B 28 Vacuum advance.

[Jeff C.]

For any one looking for this unit I ordered 2 Airtex 4V1053 from RockAuto and they came today. They are stamped B28 and were $5.15 each.
I have not tested them yet. Several years ago I got one from NAPA for a 340HP and it corrected the problems I was having. NAPA no longer has them.
Jeff

[Jim D.]

Re: B 28 Vacuum advance.

Thanks Jeff. I had my local parts guy checking and he couldn't find any using all the common part numbers. I just order two of them. $13 delivered is cheap.

[Joe L.]

Re: B 28 Vacuum advance.

For any one looking for this unit I ordered 2 Airtex 4V1053 from RockAuto and they came today. They are stamped B28 and were $5.15 each.
I have not tested them yet. Several years ago I got one from NAPA for a 340HP and it corrected the problems I was having. NAPA no longer has them.
Jeff

Jeff------


The vacuum controls stamped "B28" (as well as other B-stamped vacuum controls) are manufactured by Standard Auto Parts and sold under various brands, including Delco. As far as I know, Standard no longer manufactures this vacuum control, probably because of extremely low demand. So, either Airtex has a considerable inventory of these on hand or Airtex had Standard make up a special run for them. The latter is possible if Airtex was willing to order a large "minimum order" quantity. I highly doubt that, though. I just can't imagine that the demand for this piece would justify that sort of action.

[Jim D.]

Re: B 28 Vacuum advance.

Jeff------


The vacuum controls stamped "B28" (as well as other B-stamped vacuum controls) are manufactured by Standard Auto Parts and sold under various brands, including Delco. As far as I know, Standard no longer manufactures this vacuum control, probably because of extremely low demand. So, either Airtex has a considerable inventory of these on hand or Airtex had Standard make up a special run for them. The latter is possible if Airtex was willing to order a large "minimum order" quantity. I highly doubt that, though. I just can't imagine that the demand for this piece would justify that sort of action.

So what's your point? If they're available under an Airtex part number, let's get them before they too are gone. My parts guy checked, GM, AC, Echlin, BW, Neihoff, Wells and Standard with the same result - DISCONTINUED. I'm just glad to get a few as spares.

[Jeff P.]

Re: B 28 Vacuum advance.

Men Does someone know the spec. on this B28? What is the max advance of this unit?

[Jim D.]

[Duke W.]

Re: B 28 Vacuum advance.

In crank degrees, nominally 0 @ 4" 16 @ 8". These specs are necessary to pass the Two-Inch Rule on all mechanical lifter small blocks and L-82/TH400 if converted to full time advance.

There are two other VACs that meet the Two-Inch Rule for all other pre-emission and post-emission ported advance applications that are converted to full time.

All have been mentioned numerous times on the TDB and are also discussed in my San Diego National Convention presentation last year that can be downloaded off the Web.

Duke

[Michael J.]

Re: B 28 Vacuum advance.

Thanks for the info, that's under Airtex-Wells, right?

[John D.]

Re: B 28 Vacuum advance.

Joe Lucia's point is correct. Standard produced them for all. What you find is reboxed ones with a ton of brand names on the part. As always.
So get them while you can as Standard no longer produces them.
I know of a source for a 100% correctly made and stamped repro in limited quantitites. John

[Jack H.]

Re: B 28 Vacuum advance.

Is this the recommended advance for a '67 L79?

[Larry M.]

Re: B 28 Vacuum advance.

Is this the recommended advance for a '67 L79?

Yes.

Larry

[Timothy B.]

Re: B 28 Vacuum advance.

IMO, if your engine is a stock L-79, the best V/A control is the generic unit that matches the delco #355, that control allows 15*@ 12" vacuum. The factory stock unit was the #236 which is mentioned above and it's fine but you might get a little rattle under acceleration.

Check the engine vacuum after warm up at idle, the L-79 should be in the range of 14" at approx 750rpm so the control I mentioned works great., I can't remember the generic part #.

[Larry M.]

Re: B 28 Vacuum advance.

IMO, if your engine is a stock L-79, the best V/A control is the generic unit that matches the delco #355, that control allows 15*@ 12" vacuum. The factory stock unit was the #236 which is mentioned above and it's fine but you might get a little rattle under acceleration.

Check the engine vacuum after warm up at idle, the L-79 should be in the range of 14" at approx 750rpm so the control I mentioned works great., I can't remember the generic part #.

Jack and Tim:

This info will be in the archives............but according to Duke's Presentation Paper at the NCRS Nationals a few years ago these numbers were B20 or B26.

Larry

[Duke W.]

Re: B 28 Vacuum advance.

The best way to set up the spark advance map for L-79 is to make the centrifugal advance more aggressive and the vacuum advance less aggressive. Since L-79 idles at about 14" @ 750 a 12" B20 or B26 meets the Two-Inch Rule.

Why Chevrolet set up the L-79 distributor with the 365/375 HP VAC and the 300 HP centrifugal is beyond me, but you can definitely achieve meaningful low end torque improvement and possibly improved fuel economy without inducing detonation by following the above advice.

Duke