[mchell]

Originally Posted by Schurkey

Magnetic-pickup distributors also retard based on speed. GM used to say "1 degree per thousand rpm" but it's not that simple. It's gotta be tested. It's approximately 1 degree per thousand, but not exactly.

I didn't know that points did that. In fact, as long as the point spring kept the points under control, I don't know why they would.

Yep...I’ve recently discovered the timing retard with the HEI. Never really noticed before as I would set total and not rev it much higher after I was satisfied it wasn’t advancing anymore. Continuing to increase rpm past the total, I noted some retard taking place(2-4 degrees depending on rpm)

Thought it was my timing light at first but have since read that it is not uncommon?

[scott70]

I thought about the bolt too long when I first noticed it. I took the clamp off and the bolt would go all the way down. It does have vac advance can but I dont use it. This is the dui "tripower small body" and i believe they took a stock factory points dist and converted it. By the way the best ET last night was pretty much identical to my last outing in 2017 .I had the motor freshened...a slightly bigger cam from the 60919 cam and had the compression went from 9.3 to 9.7. Went 8.7 @ 87mph with 2.36 60ft. You cant launch it at all with 8" bfg t/a. Somehow one run I managed to launch just right and got a 1.92 60 ft but then messed up the run by unknowingly pulling on the shifter in 1st and pulled it right out of gear into neutral and then tried to grab 2nd gear and accidently went to 4th gear. crossed the line at 3500 rpms and ran a nights best ET of 8.4 @ 84 mph.,,,lol. I really should have a different set of rims with some sticky tires for when I go to play at the track.

[firechicken]

Just goes to show how so much e.t. can be gained or lost in the first 60 ft.

This has always been my struggle even with drag radials.

[AG]

Originally Posted by scott70

I really should have a different set of rims with some sticky tires for when I go to play at the track.

Be careful with sticky tires and a Muncie, I shreaded mine when I used to race a stick.

[64speed]

The Summit Ready 2 Run is MSD for much cheaper

[scott70]

I'm getting a msd 8528 from a member here ,new in the box for a decent deal. Have to change plug wires also because one cap is female and the other is male. After it went from 33 to 34 at the end of the night it did manage to stay there ,,haven't checked it yet after the ride home. A couple of years ago I remember the power felt off so I checked it and it managed to go from 33 to like 38. Weird how it can sometimes retard and other times advance. Once I get it out and get the msd going I'll check the dui over and see if what cliff said is happening. Even with sticky tires I wouldn't launch hard. Right now I Rev it some and basically let the clutch out quickly and let the tires chirp which takes the rpms low,,probably like 1500 rpms and then try to feed the throttle. Problem is it usually breaks free again and also some in 2nd. Kills the ET and mph. I'd probably launch the same way but I shouldn't have to worry about any spinning after that with some street legal drag radials. If I had a auto trans,3000 converter and sticky tires I believe the car would be way into the 7's and 90mph+. Also in the past I've tried moving by hand with the clamp tightened and I couldn't move it. When I had it on the dyno I asked the guy who freshened the motor to look over the distributor and see if he could see what would cause that. I also asked him to check that the distributor wasn't long and pushing down on the oil pump shaft..maybe not letting it tighten. He said once tightened down there was still a small bit of play up and down so I guess it wasn't too long.

[Sun Tuned]

I had not seen where you had answered if it was built as a vac adv unit or not. I did see where you touched on that and that it was not hooked up.

I was going to say, and to add more to what Cliff said about the pull pin hole, since this distributor was/is likely built off a factory point distributor, there are quite a few things that can/will cause erratic timing.

Very likely what they did is drill and mount a Chrysler magnetic pick up on a factory GM breaker plate. At least that’s what they were doing. I know this because I supplied them the Stinger conversion plate they originally took the hole locations from. Then they made a drill jig from that.

As such, and in addition to the loose vac adv pull pin hole, first you’d want that snug but not tight. It’s got to have just a little play, just enough to put the pin into but no more. Most all stock distributors and including the HEI’s the hole for the pull pin is rather loose out of the box. Simply turn them over and close em up with the ball end of a ball pien hammer till they fit good.

Next thing, especially on these breaker plates, watch closely the fit on the top bushing of the housing. These things were a tad loose when new anyhow and after 50 years they ain’t getting any better. I realize they sit on a round housing base for the grease well but you need to look over the fit on that bushing. It should be snug and not drag or have tight spots. Remember the vac advance is supposed to be able to rotate this plate without much effort. So it doesn’t need to be stiff, whether you’re using vac adv or not.

Need to be looking for .008-.010 air gap clearance between the reluctor teeth and the edge of the mag pickup.. Try not to use anything to gauge that except a brass feeler gauge set or some plastic. They’ve always said only use no magnetic gauges for this and as I’ve done it myself and never seen an issue with using regular feeler gauges it’s best to use the non magnetic variety.

I think your issue is you’ve got some loose parts moving around that shouldn’t be. And even though the vac adv is plugged off there still could be enough monkey motion in the works to see the issues your having.

[scott70]

Originally Posted by Sun Tuned

I had not seen where you had answered if it was built as a vac adv unit or not. I did see where you touched on that and that it was not hooked up.

I was going to say, and to add more to what Cliff said about the pull pin hole, since this distributor was/is likely built off a factory point distributor, there are quite a few things that can/will cause erratic timing.

Very likely what they did is drill and mount a Chrysler magnetic pick up on a factory GM breaker plate. At least that’s what they were doing. I know this because I supplied them the Stinger conversion plate they originally took the hole locations from. Then they made a drill jig from that.

As such, and in addition to the loose vac adv pull pin hole, first you’d want that snug but not tight. It’s got to have just a little play, just enough to put the pin into but no more. Most all stock distributors and including the HEI’s the hole for the pull pin is rather loose out of the box. Simply turn them over and close em up with the ball end of a ball pien hammer till they fit good.

Next thing, especially on these breaker plates, watch closely the fit on the top bushing of the housing. These things were a tad loose when new anyhow and after 50 years they ain’t getting any better. I realize they sit on a round housing base for the grease well but you need to look over the fit on that bushing. It should be snug and not drag or have tight spots. Remember the vac advance is supposed to be able to rotate this plate without much effort. So it doesn’t need to be stiff, whether you’re using vac adv or not.

Need to be looking for .008-.010 air gap clearance between the reluctor teeth and the edge of the mag pickup.. Try not to use anything to gauge that except a brass feeler gauge set or some plastic. They’ve always said only use no magnetic gauges for this and as I’ve done it myself and never seen an issue with using regular feeler gauges it’s best to use the non magnetic variety.

I think your issue is you’ve got some loose parts moving around that shouldn’t be. And even though the vac adv is plugged off there still could be enough monkey motion in the works to see the issues your having.

Trying to go from my poor memory,,,when I first started to install the dist years ago,I was looking it over and I believe as I spun the dist the reluctor teeth werent the same air gap as you spun it around,I think one of them was practically touching the mag pickup.I called dui and told them,,,they said to adjust the air gap to whatever they said on the closest tooth. I also remember saying I was surprised there was only one screw holding the pickup adjustment. I thought if that screw ever loosened the pickup could float anywheres. They said theyve never had one move on them.
Once I get the other dist in and this one out Ill have to see exactly the possible loose areas your talking about. Yes the dist has a vac can but I dont have vac hooked to it. You obviousilly know dist lingo alot better than I do so Ill have to look it over to see what exactly where you want me to look.

[ZeGermanHam]

Have you given any thought to sending your DUI distributor to the company (Performance Distributors) and having them inspect and refurbish it?

[scott70]

Originally Posted by ZeGermanHam

Have you given any thought to sending your DUI distributor to the company (Performance Distributors) and having them inspect and refurbish it?

I sent them an email when I started this thread asking questions and told them what it was doing. Never heard a word. If it is loose parts Im a little ticked because its done this ever since I got it from them. Honestly If I do anything with it I would probably ask someone here on the site to look at it.

[Sun Tuned]

I’m sure they will get back to you.

Hard to say what they will do as far as a fix. I know they won’t service anything out of warranty. Even if your local..

Really the vac adv hole being loose as far as I’m concerned is more a matter of snuggling up a loose fit and removing a potential lag time between the vac on /vac off of the advance itself. Much like a carb accelerator pump when you adjust it. Still though ,if there’s a decent amount of slop it can affect things.

If the unit had some bushing wear in it that too can certainly cause things to move around. They’re good about checking stuff like that but it’s still possible.

Take a look when you get a moment and let us know.

[HWYSTR455]

Just to throw it out there, the Programmable MSD 6AL-2 accepts a MAP sensor for vacuum advance, so you can use the less expensive MSD non-vac dizzy as a trigger. The box also does away with weights and springs.

https://www.holley.com/products/igni...ip/parts/65303

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[scott70]

DUI did email me back today,,,,they didnt specifically mention anything about the total timing moving around but did mention they thought there might be a problem with the pickup coil by looking at the yellow wire being burnt on the outside insulation. They said the module would never get hot enough to burn like that from just contact. Once I get it out I can inspect it closer for these possible multi issues..

[Sun Tuned]

If the pickup has been compromised and overheated it very well could cause some false/erratic/early/late triggering.

Sounds like you’re on the right path.

They may wish to look at it, or simply send a replacement pickup.

They’re good people. They’ll get you fixed up and if not ask em who can.

[Formulajones]

Yep, just what I was trying to convey earlier. I had a pertronix that did the same thing. Exhibited erratic timing and eventually would get hot and completely shut down.
I had a hunch yours might be getting hot with that discolored wire. I just could never see the wires on the pertronix doing that because they are all black anyway.

[Dragncar]

Or you can just avoid it all and properly rebuild a PMD single point (cast iron best) distributor with curve set up on a Sun machine with your MSD box, done.
Points last forever, no stupid reluctors, magnetic pickups ect to fail. Do not even need a condenser for the MSD. You can keep a new one under the cap to hook up if your MSD box ever fails and drive home.
Best Pontiac ignition short of a crank trigger.
You will not get any more power out of a electronic distributor than points triggered MSD. And it sure as heck is not more reliable.

[Formulajones]

Originally Posted by Dragncar

Or you can just avoid it all and properly rebuild a PMD single point (cast iron best) distributor with curve set up on a Sun machine with your MSD box, done.
Points last forever, no stupid reluctors, magnetic pickups ect to fail. Do not even need a condenser for the MSD. You can keep a new one under the cap to hook up if your MSD box ever fails and drive home.

Yep, I run 2 cars here that way, our daily drivers. Rock solid dependable.

[Cliff R]

Third vote for using a stock points distributor to trigger the MSD. Not sure why folks are afraid of points and think that even when you use a points distributor it needs a Pertronix in it.

For those using stock points distributors set the dwell on one set then remove them and put them in the glove box with a head lamp and screwdriver. Install the second set, set the dwell and good to go. If you ever have any issues you are running again in 5 minutes or less. When your Pertronix, MSD, or other bug-zapping unit takes a chit, and it will sooner or later, you'll be on a roll-back instead.......FWIW....

[Formulajones]

The great thing about triggering the MSD with the points, is that if the box ever failed, I can swap a couple wires around on the coil, bypassing the box all together and drive away in 2 minutes, with a break for ice tea .

[HWYSTR455]

Although I don't mind points for some cars, I think from a performance and reliability perspective, electronic ignition is the only way to go. To think a 50 year old distributor, with poor production tolerances (in today's standards), and electromechanical triggering, is going to be 'better' than running something new is just pure denial.

With that said, I don't agree with the 'technology' of using 'multiple' sparks to light a cyl, it's like a match, do you keep striking it once it ignites? But, I'm not going there. It is unfortunately about the only way to be able to run certain types of distributors, so, a necessary evil.

Run what you want, run what you understand, it's your' car. Personally, it's very rare I would recommend someone go 'back' (wards) to points.

And we haven't even touched on weights, springs, and vacuum cans. Yeah, those are precise and flexible.


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