tankdiver Posted September 2, 2014 Share Posted September 2, 2014 hi can any one help when accelerating it tends to backfire in the carb .I think the main jets are over fuelling and have heard of a Marcus conversion but don't know where to get it or to the size of the main jets. I replaced the engine with a cvrt :nut: jaguar engine Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted September 2, 2014 Share Posted September 2, 2014 hi can any one help when accelerating it tends to backfire in the carb .I think the main jets are over fuelling and have heard of a Marcus conversion but don't know where to get it or to the size of the main jets. I replaced the engine with a cvrt :nut: jaguar engine The Marcus modification to the carb was to overcome a flat spot which had been a problem from the start with the Fox, causing a lot of gearbox problems. Various parts were changed over a period when different Mod Instructions were released. The Marcus mod was a different baseplate, reduced stroke of accelerator pumps to reduce the bore wash as I recall. You could try Richard Banister as he know this modification and will know if it is available. You might find a complete modified carb also. Quote Link to comment Share on other sites More sharing options...
timbo Posted September 2, 2014 Share Posted September 2, 2014 The new baseplate Richard refers to is stamped with the word MARCUS so it should be readily apparent if it has been done. I have a box of carbs somewhere in the back of the garage if you decide you need one, I'm sure I could find a reasonable one. Tim Quote Link to comment Share on other sites More sharing options...
tankdiver Posted September 2, 2014 Author Share Posted September 2, 2014 The Marcus modification to the carb was to overcome a flat spot which had been a problem from the start with the Fox, causing a lot of gearbox problems. Various parts were changed over a period when different Mod Instructions were released. The Marcus mod was a different baseplate, reduced stroke of accelerator pumps to reduce the bore wash as I recall. You could try Richard Banister as he know this modification and will know if it is available. You might find a complete modified carb also. thanks for that I will have a look and see if my old one has it on Quote Link to comment Share on other sites More sharing options...
tankdiver Posted September 2, 2014 Author Share Posted September 2, 2014 The new baseplate Richard refers to is stamped with the word MARCUS so it should be readily apparent if it has been done. I have a box of carbs somewhere in the back of the garage if you decide you need one, I'm sure I could find a reasonable one. Tim thanks Tim I will look at my old carb to see it has the mod again thanks Quote Link to comment Share on other sites More sharing options...
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