need help
 

Pulled motor this winter to replace valve seals.1989 454 mag
Sent heads out for valve job. Swapped cam don't have specs on me but it's about the same as the stock 502 cam. Put in comp 911 springs and 1.72 roller rockers. Added emi thunder stainless risers and manifolds. Got rid of the thunderbolt and put in Msd distributor wires and coil. Timed it boat runs mint until 4000 rpm.. between 3800 and 4200 depending on the run it starts cutting out and almost like it's hitting a rev limiter and miss firing. I still have the stock q jet. Bumped the jets up in the primaries and metering rods in secondaries. No change. Boat will rev in N over 5k. Will not go over 4ish under a load. And I am running a 23p mirage which I ran last year to 4800

Was the cam degreed in when installed? It sounds like a timing issue with either ignition or cam timing, and it sounds like you verified ignition timing is correct.

i think its running too good to be cam timing. Im hoping its running out of carb. Gonna order a holley 850 this week and hopefully that solves it

need cam specs..need to know the duration at .050..

think we got it squared away.. didnt have big enough jets. thanks guys