[stan_the_man]

Question for all of you guys............

Just got finished tuning my Nova. (350/350, HEI-GM)

Setting the timing, I unplugged the vacuum line at the distributor and clamped it. Then I set timing to 11 degrees BTC. Plugged the vacuum line in and no change on the reading (still 11 deg). The vacuum from the dizzy is connected to the timed port on the passenger side of my edelbrock 1406 carb.

Out of curiosity, I moved it to the full vacuum port on the drivers side of the carb where I currently have the modulator connected from the trans.

When I switched them........... the car's idle jumped up and I could not read the timing mark down on the crank anymore. The vacuum advace really kicked in on the full port. On the timed port = no change.

Which way is normal? I know this has been covered and I've searched but I didn't find out if the idle, or timing, jumps up after reconnecting the dizzy to vacuum.

Just going over my last few checks........ Tomorrow night is my first trip to the strip. And I don't mean strip club! haha

 

[Baddbob]

Most run the vacume advance on manifold vacume, you can change the amount of vacume advance to suit what the engine needs by using a limiter or buy a can with the right amount of advance.

 

[74 hatchback]

Since your going to the strip, I would forget the vacuum advance and just set inital to 16 degrees and put light springs on the mechanical advance, ive ran this for years and works good that way, i never had luck hooking it up.

 

[The Big Al]

Question for all of you guys............

Just got finished tuning my Nova. (350/350, HEI-GM)

Setting the timing, I unplugged the vacuum line at the distributor and clamped it. Then I set timing to 11 degrees BTC. Plugged the vacuum line in and no change on the reading (still 11 deg). The vacuum from the dizzy is connected to the timed port on the passenger side of my edelbrock 1406 carb. Timed port is wrong!

Out of curiosity, I moved it to the full vacuum port on the drivers side of the carb where I currently have the modulator connected from the trans. Full vacuum port is correct

When I switched them........... the car's idle jumped up and I could not read the timing mark down on the crank anymore. The vacuum advace really kicked in on the full port. On the timed port = no change.

Which way is normal? I know this has been covered and I've searched but I didn't find out if the idle, or timing, jumps up after reconnecting the dizzy to vacuum.

Just going over my last few checks........ Tomorrow night is my first trip to the strip. And I don't mean strip club! haha

The correct way is the port with vacuum.
Just reset the idle. This is normal.

The vacuum advance is for cruising giving the engine more timing while not under a heavy load. When a load or heavy throttle, vacuum will drop and advance will cancel.

 

[stan_the_man]

The correct way is the port with vacuum.
Just reset the idle. This is normal.

The vacuum advance is for cruising giving the engine more timing while not under a heavy load. When a load or heavy throttle, vacuum will drop and advance will cancel.

Thanks Big Al!! You're help is greatly appreciated.

Should I put the modulator on the timed port then or runa tee on the full vacuum side and connect both????

 

[Baddbob]

No T, don't use the timed port at all. You might have one of those canisters that pulls 15+ degrees of advance which often times is too much for a performance car with a high initial setting. I usually find 5-10 degrees works well and most of the curves I've ran started with 18degrees initial, 20ish degrees mechanical, for a total of 38 depending on what the engine combination is.

 

[stan_the_man]

No T, don't use the timed port at all. You might have one of those canisters that pulls 15+ degrees of advance which often times is too much for a performance car with a high initial setting. I usually find 5-10 degrees works well and most of the curves I've ran started with 18degrees initial, 20ish degrees mechanical, for a total of 38 depending on what the engine combination is.

I don't have a canister. I'll ask again........... Where should I plug the modulator in at?