lynwood78

I'm planning to put in a 351W in my 69 in the distance future. Right now I have the stock 302. I really want to a Holley750 CFM four barrel carburetor for my stang. Will it be sufficient enough? Thanks
750 CFM Four Barrel Street/Strip Carburetor
750 CFM Four Barrel Street/Strip Carburetor
750 CFM Four Barrel Street/Strip Carburetor

David09sp

I am unsure why you even need a 750cfm. That is a pretty steep suckn. Instead for optimum efficiency I would take a 600-650 carb. Unless you are highly modding cam, in, heads etc.

Not a d.p fan.

kalli

from what I hear double pumpers are the better option on manual gearbox and vacuum secondaries for auto trans
no matter which carb you're going for 750cfm is _way_ too much
friend has one on a strong running 396ci chevy and even there we could discuss if smaller wouldn't be better

a 289 running at 6000rpm (this is very good for a 289) will suck max 500cfm (hence the autolite 4100 with 480cfm)
a 289 running at 8000rpm (that's insane) will suck 650cfm (i think that's why shelby gave the GT350 a 600cfm carb)
and those values above are for 100% volumetric efficiency. no offense but that's something a brand new engine will not even have (unless you turbo/supercharge the thing)

so if your 289 is like mine, a bit modified (manifolds, mufflers) then 500cfm would be perfect. I went for 570 as I got that one 2nd hand. A LOT of my pals run 600cfm because thats what holley recommends for 289. Pity they do not specify on what they believe a 289 should do. It seems they only sell carbs for highly modified engines.

All the above is based on maths. not on experience.
Now if you get a vacuum secondary you can overcarb a little as the secondaries only open if the engine wants them open. you can tune a lot here. With a DP it's more problematic as it opens the secondaries on how you press the pedal.

So if distant future is very distant then why run a carb that might fit in 3 years for the next 3 years on your good 289 ending up in bad throttle response, fouling spark plugs and not as good performance.

The carb should always match the rest of the engine and a 750cfm just does not fit a 289.

It's the same effect like when your mother got you shoes 3 sizes too big as a kid. They will fit in the future. but you complain, can't walk properly and you get blisters
Now in relation of 750cfm this is like giving you the shows of a clown

more maths:
351 @6000 and 100%VE=600cfm

long story short you shouldn't put your car anywhere near a 750DP. unless you plan to rev the 351 up until 8000rpm
then get one. if you send me a video of your car doing that then you deserve me sending a bottle of nice German beer.
Hell I'll even throw in a cuban cigar ...


christ I'm bored. ...

tyler72

As far as mech secondaries, I like mine. I had a vac sec Speed Demon, and it would cause the engine to starve for fuel, and the secondaries would open inconsistently. Sometimes they would open at 3500 RPM, and sometimes they would open at 5200 RPM. I took it off and exchanged it for a Mighty Demon mechanical secondary, and it is just about perfect. And it is on a 352 CID (347 based) engine that is pretty radical, so I would not recommend anything any bigger than that for a 351.

kalli

Hi Tyler,
couldn't see in signature I take you run a manual gearbox?

my77stang

650 DP for a modded 351w FTW

tyler72

Kalli, no, I have a mildly built C4 auto. It has a Pro-shift TCI Auto/Manual valvebody, a TCI Pro-shift servo, and an ACC 3000 stall converter. It all works out just right with the cam I have.

my77stang

i was like 5 minutes from tylers house last week but never got to meet up

=(

tyler72

Yeah, dude you need to see the car, I got it going pretty good now, but still need to work on the newcarb some. I ran a 8.291 @ 83 MPHin the eighth mile. Only1.7 60 ft time. It was awesome. I outran a new superchargedRoush a couple of times. We were pretty much neck and neck, although he did beat my time by a tenth of a secon one pass.

urban_cowboy

Huhh, a 750 is going to be way overkill for a 351W. I have a 750 double pumper for my 383W and have had to jet it way down. I should have put a 700 on it, but 20/20. 650 will be more than enough for you, and it will be much easy to tune.