LA Mopar electronic distributor retaining clip

[AJ/FormS]

Crap I got one of thse around here somewhere.

Don't be bending on those arms until you understand the consequences of said bending

 

[prorac1]

Crap I got one of thse around here somewhere.

Don't be bending on those arms until you understand the consequences of said bending

Well we didn’t do it on purpose. Lol.

He did it by accident trying to pop the reluctor off like you do on a stock distributor.

He’s going to work on flattening it back out tomorrow.

As you can see from the picture, the spring is up at an angle a little bit.

 

[Mattax]

Closest thing I could find on the Internet was this post from another board. It looks like what we may have here is a real deal, discontinued, Mopar performance distributor.

View attachment 1715310786

My only concern is, it looks like one of the tabs that hold the springs might’ve been bent up. We might have to bend that backed out. But it was kind of a mystery upon disassembly.

View attachment 1715310787

Or it’s an optical illusion. I’m not sure yet

One of the MP distributor made by Mallory. Uses YH advance mechanism.
I've posted about them here, and Moparts and at RacingFuelSystems forum.

 

[prorac1]

One of the MP distributor made by Mallory. Uses YH advance mechanism.
I've posted about them here, and Moparts and at RacingFuelSystems forum.

Thank you. What is a YH advance mechanism?

Is it a good distributor?

 

[Mattax]

The long and short of it. Not a particularly good design for an advance mechanism. With a fair amount of work a decent curve can be made, but not as good as can be made with a Chrysler mechanism. The rest of it is fine.

If you just want to get things running, it is fine. If you're going to use vacuum advance, try to slow the curve as much as you can around 1800 to 2800. Even if you have to use more initial timing than stock because its hot rodded, the mechanical timing in the 1800 - 2300 rpm range should be similar to factory timing. Otherwise it will ping at moderate throttle when using vacuum advance.

The design issue and possible improvements discussed here. Modifying YH Advance Weights
I haven't done the major weight modification yet. Your on your own if you try it. Working with a Chrysler built unit at the moment, don't want to mess with Mallory built one since its my fallback and baseline.

Canyoncarver is working with a Mallory YT which is basically the same as the YH
Distributor springs

 

[prorac1]

The long and short of it. Not a particularly good design for an advance mechanism. With a fair amount of work a decent curve can be made, but not as good as can be made with a Chrysler mechanism. The rest of it is fine.

If you just want to get things running, it is fine. If you're going to use vacuum advance, try to slow the curve as much as you can around 1800 to 2800. Even if you have to use more initial timing than stock because its hot rodded, the mechanical timing in the 1800 - 2300 rpm range should be similar to factory timing. Otherwise it will ping at moderate throttle when using vacuum advance.

The design issue and possible improvements discussed here. Modifying YH Advance Weights
I haven't done the major weight modification yet. Your on your own if you try it. Working with a Chrysler built unit at the moment, don't want to mess with Mallory built one since its my fallback and baseline.

Canyoncarver is working with a Mallory YT which is basically the same as the YH
Distributor springs

Currently we’re running 20 degrees of initial timing.

It’s a stock 1983 318 with a Holley street dominator intake, and Holley 390 vacuum sec carb.

The cam is very similar to a 1968 4 speed 340 cam. 214/224, 444/466, 104 intake centerline.

With the distributor as is, it has around 39-40 degrees of total advance.

It did spark knock under load at lower rpm.

Vacuum advance is hooked up, but I’m not sure what it’s pulling.

I’m planing on limiting total advance to 34 degrees and going from there.

When do you determine when to eliminate vacuum advance

Thank you for all the info. Greatly appreciated.

 

[prorac1]

Crap I got one of thse around here somewhere.

Don't be bending on those arms until you understand the consequences of said bending

Actually, looking at it closer, he didn’t bend the plate, he stretched the spring.

Looks like we might be buying a spring kit. Lol.

Mallory springs I’m assuming?

I guess it beats bending a hard part.

 

[Mattax]

When do you determine when to eliminate vacuum advance

Drag racing. Its one more thing you don't need as it doesn't do anything at WOT and cool off and part throttle economy are not needed.
Hot rodders sometimes skip it because its easier not to use it.

Starting at the bottom right of the page is a good basic explanatoin of why centrifical advance is needed. And on the next page is vacuum advance.
Ignition System Analysis (Session 259) from the Master Technician's Service Conference

In my opinion, your engine should not need that much initial timing. Something in the range of 8 to 16*, 650 to 750 rpm would be more like it.
Here's a chart Barry Grant used to have posted for ballpark starting points.
Distributor starting point for a curve

Agree 32 - 34* should be about the max. for initial plus mechanical.
Around 50* for initial plus mechanical plus vacuum under highway cruising conditions.

 

[Mattax]

I posted some early factory 318 timing curves here.
Erratic Timing

Might be interesting to see what the books show for timing on the 80s Diplomat Police 4 bbl packages. Sounds like your engine setup is similar to those.

 

[halifaxhops]

Finding those Mallory spring kit will be a bit of a challenge now they used to be everywhere. I have no idea what that "plug" is holding the cam plate down.

 

[prorac1]

Finding those Mallory spring kit will be a bit of a challenge now they used to be everywhere. I have no idea what that "plug" is holding the cam plate down.

Summit makes a kit, but I’m going to start by replacing the bent spring with one of the FNO springs I have and see where it puts me.

Advance was coming in pretty quick before.

 

[halifaxhops]

those you can adjust the max mechanical advance on. they are nice for that, no messing around with the slots. try not to bend the tab it will change the rate of advance on the weights. they are for fine tuning just do a spring change for now.
I prob have springs that I can sell if needed would like a pic of the both springs from the top to see what you have.

 

[toolmanmike]

those you can adjust the max mechanical advance on. they are nice for that, no messing around with the slots.

Looks like 2 screws to adjust?

 

[halifaxhops]

yup you then should use a slot key but you can measure them and do it that way also. A member here did a good chart on them. prob show up in a search.

 

[halifaxhops]

That one looks like it is all the way to one side. Been a bit since I was in one.

 

[prorac1]

Here’s a picture of it all back together from the top. We have one factory spring from the Mallory/Mopar distributor. The other one is out of the FBO kit.

We accidentally bent the spring mounting tabs pulling it apart. So we completely disassembled it and bent everything back to where it supposed to be, verify that nothing else was damaged, and are currently putting it all back together.

We didn’t realize what we were working with , until we went to pry off the reluctor and the whole bottom plate pulled up and bent the tab in the spring. But I think we came out with our *** intact. LOL

 

[prorac1]

yup you then should use a slot key but you can measure them and do it that way also. A member here did a good chart on them. prob show up in a search.

Yep. I’m reading that tutorial right now. We put the degree wheel on top of ours and were able to move the rotor 29 distributor degrees. That doesn’t sound right to me. But, we want 14° of mechanical advance, so we would limit that down to 7° at the distributor.

But is it right for us to get 29° at the distributor Max advance? Wouldn’t that be 58° at the crank? I understand there’s a lot of adjustment but who would ever need that much? Unless I’m understanding it wrong.

 

[prorac1]

Yep. I’m reading that tutorial right now. We put the degree wheel on top of ours and were able to move the rotor 29 distributor degrees. That doesn’t sound right to me. But, we want 14° of mechanical advance, so we would limit that down to 7° at the distributor.

But is it right for us to get 29° at the distributor Max advance? Wouldn’t that be 58° at the crank? I understand there’s a lot of adjustment but who would ever need that much? Unless I’m understanding it wrong.

Never mind. LOL. The bottom advance plate came loose from the top plate. Therefore it wasn’t working correctly on the bench. It wasn’t stopping the amount of advance. We now have the bottom plate attached. We’re going to re-check the advance with the degree wheel in the morning.

 

[toolmanmike]

Never mind. LOL. The bottom advance plate came loose from the top plate. Therefore it wasn’t working correctly on the bench. It wasn’t stopping the amount of advance. We now have the bottom plate attached. We’re going to re-check the advance with the degree wheel in the morning.

Looks like you are getting it sorted out. And you wonder why Hoppy got into distributors! LOL They're fun.

 

[prorac1]

Looks like you are getting it sorted out. And you wonder why Hoppy got into distributors! LOL They're fun.

Yeah. No doubt. LOL.

What didn’t help, was when we delve into this we thought we were working with an aftermarket stock replacement. So when we put the two screwdrivers underneath the reluctor to carefully and gently pry it up, we bent the living crap out of everything under there. LOL. We realized it as soon as we got another layer or two down into it what we had done, and have spent the last day and a half on bending things and putting them back to the way they’re supposed to be. LOL.

It’s how we roll. LOL

But we’ve learned a lot about distributors in the process. We have that going for us now. LOL

 

[Mattax]

those you can adjust the max mechanical advance on. they are nice for that, no messing around with the slots. try not to bend the tab it will change the rate of advance on the weights.

On those when you reduce the slots, it also reduces the tension on the primary spring.

 

[prorac1]

On those when you reduce the slots, it also reduces the tension on the primary spring.

Yeah. I guess that would be a side effect.

I need to order the summit spring kit also.

Nobody local has a spring kit with the long springs.

 

[Mattax]

Try it with the one it has?

 

[prorac1]

Try it with the one it has?

We would, but it got stretched out while we were pulling the distributor apart.

We thought we were working with a stock replacement distributor, which it looks like from the top. But when we went to slide the reluctor off it pulled up on the entire shaft because this one with Malory internals is a different design. We bent all kinds of ****. LOL. But we have everything back straight and correct.

It’s what we do. Lol

 

[prorac1]

Try it with the one it has?

Currently. We have the elongated purple/blue spring that the distributor came with, combined with a heavy gold spring from the FBO kit. We’re going to start there and see where we end up.

Total timing is set for 34°.

Ironically, we are currently reading your article on tuning vacuum advance canisters. LOL. Thank you for all the help in this thread, plus the great article.