Distributor Vacuum Advance Part #

[Barry K.]

Re: Distributor Vacuum Advance Part #

Man, I haven't posted here on this board in a LONG time, probably almost a year or maybe more since before they changed to this new forum software.
Looks like I managed to jump back in here on a pretty controversial thread!

[John D.]

Re: Distributor Vacuum Advance Part #

Barry, Eliminate the vac advance. Just do like some of the old bubbas did and put a nice tach weld on the advance plate to the case. You haven't lived until you try and undo that old hot rod work.
I was just kidding Duke and Joe.
I did goof for sure. The VC 1802 is the B22 advance and it works quite well on the 63 FI's. in lieu of the 201. The VC1810 B28 is no longer available but a good repro is in the works.
I doubt that the VC 1802 will be available for much longer the way things are going.

[Barry K.]

Re: Distributor Vacuum Advance Part #

Barry, Eliminate the vac advance. Just do like some of the old bubbas did and put a nice tach weld on the advance plate to the case. You haven't lived until you try and undo that old hot rod work.

[John H.]

Re: Distributor Vacuum Advance Part #

The VC1810 B28 is no longer available

John -

Actually, it is available, and from GM - it's P/N 88924985, AC-Delco #D1312C; I just received some (stamped B28) from GMPartsDirect.com (Flow Chevrolet in South Carolina), and they Mityvac check dead-on to specs (plunger starts at 4"-5" Hg., fully-deployed to the stop at 8" Hg.). They didn't have them in stock and had to special-order them, but it only took about 10 days.

[Duke W.]

Re: Distributor Vacuum Advance Part #

Are you trying to corner the market, John.

A friend with a 1968 Motors Manual checked out their dist. specs for 65 250/300 HP and they list:

Start 5-7", 12 @ 14"

They list dist. degrees, so this translates to:

0 @ 5-7", 24 @ 14"

which adds yet another set of published numbers, however:

24 @ 13" Corvette News
22 @ 12" AMA specs
Both start at 5-7,

So this could be expressed as 0 @ 5-7, 22-24 @ 12-13", which would be an acceptable tolerance range for nominal specs of 0 @ 6, 23 @ 12.5"

Duke

[Barry K.]

Re: Distributor Vacuum Advance Part #

just to be safe, in case the original "236" ever goes belly up on my '65 L76 I just ordered a couple of the VC1810's from GMPartsDirect myself.
For only $5.95 each I don't mind having a few sitting around collecting dust just in case I ever need one.

[Joe L.]

Re: Distributor Vacuum Advance Part #

Are you trying to corner the market, John.

A friend with a 1968 Motors Manual checked out their dist. specs for 65 250/300 HP and they list:

Start 5-7", 12 @ 14"

They list dist. degrees, so this translates to:

0 @ 5-7", 24 @ 14"

which adds yet another set of published numbers, however:

24 @ 13" Corvette News
22 @ 12" AMA specs
Both start at 5-7,

So this could be expressed as 0 @ 5-7, 22-24 @ 12-13", which would be an acceptable tolerance range for nominal specs of 0 @ 6, 23 @ 12.5"

Duke

Duke-----


The problem remains, though, that there is no GM vacuum control which could reasonably have been expected to have been used which produces 20-24 crankshaft degrees of advance @ 12-14" Hg.

[John D.]

Re: Distributor Vacuum Advance Part #

just to be safe, in case the original "236" ever goes belly up on my '65 L76 I just ordered a couple of the VC1810's from GMPartsDirect myself.
For only $5.95 each I don't mind having a few sitting around collecting dust just in case I ever need one.

I was thinking that one time I had a 238 vacuum advance and had no clue what it was. I have a ton of junk VA's and will look thru the box. If you guys can come up with a real deal 238 I may be able to get it rebuilt.
If you are planning on showing your car put a 236 on and you got it made. The B type VA's ain't worth a crap for judging. If the manual says 236 then go with it for the moment anyhow. Better than getting dinged.
Don't go nuts guys worrying about 236 VA's as they are a coming. John
I found the 238 24 VA!!! It has a little ding in it but it can be doctored up. It can also be rebuilt you know. This is a rare part from the sounds of it. It had to come from an FI distributor. This post was started by Frank I see and was hi-jacked. I never hi-jack posts.

[Wayne M.]

Re: Distributor Vacuum Advance Part #

Duke-----


The problem remains, though, that there is no GM vacuum control which could reasonably have been expected to have been used which produces 20-24 crankshaft degrees of advance @ 12-14" Hg.

Joe -- can you explain why "no GM vac control expected to be used that gives 20-24 crankshaft deg. @ 12-14" Hg ?"

The proof is in the pudding ! I'm looking directly at the Delco Remy Test Specifications DR-324 S-2 (sheet dated Jan 1, 1966) that shows for the 1116238: 5-7" Hg to start advance; 11.7 - 14 " Hg for max advance; 12.5 deg max distr. adv. (25 deg max crank adv.) Note: advance tolerances are +/- one degree.

And this puppy does exist, per my previous pic. Too bad nobody has admited having one on their '65 low-horse distr.

[Barry K.]

Re: Distributor Vacuum Advance Part #

Don't go nuts guys worrying about 236 VA's as they are a coming.

oh? I vaguely remember you saying something not too long ago about this on VH. Are you going to start making repro's of the "236"?
If so I guess I just spend $28.00 needlessly....

[Joe L.]

Re: Distributor Vacuum Advance Part #

Joe -- can you explain why "no GM vac control expected to be used that gives 20-24 crankshaft deg. @ 12-14" Hg ?"

The proof is in the pudding ! I'm looking directly at the Delco Remy Test Specifications DR-324 S-2 (sheet dated Jan 1, 1966) that shows for the 1116238: 5-7" Hg to start advance; 11.7 - 14 " Hg for max advance; 12.5 deg max distr. adv. (25 deg max crank adv.) Note: advance tolerances are +/- one degree.

And this puppy does exist, per my previous pic. Too bad nobody has admited having one on their '65 low-horse distr.

Wayne----


You "beat me to the punch". I was just about to post almost exactly what you have stated. Here's the deal:

The GM #1116238 was used ONLY for the following applications:

1965 396/325 hp in passenger cars

1965 327 with 4 barrel carb, all models except SHP

The GM #1116238 was discontinued in July, 1966 and replaced by the GM #1115357. I THOUGHT the 1116238 and the 1115357 were the same or nearly the same in specifications. However, that proved to be a false assumption. They are actually quite a bit different. This is a HIGHLY unusual situation. Generally, when GM replaced a vacuum control with another, the replacing part had specifications very similar to the replaced part (e.g. '201' and '163') or they simply discontinued the vacuum control without supercession. But, not in the case of the 1116238 and the 1115357. The specs are as follows:

1116238= 5-7" Hg to start the plunger; 23-25 crankshaft degrees advance @ 12-14" Hg

1115357= 7-9" Hg to start the plunger; 20-22 crankshaft degrees advance @ 16-18" Hg

You will note that the specs I came up with for the 1116238 are virtually the same as the ones you quote from the Delco information.

So, the 1116238 is the vacuum control that "I didn't think existed". Now, everything "lines up" and I feel very confident that the 1116238 was the vacuum control used for 1965 base and L-75 engines.

By the way, the NAPA/Echlin VC-1605, aka "B9", replaces the GM #1115357. However, other than in the sense that the 1115357 replaced the 1116238, it does not really replace the 1116238 since its specs are really so much different.

[Jim D.]

Re: Distributor Vacuum Advance Part #

To add some more info. to an old thread, I decided to post a pic. of mine. 1965, 300 HP built in April 1965. I'm willing to bet this is the original vac. can since the valve covers had never been off this 1 owner, low mile original car.

[Joe L.]

Re: Distributor Vacuum Advance Part #

To add some more info. to an old thread, I decided to post a pic. of mine. 1965, 300 HP built in April 1965. I'm willing to bet this is the original vac. can since the valve covers had never been off this 1 owner, low mile original car.

Jim----



GM #1116238 (i.e. the part number you have pictured) is the one that was installed when the distributor was manufactured.

By the way, if you have any pre-ignition problems with this engine, this vacuum control could be part of the underlying cause.

[Jim D.]

Re: Distributor Vacuum Advance Part #

Thanks Joe. I was a little concerned that the Tech. Manual called for a 236 when I knew mine was an original. Then I found out that the manual is wrong. I have a VC 1802 that I'm going to put on it because of the problem you're talking about.

[John D.]

Re: Distributor Vacuum Advance Part #

Jim, That's a very rare vacuum advance you have. One time I pulled one of those from a 65 FI distributor. But bubba put it there as those are typically the 236"s. JD