L78 396/425, vacuum advance cannister GM # 1116163

[Gary C.]

Mine has failed where can I get a replacement?

[Joe L.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

Mine has failed where can I get a replacement?

Gary------


Very easy. There are several NOS examples on eBay right now.

[Gary C.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

Yes at $US200 or above. I am looking for a non-matching number equivalent.

[David H.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

Yes at $US200 or above. I am looking for a non-matching number equivalent.

Gary

If NM# is ok, have you considered an adjustable vacuum? Link below, but there are several vendors. Price around $55.

Dave

ACCEL Points Style Adjustable Vacuum Advance Canisters 31034

https://www.summitracing.com/parts/acc-31034

[Richard M.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

My thought is that it's possible your engine needs further analysis to determine the best VAC unit to use, particularly if the internals are unknown. Since it isn't important to retain a "163", and attain correct functionality, I'd advise a read of Duke's Tuning seminar, along with Lars VAC specification list.

Also, I'm unsure if your VAC source is Ported or Full Time, but Full Time is the best method, requiring some vacuum readings as out lined by Duke.

Which is in the DoRD Sticky, under Tuning......

Quick Link

HERE

Rich

[Duke W.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

That ...163 VAC is a boat anchor and is NOT the original part number for the engine. It doesn't pass the Two-Inch Rule nor does the OE 1115201.
L-78 should have full time vacuum advance (you NEED to verify), and typical idle behavior is 14" @ 900 if the engine has the OE equivalent cam, but assume NOTHNG unless you've owned the car since new and have detail service records.

The 12" "B-26" VAC passes the Two-Inch Rule idling at 14" idle vacuum, and the NAPA number is VC-1765. This part is manufactured by Standard Motor Products and is available in at least a half dozen "brands" including Delco... same part, just a different box and marking channel. Buy on convenience and price. Any parts store should be able to cross reference the NAPA number to whatever brand they sell.

There are reports that various currently available VACs do not meet spec, so I recommend you buy locally, and before you accept and pay, check it with a vacuum pump that the pin starts to pull at 6" Hg and is fully deployed at 12" +/- 1". A few years ago they were about ten bucks, but nowadays you have to add a Bidenflation premium.

To install, pump down the installed VAC to pull the stationary pole piece to the full advance position. This will expose the forward screw so you can remove it. Remove both screws then slowly tilt and wiggle it to disengage the pin. Pump down the new part and install.

The ....163 VAC that may take as much as 18" to pull to the limit was part of an ill-advised GM parts consolidation that occurred decades ago and the aftermarket followed suit. The SMP manufactured ...163 clone is stamped B1 and it doesn't even pass the Two-Inch Rule for a base engine that with a manual transmission typically idle at 500 @ 18".

If you're worried about judging consider that the VAC is worth 3 points, two for originality and one for condition. Back when I judged Mech I at chapter meets I would deduct one point for a B-number VAC because it's an OE replacement. Someone once told me I should deduct all three points as if the VAC was missing. Some people should not be allowed to judge!

As long as there is an available SMP manufactured VAC that passes the Two-Inch Rule I NEVER recommend an aftermarket "adjustable" VAC, and of the dozen or more available for Delco single point and TI distributors there is one of only three (8" B28, 12" B26, and 15" B22) that is a "best fit" according to the Two-Inch Rule for any OE engine and even modified engines like a bigger than OE cam.

Set idle speed as low as possible commensurate with accept idle quality in neutral with a manual transmission and DRIVE with an automatic. If equipped with air conditioning the compressor should be engaged. Measure idle vacuum and apply the Two-Inch Rule and pick the least aggressive of the above three that meets The Rule.

The Rule is not applicable to emission controlled engines (or '63 L-84 for some unknown reason) that have ported vacuum advance, but as long as your car doesn't have to be periodically emission tested I recommend converting to full time vacuum, and this may require a different VAC (Ported vacuum advance is an emission control strategy.)

If you want to take a deeper dive into this subject look at the restoration documents near the end of the sticky section, and scroll down to the tuning center, download the pdf, and enjoy the read.

Duke

[Gary C.]

Re: L78 396/425, vacuum advance cannister GM # 1116163

Thanks David, I will try it.
Gary