So after replacing the plugs, I got the leads mixed up between cylinders 2 and 3. Needless to say it could barely hold idle and backfired through the carbs. The thing is; I'm running twin Solex sidedrafts (7K with electronic distributor) and there was backfiring from all 4 cylinders/carb throats, even though only two leads were swapped. I would have thought that only cylinders 2 and 3 would be backfiring, while 1 and 4 would still be running fine since it has it's own fuel delivery and timing correct.

 

Anyone with ideas?

I had the same issue of backfiring through the cabs. In my experience 99% of the time it is caused by the timing being too retarded or they are running too lean.

I'm getting my twin weber 7k powered rolla tuned very soon will let you know what the tuners thoughts are on the issue.

Cheers

I had the same issue of backfiring through the cabs. In my experience 99% of the time it is caused by the timing being too retarded or they are running too lean.

I'm getting my twin weber 7k powered rolla tuned very soon will let you know what the tuners thoughts are on the issue.

Cheers

 

It was because I had the leads for cyl 2 & 3 swapped.

I was just curious why ALL of the cylinders were spitting and popping; after all, cyl 1 & 4 should not be affected right?

Yeah cylinder 1 and 4 shouldn't be effected by the mismatched leads.

Are you running a standard cam?

If not the overlap of intake and exhaust timing could be to blame. As the exhaust valve may not be closed when your intake valve opens and if you have high exhaust pressure this can flow back through the intake.

Also ensure you have good spark and ignition coil / ignitor to burn all the fuel that is put in.

 

So after replacing the plugs, I got the leads mixed up between cylinders 2 and 3. Needless to say it could barely hold idle and backfired through the carbs. The thing is; I'm running twin Solex sidedrafts (7K with electronic distributor) and there was backfiring from all 4 cylinders/carb throats, even though only two leads were swapped. I would have thought that only cylinders 2 and 3 would be backfiring, while 1 and 4 would still be running fine since it has it's own fuel delivery and timing correct.

 

Anyone with ideas?

Good day I can check it out for you if you want, I am not so good at explaining but I can tune it for you.