6066 (1960-1966) GMC Truck Club

6066 (1960-1966) GMC Truck Club (https://6066gmcclub.com/index.php)

- GMC V6 and V12 Engines (https://6066gmcclub.com/forumdisplay.php?f=9)

- - Timing and Tuning (https://6066gmcclub.com/showthread.php?t=48700)

Re: Timing and Tuning

This engine is on propane. It's got a single barrel carb. I have. I do not know the maker.

Re: Timing and Tuning

Can you send some pics of the carb?

Re: Timing and Tuning

I will on Tuesday when I get back to work.:lolsmack2:

Re: Timing and Tuning

Quote:

Originally Posted by GMCDAC (Post 57285)

Hi David, and Scoutmann, I am going to stick my neck out here and guess that the carb you are using is "ported vacuum" which means there is none at idle. "Direct vacuum' usually comes from the intake manifold or the carb base. On the rochesters and holleys I have I just use direct vacuum. Then you will notice the difference when the line is disconnected.

If you have one of those vacuum type brake bleeders the vacuum advance can be tested with that.

DAC

Thanks for the education Doug! I guess I won't worry about disconnecting it in the future. F.Y.I. My new vacuum gauge in installed consistently reads 20 psi at idle.

Re: Timing and Tuning

Its a Marvel Schebler 3c-7050T on an Impco VFf30 LPG regulator