I removed my Glen-Ray re-cored radiator and I'll perform this test when I install a radiator that I am borrowing from a friend.
My radiator overflowed quite a bit with a 16 lb cap, and a 50/50 glycol/water mix, every time I shut her down after it hit 220 degrees.
I can't find any info on a cavitation plate or a plate on the vanes. Can anybody explain this and if I can purchase a cavitation plate? Would a water pump cavitate at 3,500 rpm or only at much higher rpm?
Would it make sense to purchase and test a slightly smaller water pump pulley to spin the water pump faster, maybe 6" or 6 1/4"? If so, where would be the best place to purchase smaller pulleys?
Since the radiator is stock it should have been properly sealed to the core support. I never heard anything from my 18" clutch fan. Plus, I'm under the impression that the fan wouldn't have much effect at 75 mph.
I had my radiator restored at Glen-Ray because of the original overheating issue. Since Bob installed a new 3 row core the fins wouldn't be an issue.
My initial timing is 12 degrees and all in @ 33 degrees @ 1,800 rpm (vacuum advance disconnected) and with the vacuum advance connected all in @50 degrees @ 2,200 rpm.
My spark plugs are Champion RN12YC. Attached are pictures of their condition. There doesn't seem to be a lean condition. The step-up rods for my stock 1969 340 AVS for a 4 speed, are correct. The original 1969 340 spark plugs are Champion N-9-Y. Could the difference in the spark plug heat range cause this much of an overheating issue?
I started this reply yesterday and left the page open. I didn't responded immediately because I was doing more research. I see there are some more replies didn't show up in what I read and responded to yesterday. I will respond to them in another post.
Thanks to everyone for all the feedback.
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