I'm wanting to put my holley 4010 750 dual feed on a 352 that's in my '66 f250. Obviously a 750 is way to big for a mostly stock 352 with only bolt-ons (intake, headers, electronic dist.) So what size jets can I put in it to make it a little more friendly to the 352? It has #75 jets in it currently. Do the jet numbers correstpond with the cfm? Like #75 jets are for a 750 cfm, #65's are for a 650 cfm??

 

I have a 750 on my 390 witch is basically the same motor and I have 62's in it well I got it from my dad it had 60's and they were to small for the 390 but it ran his 428 great and I haven't really done any thing to my 390 other than put the intake on and my heads are to a 428 though that's the only thing I have done to the motor.

 

Different carb manufacturers have different ways of labelling their jets. For motorcycles, most jet sizes relate to the orifice in mm, a #66=.066mm for example. Holley jets are produced in batch by orifice size (75=0.0075", a big jet) but are flow tested at manufacture for specific labelling (some 75's may be labelled 73 or 78 after flow testing). But differences in venturi flow will give different results to different engines with the same jets/carburetion. Different vacuum porting and camming are obvious sources of variations, and there are others too (such as a worn brake boosters or leaky vacuum lines). Correct jetting is a function of getting the right fuel mix within parameters for a particular engine, so you can only go by CFM in a general way. I suggest you start with the smaller jets and see where that takes you.

 

If your engine is stuck it should be around 448.8 CFM max. by using this formula

 

You just can't know until you put it on and tune it. I'd start with it at Holley's factory calibration and go from there.