'67 L-79 Vac Advance Unit

[Craig Jewett]

Does anyone know where you can obtain an exact replacement for the vac advance unit? I am aware that CC sells one for $ 41.95 (!!), but just because it has the correct number (236) stamped on it, does that mean it will provide the correct rate of advance ? It should provide 0 degrees at 4 inches of Hg and 16 degrees at 7 inches of Hg, according to the '67 Chassis Overhaul Manual. Or am I worrying too much and will any new one that's available through NAPA going to suffice, considering how the car is now driven ?

Thanks in advance..

Craig Jewett '67 L-79 A/C coupe...

[Joe L.]

Re: '67 L-79 Vac Advance Unit

Craig----

The GM #1116236 vacuum control has been discontinued for many years. You might be able to find an NOS example around, but you will probably have to pay dearly for it. Very likely, much more than CC is charging for what is probably a "reproduction".

Original GM Delco-Remy supplied vacuum controls had two sets of numbers stamped on the underside of the control mounting bracket. The first set of numbers was a 3 digit series and represented the last 3 digits of the control part number(in this case "236") the second 2 digit series of numbers represented the maximum advance that the particular unit could produce. These numbers are very difficult to see when the control is mounted on the distributor and installed in the car.

All of the "modern day" distributor vacuum controls that I've seen, even the ones still available from GM under the original part numbers, lack these inscriptions. That's because I don't believe that GM actually makes these anymore since GM dismantled their distributor manufacturing operations in Anderson, IN. Consequently, these parts are now made by a vendor and supplied to GM for service.

Aside from the inscriptions, the "modern-day" controls, both the GM and aftermarket(which are probably supplied by the same vendor)have a very slightly different external configuration. This difference is so slight that I would not be concerned about it. In any event, the aftermarket (NAPA) vacuum control will work perfectly.

[Joe L.]

Re: '67 L-79 Vac Advance Unit

Craig----

The GM #1116236 vacuum control has been discontinued for many years. You might be able to find an NOS example around, but you will probably have to pay dearly for it. Very likely, much more than CC is charging for what is probably a "reproduction".

Original GM Delco-Remy supplied vacuum controls had two sets of numbers stamped on the underside of the control mounting bracket. The first set of numbers was a 3 digit series and represented the last 3 digits of the control part number(in this case "236") the second 2 digit series of numbers represented the maximum advance that the particular unit could produce. These numbers are very difficult to see when the control is mounted on the distributor and installed in the car.

All of the "modern day" distributor vacuum controls that I've seen, even the ones still available from GM under the original part numbers, lack these inscriptions. That's because I don't believe that GM actually makes these anymore since GM dismantled their distributor manufacturing operations in Anderson, IN. Consequently, these parts are now made by a vendor and supplied to GM for service.

Aside from the inscriptions, the "modern-day" controls, both the GM and aftermarket(which are probably supplied by the same vendor)have a very slightly different external configuration. This difference is so slight that I would not be concerned about it. In any event, the aftermarket (NAPA) vacuum control will work perfectly.

[Jack H.]

Re: '67 L-79 Vac Advance Unit

Joe gives you solid advice regarding original, service replacement and aftermarket functional equivalent. Some Corvette catalog house claim to have a limited supply of original AC-Delco vac advance units and checking (via phone) on the single/dual markings is a smart move prior to purchase.

If you have the original unit and it simply looks bad, you might think about removing it and re-doing the surface plate. If you've lost the original then the universe is two-fold, a correct used original or and old NOS GM service spare. Either will be pricey compared to a NAPA functional equivalent.

[Jack H.]

Re: '67 L-79 Vac Advance Unit

Joe gives you solid advice regarding original, service replacement and aftermarket functional equivalent. Some Corvette catalog house claim to have a limited supply of original AC-Delco vac advance units and checking (via phone) on the single/dual markings is a smart move prior to purchase.

If you have the original unit and it simply looks bad, you might think about removing it and re-doing the surface plate. If you've lost the original then the universe is two-fold, a correct used original or and old NOS GM service spare. Either will be pricey compared to a NAPA functional equivalent.