vacuum advance

[rkmj67]

hello everybody, with my vacuum advance plugged, i have my initial timing at 18, then when i hook it back up it goes to 44, i run manifold vacuum for advance, does that seem to high, will that cause idle problems?

[hugger73hatch]

Seems high. I'm sure others will chime in here, but need more info on setup.

[rkmj67]

motor is 327--9.1 CR, comp cam 274-286 230-236 487-490. vortec cylinder heads, edelbrock vortec performer rpm, pertronix flamethrower hei ignition, turbo 350 trans, 2800 stall, 4.10 gears in a 67 camaro

[hugger73hatch]

I would think somewhere in the 34-36 total timing range, probably closer to the 34, and being too high can affect idle.

[rkmj67]

i think 44 is kind of high to, might try a different vacuum canister.

[stroker1]

I assume you are driving it on the street since you are running a vaccum advance. So if you are I recomend that you run it connected to a timed vaccum port on the carb. The way you have it, it will see full manifold vaccum all the time. 44 degrees is too high for full throttle under a load. I would get a timing curve kit and work on the initial timing and overall timing with vaccum unhooked and plugged. Then check it hooked to a timed port. A timed vaccum port loses vaccum signal at WOT.

I think I explained that right?!

[78 C10]

I run with 12* initial 34 total by 2700 RPM with the vac advance hooked full manifold vac. I also made a limiter plate so I only get 8* of vac advance. I can feel it in the seat of my pants after setting it up this way compared to the way it was.

[Craig W.]

If you get part throttle detonation, switch to a 10 degree can or an adjustable one.

Under light throttle, that much advance isn't a problem. It'll help the engine run cooler, get better mileage and be more responsive.

Manifold vacuum is what I always recommend. At WOT, it'll go away anyway and you'll be left with the intial plus centrifugal advance.

If you want to read more of my takes on ignition advance, go to www.2quicknovas.com/tech.html and click on the ignition article.

[JES]

44 @ at idle is too much. do what Craig said and you'll be good. John Eric.

[rkmj67]

where can i get a 10 degree can, or does anybody know a part number?

[78 C10]

you can get one at an auto parts store I believe they were used on older cars not equipped with an EGR. I might be wrong but it seems like I just heard that a couple of days ago.