flynnhart1
Seaman Apprentice
- Joined
- Apr 5, 2013
- Messages
- 42
I?ve seen a lot of posts here from people asking if anyone has changed from a 2-barrel carburetor to a 4-barrel carburetor on a stock 4.3L Vortec engine. My boat is a 1997 Sea Ray 185BR with the Mercruiser 4.3LX Gen+ engine. According to the Mercruiser Service Manual #18, 4.3LX refers to the 2-barrel setup and 4.3LXH refers to the 4-barrel setup. It appears that Gen+ refers to the Vortec heads. So, to make a long story short, I have the 4.3L engine with the 2-barrel carburetor and Vortec heads. As a 4-barrel carburetor was a factory option from Mercruiser and the Edelbrock 1409 is basically an exact copy of the original Weber 4-barrel option (AKA: Carter AFB) I felt that making this changeover was something that would work nicely. My engine was factory stock with the 2-barrel/Vortec setup when I decided to convert it to a 4-barrel setup. I installed an Edelbrock 1409 (4-barrel) carburetor with the 1485 calibration kit and an Edelbrock 2114 manifold on the engine. Everything else is stock. I checked the engine compression and vacuum before doing this modification to help me convince myself that this was a healthy stock engine. All cylinder compression ratios were in the 170-180 range. Installation was really straightforward with the exception that I needed to grind a small amount of metal off of the rear engine lift bracket to get the manifold on. I could have elected to leave the bracket off, however, as it also holds the main wiring harness in place I opted to grind a clearance in it so that I could reuse the bracket. Five minutes with my air grinder and it was as good as factory. I installed the original Mercruiser 4-barrel throttle cable bracket and the Mercruiser 4-barrel steel fuel line (again, I could have opted to fabricate something else but I wanted this to be as close to factory as possible). I also installed a K&N spark arrestor, the updated GM intake manifold gaskets (very important IMO), and a new thermostat kit.
So, now for the verdict. The stock Mercruiser horsepower rating for my 2-barrel setup is 190HP. The Mercruiser rating for the 4-barrel is 205HP. Edelbrock told me it is probably closer to 220HP with their carburetor/manifold (I would say that 30HP from a carb/manifold is optimistic). The boat runs very well overall and I would say that the biggest gain was in throttle response, especially in the cruise to WOT range. If I?m cruising along at say 3000 RPM and I nail it, the response is noticeably improved. Out of the hole power is also noticeably improved, however, not as much as the cruise to WOT response. Top end is the basically the same (top end speed is mostly dictated by the propeller characteristics, not the carburetor). The engine starts immediately, idle is very smooth, and there are no hesitations or surges anywhere. Gas mileage should not be much worse as up to ? throttle, the carburetor is using only the primaries so below WOT operation it is only running on 2 barrels.
Was it all worth it? This is a question that can only be answered by each individual that opts to make this change. It was not cheap by any means. Possibly it makes the boat somewhat unique and may improve eventual resale value in that the vast majority of 4.3L engines have the 2-barrel setup. All I can say is that I am happy with the way the engine runs.
So, now for the verdict. The stock Mercruiser horsepower rating for my 2-barrel setup is 190HP. The Mercruiser rating for the 4-barrel is 205HP. Edelbrock told me it is probably closer to 220HP with their carburetor/manifold (I would say that 30HP from a carb/manifold is optimistic). The boat runs very well overall and I would say that the biggest gain was in throttle response, especially in the cruise to WOT range. If I?m cruising along at say 3000 RPM and I nail it, the response is noticeably improved. Out of the hole power is also noticeably improved, however, not as much as the cruise to WOT response. Top end is the basically the same (top end speed is mostly dictated by the propeller characteristics, not the carburetor). The engine starts immediately, idle is very smooth, and there are no hesitations or surges anywhere. Gas mileage should not be much worse as up to ? throttle, the carburetor is using only the primaries so below WOT operation it is only running on 2 barrels.
Was it all worth it? This is a question that can only be answered by each individual that opts to make this change. It was not cheap by any means. Possibly it makes the boat somewhat unique and may improve eventual resale value in that the vast majority of 4.3L engines have the 2-barrel setup. All I can say is that I am happy with the way the engine runs.
But if used for saltwater or brackish water, there are extra ports on the 2114 that allow for anode installation.
