Washed the engine compartment now the 12a J-Bridge is misfiring above 4000rpms. Timing light says the engine fires above 4000rpms but the timing is way off, as in the timing light will light up but none of the marks on the front pulley can be seen.

Idles great, timing fine above 4000rpms.

MSD direct fire. Replaced MSD box and 1 coil already, didn't fix.

Put in another set of plug wires, didn't fix.

Went back to STOCK ignition using ignitor and no MSD box, didn't fix.

Routed power, pickup, and coil wires for MSD away from each other, didn't fix.

Removed and cleaned out carb, put it back on tight with no leaks, didn't fix.

Any ideas? Think the alternator or other electronic device is shorting and interfering with ignition system?

Thanks,

 

Moisture under the distributor cap?

 

new cap and rotor

cleaned out the glass fuel filter before the carb.

stumped. HELP!?!?!?!?!

 

Just a stab in the dark since I know nothing about timing, but is it possible that the belt is slipping?

 

There is no belt.

 

So then what "marks on the front pulley" are being looked for?

 

There's timing, it's just not belt controlled....the marks are timing marks.

 

hmmm

Well, I didn't say that I thought a slipping belt would affect the timing =)

I meant that the belt could be slipping and thus the marks wouldn't show up in the right place?
(i.e., perhaps it's not necessarily a timing issue?)

But, like I said, I know nothing about timing

So I'll just watch the thread and learn, hehe

 

also installed 2 other distributors and same thing . . .

 

I have the same problem with my streetported 12a, the only conclution I can come to is the mixture is becoming to rich or lean at high RPMs. fuel delivery problem? I believe my problem is a overy rich mixture at high RPMs due to inseficient carberator flow capacity.

let me know what you find... maybee it will help me too

 

I have a miss above 4k that is cured by a stroke of the accelerator pump, so I figure it's a carb problem.

But if the timing mark doesn't show at 4k it must be a slipping distributor, and I can't figure that.

B

 

Replace your plugs regaurdless of how they look and it should fix the prob.