Is my carb to small?

I have a 750 holley dp with a holley hp main body. Im wondering if there is much to be gained switching to a larger carb. Like a 950 hp? My combo is a 470 ci comp solid cam lift intake.570 .573 lift exh. Durations at .050 is 251 int 258 exhaust. M1 intake 3800 stall converter, 4.10 rear gear in a 3800 pound car with me.

DEFINITELY...............

x2

Needs a 850 cfm!

Replaced my 750dp single plane intake on my 360 with a Ported 6 pack intake and the old mechanical direct connection 6 pack carbs that have a true 1,000 + CFM and it's faster so I would say YES.

950. Maybe. 850. Absolutely.

I think it's a slam dunk. If you're buying a 950HP carb, make sure it's one of the newer ones that were actually 950 cfm, and not the earlier ones that the 950 was just a name.

R.

what do you guys think im leaving on the table staying with the 750?

ET and MPH....

i have not ran this combo yet, hope i picked some up over the old engine. my old motor was the same edelbrock heads, unported with a little smaller cam (comp xe282s). and 452 ci. it went 11.49@117 on the coast (woodburn oregon in july) with clocks i trust. the closest 1/4 mile is spokane washington and at that track its gone 11.75@115 after they put a new timing system in. with thier old timing system it went 11.35@119. our closest 1/8th mile track it went 7.34@93.9

Just put a new 4150 1000cfm Quick Fuel on a mild 446 with Indy heads, went 11.2 @ 123 first night out on street tyres.

You have already been convinced but yeah you need more !!!

I ain't a drag racer but the Q reminded me of a statement by my advanced tune up instructor way back who stated that if you have over 1" of vac at WOT then the carb is too small (too much restriction at the venturis)

I have ALWAYS went faster going to a bigger carb Up to 1050 on a small block.

Yeah, I'm sure there's room for improvement with a different carb. But you can't just go by the carb's advertised size; you need to take into account venturi size, throttle plate diameter and booster type.

A Holley Ultra 950 HP with a 1.60" venturi is going to run differently than a Quick Fuel Q-950 with a 1.45" venturi... and, NO, bigger isn't necessarily better when it comes down to what makes a particular combination go down the track faster.

Brad, i got a quote from prosystems, he suggested a 950 with his blocks ect. i might go that way. he mentioned gains that seemed like alot to me. am i leaving 25-30 hp on the table with what i have? or am i leaving 5-10? i guess thats what im wondering.

Put a vacuum gauge on it and see what it says at WOT. That is probably the best way to see if you need a larger carb.

No doubt that a larger carb will make more power at WOT on your engine but you might not like the larger carb on the street. All depends how you use the car. If it was my car I wouldn't spend the money for a new carb but if a good deal came along I might pick up another carb just for fun.

I had a like new 1000 HP Holley for sale on here for $400 not too long ago. That is the kind of deal that you might want to take advantage of.

Is PJ saying his "950" is worth 25+ HP over your current carb? Seems like a he11uva lot... but I don't build & sell carbs for a living.

If you are going to buy a carb, and then start changing it around, can I suggest you talk to ThumperDart first. He can modify an out of the box piece or build you a whole custom carb for your combo. He's a straight shooter and knows his stuff.

andy, i seen that deal but by the time i did it was gone .

That many inches and those heads your leaving a lot on the table I have used a bunch of different size carbs. on motors like yours, both stock stroke an bigger stroke than yours, all of them like the bigger carbs.(850CFM+) at the track I do have several Holleys on the shelf collecting dust if you want to borrow a couple of different ones to try them, 850 Holley D.P. and Holley 1000 HP with annular boosters as well as several 1050 CFM Dominators AKA, let me know if you want to try a couple of them When does Walla Walla season start?

I ran an 850 dp and a 950 HP with the smaller 1.45 venturi, and the 950 et'd better in my full weight 440 challenger. It felt snappier and had better shift recovery.
Mick

The Holley metering (CFM vs. pressure drop across the nozzle) is designed to operate accurately at 1.5" Hg.
If you pull more than that (bigger engine, smaller carburetor; sometimes small plenum):
1. you're leaving some power on the table
2. your A/F BSFC will be slightly off (rich on top)
3. the carb is flowing more than it's rated at

Below 1.5" the signal isn't as effective as I'd like, and needs some work-around with air bleeds etc. but can still help.
Below 1": stop unless you enjoy pain.

cab, thats a hellava nice offer/ i hate to borrow stuff though. it always seems to come back to haunt me. thanks for all the input. greatly appreciated

You don't want the new 950, the Venturi design is not right. I've spent a lot of flow bench time with them. The Quick Fuel 1050 4150 is a much better choice, and I would suggest annular boosters. Custom carb would be ideal.