Finished rebuilding my engine after a valve head came off and punched a hole in a piston, it got new piston and rod, shells, seals, recon head with new valves and a full piper 285 cam kit. Been running it this week gradually building up the revs, everything seems to be fine.

Until i get just over 5k rpm, it seems to hit a soft limiter? It went past this before on standard build (very rarely though). It's absolutely fine up until this point using varying throttle loads, but over it whether light or wide open throttle it seems unhappy.

I thought it'd be a coil pack but it was fine at ford fair on track so it shouldn't be any different now, maybe valve float but the springs should be correct since they came brand new in the kit from Piper?!

Engine is original 1.6 efi in xr3i, cam was run in according to Piper's instructions. PLENTY of millers assembly lube was used and i followed the Haynes CVH rebuilding book.

I'm lost for a cause at the moment, anyone got any ideas?