vacuum advance question

[txchainsawgogi]

What would cause the engine to run roughly with the vacuum lines connected, specifically to the advance on the distributor.

If I cap off the vacuum advance it starts and idles and runs much smoother.

[Grim 82]

Sounds like you are using manifold vacuum. You could switch to a timed vacuum source.

[jaredts]

Where is your timing set, or has it been set?  Timed vacuum might help or retard your timing and leave the vacuum alone.

[txchainsawgogi]

I haven't set the timing yet... it was doing the same thing with the old distributor. I figured a new one would help, and it did with everything but the vacuum advance.

[jaredts]

I think you need to set your timing before you try to troubleshoot any further, but if you just wanted to play around you could try to retard your timing a little and see if it makes it run as well as it does with the vacuum unhooked.

[txchainsawgogi]

I've never timed a truck before...only a few motorcycles. I'm sure I could do it though...

[Grim 82]

Nothing to it. Do you have a timing light? Make sure to plug the vac advance hose when you do it.

[txchainsawgogi]

Id have to borrow one from autozone or some place. My haynes manual mentions a VECI label with tune up specs that's long gone from the engine compartment.

What do I do?

[Grim 82]

The VECI label will give you the factory spec timing baseline,  but I would ignore that and set it between 8-12 degrees before TDC. Most labels will say 4 or 6 degrees BTCD. I run mine at 12 BTDC without EGR. If you can get a dial-back timing light and set your total advance and work your way back to initial timing that would be prime.

[454ss]

Id have to borrow one from autozone or some place. My haynes manual mentions a VECI label with tune up specs that's long gone from the engine compartment.

What do I do?

I've got a timing light (well, 2) and can help if you want, possibly this weekend.

[txchainsawgogi]

Dang, can't seem to find anyone that loans timing lights. Kind of lame. 454 id take you up on that but my truck isn't street legal(or even in my name yet) and another ticket is the last thing I need.

[454ss]

Well, where are you? I don't mind taking a drive. 

[beastie_3]

I think O rileys/kragens does.

[beastie_3]

No harm in buying one, too. Good investment IMO.

[bake74]

   Have you checked your vacuum advance on your dist. yet to see if it was operating properly ?  Check the most obvious first is my theory.