[brad01]

What could I use for a limit bushing for the mechanical advance for this distributor? I would like an 18 degree limit or close. Thanks

[will slow gto]

I think you’d get more eyes on this thread if you post it in the Street section.

[b-man]

Originally Posted by will slow gto

I think you’d get more eyes on this thread if you post it in the Street section.

Thread moved.

If it’s not a truly model or year specific question this forum is the best option.

[brad01]

Thanks!

[AG]

You can buy a MSD bushing/spring set and use their bushing. You will have to file two parallel edges to make it fit into a stock distributor slot.

[Sun Tuned]

Well the first thing you need to do is find out where your at on advance as it is now. Then you know where you want to be, so a little math gets done.

Lots of ways to get this done. At the end of the day it really doesn’t matter how you do it ,as long as it stays put when done, you don’t want it to change because whatever you did fell off for instance.

These are but just several ways…

1. Welding up the slot
2. Napa used to sell a brass sleeve for this
3. Black aquarium tubing
4. Tail the weights ( weight modification)

Number 4 I don’t recommend, but it’s a method.
Requires much time and hard to go back ( easily) if you went too far.

Hope that helps.

[Formulajones]

Couple things you can do. Advance kits used to come with the little bronze bushing that snaps onto the stud. I then solder those in place, and file if need be for the desired centrifugal advance I'm looking for.

Unfortunately now most of the advance kits come with a plastic bushing. I don't recommend using those as they do crack and fall off over time.

What I've had to resort to is bronze bushings in the nut and bolt sections of the local hardware store.

What I sometimes also do is weld the slot and file as necessary.

[brad01]

Thanks! AG would you have a part # by chance? I have it set up on manifold vacuum. 16 initial, 18 mechanical and 10 on the can. Runs well. crower 60243 461 stroker.

[AG]

MSD is 8464 for $21.08
Summit is 850120 for $13.99

[Formulajones]

Brad
Your first post you mentioned you're looking to limit mechanical to 18 degrees but in your last post you mention you already have that...??

16 initial with 18 mechanical and another 10 thrown in with vacuum is perfectly fine and should provide good drivability and performance on modded and even stockish setups.

[Kenth]

I cut a piece of 1/4" brake pipe and attached it with some Loctite and an E-clip.
This ususally ends up with 18°-20° centrifugal advance in most Pontiac points distributors.
Then i´m setting the total mech advance to 30°-32° w/o the springs at idle speed and usually the initial will be around 10°-12° with the springs.

FWIW

[brad01]

Thanks for the help. Formulajones, The guy who curved my distributor did a trick setup. He drilled a small hole and tapped the plate the weights sit on with a tiny set screw with an allenhead being adjustable a great idea. All was going well until months down the road the screw started to move and I started to hear pinging. I ended up getting the timing back to where I wanted but the allen head is stripped out and I can't get the set screw out. I am going to weld the screw in place on both ends and use one of the above techniques.

[bob prichard]

Thank you for this thread. To those of you running the 18-20 degree centrifugal with 12-14 degree initial, what are you running for gas?

I have a Butler built 461 with Edelbrock heads and 10.2 compression. In order for me to run 13 initial and 19 degrees in MSD Ready to Run, I have to add octane booster to my California 91 octane. I don’t run vacuum advance at all since Jim Butler told me he didn’t recommend it due to possible detonation issues. I do have a can that will work with my low vacuum, but have not gotten around to trying it.

[Formulajones]

We run 91 Arizona pump gas in everything. Same stuff Cali has.

10:1 with aluminum heads shouldn't be a problem as long as you aren't running a really tiny cam with short duration and the ICL is correct.

I have several examples here running a decent amount of compression with both iron and aluminum heads, with a vacuum advance, that run perfect on the cat pee we have for gas. Even pulling down respectable gas mileage.

Initial and centrifugal have to be dialed, and the vacuum can needs modifications to limit travel and the amount of vacuum pull.

Can't even imagine not running a vacuum advance on a street car, there is nothing but benefit and no draw back. Removing them is the old school way of thinking back before people understood the benefits of having it. It was just much easier to discard it rather than go through the effort to dial one in properly.

[bob prichard]

Originally Posted by Formulajones

We run 91 Arizona pump gas in everything. Same stuff Cali has.

10:1 with aluminum heads shouldn't be a problem as long as you aren't running a really tiny cam with short duration and the ICL is correct.

I have several examples here running a decent amount of compression with both iron and aluminum heads, with a vacuum advance, that run perfect on the cat pee we have for gas. Even pulling down respectable gas mileage.

Initial and centrifugal have to be dialed, and the vacuum can needs modifications to limit travel and the amount of vacuum pull.

Can't even imagine not running a vacuum advance on a street car, there is nothing but benefit and no draw back. Removing them is the old school way of thinking back before people understood the benefits of having it. It was just much easier to discard it rather than go through the effort to dial one in properly.

Thanks for your input. When I first encountered this issue I called Edelbrock and spoke to one of their techs. He told me that our 91 octane was inadequate for my compression level.

[Formulajones]

Maybe lack of experience with it?

I'm running 11:1 with iron heads on 91 with one engine. 10.13:1 with another iron headed engine and one that is 10.4:1 with iron heads.

On engines with aluminum heads one is 10.84:1, the other is 10.2:1 which is honestly not even pushing the envelope all that far compared to what some are building these days using aluminum heads and pump gas.

Cam timing is a huge player.

[Formulas]

I have 4 points distributors apart right now on my bench one thing i observed was differing profiles on the center advance cam on the shaft also differing slot widths that the limiting pin works in

So in other words there isn't a way to tell X bushing will do X in every points dist, just have to modify and test what you have

[dataway]

I started with sourcing the info that showed exactly what OEM parts were used in my vehicle in stock form ... and progressed from there to make sure I had those parts and from there to determine what was necessary to make those parts do what I wanted. I used basically all OEM parts but took out some of the mechanical advance, and used a vacuum can recommended by the experienced folks here.

As an example ..

[Sun Tuned]

Excluding the distributors that have been through the commercial rebuilders, which all have a very distinctive appearance.

When you flip the advance cam/weight assembly upside down you will see a series of numbers and letters.

The three digit number works as follows… the first digit will be a line code and the second two numbers is what that advance cam assembly is capable of in crankshaft degrees advance.
So… 528 would be 28 degrees advance

The second set of letters will always either be CW or CCW
Clockwise or Counterclockwise as viewed from the shaft drive gear end of the unit.

[lust4speed]

My first thought is you either have more advance than you think, or the compression ratio is higher than you think. For our lousy California 91 octane gas I set up aluminum headed engines to be between 10.2 and 10.3 true compression ratio, and set up distributors for 32 degrees with Kaufman heads and 34 degrees with the current Edelbrock heads. Cams are at least Stump Puller sized. We simply don't get pinging on the lousy California 91 octane gas with the above specs.