Frank O'Donnell

Can anyone list the original GM part number for the distributor vacuum advance for a 1965 327/300hp with air and automatic. Can't seem to locate its listing in the AIM. The one currently on my car is not factory correct.
Thanks in advance!
Frank O'Donnell
Baltimore, MD

0Willcox Corvette

In the 1966 parts book, it's listed as 1115357. This application shows fitting 65 Corvette exc. sp h/per, and FI cars. This same application shows exactly the same in the 1969 1971 and 1972 GM parts book too!

65 Corvette (327) (exc. Sp. H/Per., F.I.),
69-70 Corvette (350) (exc. H/Per., Sp. H/Per.) . . . . . 1115357

BarryK

Frank, I believe that is the B26 or B20 vacuum can. They are available at your local parts store such as NAPA, etc as an Echlin VC1765

the specs are:

starts at 5.7"Hg
adds 16º advance
Advance all in by 11-13"Hg

having the specs and part # to get the correct can is one thing but first thing I'd do before going out to get one would be to check your motor. Has ANYTHING been done to it since '66 . 42 years is a long time and who knows who has been inside the motor and changes made to the motor during that time can change it's operating characteristics, including the level of vacuum it produces which is key to selecting the correct vacuum can to use.
Does your motor still have the factory cam, compression still the same as when it was new, etc?

I'd use a vacuum gauge to measure the vacuum at idle in park and at idle with the trans in gear (have a friend, wife, whoever, put it in gear with foot on brake) and look at your vacuum reading and determine from that which would be the best vacuum can to select.
good chance that you may still end up with the same VC1765 can but I figure it's safer to check before just going out to buy it since 42 years is a long time and anything could have been changed out in the motor.

1snake

According to an article written by "master tuner" Lars, the advance unit for your car is a VC1605 (stamped B9).

Jim

JohnZ

The 1965 Corvette Shop Manual Supplement shows all '65 Corvettes using the same "236" vacuum advance unit, with 0* @ 4" Hg. and 16.5* @ 8" Hg.; that's the "B28" can that was the VC-1810 before it was discontinued, now GM #88924985 and AC-Delco #D1312C.

BarryK

opps, John is right, as always.
I misread the original post as a '66, not a '65. maybe i saw Willcox's reference to the '66 parts book, either way I had '66 in my brain, not '65.
sorry.

1snake

John

I'n not dis-agreeing but maybe you can clear this up. I have several sources (none are GM) that show all 65 327's used VC-1605 except the Hi-perf that used the VC-1810.
The VC-1810 is still available. Maybe they are old stock but there are alot of them still out there.

Jim

BarryK

Jim

according to my '65 AMA specs:

250hp & 300hp motors show vac adv start at 6"Hg
this would equate to a VC1765

350hp, 365hp, & 375hp motors show vac adv starting at 4"Hg
that would equate to a VC1810

confusingly, the '65 suppliment of the Shop Manual lists the same vac adv can, the VC1810 specs, for ALL the motors as John mentions so either they all used the VC1810 or the SHP motors used the VC1810 and the non-SHP motors used the VC1765 but neither of these sources list specs that would equate to a VC1606 which has a starting point of 7-9"Hg and gives a total advance of over 20º. 20º of vacuum advance is a lot!

BTW, the VC1810 has been discontinued and very few places still have them left in stock.
some vendors are selling what they are calling the VC1810 but if tested do not match the same specs as the original B28 can.

JohnZ

Even different GM sources have conflicting information for '65 VAC usage; probably the best approach is to select the one that's fully-deployed at least 2" Hg. below the engine's manifold vacuum reading at normal idle, regardless what the conflicting information says.

BarryK

John, that's what I suggested back in post #3.
BTW, since I don't have a PG on my car but the OP does, is it correct to take the vacuum reading with the tranny in drive to determine the level of vacuum rather than in Park? That usually drops the idle rpm's by about 200rpm or so plus puts the motor under a bit of a load which would affect the vacuum level.
I would assume this would be the better method of reading vacuum for the use of determing the correct VAC but I could be assuming wrong.

1snake

Barry

Definately take the vacuum reading with the tranny in drive.
As for the VC1810 not being available, have your parts man cross reference to a Wells brand. They are stamped B28 and have the same specs. as the original, I tested all of mine. I have one on my Cobra and bought 2 more last month when I heard they were discontinued. At that time my Napa man did a computer search told me there was NO shortage of them and I could have as many as I could afford.

This is from an article written by Lars and Duke Williams:
VC1605 B9 1965 impala 396 Exc. High Perf.
1965 327 All Exc. FI
1969 327 Camaro, Chevelle, Impala
1969-70 Corvette 350 Exc. High Perf.
1969-70 350 4-bbl Premium Fuel
1970 350 Camaro, Chevelle, Impala High Perf.
1971-72 350 2-bbl AT
1971-72 307 All


Jim

BarryK

Jim
My local Napa does not have them as of 3 months ago and I was told they couldn't get them anymore. I was also working at a Saturn dealership who of course can get any GM part and they searched thru ALL GM dealerships in the country and found a total of 5 units spread out everywhere.
It's been recently posted that GMPartsDirect.com has them.

Yes, I know all about where that VC1605 info came from, it's in Lars tech paper on Vac Adv Specs, I have it posted on my Tech Articles page. But if you look at the actual specs of when it starts to come in and how much advance it supplies it doesn't match up with any of the GM specs listed in the Shop Manual or AMA specs for the '65 corvette VAC usages.

1snake

I never looked at the specs. but you're right, they look odd. Have your Napa guy cross the Borg Warner V329 to other brands. Wells DV1810 is what I got. I just called the local Napa and was told the warehouse has them and I could get one this afternoon. Alot of parts counter "kids" don't have a clue about the old stuff.

Jim

ctjackster

didn't I just read some advice from you on this subject (C2 Vac advance cans and supercession of part numbers) in CE, or did I dream that? I have been on vacation for a week and a half, and am a bit foggy

1snake

There's a long thread on the NCRS forum about this started by the OP. Seems that it was a 1 year only part and the VC1605 - B9 is the correct one for this application just like Lars' tech. article pointed out.

Barry - Those are the correct specs. The shop manual is wrong.

Jim

BarryK

not exactly what the thread over on NCRS is saying.
They are saying that it's the closest to the original part number which is discontinued but that FUNCTIONALY the VC1765 is the best replacement to use.

Turns out the OP was looking for the exact part number stamped on the unit for judging points but unless he can find a good used one he is out of luck. In the meantime what Duke has been stressing over on that thread, same as I happened to be on here, is that the VC1765 would be the best functional replacement, forgetting about the part numbers.

since the shop manual lists ALL applications with the "236" B28 can I'd also believe it was wrong but i'm going by the '65 AMA specs that list three different cans used

0Willcox Corvette

John, Barry and 1snake,

I’m lost and curious and would not intentionally mislead the OP.

The book I pulled the part number from was a late production 66 parts book. It lists the 236 as fitting the 64-67 Corvette w/sp H/Per., F.I. 327 with distributors 1111060-62-63-64-69-70-85-86-87-88-119-125-156-157-196. Would GM have issued it as a service replacement this early? The application also shows 64-65 passenger cars with h/p 409.

The listing also specifies the 357 as being the standard performance advance with distributors 1111109-37-73-75-76-98-109-120-126-137. (There are other applications listed for this advance which included but not limited to, 65 passenger car, Series 10 trucks and basically all low horse cars)

Ernie

BarryK

Ernie

not sure without looking it up which can the "357" is.

The "236" can, also known as the B28 or the VC1810 is the can that was used on the hi-performance or "SHP" motors.

Now, at this point I believe it's generally accepted that the '65 Shop Manual supplement is wrong when it lists the "236" for ALL applications. I give more credence to the '65 AMA specs that has three different cans listed as in use for that year although they only give the actual specs of the cans, not the part numbers (at least I haven't found the parts numbers listed in the AMA specs, just the specs).

I know the "236" cans were used on the 350hp, 365hp, and 375hp fuelie motors in '65 and I'll assume also in '64 although I don't have the AMA specs for the other years.

It wouldn't make any sese to use the "236" cans for the non-SHP motors because it brings the advance in at such a low vacuum level - between 3-5"Hg and the regular motors such as the 300hp didn't need that because they produced higher vacuum levels.

Reading the thread over on the NCRS board it seems that on the base and 300hp motors GM seems to have been changing cans pretty much yearly to different models - almost like they were still figuring out which can would work best. try one can this year, than try a different one the next year, change it again, etc.


The OP was looking for the exact can with the correct part number for judging purposes and it seems that the 300hp in '65 used the "238" can but it was a one year only part and replaced in '66 with the "357" can which was than discontinued in '93.

so, bottom line seems to be that the OP needs to find an original "238" can of that one year only part if he wants full judging points BUT if he wants the best FUNCTIONAL can for actual driving of the car the current VC1765 is probably the best match.

Are you an NCRS member with access to the NCRS forum? If so I can PM you the link to the thread over there. I don't think the Mods here would like me posting a link to another forum in an open thread like this one.

plaidside

John,
Do you take the vacuum reading with or without the vacuum advance connected?
Thanks,
Joe

BarryK

Joe
until John chimes back in, I have learned the procedure with the vac adv hose disconnected and plugged so always did it this way, same as reading vacuum to set idle fuel mixture.