....
then, run a cooling system pressure test... that will reveal all of the above plus tell you if you are losing coolant thru a bad freeze plug , hose, ect... if both of those show good... then start looking at water flow thru the rad. air flow thru the rad... collapsed lower hose,,, stuck exhaust butterfly valve... plugged INNER exhaust pipe... ect...

 

"You need to do a couple of tests before you do anything else or start spending money..."
Yeah, that's what I'm thinking too, try to keep it logical, and not buy five things, and it's maybe one of them.

I took another look at the car today, and installed the plug rings. When I went to drive it it wouldn't shift, and I had another issue on my hands to sort out. It was acting up, and i drove it back home, and saw that the hose for the vacuum thingy on the side of the transmission was off. I sorted that out and took it for another spin, and the hesitation in the engine seemed to be gone, but when it idles, it's like it misses a beat every now and then, but it's always had kind of a rough idle. It is pretty cool today, around 70f, so it was a good day to test it, since there wouldn't much of an external influence on the situation. I took it out on the freeway, and it climbed past 180f, and headed towards 195f, and I turned off. On a day like this, it should have remained around 170-180 (used to). If it just sits and idles, it's dead on 180f. I wonder if the thermostat I installed is a 180f version, and that's why it holds exactly there, and I could try a 160f, and see if that helps the situation. Someone had also removed it previously, so maybe it has always needed a free-flowing water system, and I've made it worse by installing the thermostat?

I'll do the compression test, the more that's known the better.

Thanks for the help guys.

 

When it was back from the freeway run and still running, I tried to check the radiator hoses, and they felt uniform and didn't seem to collapse in any particular area. I tried to rev it a bit to see if anything would change, and the only thing that happened was that the car alarm on the Honda that was parked behind it went off, lol.

The fan clutch felt like it had some resistance to it, but not too much. How do you check that?

I just did a compression check on it, and it looks something like this. One of them seemed high, so I redid that one, and the numbers moved down a bit, so who knows how accurate this is (Harbor Freight gauge), but it's at least a good baseline.


- Distributor -
140 - | - 132
150 (165 first run) - | - 128
147 - | - 132
124 - | - 132
- Fan -

 

Here's something that's free to do. Gap your plugs correctly. I just did that on my Riviera and it went from missing occasionally at idle to never missing again. Just a thought since you said it was missing, though it does not solve the overheating issue. Good luck

 

To get a 30 deg mark is easy
Opposite 0 deg is 180, evenly between them is 90, divide 90 into 3 equal parts is 30 deg done

 

been chipping away at the things to look at, and got a 160 degree thermostat installed, an it now idles at about 165f instead of 180f.

I also changed the oil in it, and it still seems like it drops the pressure to about 12-13psi after it has warmed up properly. This seems to be standard after doing some googling around on Nailhead oil pressure, so it's less of a worry.

With my newly acquired dial-back timing light I managed to extract the following:

Initial : 11 degrees (vacuum plugged)
Vacuum: 23 degrees (vacuum connected)
Advance: All-in @ 2,000 rpm, with a 16 degree advance in addition to the initial 11 degrees for a total of 28 degrees (vacuum plugged)

After running through this in the morning I took it out on the freeway, and it's still running hot. I made sure to run it up to 3,000 rpm / 65/70mph to do a thorough test. The temp gauge climbed up to about 195, so I hopped off and let it cool down for a few minutes, and drove it back. on the way back I held the revs down, and it warmed up a lot slower than when I went straight to 3,000.

One more change that I did before the Tucson trip was to change the axle ratio to 3.42:1 from a 3.08:1, and I also went with a slightly taller tire to compensate a bit. The car drove fine for hours before overheating, so I don't think this contributed in any major way in regards to the temp going up.

 

If I'm reading this right, you have 40 degrees advance going down the road with the vacuum advance connected. That's enough that it shouldn't be a problem. It doesn't heat up at idle, so your fan seems to be working fine. It only heats up at freeway speed, but not severely hot, like there's a crack somewhere or a blown head gasket.

It sure sounds like a dirty radiator to me. Do you have a radiator shop nearby that could check it and perhaps boil it out?

 

Yeah, it would be nice to confirm the 23 degrees with vacuum + the 16 mechanical advance @ 3,000 rpm, so that's settled.

The problem with the radiator in the Wildcat cat is that the inlet/outlet is top passenger side and bottom driver's side. The core is 28", with a total width of 34", so it's almost like a pickup truck size. The one in there is a "Harrison", and I read that GM changed to Delphi in '95 and stopped the Harrison brand at that time, so it's at least 20+ years old, and it's a two-core.

 

Have the radiator recored with a 3 row core and install a new water pump for an air conditioned car if you haven't already.

 

I'm back with some new data. My mom is visiting, so she had to handle the throttle on the carburetor while I took the readings, lol.

To recap from before:

Initial : 11 degrees (vacuum plugged)
Vacuum: 23 degrees (vacuum connected)
Advance: All-in @ 2,000 rpm, with a 16 degree advance in addition to the initial 11 degrees for a total of 28 degrees (vacuum plugged)


Now, with the vacuum connected:

RPM | Degrees timing

900 | 33 degrees (same as above: 11 initial + 22 vacuum)
1700 | 44 degrees (it's started the advance slightly)
2400 | 49 degrees
3200 | 51 degrees

The readings for the last two could possibly be the same, since it should stop advancing at around 2,000 rpm according to the initial reading.

I'm not sure when the vacuum advance should be going away? It's been mentioned that it isn't active during WOT, but if it doesn't go away by 3,200 rpm, does that mean the engine is over-advancing and causing problems?

The first couple of posts here talks about the various advances being added up, and someone thinks 52-53 @2,800 is what he's looking for, and the next post says that anything over 50 would self destruct by them time you're at the end of the 1/4 mile:

https://www.jalopyjournal.com/forum/threads/quick-question-about-distributor-advance.505665/


Any thoughts?

Thanks!