Reply to "UPDATED - Backfire under Low RPM / Load (4th or 5th Gear)....."

rockyMember

Thanks, guys.

The plugs are AC R43TS

The car ran well with this carb, then I spun a bearing in Sept. The car is back with a new 10:1 compression motor (Closed Chamber GA heads / flat pistons) and ran well during the break-in period (which I admit, the engine was treated pretty mildly) except this "off-idle stumble".

The "off-idle stumble" kept getting worse, and in the process of troubleshooting, I noticed the 4th/5th backfire. If I don't load the engine at low RPMs, I would not have noticed it.

Here's better pictures of all the plugs and the best pictures of linkage I have.

Maybe I need to pull the carb off, but I want to be as sure as I can before I get too serious.

More New News:

Last night I attempted to make some minor adjustments to the Idle screws. I could not get the idle to drop (reduce RPMs) by adjusting (turning in) the screws with the exception of the Passenger Side rear.

Primary Accelerator Pump Linkage

Secondary Accelerator Pump Linkage

Thanks

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