C2 Overheating/Timing/Vacuum Advance?

[Les Jacobs]

I recently purchased a 1963 with a 327/340HP believed to be stock. The engine runs well and maintains a solid 180 degrees at highway speeds. But at idle the temp rises to 220 plus (where I shut it down). I did a little testing and found that the vacuum is a little low at idle (12 psi), and the vacuum advance only provides about 1 or 2 degrees advance at that point.(Further testing of the vacuum advance showed that it was not leaking, but that it reached a max advance of about 7 degrees @ 20psi) The base timing is set for 6 BTDC so at idle the total timing is about 7degrees BTDC. My question is given that the timing should be around 14BTDC, could the 8 degree retardation be responsible for the hot idle? FYI I found a Mallory Unilite product replacing the points. Thanks in advance. Les

[Jack H.]

Re: C2 Overheating/Timing/Vacuum Advance?

(1) How is coolant temp measured? If via the dash gauge, you're fooling yourself, get a thermometer....

(2) Advance at idle sounds low, what does the shop manual call for?

(3) Mallory SS ignition isn't a bad item, but the Breakerless SE module is superior in my book.

(4) Hot engine at idle and normal when driving points to the fan clutch and fan shroud sealing. Hot engine at highway speed and normal temp at idle points toward the water pump and radiator core integrity.

[Duke W.]

Re: C2 Overheating/Timing/Vacuum Advance?

Replace the vacuum can with a NAPA Echlin VC1810 - 16 degrees max at 8". Set the initial timing at 10-14 (vacuum can disconnected); 12" at 900 is about right for a Duntov cam.

Duke

[Les Jacobs]

Re: C2 Overheating/Timing/Vacuum Advance?

Jack, I measured the temp with a thermometer taped to the radiator.

2. Advance spec at 700rpm, 0 base, plus 14 degrees for the vacuum advance. Im measuring about 6.

4. I was thinking fan clutch too, but decided to investigate the timing first since there were other symptoms ((stumbling when taking off in low gear)).

So the question is, could a 8 degree retardation in timing result in overheating

[Wayne W.]

Re: An The Answer Is ?

A definite Maybe, but not likely , not totally. The more advance, generally the cooler, but, it probably is not the whole cause. As Jack says, hot at low speeds usually indicates low air flow. That translates into Fan, Fan Clutch, Shroud, Seals, etc. with the timing contributing.