So I've recently thrown a fresh 350 in my Camaro. My old HEI dizzy was bad so I bought a new one, Allstar performance I believe. The mechanical advance seems to be set for full advance at a very high RPM. From what I've read, for street cars, you want the base timing + full mechanical advance near 36 BTDC between 3,000-3,500 RPMs, so I would need to put lighter springs on correct?
I'm thinking this is what's causing my car to stumble when going from 20 MPH to WOT but flawless when going from 60 MPH to WOT - sound like a possible cause or am I making rookie assumptions?
This new dizzy has an adjustable vacuum advance on it. I have it plugged into full manifold vacuum. My base timing is 6 BDTC and I believe when the vacuum advance is connected, my advance is brought up around 24-26 BDTC. At idle, how much advance should it be pulling?

 

At idle, the vacuum advance should be capped off, then set base timing. Alot of folks start at a base of about 12BTDC, and usually go up from there. Mine happens to be at about 15 right now (since my off-the-shelf distributor won't get to the magical 36) ... the 15 gets me to about 28 total at 3000rpms.

The way I was told, and consequently did mine, was ...

I lossened the dist bolt just enough for ME toi be able to turn dist, but not let it turn on it's own. Then I set my base at 12, put timing light in the car, and went driving. At WOT, I got no spark knock, so I advanced the base 2 degrees to 14, and went WOT again, no spark knock, so I advanced to 16 and went WOT again. At 16, I got slight spark knock, so I backed it down to 15, tested again, so knock that I could hear, and I locked it down there. Then checked my total at 3000rpms (which was about 28 as I mentioned). Like I said, I can't get higher without spark knock, so I'm stuck there until I get time to change springs/weights in my distributor.

Hope that helps. I'm certainly no expert at all this, but that process seemed to work fine for me.

 

I did the whole eliminate vacuum advance on my last motor because I couldn't get it running right. I brought it to a guy that has done drag cars for 30 years. Up to that point I had never heard of eliminating the vacuum advance. I wasn't a huge fan because it makes the car a bear to start, even at only 12 deg adv. i.e. If your foot is off the gas, it acts like the battery is dead; too much gas and it floods. Finding that "sweet spot" to get it to start isn't something I want to have to do on a daily driver.
I could probably set the base to 8 BDTC but at 6 BDTC, it's easy to start - One pump, turn the key when it's cold; and just turn the key when it's warm.

 

Mine was easy to start at 6BTDC too. But at 15BTDC, it starts just as easily, but really runs all out alot better. Try bumping timing up and reducing idle at carb and see what happens with a foot to the floor run.

 

Like I said, running at 12 deg adv. with no vacuum advance, it's a bear to start. Also, the idle is set as low as it will go - 1050 in park, 700 at idle.

 

id go get a dizzy recurve kit, it will come with instructions on which springs to use for what advance curve you want. You can also spring for an adjustable vaccuum advance can for some fine tuning. I got both not too long ago from one of the new pepboys speed shops for $25 for the vacuum can and i think $20 for the recurve kit.

 

I do have the mechanical advance recurve kit, I just wanted to confirm that the mechanical should be fully advanced around 3000 RPMs and 36 degrees.
The dizzy has an adjustable vacuum advance, I just don't know how much advance should be "pulled."

 

Assuming this a carb motor, with all this vac advance talk. This sounds more like an accelerator pump problem.