OK, I re-curved my Mallory Unilite yesterday. I set the curve limit to allow only 16 degrees advance beginning at 1200 RPMs, and all in by 2800 rpms. As most know, the car has a small roots blower on it, so it likes A LOT of initial advance. It seems semi happy around 20ish degrees advanced.

So - I start the thing up, let it warm up a little but and disconnected the vacuum advance. Engine almost died, but I saved it by advancing the timing. I set it at 22 degrees advanced and set the idle about where I wanted it...about 900 rpm's. I rev it up and the mechanical advance stops it at 36 degrees...about perfect I think...

So I connect the vacuum advance hose back up, and the idle takes off to 1400 rpms, and the timing goes to over 40 degrees.

I can't adjust the carb down enough to idle. I have both the primary screws not even touching the arms now, and it still idles way too high. I know I'm "supposed" to have the idle slots exposed in the carb like .050, but no way....

It's gotta be something stupid I'm overlooking. I don't think my power valve is blown, because it'll stall if I turn in on the 4 corner idle screws...plus I haven't backfired the thing (thank god)...

-I do have an adjustable vacuum advance...should I turn the thing in until I can control the idle? I'm just concerned it won't advance enough if I do that at light-load cruising speeds like it should. Any advice?

EDIT: I guess another possibility is to keep the vacuum advance hooked up and then back the timing down to 22 advanced...is that the way to go??

Double EDIT lol...I do have a third option...and I might try this one. I could hook my vacuum advance up to the "ported" connection on my carb and try that. That way, the vacuum advance won't interfere with my idle...

 

OK - I just went out and reconnected the vacuum advance can to ported vacuum, and I was able to at least get my idle fairly stable at 900....smells like it might be a little rich, but that's nothing new. I'll give it a road test and see if it responds better with the quicker advance springs in it.

I may have been too conservative and maybe should have went with the lightest springs to have it all in by around 2K rpms...but that sounded pretty aggressive...


EDIT: Well - road test is over...about 1/8th tank of gas...lol Went around the block a couple times. Engine seems to like it!! I think it wants even more actually, but I think I'll keep it where it's at for now. I have a boost retard, and I had it set to take out 2 degrees of advance per pound of boost, and I set it down to 1 pound....it liked that even better! But-it is a cool day right now (maybe 48 degrees) - so I'll see if it's just as happy when it warms up around here..