Hey all, need to get the info on the diode used in conjunction with the MSD system to prevent engine run on. I know how to install it, but dont know the actuall diode # to go get. I've got a message out to MSD, but no word yet. I'd like to get the darn thing and install it.

1a100V; get it at Radio Shack or somewhere similar.

MSD run-on (http://www.msdignition.com/1troub1.htm#runon)

Jody

Call it overkill but I like to use the 3 amp rectifier diodes myself. They are type 1N5402 or 1N5404. Radio Shack's catalog numbers are 276-1143 and 276-1144 for $1.49 and $1.59 respectively.

kewl thanks guys, hate going just up the street and having it chug after I get there.

I'll be damned that after installing the diode it still has run on. Correct me if I'm wrong, but doesnt the diode go inline by the #4 post on the regulator? Thats what I gathered from MSD's site anyhow.

Maybe the runon is caused by the idle set a little too high.. that is why in the late 60, early seventies the idle was set with an anti-dieseling solinoid that closed the throttle plates when the ignition was turned off. If your idle is above 650-700 rpm and the engine is hot there is a good chance it will runon without installing some type of solinoid.

Clarify what you mean by run-on. Is it like you never shut off the key, or the stumbling, dieseling kind of run-on?

Does your generator light still light up when you first turn on the key?

Do you have the vacuum advance hooked to manifold vacuum?

MJM,
Didnt touch the idle when I switched from the points dist to the magnetic with the MSD. Engine didnt run on prior.

onovakind,
stumbling, diesling kind.
Will have to check on the gen light in the AM.
Vac is to manifold as always.

Think in the mean time, I'll bump up the diode to the 3a 400v and see if that stops it.

A bigger diode won't make any difference at all, but it will make a difference if the diode is installed backwards. The light bulb is in series with the diode, and if it's a regular bulb, it draws about 0.10 amps. If it's the deiseling type of run-on it's likely the diode will make no difference at all either way.

What is your initial timing? If you can increase the initial timing by vacuum advance or mechanical advance to the optimum value, you can close the throttle blades more and the engine will stop when you want it to.

got timing set at 10*. Put new diode in at 1:30 this morning. Ran it today for an interview. Still diesled. Dropped idle back down some. Drove around more on freeway. Shut off in gear. Remembered about indicator light. Started back up. shut off, no light, no run on. See what happends later.

Shut it off in gear. Problem solved, smile.gif .

I've been doing that already..Shuts off nice and easy. Very low on the embarassment factor.

THIS IS A GREAT POST!!!! And I wished I read it 24 hours earlier. It would have saved me $200 dollars and change. I put in a new voltage regulator because of a suspected drain down of the battery, the car get running after turning the ignition off, and I used my kill switch on the ground wire of the coil. The car died alright, along with my MSD 6AL!!!!! Darn. Got a new one, and put the diode supplied at the wire running offf the voltage regulator below... the BROWN wire, with the bar on the diode closer to the regulator. Car runs great and turns off great. Didn't install the original MSD or I might have Known this. READ THE FORUMS... LOL.

If you are going to put a kill switch on an MSD system, put it between the white wire and ground. The box will not fire if the white wire is grounded.

My idle is set at 1100rpms, and i have the timing locked out at 39 degrees.

No engine run on.

Does this problem occure when the engine is Cold and Hot? Just Hot? How hot does it run?

havent check the temp. temp light not coming on.
Bear in mind that the runon only began after switching to the new dist and msd control. All other items were initially kept the same. I've since adjusted the idle up and down. (sorry no tach as of yet to confirm rpm) I've regapped the plugs to .040 from .035. That actually seems to have killed the low end a bit. Otherwise, engine runs great with a tad bit of hesitation when its cold. Soon as it's warmed up no hesitation at all.

If you have an electric radiator fan, the fan can power the ignition after shutdown till it spins down. It acts like a generator.
David

David, standard old waterpump with 7 bladed fan. Perhaps I'll have to delve into it deeper and see if anything is bleeding back. I thought it might be the stereo, but have shut if off before the ignition without a change. Like I had mentioned though. this only started after changing the dist and running the msd. No problems with the stardard points dist.

hello,,
need help my 67 camaro conv BB wont shut off with ignition switch
i am running 1 wire altenater,,start runs fine dont stop when you turn key switch off,,my distrubitor is Accel ,,where do i need to install this diode ???
i know where to buy it ,,but need know where in circuit to install it ??.
thanks
Herm
kd8pe1@juno.com

Go to MSD website and print out these pdf file instructions from page 8. It shows the wiring diagram. http://www.msdignition.com/pdf/6%20series/6series.pdf

that diode goes in only one way. check it out.

Early Ford and GM: To solve the Run-On problem, a Diode is supplied with the MSD in the parts bag. By installing this Diode in-line of the wire that goes to the Charging indicator, the voltage is kept from entering the MSD. The diagram below shows the proper installation for early Ford
and GM vehicles.

Note: Diodes are used to allow voltage to flow only one way. Make sure the Diode is installed facing the proper direction.

http://www.msdignition.com/images_2003/trouble-s.gif

I used to have this problem. I had a vacuum leak which contributed to the problem because the idle was rough it would speed up and slow down. Is your idle a constant speed???

Also try advancing the timing. The timing advancing devices are sometimes different there are three main ones though. Does the new distributor have a vacuum advance??? If your valves start clattering then it is too far advanced.

Diesling or run on in your case is usuall because the engine has to much momentum built up and hot carbon ignites teh fuel that is being drawn into the engine. It is called desieling because its teh same concept as a deisel they dont have spark plugs and rely on compression and heat to ignite also because deisels dont fire everytime, just like with what happens in you car at this time. It is one of the worst things for your engine.