Dave Witman

have a 64 with 327 and new dart heads manual trans. running holley 4160 carb. Not sure on what cam is installed but is lopy and has only 8hg vacuum at idle. Mechanical is 15 at idle 36 all in by 2500 which is a little early. B26 vacuum can. The problem I have is car boggs bid time off idle but runs fine otherwise. The bog goes away with the vacuum can removed. So when I saw this I thought I would just try ported vacuum but the problem with that is the ported fitting is reading full idle vacuum also. The idle speed screw is only adjusted in 1 1/2 turns so I don't think the primarys are open to far but not sure. Thanks Dave.

JohnZ

With only 8" Hg. vacuum at idle, you need the "B28" vacuum can, connected to a full manifold vacuum source - it's fully-deployed at 8" Hg. (the B26 isn't until manifold vacuum reaches 12" Hg.). What LIST number Holley do you have? Most Holleys didn't have a "ported" vacuum source at all until 1969. Most "bogs" result from incorrect accelerator pump adjustment or incorrect pump squirter sizing.

Dave Witman

The b28 can is on order the carb is a holley 80770-1 Thanks

mechron

Sorry Dave, Your problem is in the accelerater pump circuit on that holley. Adjust the primary pump lever to zero tolerance. Make sure the acc pump diaphram under the front bowl is not ruptured.

also a common problem is that guys back in the day over overtighten those 4 cam screws and warp the primary diaphram pump cover under the primary float bowl. Fuel would just leak out under. Is the pump cam in place?? Is the check ball under the diapfram on the pump in place and the check ball under the primary squirtes is in place...

Bottom line, if you do not get a big squirt out of the acc punp nozzles even with the slightest opening of the throttle plates the engine is going to bog

waltonb123

I recently had a bit of a hesitation on my 4160. I thought I had everything adjusted perfect until I installed an 02 gauge. I was actually very lean 16.5. So I changed jets and my hesitation went away to!
Bob

Dave Witman

The acc pump circuit has been redone and adjusted it does run fine without the vacuum advance. I have the means to install o2 tester which I wiil do next. Dave

waltonb123

I would first change your vacuum can as Johnz said. All bets are off till you get that right first.

Dave Witman

Yes I agree can is on order echlin must have discontinued them napa has no number for them. Dave

waltonb123

I used an adjustable can from Summit.

JohnZ

ALL vacuum advance cans are made by Standard Products, and are re-boxed by everyone else who sells them - here are the numbers for the "B28" can:

NAPA/Echlin VC-1810
GM #88924985
AC-Delco #D1312C
Airtex 4V1053
BWD V329
Standard VC-177
Wells DV1810
Niehoff DR305