Easy way to limit the HEI mechanical advance?

[Intragration]

Yeah, the old points setup won't work with the HEI distributor. Depending on which stock HEI weights and centerplate you have, it's a crapshoot whether they'll do what you want them to. There are many different ones that were available, some will work, some won't. If you're looking for 20 degrees mechanical by 3k RPM, the Moroso weight and spring kit with the lightest springs works great. I used a small piece of aluminum for limiting vacuum advance.

My problem seems to be that the mechanical is too slow and the vacuum is too much for my engine...so I am either setting the initial too low or the engine is running too advanced at speed, killing the power output....I gotta change something.

Ok, I see you have the stock vacuum advance. It's really easy to make a limiter for it, I'll make a drawing of the part I made. It stops vacuum advance at about 11 degrees, you could make it for just about any limit you'd want. As for mechanical, I'm telling you, the Moroso with the lightest springs was exactly what I was looking for, you might want to give it a try. I'm at 15 degrees initial, with 35 total at just under 3k RPM. It took me a long time to finally get to the point of the Moroso kit, I was stubborn and thought I could make it work on my own. I finally realized that I didn't have heavy enough weights, no matter what I was using. The Moroso with their light springs and their centerplate was the perfect combination for me.

 

[bill]

When I was buying parts for my engine a few yrs ago, I was assuming that this distributor I bought was an upgrade for an stock distributor and was correctly fitted with weights/springs which make it work better for older, higher compression engines SBO's....and the dealer I bought it from said it was for ALL small block Oldsmobile engines....but as with anything you buy...you get what you pay for.....

 

[bill]

Yeah, the old points setup won't work with the HEI distributor. Depending on which stock HEI weights and centerplate you have, it's a crapshoot whether they'll do what you want them to. There are many different ones that were available, some will work, some won't. If you're looking for 20 degrees mechanical by 3k RPM, the Moroso weight and spring kit with the lightest springs works great. I used a small piece of aluminum for limiting vacuum advance.

My problem seems to be that the mechanical is too slow and the vacuum is too much for my engine...so I am either setting the initial too low or the engine is running too advanced at speed, killing the power output....I gotta change something.

Ok, I see you have the stock vacuum advance. It's really easy to make a limiter for it, I'll make a drawing of the part I made. It stops vacuum advance at about 11 degrees, you could make it for just about any limit you'd want. As for mechanical, I'm telling you, the Moroso with the lightest springs was exactly what I was looking for, you might want to give it a try. I'm at 15 degrees initial, with 35 total at just under 3k RPM. It took me a long time to finally get to the point of the Moroso kit, I was stubborn and thought I could make it work on my own. I finally realized that I didn't have heavy enough weights, no matter what I was using. The Moroso with their light springs and their centerplate was the perfect combination for me.

I have an aftermarket HEI unit I got of Ebay. It works fine, just needs to be recurved for my engine. It doesnt have an adjustable canister....and I have heard that they dont last. So, Im gonna get either the moroso or the crane HEI kit and see what happens and also limit the travel of the vacuum advance....thanks for the advice/help!

 

[bill]

Well, today I pulled the springs off my HEI, and they are the lightest springs you can use....also the weights are larger than the after market kits, so I only have the adjustable or OEM vacuum advance left to buy. It seems as though the HEI I bought for my engine was built for older, higher compression engines, rather than the newer lower compression ones. Any advice on making a vacuum advance limiter?

 

[Intragration]

Bill, do you know if the weights and centerplate are stock GM? If so, they should have numbers stamped on them. You can use these to look up what advance they will provide. Even if they're bigger, it's possible that the ramp machined into the centerplate will not provide enough advance, even with light springs. If you have the numbers, I can look them up for you. I had found the info doing an Internet search. Here is a picture to give you an idea of the vacuum advance limiter I made. I made it out of thin sheet aluminum. Just a body with a hole to screw it down with, I believe one of the vacuum advance canister hold down screws, and a tab at the end that goes between the end stop and the rod on the vacuum advance unit. When vacuum is applied, instead of hitting the original end stop, the rod now hits the tab. You may need to finesse it a little to get it to sit flat and work just right, but once it's in, it works. Let me know if you have any questions.

 

[bill]

Without seeing a stock unit, I cannot say if they are stock parts, and I saw no numbers on the weights..... Just from looking at them, they are much bigger overall than the kit parts, which lead me to the assumption that they are also heavier. The black springs match the kits lightest springs in size and coil count...so I left them in there. I like the design of the limiter...gonna look into that further....it may be all I need to fix my problems. If you look at the pic on page one of this thread, my weights look like those...springs do not.
Thanks again!