A C Delco vacuum advance units

[John P.]

Hello, Can anyone give me the advance and vacuum specs on the A C Delco advance units D1310C and D1316A. I am setting up a distributer for a 1967 427/435 that has been converted to full time vacuum advance and would like to have full advance of 16 degrees at about 10" vacuum.
Thank you all so very much for any and all help. John

[Joe L.]

Re: A C Delco vacuum advance units

Hello, Can anyone give me the advance and vacuum specs on the A C Delco advance units D1310C and D1316A. I am setting up a distributer for a 1967 427/435 that has been converted to full time vacuum advance and would like to have full advance of 16 degrees at about 10" vacuum.
Thank you all so very much for any and all help. John

John-----


The D1310C will provide 16 CRANKSHAFT degrees of advance at 11-13" vacuum. It requires 5-7 inches of vacuum to start the plunger.

The D1316A I can't find any information on. Does it have a "B--" number stamped on it?

[William C.]

Re: A C Delco vacuum advance units

the D1316A is GM part number 1116236 starts at 3-5 inches, all in at 6-8 degrees, 16 degrees (crank) advance, a great hi-perf vacuum can.

[John P.]

Re: A C Delco vacuum advance units

Thank you Joe and William, I certainly appreciate this information. I will use the D1316A. John

[Joe L.]

Re: A C Delco vacuum advance units

Thank you Joe and William, I certainly appreciate this information. I will use the D1316A. John

John----

For some strange reason I had the control of the actual Delco number D1316A listed listed in my notes as D1316. That's why I couldn't find the D1316A. With these vacuum controls the "suffix" alpha character is CRITICAL. For example, a unit without a "suffix" can be a completely different unit than a unit with the suffix even if the number portion is the same. In any event, the Delco number was D1316A and it's also known as GM #1116236 as Bill mentioned and with the specs he also described. D1316 is a non-existent number.

[Duke W.]

Re: A C Delco vacuum advance units

The L-71/72/78 cam pulls about 14"@900 so using the "Two-Inch Rule" (see archives) you need a Vacuum Advance Control that produces maximum advance at no more than 12". The VAC that meets this spec is stamped "B20" and has specs of 0@6", 16@12".

It doesn't make any difference what brand you buy. Delco no longer makes them. They buy VACs from Standard Motor Products, which have the SMP alphanumeric ID scheme and SMP is the source of most brands - Echlin, Niehhoff, BWD, and, of course, Standard/Blue Streak.

A couple of years ago I did extensive research on distributor parts, and found the Delco online catalog confusing and suspect. They appeared to be in the process of changing all the part numbers, so I recommend you buy another brand, and like I said, they are the exact same sourced parts and have the same stamped ID data including current Delco replacements. The VAC you want is stamped "B20". If you have a non-OE equivalent cam that produces different idle vacuum, use the "Two-Inch-Rule".

The "B20" is NAPA VC1765, BWD V375, Niehoff DR320 or SMP VC-181. The Delco number I came up with was D1382, but my notes show it as "discontinued", replaced by D1310C. My notes do indicate that the 8" VAC (B28) was D1316 (discontinued) and replaced by D1312C. Like I said, all these data from the Delco online catalog is suspect, which is why I recommend buying other brands, which appear to have more accurate catalog data.

The 8" VAC (B28) is more aggressive than necessary for the SHP big block and may have more propensity to detonate.

A number of L-71 owners have made the switch to full time vacuum advance with a B20 VAC with excellent results - cooler operating temps in low speed traffic, better fuel economy, and less propensity to detonate than with the OE ported setup. The OE "201 15" 15.5" VAC is okay for the ported setup, but the engine doesn't generate enough idle vacuum to pull it to the limit at idle, which is why the L-71 conversion to full time vacuum advance should be accompanied with swapping in a B20 VAC.

Duke

[Joe L.]

Re: A C Delco vacuum advance units

Thank you Joe and William, I certainly appreciate this information. I will use the D1316A. John

John------


I'm still curious about the vacuum controls you have. The D-1316A is part of an old series of Delco distributor vacuum controls that have not been manufactured in years. This control should be stamped "MS 236 16".

The D1310C is part of a much newer series of controls actually manufactured by Standard Motor Parts. It should be stamped "B20".

Is the above what you have?

[John P.]

Re: A C Delco vacuum advance units

Hello Joe , The D1316A is stamped as you noted ( MS 236 16 ) the D1310C is stamped ( B26 ). I installed the D1326A with the initial timing set at 10 BTDC. The car runs fantastic, substantially cooler, and idles like a dream. Again thank you all for your valuable information. John