Dist cap PROPLEM FOUND pics added.

Don W.

Don W.

Stab it and steer it
Look at the marks past each terminal. I have an MSD 6al. Multiple sparks going nowhere? What the heck. I just learned of the Ford rotor mod a week or so ago and will be doing that but thought I'd post this and see if anyone has any comments.

It irritates me that MSD can't mod the cap a bit to line up better instead of apparently blindly following GM's design. I'd be curious if the folks that have the full MSD Pro-Billet Dist have the same issue.

(BTW I drilled the hole you see.)

Thanks all

Inside-dist-cap.jpg
 
Last edited:
4C FED

4C FED

Absolutum Dominium
Re: Dist cap weirdness

Re: Dist cap weirdness

Don W. said:
Same question I asked...

http://www.syty.net/forums/showthread.php?t=21073
Click to expand...

Use an old cap and cut the center out just inside of the 6 terminals on the top.
When you do the rotor mod you can then see where to mark the stock rotor on where to place the Taurus tip. You can also see how close the Taurus rotor is to the terminal after the mod and adjust it closer if need be.

If you need a pic of what I'm talking about I can take one for you.
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap weirdness

Re: Dist cap weirdness

4C FED said:
Use an old cap and cut the center out just inside of the 6 terminals on the top.
When you do the rotor mod you can then see where to mark the stock rotor on where to place the Taurus tip. You can also see how close the Taurus rotor is to the terminal after the mod and adjust it closer if need be.

If you need a pic of what I'm talking about I can take one for you.
Click to expand...

I was just gonna drill holes but cutting the top out entirely sounds better.

Any ideas on what's causing the marks?

Thanks!
 
4C FED

4C FED

Absolutum Dominium
Re: Dist cap weirdness

Re: Dist cap weirdness

"Many people don't realize it, but when using a multi-sparking ignition, the multi-sparking can continue even after the rotor tip has past the terminal and the spark is forced to jump a huge gap. Most centrifugal advance rotors have very narrow tips because the assumption has been made that there isn't any rotor phasing shift to contend with. Some vacuum advance rotors have tips that are wide enough to accommodate a multi-sparking advance. If you use a multi-sparking ignition that was designed for an 8-cylinder engine on a 4-cylinder engine, the multi-sparking which is usually limited to 22.5 degrees of crankshaft rotation, now continues for 45 degrees of crankshaft rotation. No rotor in production has a tip that is wide enough!

I solved this problem by cutting a new brass rotor tip with a longer trailing edge that can handle a full 45 crankshaft degrees of multi-sparking. The reduced spacing between the rotor tip and an adjacent terminal is still wide enough to prevent crossfiring.

The extra long trailing edge on my rotor tip can also accommodate the rotor phasing shift caused by electronic boost retard used with Turbochargers."

http://www.openroad.ca/volkswebbin/viewtopic.php?id=85030

Probably residue from the multi spark as it is firing.
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap weirdness

Re: Dist cap weirdness

4C FED said:
Probably residue from the multi spark as it is firing.
Click to expand...

Exactly what I was thinkin'. I was just looking for other opinions.

Thanks for your posts. That last with the fancy rotor is cool. I'll see if I can mod mine. If it works I'll stick it up here.
 
Daryl H

Daryl H

Donating Member
Re: Dist cap weirdness

Re: Dist cap weirdness

I always wondered if it would be advantageous to physically move the cap to a better position and electrically advance/retard the timing as needed to strike the center of the post.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Dist cap weirdness

Re: Dist cap weirdness

How many miles are on your cap? I have a MSD 6AL, Conrad cap & rotor (brass terminals) and stock coil. Mine doesn't have the white mark on the cap housing but my terminals look like yours.
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap weirdness

Re: Dist cap weirdness

dgoodhue said:
How many miles are on your cap? I have a MSD 6AL, Conrad cap & rotor (brass terminals) and stock coil. Mine doesn't have the white mark on the cap housing but my terminals look like yours.
Click to expand...

No idea exactly, I'm thinking maybe 2500? Terms have always looked like that even on previous caps. Just don't recall ever seeing those marks before.
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap weirdness

Re: Dist cap weirdness

Well even with the Ford "mod" my dist is off by quite a bit. I'm gonna look into this further. News at 11:00...
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap weirdness

Re: Dist cap weirdness

After this post I took the shaft out of my dist and wanted to see if I could remove the coil (or whatever it’s called) and see what locates the thing and possibly re-index it. No joy, the clip that holds it in place looked like I’d have to destroy the thing to remove it and I didn’t want to do that.

Next step, getting smarter as I go:), was to go to NAPA and ask them to bring me a dist so I could look at it. Bingo. Check the picture carefully and you’ll see what I’m gonna try and explain. The dist on the left is my old one with the reluctor at the “signal” point. Now look at the notch for the rotor and see how it is about 1/12 of a turn past the #1 marked on the base. Now look at the new dist on the right and see how it’s pointing at the screen. (Which is where the #1 would be if I’d have put it there.)

The difference is NOT the location of the reluctor on the shaft but the location of the coil on the base. Look at the orientation of the three screws and you’ll see what I mean.

A pic of my modified rotor is shown only because I did it before I figured out what was wrong with the dist. I cut open my old cap and on the old dist the rotor must have been a good 1/4" past the contact in the cap when the coil fired. Now they lineup perfectly.

I suggest everyone take a look at their dist.

Any questions post ‘em up and see if I can answer.

Distributor-Phasing.jpg


Modified-rotor.jpg
 
WyoSyclone

WyoSyclone

Active member
Re: Dist cap PROPLEM FOUND pics added.

That's a cool pic of those distributors side by side, Don. Could explain some guys stabbing new distributors in the same orientation as the old one, then not being able to get it to start/run right.... I seem to remember some guys talking about interference or stretching the wires too tight...might explain a lot of things.:tup:
I scored a brand new MSD pro-billet for $180 from a local car club guy this week. I'll be stabbing it this weekend and will take some pics of it for comparison... good to have in one thread.
 
sly dvl

sly dvl

Ya, it's got a Turbo
Re: Dist cap PROPLEM FOUND pics added.

The center "star" is splined onto the rotor shaft. It's quite common for the splines to wear (don't ask me why) and the points no longer line up in relation to where the rotor should be. I've replaced several distributors (on customers vehicles) because of this. Set the timing, & a week or so later it's way off again. Check the star and sure enough you can move it back and forth on the shaft splines.
Good find!
 
Don W.

Don W.

Stab it and steer it
Re: Dist cap PROPLEM FOUND pics added.

MSD's they are NOT. Both are over the counter rebuilds. The "correct" one on the right is NAPA. The other is, I don't know, 2-3 years old. I know where I bought it just don't know the brand.

sly dvl The "star" on the bad one was tight. I didn't check the new one.
 
turbodig

turbodig

Active member
Re: Dist cap PROPLEM FOUND pics added.

DaveP said:
OK, cool. Thanks. I didn't think NAPA would source MSD as a rebuilt, but I was confused. Now I'm not, and will watch for the 3 screws. If I see them, I now know to verify rotor position.

Thanks. Once again, I learned something from you Don. :tup:
Click to expand...

I'd never seen one like this, either. My stocker is much different.
 
M

MyNewSy005

New member
Re: Dist cap PROPLEM FOUND pics added.

I had a similar prob on my old stock dist. Replaced with an MSD and never looked back. Seems to idel a little smoother than the stock one too.

Wyo - the issue you spoke about where the wires being pulled too tight. I had the same one. It turns out you can be a single tooth off when re-stabbing the dist and it will rotate things just enough where the tach wires wont have enough slack in them to rotate the dist to set the timing. Solved this issue by rotating the plug wires on the cap but you can also just keep re-stabbing the dist till its right.
 
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