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Hi..

I doubt seriously its the routing on the plug wires. I can lterally wrap my MSD wires together and no miss at 7500rpm in my race car.

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That is encouraging. They can't touch anywhere based on my draconian separation regime, and this is the third set, so it looks like I have spare MSD wires for the next several years.

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Cant see it being mechanical, a valve spring doesnt know if its undfer load or not, all it knows is RPM,right?..If you can rev it in neutral, and no misfire i would think its got to be spark or fuel related.

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my first thought would have been the 6al, but you SEEM to have eliminated that.

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My second thought would be fuel pump,filter,or some sort of undervoltage issue

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I have been going simultaneously broke and insane. Mosin

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Hi..

I doubt seriously its the routing on the plug wires. I can lterally wrap my MSD wires together and no miss at 7500rpm in my race car.

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That is encouraging. They can't touch anywhere based on my draconian separation regime, and this is the third set, so it looks like I have spare MSD wires for the next several years.

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Cant see it being mechanical, a valve spring doesnt know if its undfer load or not, all it knows is RPM,right?..If you can rev it in neutral, and no misfire i would think its got to be spark or fuel related.

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It definitely does not occurr without a load, and even under load it is sporadic. I spoke with a helpful person at 440source who was thinking it WAS a valve/spring based on the description, as he was thinking the springs are under a different type of pressures and load under load (if you will) and thus recommended a compression test first. This is certainly still on the near horizon if my above plans for the fuel system don't pan out, but I really appreciate the input!

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my first thought would have been the 6al, but you SEEM to have eliminated that.

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I actually did eliminate it completely and run the dizzy straight as per MSD tech's instructions. That didn't yield any change, so they swapped the dizzy out under warranty... and still no change. In the process of swapping out the dizzy I noticed that I still had the ballast resistor in line, which meant that my coil had not ben getting the full 12v for ~12K miles (!). It had also been mounted horizontally for all that time, so I swapped out the coil with a new Blaster 2, mounted it vertically as pictured above, and ran the 12v lead directly from the battery... and no difference.

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My second thought would be fuel pump,filter,or some sort of undervoltage issue

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The pump is a brand new Carter (CRT-P4600HP - 8 PSI) receiving 12v+ at idle, but I'm not sure if there is a voltage drop under load. The stock mech. pump has been removed. The filters have been replaced a few times, but I am going to go over the entire delivery system again and bypass the tanks, switch valve, and pre-pump canister filter, as well as the post-pump Holley regulator. I should add, I have tried running without the press. reg, and with high-flow needles and seats, and that didn't cure the problem, but I hadn't eliminated the tanks and switch valve from the loop. A more thorough/systematic process is next... and I will certainly post the results!

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Did they install a NEW oil pump drive or re-use it on a new bushing? What about the fuel pump push rod? I've had bad distributor drives do that at different RPMS. Pull the distributor and using a large flat blade screwdriver, try and wiggle the oil pump drive side to side and back and forth while it's installed. If it moves at all, replace it and the bushing.

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