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You could check the resistance on the 7K chip.

Tom

https://board.moparts.org/ubbthreads/showthreaded.php?Cat=0&Number=1058548&page=0

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I would remove the chip and go out and test it now while your thinking about it. I had a 7000 RPM chip kick in at 5600 RPM on a MSD 7AL2 on a engine dyno test after working fine for more than ten pulls that took soem work to figure out what went wrong, of course that was the last thing we changed I have also seen a lot more chips go bad than that one on the dyno I would try it in 2nd gear Good luck on finding the real cause, please let us know what you find and what fixes it

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The reason I asked the rev limiter question was a friend had the same problem. miss at the top end. First thing he thought of was the springs, nope, wires? no, plugs?no switched out the msd box, no, pulled the high limit chip, BINGO!!!!! Give that a try first,good luck

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Thanks, man I hope it that simple! it would make my year!

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Thanks, man I hope it that simple! it would make my year!

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You jetted up... did it pick up speed... if so, keep
jetting up.... it could be your springs, the hyd cam
springs dont like rpm much above 6000(too light to handle
the weight).... we had this same problem(my buddies ford
pick up) last week during the Hot Rod Drag Week, we
tightened the pre-load some and it helped a little.
Also you jetted the front 2 jet sizes and the rears
4 sizes... try going up the same amount on each
(if you were in the ball park)

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It didnt pick up at all....the reason I staggered it front to back so much was because it still has a 3.5 PV up front. I started at 76/82 and ended up at 78/86 and it did not pick up or slow down for that matter. I couldnt run anymore than 32-34 degrees of timing either, i put in 38 and it seemed to hurt it and dropped 2 mph...I've been going over the timeslips and i'm coming up with more ideas. The current cam is ground on a 108 and manfu recommended installed at 104...the old one was ground 108 and installed 106. could this new cam be building more cylinder pressure causing me detonation problems? I have no real numbers but the TRW's are approx 18 thou out of the hole and i'm using a 40 thou fel pro, the heads are 308's with maybe one or two clean up cuts on them...where's my comp ratio most likly at??? With the old cam and no other changes i could run 40 degree's or timing on 93 octane

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This appears to be a simple case of operator error!

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Its a brain malfunction, clearly i should have sold this car years ago!

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My 70 340 ran best with 32 degree's with the 509 if the 509 is old it is a racer brown model I'm talking mid late 70s. The Comp is definitly building more cylinder pressure. Have you tried 30 total and or racing gas? at least 100 octane? Just curious, I also had 340 do the same thing and it was the valve springs but I would check the timing before going threw the hastle

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I had the same problem about three years ago. After a lot of jetting changes it turned out to be the plugs. If pulling the chip out doesn't work, changing the plugs is a cheap way to go. By the way, my Duster is running 11.70's now.

Good luck,

Raul

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I tried some 110 with no effect and I pulled the MSD chip with no effect then I decided to check the 6 month old Cap and rotor that I figured wasnt an issue. The small ball that rides the rotor tang was burned flat and there was a large burn spot on the tang. I only had another used cap and rotor to try but it made an instant difference. I'll get a new cap and rotor this week and see if thats it. What would make an MSD cap/rotor go bad that fast??

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It could have been a slight gap between the ball
and rotor to cause a arc.... or alot of tension
on the rotor and ball or if it had moisture on it.
Glad you found your problem.... how long has it been
in there

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I tried some 110 with no effect and I pulled the MSD chip with no effect then I decided to check the 6 month old Cap and rotor that I figured wasnt an issue. The small ball that rides the rotor tang was burned flat and there was a large burn spot on the tang. I only had another used cap and rotor to try but it made an instant difference. I'll get a new cap and rotor this week and see if thats it. What would make an MSD cap/rotor go bad that fast??

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It could have been a slight gap between the ball
and rotor to cause a arc.... or alot of tension
on the rotor and ball or if it had moisture on it.
Glad you found your problem.... how long has it been
in there

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Hey Derick,
What does it run in the 1/4?

New cap and rotor will be a
cheap fix. Good luck and lot
of fun with it!

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I see it's a MSD cap and rotor, but what brand distributor is it? I might check the play of top end of the distributor shaft.

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You have a beautiful car!!!! My small block does that to the cap and rotor also. Something I ran into with the MSD 6al and MSD distributor, is I had random misses up high over 5500 . MSD tech told me to get shielded cable between box and Dist. $18.00 at Jegs, fixed it.

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Thank you I appreciate the compliment A shielded cable huh...never heard of it but i will look into it tomorrow thanks!