Hi I have a 74F250 with a 300 six that I put Clifford 4 barrel intake manifold on. At present I have a holley 465cfm square bore with Vacum secondaries on the engine,the carb is mounted "parallel" with the engine & the carbs "primaries" are to the rear of the open plenum intake manifold. I installed it this way because it was the simpilest way to hook up the throttle linkage.
The engine had a bad flat spot at low rpms and on acceleration, I added a 50cc accelerator pump and that helped a lot. Still the low rpm torque seems kinda week, untill the engine revs up quite a bit there isn't much power available. Could the carbs orientation on the intake manifold have anything to do with that? I am planning to remount the carb "crossway" on the manifold with the primaries "outboard" on the intake manifold. I suspect the air/fuel flow to all cylinders would be more balanced. Will this help? Would a carb spacer help? I purchased a 1" spacer but I havn't installed it yet. I have completely rebuilt this motor, 9/1 pistons, ported and polished the head, stainless valves, roller rockers, ect. I am using the clifford "RV/torque" cam. I switched from points distributor to the ford duraspark. I am using a new stock coil. Would a hotter coil help? What about advance? I am using the original advance settings. I am thinking I should bump that 2-4 degs. just to see if it helps. Any suggestions would be appreaciated. Thanks

 

You will find a lot of info on this topic in the [link:www.ford-trucks.com/cgi-bin/dcforum/dcboard.cgi?az=list&forum=DCForumID9&conf=DCConfID 1|Inline Six Forum].

I have a friend that is following my design to split a Clifford manifold front/back to make it like a dual plane V8 manifold. This should increase low end response a lot. In the normal configuration it is set up like a single plane manifold that you all know is good for high rpm HP but bogs on the low end. You have to mount the carb so that you have a primary and secondary feeding each half of the manifold of course.


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