I recently found the hard way that when you change ignition boxs you better check your timing for problems.On the dyno the week before the (505 medium riser duraspark dist dual quads C5AE-F heads)and liked 34 degrees total timing.I took it home and we installed it no changes. I went to the track on the last friday the car launched hard but fell on its face and just wouldn't pull . I tried 3 passes and parked it.Checked fuel pressure and it was fine.We checked the timing with 2 difrrent lights and it had 58 initial degrees and who knows what total. Took it apart on monday had 5 burned plugs and the head gasket burned out between 3 and 4 an inch wide.After talking to many diffrent people it seems that diffrent MSD boxes can give much diffrent timing results with no other changes made .Barry poole told me he had the same problem but less harsh.Another FAST racer added a MSD 6AL box and had 80 degrees of timing.I just thought maybee this might help someone else from a similar problem or worse .I sure could have had more damage than I ended up with pistons are fine heads tested well.Just remember to check when a change gets made a few minutes can save a lot of heartache,time and money.

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Sorry to hear about that.  That's good info for the rest of us.  Just wish you had seen a post before it happened to you.

Hope you get 'er back on track soon.

Chris S, Commerce, Michigan

1969 Mach 1 428CJ 4 speed Q-code (under restoration)
1969 Torino Cobra, 4 speed Q-code
1965 Mustang Coupe 289-4v
1987 Mustang GT
1999 Audi A8 Quattro
1996 F150 Parts Chaser

thanks for the heads up.

1965 comet a/fx style clone... work in progress.
1969 f-100 ranger 390 grand father bought new.

When the MSD box was first introduced it got its signal from the trailing edge of the trigger
Now I believe some of the boxes are wired correctly and get the signal from the leading edge of the trigger

MSD was aware of the problem but would not do a recall because
IT WORKED
why soil a good name with an unnecessary recall

You dont have to take my word for it
Get your old spare box
wire it like normal
check your timing
swap the 2 wires to the pickup
check your timing

58 initial degrees is extreme! I would almost think it would try and fire the motor backwards.

Josh

I have a MSD Digital7 programable box I think it retards the timing when turning the engine over.

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for the box to pull out on startup?

it's only 20 degrees on my Mallory. Something is screwy and I can't see how the car would start or run with that much timing. I also don't get how the box could cause that to happen but I'm no ignition expert and never liked MSD stuff anyway.

He checked timing with a light at an unspecified RPM. His initial/cranking timing would be less than the number checked if he has a really fast curve in the distributor...it's already advancing at 1000 RPM....

Barry Rabotnick
Survivalmotorsports.com

the distributor adds 20 deg at full advance. That makes 60 at cranking speed and the box pulls out 20 so it's still trying to start with 40 degrees. May happen but my ign is locked at 38 and it's a bit hard to start hot even with my box taking timing out.

I also can't see how the motor would run even if it did start. For years I set my timing by ear. Rev it up, advance dist until it ran rough then back it off a little. Finally put a light on it and I was at 38. I doubt I ever got past 45 before it was to the point of hurting itself.

It didn't start to bad but it sure ran crappy above idle.

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