5 GT Turbo Missfire still

[ash ggturbo]

So after some advice I got myself a standered carburettor and took my group A off.
Strange thing I'm still getting the missfire at crusing speed between 2k and 4k
Rev it it's fine idle little lumpy worse with the new carb but will drive half or full throttle fine I'm at my Witts end now any advice would be great

 

[Adey]

have you set the idle mixture properly? that can make it idle lumpy.

is it actually missfiring?

have you got a video? whats the spec of the engine?

 

[ash ggturbo]

have you set the idle mixture properly? that can make it idle lumpy.

is it actually missfiring?

have you got a video? whats the spec of the engine?

Yeah man set it as i have with any other 3 turns out and adjust from there but no matter what I do with idle or mixture it's still lumpy and missfires
No air leaks done smoke tests
Ree set tappets new plugs with all diffent gaps I'm at a loss

 

[sparkie]

Could be an ignition issue. You don't know the spec of your car, specifically the cam. If it's been reground the mesh gear beneath the distributor is likely to be slightly off. Between 2k and 4k your ignition timing will be advancing. If the distributor cap is out of alignment the spark will have to start jumping larger and larger distances from the rotor to the distributor pegs. If you take the dizzy cap off, look at where the oxidation on the pegs is located inside the cap. It should be in the middle of the peg. If its at the edge of the pegs, then you will need to rotate the dizzy slightly to bring the pegs back towards the rotor.