Since the recent install I've suffered from a hot run primarily at highway speeds. I replaced the T-stat 180* with no change, so since I knew the total timing might be high, I focused alittle on that and took the 1st step towards a distributor re-curve. I did a base (with vacuum plugged) first and the figures are as follows:
15* @ idle (600ish)
25* @1500
28* @2000
35* @3000
38* @3500
She maintains 15" at idle
I welded a length of nail into the backs of the slots on a 15R govenor and reduced its lenth to .340 I effectively reduced my total timing to:
15* @idle
25* @1500
28* @All other RPMs
I have to say the car seems to have responded well to the changes,
though it's clear the springs will also need attention. But this did nothing for the heat condition.
What Gives>>>>
I have a pretty persistant exhaust flange to head pipe leak which hits directly on the block could this be related?
I have a new Modine Stock replacement radiator, it's for a non-A/C car, could this be an issue? Any interchanges?
Carter supersix, runs, idle and accelerates too well to be suspect...I think?
ZFR5Ns...Has anyone warmed up with these?
It does see up to 190* in traffic but has crested 210 on the highway.

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225 .030
.020 off the block .100 from head
Comp 264
904 Tranny
New Ebre-ting

http://s78.photobucket.com/albums/j103/edrod01/

210° isn't all that hot, really. What indications of an overheat condition do you have? Your timing sounds good, your carb and thermostat and radiator sound good...but that 15" of vacuum at idle sounds quite low unless you're at high altitude above sea level. Where're you located? Exhaust leak isn't helping you any, but is probably is not causing this condition.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm in Florida. I didn't check the vacuum while tinkering today, but I recall 15" from prior tunings I know I have seen it as high as 18".
Make no mistake the car hasn't "overheated" but I saw it rise north of 220* in some gridlock I caught after a little highway session. Seems pretty warm. I thought 15 " seemed low too, but chalked it up to the Comp Cam.

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225 .030
.020 off the block .100 from head
Comp 264
904 Tranny
New Ebre-ting

http://s78.photobucket.com/albums/j103/edrod01/

I don't think the 264° cam is "hot" enough to drop idle vacuum to 15". What's the overlap on it, and where've you got it installed (centrelined)? How's the engine idle? Smooth and slow, rough and fast...?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

When measuring the idle are you leaving it in park and checking, or is that in 'D' and checking? if in D that would be a little low, if in park---Houston we got a problem...

The vacc. will come up a bit when you get your timing dialed in (that 28 degrees was mechanical plus initial no vacc. advance yet, right?) and hopefully you degreed the cam.

-D.Idiot