six pack tuning

[boss429kiwi]

Hi

I have had 12 months of trouble free motoring, however last weekend my 440/6 started to run rough.
It will struggle to idle and runs very rich.
It drives nice above 3000rpm, but stumble below these rpm's.

I removed the center needle and set, and cleaned.
I checked the float levels and adjusted.
Replaced the plugs, which had fouled up.
I did a vacuum check using some carb cleaner. I found a "possible" vacuum leak, as I handled the rear manifold vacuum hose that goes to the "tin can" it crumbled in my hands. I replaced.
Screwing in the center mixture screws makes very little difference to idle!

I test drove and it will now idle "better" and run "better" below 3000rpm, however still runs rich and stumbles somewhat down low.

Its worth noting that my idle problem seems to come and go???

Any suggestions?

[404NOTFOUND]

I just had the same problem suddenly minus the rich condition. Found a plug wire arcing to ground. Check yours in the dark. Not likely the cause but one variable that is easy to look for. I've got new plug wires on order.

[Chryco Psycho]

Power valve in the center carb could be stuck open too

[Nacho-RT74]

maybe this helps ?

http://imageshack.us/g/269/carbs1.jpg/

[BrianShaughnessy]

When stupid things happen with a 6 pack...  I start with cleaning the needle / seat on the rear carb.