background is rebuilt 1500 miles ago (no new sensors ), running t34, 803's, msd chip

builds up fine, but when i try and rev it more, say past 4k, starts to miss a little and hesitate. will till rev up, but just doesn't feel smooth. have turned boost down from 20 to 13, to see if it was blowing the spark out, but no different.
popped the plugs out, 1,2 and 3 were quite black, but with a light brown tinge on the ground terminal, 4 was mainly black. couldn't adjust gaps due no knowing the right distance, but all 4 were the same.

its running ngk iridium plugs, magnecor leads of unknown age, fairly new dzzy cap and rotor and a 500 mile old grp a coil

any ideas where to look next? want to sort it before i go for a dyno setup

cheers
Dave

 

iv got the same prop did u sort yours out if sowhat was it thx

 

hi mate dus the rev counter go through the roof as it missfires?

 

Have you tried reducing plug gap to 0.6-0.7?

 

Is your phase sensor gapped correctly?

What sort of condition are the leads in, check for micro holes in both the end caps on each one.

 

Rev counter stays normal

haven't reduced the gap, as i didn't know about weather it was the same on iridiums

whats the correct phase sensor gap? i will recheck it. leads seemed ok when i put them back on, but will have another look

 

Seem to have solved it

took the plug gaps down to .65 and its much better

 

When mine had a missfire, it would be perfectly fine until 3-3.5K then would mis badly, under 3-3.5k (off boost) no probs,

Mine was the HT Leads, i borrowed a mates set first before spending Łs.

Worth a try?

 

Thanks for all your post, I have the same problem and now it has been sorted!