i have two 750 carbs on my tunnel ram ,i would like to be able to put two 850 main bodies on the 750's metering blocks,base plate and bowls.Will i ever get it to run right ? what do you guys think

I think the biggest issue would be the base plate. I had an 830 holley one time which is a 1000cfm main body on a 750 base plate, but the base plate was beveled out to match the diameter of the venturi. I would think that having the bottom of the venturi much larger than the throttle blades wouldn't work well unless you were to machine the base plates to match.

I would just go ahead and put 850's on it if I had to have the extra cfm's. I don't know the size of your engine,but if not to big the 750's DP with the airhorns milled off,PV plugged and sq jetted @ 80 will work great.Set your idle screws @ 3/4 turn's and adjust your idle speed to that.
Hope this helps and saves you a little $$$.

Like D100 said theres a 1.720 bore in the 750 body/baseplate and a 1.750 bore in the 850 body so theres going to be a visable step....but the biggest problem is the 750 and 850 have the idle circuits in different spots in the baseplate and it will not idle/work....you would need a baseplate and body from 850's....Jesse

Thanks to all

I always thought that on a daul carb , that the carbs where set up much different ftom a single carb. application