L88 Vac Advance (?, no nipple) Can

[Wayne M.]

I see that Delco Test Spec's book shows the vac can for the '67 (1111240); '68 (1111295) and 1969 (1111927) distributors all call for can # 1115373. Same Delco book has a note opposite the can # that says "used only to secure circuit breaker plate". Further, in the Delco section for vac can spec's, there is NO 1115373 listed.

Now, one has popped up on eBay, and close-up shots of the flat of the mounting bracket reads "MS 373 12" If there's no advance, what's up with the "12" ?

[Duke W.]

Re: L88 Vac Advance (?, no nipple) Can

I know for sure that the '67 VAC nipple was cut off to prevent anyone from attaching a hose. Beyond that it was a fully functional VAC AFAIK.

It's possible that the 1115373 VAC was manufactured for a specific engine configuration, but never used for a production engine due to a change in spec before the engine was released. The part number would indicate an approx 1961-3 release date, so these had probably been in inventory for a few years.

Thus the "373" would be useless until another application came along, or in the case of L-88 a VAC was just required to locate the stationary pole piece of the TI. The specs were irrelevant.

Another alternative would be to come up with a bracket to locate the pole piece. One was made for the HEI distributors and was OE on my Cosworth Vega, which did not have an OE VAC.

So GM came up with a use for the 373 VAC, which means at least some of them - a little over 200 - didn't have to be scrapped.

The "12" indicates that the VAC provides a maximum advance of 12 crank degrees.

Perhaps the reason why the specs are not listed is that the 373 was only used on L-88 with the nipple cut off, so the specs are irrelevant.

The 1115373 VAC was available through service parts and is listed in the P&A catalogs I have, which range from '77 to '80. I don't know if the nipple was cut off the service part, but I expect it was. The only listed application is '67-'69 427 HD w/chain drive cam.

At some point the aftermarket came up with a bracket to locate the breaker plate/pole piece for single point/TI applications like racing engines where a VAC is not required.

Does this 373 on ebay have the nipple intact or cut off?

Duke

[Wayne M.]

Re: L88 Vac Advance (?, no nipple) Can

I know for sure that the '67 VAC nipple was cut off to prevent anyone from attaching a hose. Beyond that it was a fully functional VAC AFAIK.

It's possible that the 1115373 VAC was manufactured for a specific engine configuration, but never used for a production engine due to a change in spec before the engine was released. The part number would indicate an approx 1961-3 release date, so these had probably been in inventory for a few years.

Does this 373 on ebay have the nipple intact or cut off?
Duke

Duke -- here's the eBay link -- too bad seller didn't provide an overall pic showing the advance arm (fixed ?). Nipple is just a pimple.

http://cgi.ebay.com/ebaymotors/1969-camaro-ZL1-Corvette-L88-373-vac-advance-427_W0QQitemZ330274240199QQcmdZViewItem?hash=item330274240199&_trkparms=39%3A1%7C65%3A10%7C240%3A1318&_trksid=p4506.c0.m245

Checked my four volumes of Delco DR324S specs, and the 1115xxx series vac advance first shows up in the '64-66 revision of the 56-63 supplement to the first edition. But the specific 1115373 can first appears related to distributors in the '64-68 revision (on L88 distrib's).

[Duke W.]

Re: L88 Vac Advance (?, no nipple) Can

The photo matches my recollection that the nipple was rather crudely cut off.

Duke

[Michael H.]

Re: L88 Vac Advance (?, no nipple) Can

Duke -- here's the eBay link -- too bad seller didn't provide an overall pic showing the advance arm (fixed ?). Nipple is just a pimple.

http://cgi.ebay.com/ebaymotors/1969-camaro-ZL1-Corvette-L88-373-vac-advance-427_W0QQitemZ330274240199QQcmdZViewItem?hash=item330274240199&_trkparms=39%3A1%7C65%3A10%7C240%3A1318&_trksid=p4506.c0.m245

Checked my four volumes of Delco DR324S specs, and the 1115xxx series vac advance first shows up in the '64-66 revision of the 56-63 supplement to the first edition. But the specific 1115373 can first appears related to distributors in the '64-68 revision (on L88 distrib's).

Difficult to tell from the ebay pic but this one appears to be the later issue service replacement unit that had only a bump in the area where the nipple would normally be. As far as I know, this later replacement style was never used on any production engine.

Original 373 67-69 L88 vacuum advance units appear to have had the nipple broken off to prevent use of the unit. Close inspection shows that the nipple was removed after the part was plated.

[Clem Z.]

Re: L88 Vac Advance (?, no nipple) Can

Difficult to tell from the ebay pic but this one appears to be the later issue unit that had only a bump in the area where the nipple would normally be. As far as I know, this later replacement style was never used on any production engine.

Original 373 67-69 L88 vacuum advance units appear to have had the nipple broken off to prevent use of the unit. Close inspection shows that the nipple was removed after the part was plated.

the ones i remember had the hose bib missing BUT still had a hole in the can.

[Michael H.]

Re: L88 Vac Advance (?, no nipple) Can

the ones i remember had the hose bib missing BUT still had a hole in the can.

Yup, that would be the correct original style for L88. I still have a few of the correct ones and one of the later service style with just the bump.

[Dick W.]

Re: L88 Vac Advance (?, no nipple) Can

Definitely the service replacement unit, however, they can be carefully modified to appear original

[Michael H.]

Re: L88 Vac Advance (?, no nipple) Can

Definitely the service replacement unit, however, they can be carefully modified to appear original

I suppose it could be made to look something like a real one. The diameter of the bump is larger than the dia of the outer edge of the beginning of the curve on a real one though but from 6 feet away, it would look ok.

Always wanted to put that later issue one on my 66 425 HP car but never did. Fun when people see weird things like that and wonder what it is.