jpc647

Last weekend I replaced the RPM intake with the standard performer intake. Car has a 1405 Edelbrock Carb. 350 motor, th350 trans. Pretty positive it's been rebuilt, but to relatively stock specs. Car runs about the same. Maybe a little stronger through the rpms, but it doesn't "hit as hard" initially.

After replacing the intake, I put the timing back to about 17/18 where it was. Car ran okay. I then tried 20* base timing and the car runs better. I would like to try 22*, and see if she pings. But the problem is the vacuum advance is now turned all the way into the firewall. I cant rotate it anymore. It doesn't seem like the vacuum advance canister can be relocated on the dizzy. It's all one unit.

What can I do? Can I purposely set the dizzy up to be 1 tooth off to get more timing out of it? How would I figure out what the actual timing is?

Not sure what else I could do.

joe_padavano

Yup. That's what you do. The only other option is to rotate the distributor the other way and move all the wires one space on the cap.

jpc647

Is this "normal" to be able to give a car this much base timing?

Also, after i make it "skip a tooth", how do I then figure out how much timing it'll have. If I skip a tooth and it reads 10*, per say, is it actually 10* or is it something else?

joe_padavano

There is no "normal". Give the car what it wants to run right for the setup you have. You ARE checking timing with the vac advance disconnected and plugged, right?

The timing light neither knows nor cares what "tooth" the distributor is on. It is simply flashing when it sees a spark, letting you read the timing at the crank. That's all that matters. I thought your question was related to how do you read more that 10 deg BTDC if the timing tab only goes to 10.

jpc647

No, I didn't plug it. Wow I'm an idiot. Okay, will have to redo that tonight. Could be that simple.

Just did a quick google search, just for reference, why does the vacuum advance need to be disconnected? What does that do to allow it to be timed properly(sorry if that's a dumb question).

Um, not really. The dial back light takes care of that for me. I was trying to spin the distributor clockwise more, to advance more than 20* timing(20* initial timing is right when my VAC port hits the firewall).

Sorry if my description was confusing. Trying to explain it with as much detail as possible.

joe_padavano

The definition of initial timing is the relationship between the distributor and the crank with no external advance (either vacuum or mechanical) included. It's the "hard stop" or lower limit on what the advance is in the engine. Since vacuum advance varies with engine load and mechanical advance varies with RPM, the initial is intended to be set without either of those variables included. Plugging the vac advance takes care of one, and the mechanical advance doesn't activate at idle RPMs (unless your engine is idling VERY high), so the other one is taken care of automatically.

captjim

See if this helps,
http://www.corvettefever.com/techart...curving_power/

oldcutlass

Good article!