Well the new ignition is in, where is the proper place to hook up the vacume advance?

[harshard]

I installed the new HEI with vacume advance and I am wondering which vacume port to use. My old HEI did not have a vacume canister so with the new one do I get vacume from the manifold or higher on the carb? If any one has pictures that would be great. There are several places on the carb as well as the intake I could use for vacume. Thanks, Shawn

[Sinister]

Manifold vacuum off the carb.

[j_cst_10]

It depends, you can run it on both ported or manifold. Ported vacuum creates no signal at idle and increases as you open the throttle blades and manifold vacuum gives the highest signal at idle and tapers off.

Your combination/transmission is going to determine where you run it at. You can try both and see how it responds.

[harshard]

Originally Posted by j_cst_10

It depends, you can run it on both ported or manifold. Ported vacuum creates no signal at idle and increases as you open the throttle blades and manifold vacuum gives the highest signal at idle and tapers off.

Your combination/transmission is going to determine where you run it at. You can try both and see how it responds.

When I put the ignition in the truck I did not have vacume hose and the canister had a plug on the end of it. I drove to the auto store and bought hose to go from the vac. advance to the front upper carb. port. I could not tell any difference between before and after. Shawn

[harshard]

The ignition I replaced was a bone stock(besides missing the vac. advance canister) wore out HEI. I replaced it with a brand new high performance GM model that is rated at 50,000 volts. I was really expecting some major increases in performance but so far really let down. I even replaced the wires with a high dollar set of Taylor wires.

[sean1969c10]

Did you install the HEI in the truck in your avatar? If you did you need to make sure you have a full 12 volts supplying the coil. The old points ign wire is a resistor wire, it steps the voltage down to about 9 volts to keep from burning the points. It will run the HEI but you won't get the full benifit of the HEI ignition. Usually you run the vac line to ported vacume, so above the throttle blades, this way you get ignition advance for part throttle driveablity and economy. It doesn't hurt anything to run it on straight manifold vacume like stated above it depends on what your truck likes most.

Sean

[j_cst_10]

You generally won't see any increase in performance, you just won't see a loss of performance either. High rpm is where a good aftermarket is ignition is going to shine.

[harshard]

Thanks for the info. I will check the voltage to the HEI and play with it some tomarrow. Shawn

[unclewatts]

I ran a 12 ga. wire from my battery to a 30A Bosch relay then to the HEI. I ran my ignition switch wire to the primary of the relay. Then I installed a ground wire from the HEI to the intake manifold. This setup insures full voltage to the HEI and it puts less stress on the ignition switch and works great!