750 double pumper or 850 double pumper???

[1971scamp383]

hi all....here is my build....383 .030 over...stock forged crank polish and new bearing....edelbrock double roller timming chain...edelbrock torquer aluminium intake(i know ...but hood clearance issue but not clearing with the spacer anyway )......comp cams xe274.....soon to be remplace edelbrock 750 cfm performer series....mopar performance distributor kit with orange box....taylor 8mm plugs wires....full length hedman headers 1 3/4 ..3'' out....440source aluminium heads(2.14 1.81 )....keith black dome pistons..(6cc dome)...10.1cr right now.....2500 torque stall(stall at 2900 rpm)...freshly rebuilt 727 with b&m transkit(shift kit)...3.91 rear gear(to be change for  4.56 ) with locker lock right....i have a little bog with my edelcrap....so i want to change it for a holley.......i have a deal for a holley 750 double pumper....and a holley 850 double pumper....ive tryed the 750 double pumper and man.....its a blast.....REAL good throttle response....so dou you guys think that a 850 double pumper is gonna be better or too much for that engine???thanks a lot

[bOb shingler]

i'd guess it's going to be too much.

[Steve DeTar]

I have that same cam in a 383.  I have 346 cast iron head milled .030.  With a .040 head gasket, my cranking compression is 160psi.  Right now, I have a 650 double pumper Holley with mechanical secondary's.  The Edelbrock avs can be tuned by adhusting the air-valve on there 4 barrel.  So which ever one,..you will have to adjust.  My point being,,,  you just dont bolt one some out of the box, you will have to "fine-tune" it.  If I were or had access to a chassis dyno, you could run both and compare both which would be better for you combination...  of course with my 383 streeter, I hant the most torque in the lower rpm band.     What are you seeking in performance?

[1971scamp383]

yeah ...low end torque is what i want with that car........i know ill have to adjust the carb ...but i think that with my edel 750 vac secondary...when i floor it...the carb wont shoot enough gas to have a good throttle response......

[383man]

My son runs a 750 DP on the 400 in his Dart and it works great.  He put an 830 anular carb on it to try it and it did not run any faster then the 750 DP did.  He has run 11.40's @ 117 with that 750 DP and it seems to work very good on his 400.   I use an 850 DP on the 440 in my 63 and it works great for me.  But I would go with the 750 on your combo.   Ron

[NYrr496]

750.

[speedymopars]

750 W/ a single plane, 850 with a dual.
With that torker -750 definately

[pwmax]

Take and do some mods to the 750, and end up with the best of both worlds. You can put a new main body that eliminates the choke, and contours the entry, proform, or, I prefer genuine holley. You can buy the main body from holly, like the proform deal, and its better. Its only about $15-$20 more. Worth it in my opinion. THat will add 40-50cfm to the carb. slab mill the throttle shafts, or, you can use a die grinder, and a thin carbide bit, and "port" that area/ Then get button head screws, and make sure you use red locktight on them. Take one of the old screws out at a time, so the throttle blades stay centered. You have to mill off, file, or grind off the swedged part of the protruding screw, to get the old screws out anyhow. Believe it or not, this will add another 20-25cfm. All this, with the original veturi size, will add 60-70+cfm, and make the crab signal better.

Frank

[PureGTS]

I'd tay with the 750 H D/P. I've run a 383 with a 1050 Dominator and switched to a 850 H D/P and it was a little crisper on the launch but I felt it really needed a 750 to be properly set up. There wasn't a whole lot of difference in the time slips so  , Although the 1050 got folks to do alot of double takes on cruise night.