Mercarb 2 BBL easy mixture adjustment

"My two year old Mercruiser Re

"My two year old Mercruiser Remanufactured Mercarb 2 BBL flooded at the lake last night. Took the top off the carb to check and adjust float but decided to rebuild the carb even though it looked clean and I thought it was running good. I thoroughly soaked/cleaned all internal parts and cleaned every orifice I could find. Reassembled it w/a new needle and seat and mixture screw; other parts were good.

I picked up a new base gasket from a dealer a few days ago; it was not a thin type but about 1/4" thick. I asked why it was so thick and he responded it provides better fuel atomization.

I installed the carb w/thick gasket and set the mixture screw 1.75 turns out from the seat. The engine started immediately ran rough while it warmed up to operating temp. I wore rubber coated garden gloves due to the hot intake and T'stat tower. Using a 5/16" small socket to adjust the mixture screw, I was able to quickly adjust the mixture in the middle of the in/out stumble points.

Prior to using the thick gasket, adjusting the mixture was very touchy; finding the stumble limits was nearly impossible even on a new reman carb. The thick gasket did the trick."

"Guy
I just read the other da

"Guy
I just read the other day in a manual that Merc demands the use of their base gasket on the 2bbl as opposed to the gasket contained in aftermarket kits. You probably discovered the reason.
Bert"

"Hmm interesting. I recently

"Hmm interesting. I recently rebuilt my carb, and I've found it impossible to find the stumble limits. Twisting on the screw doesn't seem to make any difference."

"That is interesting. I've

"That is interesting. I've been fighting with mine too. I've been close, but haven't been 100% happy with it since rebuilding. Some days it's seems right on, others, it acts like it needs a tweek. I'm sure I installed the gasket that came with the rebuild kit."

"sounds like idle set screw is

"sounds like idle set screw is adjusted to high and engine is running on the primaries and therefore idle circuit wouldn't make any diff.
I always use a vacume guage and tach to adjust idle mixture. If it is not idleing on idle cirt. then there are other issues needing attn.
also the thicker gasket will greatly reduce vapor lock cond. and keep carb cooler and help keep mixture more stable as carb temp will remain somewhat more stable. A cooler carb will make more power as a cooler intake charge is more dense. also as the carb is raised, plenum volume is increased.

Kurt"

Also explains the more difficu

Also explains the more difficult starting when warm.

I've set the mixture w/a v

I've set the mixture w/a vacuum guage using the thin gasket; harder than hell to see much deviation. You won't believe the deviation you'll get w/a thick gasket! It was so obvious that I thought something was wrong. The stumble jumps out at you. You can set the mix by ear or feel! Set the base idle screw setting @ 1.5 turns and it should be right on.

"Where might we be able to get

"Where might we be able to get one of these thick gaskets? I bought a carb rebuild kit from my local Mercruiser dealer, and it came with a thin gasket."

"I got it from Lodder's Ma

"I got it from Lodder's Marine in Fairfield, OH 45014"