bowtyebob

Can anyone tell me where to find the right vacuum cannister for a '65-67 L79?
A couple of years ago I located one at GMParts Direct but the part no. (I think) GM#88924985 is no longer listed
Corvette Central shows one, however I don't know if it really is right. What is CRUCIAL is the amount of vacuum to start the plunger. It NEEDS to be about 4Hg (3-5) . I mistankenly installed one that started the plunger at 8Hg and naturally developed a horrible stumble.
Another annoying question is whether or not there should or needs to be the short rubber sleeve installed on the plunger. This will limit the amout of vacuum advance and seems to be on some and not on others.
I really do not want to resort to intalling one of those ugly adjustable aftermarket cannisters.
Any help with this would be greatly appreciated.
Thanks,
Bob

JBrooke825

search the fourm I think the # is 236. look for john z he will steer you in the right direction. any parts book will help also

SpartyGW

Sounds like you want the B28 can ( google part number vc1810 ).

Dr L-88

Based on this info, I think you need the B26 can...................

http://www.lbfun.com/warehouse/tech_...ance_Specs.pdf

bowtyebob

I appreciate that info. I could not remember if I needed a B26 or a B28 and didn't know where to find either. Looking at the specs for the B28 tells me that is the right one. The B26 needs a bit too much vacuum to start moving the plunger for an L79, especailly with today's 10% ethanol fuel. I'll check with my local NAPA store for the Echlin part.
Thanks.

bowtyebob

So that still leaves me with the issue of the 'bushing'. ...whether to use one or not. Does anyone have any experience with this. It seems to me that the can I last received from GMParts direct came without one. ....but maybe I just don't remember correctly.

rongold

There is no bushing. If you need to cut down the vacuum advance, just get a piece of 1/8" vacuum hose and push it over the actuating rod leaving about 3/16" of the rod exposed. That should be enough for the rod to fully engage the breaker plate--You may have to experiment for enough engagement of the rod. That piece of vacuum hose will cut out about 4 degrees of the vacuum advance. If you need more than that, you will have to braze up the slot.

bowtyebob

Thanks for that info, Ron. I know that at least some of these cans used the bushing, but didn't know if one was used with the L79. This is fresh factory spec engine complete with a new blueprited L79 iron cam from Crane. If it worked well in '65, it ought to work just as well now ...in spite of today's fuel.

65 vette dude

I have a L79 and I run the B26. I have 15hg at idle. The B28 can is generally used for cams that don't produce a lot of vacuum like the 30/30 cam. How much vacuum do you have at idle?

bowtyebob

Right at 15Hg. The L79 distributor specs (depending up the year) calls for 3-5Hg to start the plunger and in my experience a can that starts at 7-8 almost assures a light throttle 'tip in' problem at engine speeds in the 1000-1300 RPM range as well as introducing a stumble when pulling away from a dead stop.
Why some L79s DO NOT have this problem when using the "wrong" vacuum cannister is unknown to me although there may be a couple of reasons for this lack of a problem with some cars with the "wrong' cannister. Over-rich caruration and/or a higher than 'spec' initial timing? (12-14deg?) could be sufficient to 'cover-up' the problem.
I'm just rambling now on only one cup of early morning coffee. Experience has taught me that dionf it the way is was done originally is almost ALWAYS the way to go.

JBrooke825

that's what I think , the wrong can will give the car a weak
response . search here for the papers that lars has posted
the list of what you need is there. I know the #is 236 but I
don't know if it's a b 26 or b28 that list will tell you.

bowtyebob

I'm having trouble finding the B28. It is no longer available from GMParts direct and NAPA (and Echlin) no longer list the VC1810 (B28).

SpartyGW

AutoZone still sells the B28 can as part # DV1810:

http://www.autozone.com/autozone/par...artNumber=true

bowtyebob

Thanks, ....'sorta. PLEASE see my 'situation' in my other post:"another distributor question". I am running out of options.

bowtyebob

....make that: " another L79 distributor question". Sorry I didn'r intend to have mutiple threads on this problem.