I have replaced the 2 BBL Merc
I have replaced the 2 BBL Mercarb on my 1987 4.3L with the Reman. Mercarb recommended by Mercruiser which is the 96-98 model 2 BBL w/single mix. screw. Almost identical except the intake side of the barrels. On the old carb the barrels were separated but used a common passage way for the single mix. screw. The replacemnt carb barrels are open between them at the bottom of the carb. I set the idle speed at 650-700 rpms and tried to adjust the mixture per recommended procedures but found a wide range of mix. screw turns that had little or no effect on idle smoothing out. Any changes were very subtle and I had to have a helper watch the tach for any change in rpm. Not much change with nearly 2 full turns after initial 1.5 turn setup. It idles ok but stalls after quick throttle movements when it should be at idle. Also backfires at different screw settings. Only place to hook up a vacuum gauge is the fuel pump overflow on the bowl top.
I placed it in gear at idle and the rpms dropped to 500 so I adj. to 650. In neutral still not able to find sweet spot. Your help please.
I have replaced the 2 BBL Mercarb on my 1987 4.3L with the Reman. Mercarb recommended by Mercruiser which is the 96-98 model 2 BBL w/single mix. screw. Almost identical except the intake side of the barrels. On the old carb the barrels were separated but used a common passage way for the single mix. screw. The replacemnt carb barrels are open between them at the bottom of the carb. I set the idle speed at 650-700 rpms and tried to adjust the mixture per recommended procedures but found a wide range of mix. screw turns that had little or no effect on idle smoothing out. Any changes were very subtle and I had to have a helper watch the tach for any change in rpm. Not much change with nearly 2 full turns after initial 1.5 turn setup. It idles ok but stalls after quick throttle movements when it should be at idle. Also backfires at different screw settings. Only place to hook up a vacuum gauge is the fuel pump overflow on the bowl top.
I placed it in gear at idle and the rpms dropped to 500 so I adj. to 650. In neutral still not able to find sweet spot. Your help please.