Rtiny Posted November 8, 2017 Share Posted November 8, 2017 Hi. I need your help. Overview of setup: - Triple 44 mikunis - - Dual exhaust system, so 1 pipe for cyl 1,2,3 and 1 pipe for cyl 4,5,6. - Dual AFR - MSD and Coil - Pertronix sender unit in dizzy, +18 degrees - carter pump at 3psi Concern / Issue At idle AFR front is at 13.8 and goes to 16/17ish rear is at 10.8 and stays consistent. On Decel AFR front is fine. rear goes to 11.5 and then back to 10s Every other time its in use the 2 sensors read pretty much in sync. with load and WOT it will become the same. struggles and splutters a little to begin with, i think due to excess fuel. Pops on decel on exhaust and sometimes at the carbs. Diagnosis - Had the carbs tuned so we reading the front 3 cyl it should be good but rear is not at idle and decel. - Swapped carbs front and rear made no difference. - Adjusted float, made no difference. - Tested vacuum booster, found when the pipe is blocked off it runs better slightly. tested all lines, one way valve, booster. all okay. still suspected booster to got rebuilt and refitted last night. better brakes and doesnt struggle as much on accel. but idle and decel still same. Factors - I dont have a working tacho atm, so we did not sync the carbs but they were pretty good before. - clearances were checked 1.5 year ago - last service was about 2000miles ago, due for one now. noticed it was low on engine oil and coolant also dropped. i dont have the breather pipe connected atm. - When i had SU carbs the rear was pretty much always rich as well. i always thought it was the SUs were just over fueling. if i think of more information ill add to it or if anyone need more info please ask. its doing Skot and my head in. dont know whats causing it. I want a slightly more economical weekender and save some coin haha. Please, anything i can try Quote Link to comment Share on other sites More sharing options...
Rtiny Posted November 8, 2017 Author Share Posted November 8, 2017 Engine picture Quote Link to comment Share on other sites More sharing options...
Agno Posted November 9, 2017 Share Posted November 9, 2017 Not helpful I know but I have the same issue. I think that's part of the reason why the six pack Chargers have a different carburettor on the rear 2 cylinders compared to the front pair. Quote Link to comment Share on other sites More sharing options...
Cozza Posted November 9, 2017 Share Posted November 9, 2017 Not helpful I know but I have the same issue. I think that's part of the reason why the six pack Chargers have a different carburettor on the rear 2 cylinders compared to the front pair. I can see this being an issue under load/ acceleration but not idle. Sounds like the rear carb has a high float level or similar. I know you mentioned you’d swapped carbs front to rear and the problem remained at the rear. Any chance there is higher fuel pressure on the rear carb? Maybe leave the carbs as they are but run the fuel lines so the rear outlet of the fuel rail feeds the front carb and vice versa and monitor the afr’s. Checking the valve clearances would be a wise idea too. d3c0y 1 Quote Link to comment Share on other sites More sharing options...
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