what carb for a 470?

[bb71challenger]

I am going to have an iron headed, slightly less than 10:1 compression low deck stroker with a solid lift cam in the .520 range and am needing suggestions for a carb. I was thinking an 850 double pumper would support the engine but just want to get some advice from guys who have experience with these bigger motors. thanks!

[Strawdawg]

Most will probably say 850, but I have always found that a little bigger is better with some tuning.  If I ever planned to run the car at the strip, I would go with a 950, myself

[bb71challenger]

that's what my brother in law was saying. much easier to jet down a bigger carb than to try and get more from something that's marginal or too small. my biggest carb is a 750 so I am almost positive I will have to buy a new carb or get a new base for my proform bowls that are on the 750.

[cudabob496]

for the street, no higher than an 850 DP.
In fact, if you are not winding it above 5700 rpm, you're 750
might get you excellent throttle response on the street.
I think a 750 will easily support 525 hp!

I've read the 850 hp Nascar engines, that wind to 8500 rpm,
use an 830 cfm carb.

but, just my opinion, and everybody has one!

From Holley website: You take the engines cubic inches and multiply by the maximum RPM and divide by 3456. If you have an automatic transmission you will need a vacuum sec. carb, a standard transmission can use a Double Pumper carb. You can also use our Interactive Carb Selector Tool to help you find the correct carburetor for your particular application.

[bb71challenger]

It would be awesome to be able to use the 750 vac sec holley I already have. the formula you gave puts me at needing an 850 though. I might start out with the 750 and see how it acts before jumping right into a new carb. thanks for the information!

[nqkjw]

It would be awesome to be able to use the 750 vac sec holley I already have. the formula you gave puts me at needing an 850 though. I might start out with the 750 and see how it acts before jumping right into a new carb. thanks for the information!

That's what i'd do but ultimately i think you'll be getting an 850.

[cudabob496]

ya, and vacuum secondaries may steal some of your street quickness! Depends on rear end gearing, tranny, etc.
Make sure you got the right valve springs to rev it to 6000?

[Oldschool]

Using the old "double the cubic inches" rule, you would need a 940 cfm.  That rule works great on fairly stock combos. With your mods, you could easily run more cfm. That said, I would run a 950 Holley HP or comparable brand. A dominator 1050 would run great, but it might be a little persnickity on the street all the time. I have a buddy that is running a 1050 dominator on a 496 BB Dart with no issues at all. Still, in your application, I think a 950 would be ideal for all around performance.

BTW  --  my 528 is running two - Holley 750 HP's with no issues at all. The "double the cubic inches" rule says it should take 1058 cfm. But mine is modded and takes 1500 cfm easy as pie.....

[Chryco Psycho]

I agree with Oldschool , I would be looking at a 950 Proform for that

[bb71challenger]

The guy knows how far I want to wind it up, basically around 6500 and the basic ballpark of the cam I am going to run so I am sure he ordered the right springs. They are beehive btw and look totally awesome with their shape and small retainers. I guess I will be saving up for a 950 and go from there. Thanks for the info guys, always get the goods from you peeps.

[4 speed fish]

For the price I am a big fan of the holley 870 street avenger.It is a great carb for the price.Easy to tune.Mine was vac sec and was pretty much plug and play.

[cudabob496]

Using the old "double the cubic inches" rule, you would need a 940 cfm.  That rule works great on fairly stock combos. With your mods, you could easily run more cfm. That said, I would run a 950 Holley HP or comparable brand. A dominator 1050 would run great, but it might be a little persnickity on the street all the time. I have a buddy that is running a 1050 dominator on a 496 BB Dart with no issues at all. Still, in your application, I think a 950 would be ideal for all around performance.

BTW  --  my 528 is running two - Holley 750 HP's with no issues at all. The "double the cubic inches" rule says it should take 1058 cfm. But mine is modded and takes 1500 cfm easy as pie.....

The double the cu in rule is 2 X cu in minus 150

[Strawdawg]

Not in my neighborhood! 

[cudabob496]

Well, looks like I'm out numbered, but I've seen several articles
where going from an 850 to a 950 on on 470 cu in size engine, gained
no hp, and loses throttle response.  I think an HP 850 Holley DP is all that 470 would need, especially
since the time spent at 6500 rpm is less than 1% of total driving time,
unless the car is a weekend warrior at the strip!

[Strawdawg]

there was an article that I read in one of the mags a few weeks ago discussing why larger carbs often performed better and I have seen quite a few others that actually ran dyno tests.  Of course, a carburetor that has not been set up for a given engine may give varying results.

I base my comments on experience, but a quick google brought forth this article from a few years ago.  Theory provides an excellent starting point, but, theory does not always win races   Understanding that there is more to the process than a simple calculation from a formula probably makes it easier to except

http://www.moparmusclemagazine.com/parts/engine/mopp_0111_demon_carburetor_dyno/viewall.html