1966 engine temp

[Duke W.]

Re: 1966 engine temp & HEI

Ported vacuum advance was an early emission control strategy. The engine will operate better (lower fuel consumption, less tendency to run hot, and better normal street and highway speed driveability) with full time vacuum advance, but it's usually NOT just a matter of replumbing the vacuum can signal line. It often requires substitution of a different spec vacuum can and recurving the centrifugal.

I would have to know the specfic year, engine option, and OE ignition map specs to make a recommendation.

The only C2s with ported vacuum advance are '66-'67 CA models. Also ALL L-72s have ported vacuum advance, and I think all L-71s are also ported. My theory on this is that L-72/71 were set up to comply with CA emissions and this version was sold in all 50 states because, as a low volume option, Chevrolet chose to sell these engines in just one configuration as a cost/inventory savings measure.

A number of L-72 owners have switched to full time vacuum advance along with installing a different vacuum can and report better overall driveability, and in particular, less tendency to run hot or overheat.

Duke

[Tom H.]

Re: 1966 engine temp

Dennis- You could find a stock distributor and put in a Petronix conversion of buy the MSD Corvette distributor and use that with one of their great ignition boxes.

[john pickens]

Re: 1966 engine temp

Duke...

My 65 numbers matching 327/350 with A/C roadster has carb list 2818 Holley
but is clearly arranged with ported vacuum setup. Should I assume this is not
original arrangement? Another question- Can the vacuum can on the vehicle at present be replaced with the one you routinely recommend(the NAPA 1810) without removing the distributor? If so seems like an easy mod with the full vacuum for better drivability.

[John H.]

Re: 1966 engine temp

The vacuum advance unit can be replaced with the distributor in the car, but I'd recommend pulling it out and going through it anyway (it's probably never been touched since 1965). Good opportunity to tear it down, check bushing wear, re-shim the drive gear, clean out and re-pack the upper lube well, replace the felt lube washer for the breaker plate, make sure the breaker plate moves freely and doesn't wobble, clean up and lube the autocam and weights so they move freely, clean out and re-lube the tach drive cavity and cross gear, check/replace the advance limit bushing, etc. No special tools required, very satisfying bench job, and you'll feel the difference; also presents the opportunity to take it to a shop with a distributor machine when you're done and have the curve set up properly. Never saw a 2818 that didn't have full manifold vacuum at the advance line connection.