Missfire @2500 rpm

[doorjammer]

hi guys
At 2500 t0 3000 cruse rpm i have a missfire but when i stand on
it no miss car pulls hard . all msd new wires and cap :idea:

[gimmemud]

Vacuum leak maybe???

[itsabird]

sound,s like vac leak, to me also.

[johnracer]

More info on the car/engine would help. Street, race, ign type, vacuum advance, valvetrain, etc....if it has vacuum advance, try unhooking it. It may be messed up and advancing it too far at part throttle/high vacuum.

[doorjammer]

hi
It is a street MSD DIS........with no vacuum davance
zz4 350 /355 power plus intake open plain crane hyd roller cam
234/[email protected]/558 lift...adv dur 398.304 crane 1.5 roller rockers
demon 750 carb.......after 2500rpm......car runs strong

[cepx111]

You changed the cam correct?
More lift and duration than the crate motor cam had?
I think its fuel related.
Sounds like the power valve is trying to open up part throttle and dumping unatomized fuel down into the intake or drippling out of the boosters. With the car in park have someone rev it up to around 2500 and CAREFULLY lean over the carb and see if fuel is drippling out of the boosters.
If my memory serves me well, you need a power valve with a lower number with a higher lift cam or just take it out put a plug in it then go up about 4 jet sizes and be done.
Goodluck, Charles