Distributor with High Energy Ignition (HEI) timing

1968 350 w/HEI

I plan to buy a new distributor. I do not know what I currently have on the motor (stock or after market) and I want to start dialing the motor in. I have done my tuning: new cap, plugs wires, plugs and rebuilt the carb.

I get a "push" of power at 2500-3000 RPMs. Thoughts?

Question:

1. Type of distributor to buy?

2. What is the difference of 4 pin ignition modules?
a. Normal
b. Performance (how much performance can it give)

 

Don't think I'd replace the HEI dizzy, unless it's worn out, with lots of bushing slop, as a pretty nice unit. Good idea pulling it out, dissasembling and lubing everything, especially the centrifugal advance shaft mechanism, as tends to gum up after awhile. Depending on the centrifugal advance weights, the advance will fully kick in at the rpms, your mentioning. Not really sure of the different pin modules, as not using one anyway. Mine now has a seperate MSD box, with the MSD magnetic trigger. Main advatage of this, is a smoother multi spark idle, when running a big cam. MSD and Accel, now make replacement multi spark modules, so the seperate box, probably isn't needed anymore.

 

and NOS dizzy bodies(with bushings) are available.


bill

 

1. Worn out, how to tell : A -> Sloppy/wobbly
2. Lube, is there a preferred lube, lithium or typical bearing grease : A -> grease
3. Weights, is there a marking or color to tell : A -> one light (copper) and one medium (silver).

4. Bushings, do you have a part# : A - > ----

Thanks
RonzOlds

 

As DeltaPace said:If the bushings are sloppy, it's worn out.

I just had mine apart yesterday and used a thick, red, tenacious bulldozer grease, but darn near anything thick and not subject to running or melting should do it.

You get replacement weights and springs from a speed-shop company, like Moroso. About $10 a set, if I recall.
The standard springs to achieve the recommended "all in by about 3,000 RPM" are one light (copper) and one medium (silver).
Don't forget that the base plate under the weights is held on by two tiny "C" clips.

Wait until you find out whether yours are bad - odds are they're fine.

- Eric

 

All thanks, I have added your answers to my post.

Condenser,
I see what appears to be one under the weights. Can it be tested?

 

 

It's a radio suppression condenser - it shouldn't affect the function of your ignition.
You should be able to disconnect it and see if it runs any better without it, but they don't tend to be a problem.

- Eric

 

Eric-Thanks for the info!

I plan to take the distributor out and apart this weekend. I have to know!!!!


Timing, how far can I advance it? Symptoms or signs of too much or to little?

RonzOlds

 

i use a graphite "paint" for lubricant on the pivot pins, it's called slide coat. i have NOS dizzy shaft assemblies, on them they used a light moly-based grease for the weights and mechanical advance, but they changed the design-there are no longer the nylon pads for the weights to slide on. i would think you wouldn't want a really thick grease in there-it may hinder movement. i use acdelco 1948791, which is a light calcium carbonate-based grease, on the bushing for the vacuum advance mechanism. the main shaft bushings get some 10w40 before installation of the distributor. after that point, the shaft bushings are lubed by splash/vapors.


bill

 

HEI may differ, but for pre-HEI distributors:

The lower bushing has a good supply of engine oil... the UPPER bushing is supposed to draw grease from the 5 cavities around the upper bushing, under the plastic ring. There are 2 holes in the upper bushing for this lube transfer. The shaft has a spiral groove which tends to draw downward as the shaft rotates, which lightly draws at the grease reservoir.

Corvette Central has bushings that will work with some mods:
Shorten upper to suit
drill out the grease transfer hole to OEM size

They are brass, whereas OEM bushings are steel based.