Found an add for a used 1250 cfm dominator carb here in sweden.
I wonder if it will be way too much for my r5p7 motor.
Thanks

yes

Ok thanks

I`d go w/a 2-circuit 1050 Dominator properly set up.......

For e85?

Sure why not......

Ok im interested. Lets talk via pm or facebook?

way to big of carb

Quick rule of thumb is HP x 1.4 = CFM. So you need to be making about 900 hp before you need 1250 cfm.

Never been a believer in "formulas" per say, because few of them EVER suggest a Dominator for a small block, yet 9 of 10 run faster with a Dominator............However, in this case the 1250 is WAY too big. Too much throttle blade size, will result in very low air speed. I agree that it needs a 1050

Find out if that carb has straight boosters in it or if it has skirted boosters before buying it and converting it. If it has skirted booster then it is probally to big. I bought a Holley 1150 CFM Dominator and had it straight down boosters, I had it converted to E85 and it came back with skirted boosters so it flowed less( how much less I don't know ) after the conversion I tested that carb. on E85 on the same motor with a Holley 1050 Dominator on pump gas and the motor made 687 HP on pump gas with less torque than HP, the same motor 20 minutes later made 676 HP and 686 Ft. lbs of torque on E85 with that carb. My new bracket car has never ran any other fuel than E85

Thumperdart i read your post too fast. I read that you have a carb instead of that you suggest.

Cant see enough of boosters.

Pay attention to what Monte said because it is very telling.

Monte didn't say 1250 CFM was too much (really because it's a piss poor way to rate a carb) but that the butterflies (throttle blades) are too big.

Chances are, the 1050 would flow more than that (1050) anyway.

I also agree that those formula are a joke. One of the smartest manifold engineers I ever had the pleasure of talking to way back in 1984 told me to ignore those things. He had a chart in his catalog that gave RPM/airflow/CFM but he said it was a very loose guide and generally was extremely conservative.

I suggest a 1050 Dominator w/a good base tune instead of MOST of the stuff that`s shipped out w/too much emulsion and wrong set up for starters.......

Totally agree about these formulas in general cos EVERY motor I put a bigger carb on runs better AND goes faster.......

I agree those 1250 listed Holly carbs have way to big a throttle blade for most applications for folks on this board.

This is where it's a maybe, maybe not. How big is the engine? How heavy is the car? I have a 461 ci SB2 head engine, I've successfully made more power and quicker track times with a 1450, 2.25 throttle blade 2.050 venturi carb. Those heads are a spinoff of an SB2 head and with enough cubic inches, at least 400, the 1250 will be a good choice. Below that you better be spinning 9000 +.

Only 358cui.
Ill wait and save up some money and order a custom built carb for it.
Not sure the fuel pump can deliver enough on e85 though...

Just how true is this? If it is I see ALOT of guys running way to big of a carb. 530 HP builds with 950 carbs. By that math figure it should be running a 750. If you used a 750 instead would you still have 530 HP?