I have a fresh built sbc 383 that cuts out at 5k rpm like clockwork under load. I can stand on it and it runs very hard and strong right up to exactly 5k every time and falls on its face. feels almost like its hitting a rev limiter. im running a holley 600 carb with float level set correctly, edelbrock rpm dual plane manifold, 9.9:1 comp, lunati voodoo 60103 cam, 041 casting 1.94 heads and roller rockers. .035 plug gap. msd 6al box with a new hei dist, and a 65k volt coil. advertised to be good to 7500 rpm. this engine was a 355 until this winter when I built it as a 383. it ran all the same components except a more aggressive cam before and I installed the new distributor mentioned above as the old one was clearly worn out upon inspection, the msd was run on the old engine also. I could run the 355 to 6500 no problem and did so right before tearing it down, ruling out valve float. initial timing is 16 degrees, total falling right at about 36 degrees, set with vac advance disconnected. total is all in long before 5k rpm. rev chip installed in msd is a 6700 so its not that either. im at a loss here, it runs great right up to exactly 5k everytime, and cuts out/bogs/misfires, whatever you wanna call it, it falls on its face. feels to me like its loosing ignition but who knows. never did this before. is it possible the msd doesn't like this new dist/coil combo for some reason? would installing the ign module back into the dist and forgetting the msd be worth trying?
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