MSD distributor issues

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wildbill

wildbill

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My Duster race car is having what feels like a high RPM miss. The car usually pulls hard to 6500 RPM but it is now flattening out at about 5800. ET has gone from 12.4 to 13.0 with MPH going from about 110 to about 104.

There is visible rust on the MSD distributor magnetic pick up but none on the 8 fin reel.

Runs and starts great like always driving around the pits. Engine sounds great with no funny noises or anything. Timing verified as 35 degrees total - where it is has always been.

Plugs look good.

I have already replaced the fuel pump and filter with no effect - fuel pressure a steady 7 psi.

Anybody have similar problems or other ideas?
 
Only problems I have had with the distributor itself is the screws for the rotor were loose causing the rotor to be cocked. Other problem is the little carbon ball in the center of the cap wears out of falls out altogether. Summit has a house brand black MSD cap for cheaper that works just fine.
 
an easy way to check the coil. get an analog meter. set the scale to the lowest A / C setting. put the meter probes into two wires from the coil. order doesnt matter. then spin the shaft. if the coil is good the needle will move. i have only done this one time. so i cant say how much it will move at what speed you spin it. or the quality of signal.
 
Thanks for the replies. I may spend the $30 or so for a new pick up and see if there is any change. I also am planning to look for any obvious cam issues. The valve covers are off and the rockers look fine but I did not have time to watch each valve open and close as I rotate the engine.

This is getting old! The car is not street legal so I need to take it to the track every time I change anything to test it.
 
I am using IMM Indy heads with beehive springs. My lift is only about 0.57 inches and they only have about 50 quarter mile runs on them. I hope they are not giving up already!
 
Have you ever seen a plug wire get the core burned out of it till the pressure in the cylinder won't let the spark jump the burned out gap any longer?

I have

They start missing at high RPMs and it only gets worse till that cylinder doesn't run at all any more.

(just a thought)
 
TrailBeast said:
Have you ever seen a plug wire get the core burned out of it till the pressure in the cylinder won't let the spark jump the burned out gap any longer?

I have

They start missing at high RPMs and it only gets worse till that cylinder doesn't run at all any more.

(just a thought)
Click to expand...

Yep, Check the coil wire!

They love to burn where the core bends and touches the terminals.
 
I am running out of ideas. The pickup is rusted but still measures within spec on ohms. Plug wires all check out. Turned the engine over - all valves appear to be opening and closing the right amount. Coil checks out. No changes in plug wire routing (not too close to the pickup wires).

At this point I have to wonder if the ignition box (Digital 6 plus) is going out.
 
Just a thought ... try msdigntion.com and register. Hit the forum for troubleshooting and an MSD tech will answer and help you. I have had starter kick back since I changed from a MSD 6al-2 to a programmable. I've been looking for advice, trying different things, and generally getting frustrated enough that I was going to go back to my old ignition box. Then I found the forum and they got back to me the next day and we have just about solved my problems completely. I am very impressed by MSD now. They've got me as a customer for life.
 
Thanks. I will contact MSD and see if I can send them the box for testing. I don't want to just keep throwing parts at it that may or may not fix the problem.
 
i have sent back a for sure not working box to msd they sent it back telling me it tested good and it worked after i got it back and there were new rivets in it so they had it apart i was told this is common with msd not wanting to admit any problems with send backs .
 
I just ordered a new Summit ignition box, MSD pickup, and MSD high vibration Blaster coil. Hopefully this will fix the problem. I guess the digital 6 plus box that I have is potted in urethane and thus not repairable.
 
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