SalikDDD

i run a 670 on my 331 stroker, but i'm switching to a 750 since it will be drag racing more often then daily driving, with the 670 it performs excellently. i put the 600 on it for giggles and it was a dog, but for the 289 it was fine.

i'd say it's all in what you plan to do with it, the cam etc. so don't be afraid to go bigger if you've got the motor to back it up. as for the chevrolet, we've got a mild 350 in a K10 with a 750 on it and it runs great.

urban_cowboy

Be afraid to go bigger, unless you know what you are doing. There is no reason to put more capacity of air flow on a engine if the bore, stroke, heads, and cam cannot make use of it. All you are doing by going bigger is cause tuning problems that may can never be fixed. CID and VE rule what you need. Most people have no idea what their VE is. My 383 maxes out at about 94% based on dyno numbers, but most motors are way below that. Like I said above, plane janers may not get above 90%.

zggill04

Yeah, I'm not going to go with the 700. Just trying to figure out if the 408 will work better with it then a 625. Like I said, he races frequently, but was breaking up up top, so I'm thinking he'll be good with it. Though he said his car ran like a dog with the 650 double pumper. But that's a different carb altogether.

JMD

750 Mighty Demon works great on 66JamesStang's 408W... It is for sure not too much carb, nor too little...

I say the trade thing should work out pretty well.

Oh yea, and also, my other son is useing a 750 Mighty Demon on his strong 350 Chevy SB (aprox 450 HP), it works great, contrary to popular opinion, it is NOT too big for this engine...

In this instance, reality trumps theory.....

zggill04

Good info JMD. I figured he would be pretty good with it. He's sitting probably around the same hp as the 408, maybe a little less. I'm going to talk to him tonight and see what he says.

MonsterBilly

Here is my 2 CENTS. i HAVE A 289 PORTED AND POLISHED WITH INTAKE. I AM RUNNING A STREET AVANGER 670 CFM. MY CAR RUNS GREAT. I WAS TOLD BY EVERYONE ON HERE IT WAS TOO BIG. I CANT BELIEVE HOW GREAT IT RUNS. I HAVE YET TO TUNE IT BUT EVEN WITHOUT TUNE I DONT THINK IT COULD BE BETTER.

I SAY BUY IT AND TRY IT. IF IT IS THAT CHEAP.

67 evil eleanor

My 428 has a 735. My Boss 302 has a 650 and it shuts down at 8200, with some room left. Based on the charts and past experiencs, I would say the 650 will be more than enough and carry you up to 9000 withont fizzling out. Everything was over carbed in the old days even with the higher octane fuels. If you plan on spinning 10,000 RPM, then the 750 will be fine. Don't forget about re-jetting if you decide on that BIG carb. A wideband would be very helpful when you get into it.

kalli

i would love to hear a boss 302 spin to 8000. that must me a monster of a sound ...

zggill04

I tried to call my buddy last night but he was busy. I'm going to try him again today. But I'm either going to keep my 600 Holley or trade him for the 625 Demon.

htwheelz67

the 625 road demon is great for mild 351w's, a 750 will be a bit big unless its an annular model, the thing about demon carbs is they flow way more than their rating, a 750 demon can flow about 850-875 cfm, even the 625 can flow 725-750 cfm. I run a mighty demon 750 annular on my 408 and it runs better than my custom 950hp holley.