72 Lt-1 stumble on take off

[James G.]

Re: 72 Lt-1 stumble on take off

The stumble ocurred even with the tcs connected. I did not re adjust my idle screws though. My initial timing was running at about 14 degrees. From some of the archive discussions I have read it sounds like they don't make the b28 vac as Duke specified.

[Timothy B.]

Re: 72 Lt-1 stumble on take off

James,

I think the vacuum control is available, try NAPA auto parts.

After you set your timing and establish a reasonable idle, adjust the emulsion screws on the primary metering block to max vacuum or highest idle. Try to keep both screws approx. the same turns out to keep things balanced. After doing this you may have to set the idle speed again to a stable idle.

I am not sure this will correct your problem but it may be one of many things that are leading to the stumble.

[James G.]

Re: 72 Lt-1 stumble on take off

Thanks Tim, I will try to get to it this weekend and I will check Napa for the vac.

[John H.]

Re: 72 Lt-1 stumble on take off

James -

The VC-1810 vacuum advance unit (stamped B28) is GM #88924985 and AC-Delco #D1312C; if NAPA can't scare it up for you, GMpartsDirect.com has them for $6.00.