OVERHEATING

AJ/FormS said
At 3500 your Cruise timing should be at least 50>56 degrees.

...The reason for that, principally is that the huge 7-blade fan runs on an HD thermostatic clutch, which cycles between almost full slip and full drive, in accordance to what the temp is, of the air that is coming thru the rad.
The waterpump on mine is UNDER-driven in an effort to keep the belt on at 7200 rpm. And yes, she runs an 8-vane pump with an anti-cavitation plate.
But I gotta tell you the whole truth, the first year that she was on the road, I had a heckuva time keeping her cool. Even the second year. And like you, I tried everything.
Finally I took the engine down and honed the holes out another half a thou, and increased the top-ring gaps by IDK, maybe .003>.005. Badaboom, problem solved.
So, IMO, when all else fails, you gotta think about the ring-gaps. If/when you get a lotta heat in the chambers, sooner or later, that heat is gonna find it's way into the pistons and rings. When the rings swell and the ends butt, Bam! you got instant mega-friction, which makes heat.

My timing with the vacuum advance connected is all in @50 degrees @ 2,200 rpm.
I do have the huge 7-blade 18" fan and the thermostatic clutch.
I hope to heck there is nothing wrong with the tolerances in my engine. I had a reputable shop balance and blueprint it.

1969383S said
Is your Cruise AF mixture and timing correct or lean?

Pictures of your setup go a long way to helping resolve your issues!

I don't know what the cruising A/F ratio is. I do have the stock AVS step-up rods (No. 16546- .065" x .063 x .055). I don't think it will help, but attached is a picture of my engine before I removed the radiator and the water pump.

RustyRatRod said
"What" exactly are we reading? Idling in the driveway? Full throttle blast? It helps to know.

All of the above, including quite a while at high idle to change the oil. The plugs probably have 1,000 miles since I cleaned them. I also went up one size on the secondary jets, from the stock .095 to .098. I read that "if the firing end of is spark plug is brown or light gray, the condition can be judged to be good and the spark plug is functioning optimally." My plugs' firing end appear to be light gray.

12many said
A simpler way is to get a Gates 42026P. or similar version. Whether cavitation is an issue or not, I use these anytime I need a new wp.

That particular Gates Water Pump has the lower radiator hose outlet on the passenger side for 70 and up. The 69 Gates Water Pump has the 8 vane instead of that impellor shown in the 12many Post. Is that impellor more efficient and better at not cavitating? I'd say that fabricating and welding a cavitation plate seems to be over my head.

Scamp Rhonda said
I think you need to go back to the day that it didn't overheat and work your way forward, troubleshooting what changed to make It overheat. There is a reason why it's doing this. You'll figure it out. Check the simple things first. Don't Over complicate the thought process. Don't change parts because you're guessing. I'd make sure you have good air flow through the radiator before I did anything else. My 2 cents. Good luck!:thumbsup:

This is excellent advice. Regrettable, I never drove the Swinger on the expressway before I had the current 340 rebuilt, because I too many problems with the prior 340 block that was in the car when I purchased it. I eventually figured out that the timing gear was one or two teeth off.
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My radiator cap is a relatively new stock 16 pound cap from Mancini Racing.

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