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High RPM Misfire

ksurfer2

ksurfer2

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Motor is a 512 Stroker, 10.5:1 compression, Edelbrock Victor heads, dual eddy 1407's on a cross ram. Lunati solid flat tappet cam. .600/.600 lift, 276 @ .050. I recently installed a new MSD 6al box, new pro-billet distributor, and new Master Blaster coil. I was not happy with the timing curve I could put in the distributor. The motor wanted far to much initial timing to be happy, so total timing was too far advanced, and I could not tune. The motor was only happy at start and idle with 27* of initial. With the 10* bushing, I could get total timing at 37*, but was stuck there. Over the weekend, I locked out the distributor and installed a MSD start retard box (5* retard at start up). Now the car starts and idles perfectly and runs great at 33* locked out timing. However, it has developed a high rpm (over 4,000) misfire (feels like it is hitting a rev limiter). This did not exist before I locked out the distributor. Do I need to dial in a couple more degrees of timing?
 
Sounds like the MSD box isn't set right. Rev limiter set too low? Or maybe not enough of a coil?
 
Rev limiter on the box is set at 8,000. Coil was fine prior to locking out the distributor (I didn't even remove the plug wires from the cap when I took the distributor out, I just removed the cap and layed it off to the side).
 
451Mopar said:
I would check the cap to rotor phasing
Click to expand...
This was the issue. I finally had a chance to get into the garage and checked the phasing. Installed the adjustable rotor and had to move it about 7* to get it lined up. Now the motor is very happy through the RPM range.

Thanks for the advice!!!!!
 
Adjustable Rotor - Interesting read MSD

Cool Stuff !

I know Rick E was making adjustable reluctors for the factory Mopar Distributor

I need to drill a old distributor cap and check that out this spring for shits and giggles and see where it’s at
 
The rotor phasing is really important with a locked distributor and electronic ignition control.
I am using a stock 400 lean burn distributor in the Charger with the FiTech controlling the timing.
I made a cap with hole it it to check rotor phasing, and it was pretty good at idle, then got better as the advance came in.
I am thinking of having a fixture made to drill the reluctor at different offsets for rotor phasing.
I think the FiTech uses 45 degree lead timing, Not sure what the stock leanburn used?
The Sniper uses something like 53 degrees lead timing, so I don't think the stock lean burn dist would work without having the reluctor locating pin hole drilled 8 degrees further (4 degrees at the reluctor/Rotor phasing.
 
The wealth of knowledge on this site never ceases to amaze me. A quick post of the issue and prompt response from a knowledgeable member resulted in an easy fix to the problem. Thanks so much 451!!!!!
 
Got these somewhere

AC35CB63-6E0A-4A31-B19A-3ADAA6A6FE0F.jpeg 03349681-0C43-492D-97C3-0CC1C556E230.jpeg
 
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