Correct (best) vacuum advance 1976 L-48

[Patrick H.]

In trying to check out the 76 high idle, I see that the vacuum advance has 62118 stamped on it.
Does anyone know what this is? Google doesn't tell me much.
Or, better yet, is there a recommended one?

L-48 automatic car, no modifications to it, 1112888 distributor.

[Joe L.]

Re: Correct (best) vacuum advance 1976 L-48

In trying to check out the 76 high idle, I see that the vacuum advance has 62118 stamped on it.
Does anyone know what this is? Google doesn't tell me much.
Or, better yet, is there a recommended one?

L-48 automatic car, no modifications to it, 1112888 distributor.

Patrick------


Well, the original vacuum control was GM #1973517. I don't know if that's the best, though. The Standard Motor Products replacement is VC-211. I don't know what 62118 denotes. Probably some aftermarket part number.

[Patrick H.]

Re: Correct (best) vacuum advance 1976 L-48

I don't know what 62118 denotes. Probably some aftermarket part number.

That was my assumption as well, but I can't find reference to it.

[Joe L.]

Re: Correct (best) vacuum advance 1976 L-48

That was my assumption as well, but I can't find reference to it.

Patrick------

The only manufacturer of these vacuum controls for the past many years is Standard Motor Products. Regardless of brand sold under, including ACDelco, Standard Motor Products has been the manufacturing source. They don't use a numerical series such as the one you mentioned to identify any of their vacuum controls. So, I expect that the source of the 62118 id number is one of the "extinct" manufacturing sources that once-upon-a-time made these things.

[Duke W.]

Re: Correct (best) vacuum advance 1976 L-48

Look up the VAC specs in the CSM or AMA specs, and also measure vacuum idling in Drive. OE vacuum advance was ported, but if it's been converted to full time (which I recommend) it probably needs a different one. Is the VAC signal still ported? If converted to full time idle speed will increase, but it's simply a matter of going through the idle speed/mixture adjustment procedure to correct.

A vacuum leak will increase idle speed, but it will usually be rough due to a lean mixture. The L-48 should have a smooth idle. It's basically a stroked, low compression version of the 327/300 with a Quadrajet instead of an AFB or Holley.

Lars' VAC listing gives the stamped ID number and NAPA/Echlin part number, but we might be able to match it to one of the listings based on specs.

Duke

[Patrick H.]

Re: Correct (best) vacuum advance 1976 L-48

I'm sure it is still ported, as it's in stock configuration.
You can read more about the problems we're having here: https://www.forums.ncrs.org/showthre...L-48-automatic
The last thing I need is a higher idle speed on this car.

I'm just trying to think it through before I travel over and spend more time on the car.

[Dick W.]

Re: Correct (best) vacuum advance 1976 L-48

Patrick------


Well, the original vacuum control was GM #1973517. I don't know if that's the best, though. The Standard Motor Products replacement is VC-211. I don't know what 62118 denotes. Probably some aftermarket part number.

Shows to be still available from GM and AC/Delco