Down leg or annular?

[sc440]

I have a 4778 (700dp) on my roadrunner now, 440 10:1, 232-239 @ .05 518 lift on a 112 cam, tf 240’s,3.73 gear and 9 1/2” dynamic converter. Carb runs perfect no stumbling instant throttle response. Was thinking about getting a 850 annular. Car is a street crusier maybe run it down 1/4 a couple times. Was wondering if the extra cost of the annular would be worth it or just get a down leg?

 

[6PKRTSE]

If you know how to dial in a carb and just for a mostly street cruiser, no. It won't make that big of a difference.

 

[RJRENTON]

I have a 4778 (700dp) on my roadrunner now, 440 10:1, 232-239 @ .05 518 lift on a 112 cam, tf 240’s,3.73 gear and 9 1/2” dynamic converter. Carb runs perfect no stumbling instant throttle response. Was thinking about getting a 850 annular. Car is a street crusier maybe run it down 1/4 a couple times. Was wondering if the extra cost of the annular would be worth it or just get a down leg?

WHY....??? IFwhat you have now and you are satisfied with the performance, IMO, there is no need to change your current setup......or do just like to spend $$$ or does one of your "buddies" (aka carb expect) think you should change? Perhaps, these buddies would help pay for a new carb. Ask this "expert" what is the delta pressure difference between the two venturi designs in fuel feed and atomization/distribution. They probably don't know.......Jmo.....
BOB RENTON

 

[66 Sat]

Have to agree with Bob here.
Your own words "Carb runs perfect no stumbling instant throttle response".

How can you improve on perfection?

 

[sc440]

WHY....??? IFwhat you have now and you are satisfied with the performance, IMO, there is no need to change your current setup......or do just like to spend $$$ or does one of your "buddies" (aka carb expect) think you should change? Perhaps, these buddies would help pay for a new carb. Ask this "expert" what is the delta pressure difference between the two venturi designs in fuel feed and atomization/distribution. They probably don't know.......Jmo.....
BOB RENTON

I do like spending money lol, I just feel like I am giving up some top end performance with the smaller carb. I don’t have any “buddies”telling me anything.

 

[khryslerkid]

Thought this might have been the "Blue Forum".

 

[RJRENTON]

I do like spending money lol, I just feel like I am giving up some top end performance with the smaller carb. I don’t have any “buddies”telling me anything.

How much top end performance will be gained????? " best guess...or are you using the old reliable seat of the pants measurement........"giving up some top end performance with the smaller carb"....150 CFM difference....(700 vs 850) ? Very likely you'll be slower with the larger carb......jmo.......your $$$$.....have at it.......
BOB RENTON

 

[RemCharger]

I have a 4778 (700dp) on my roadrunner now, 440 10:1, 232-239 @ .05 518 lift on a 112 cam, tf 240’s,3.73 gear and 9 1/2” dynamic converter. Carb runs perfect no stumbling instant throttle response. Was thinking about getting a 850 annular. Car is a street crusier maybe run it down 1/4 a couple times. Was wondering if the extra cost of the annular would be worth it or just get a down leg?

Definitely run it down the track as is, so you know where it stands. But I do agree with your thought process, not many engine builders would suggest an old 4778 for a trickflow head 440. Probably won't see much difference with the annular imo

 

[sc440]

Definitely run it down the track as is, so you know where it stands. But I do agree with your thought process, not many engine builders would suggest an old 4778 for a trickflow head 440. Probably won't see much difference with the annular imo

Yes, the 700 is only being used because i have had it for years got it brand new from brother in-law for a steal. It was ran on my old 383 I had in the car before I built this 440. It worked great on it too.

 

[sc440]

Really need to put my vacuum gage on it and drive it wot and see what it reads.

 

[33 IMP]

After seeing a dyno test many years ago, where the annular carb had a HUGE low end advantage over a downleg carb of the same size, I like the annular booster design. The annular boosters are supposed to flow a bit less than the downleg, but I'm not sure I believe it.
For yours, I might try an 850 annular double pumper, and expect probably 800 cfm out of it.
But, as said above, it's kinda real hard to improve on perfection, and you might not see ANY improvement over the carb you have, in normal use. You might see a couple tenths at a dragstrip with a bigger carb....... but I wouldn't guarantee it.

 

[WileERobby]

I do like spending money lol,

First... listen to what these guys say, they're right !! Leave well enough alone ! Second... what would you like to buy for me ?

 

[gtxdana]

I have a 4778 (700dp) on my roadrunner now, 440 10:1, 232-239 @ .05 518 lift on a 112 cam, tf 240’s,3.73 gear and 9 1/2” dynamic converter. Carb runs perfect no stumbling instant throttle response. Was thinking about getting a 850 annular. Car is a street crusier maybe run it down 1/4 a couple times. Was wondering if the extra cost of the annular would be worth it or just get a down leg?

What manifold are you using and what RPM range?

A 700 DP is on the small side for a 440. You should pick some up top and the annular boosters do work better especially down low.

 

[sc440]

Performer rpm manifold, 6000 max

 

[PROSTOCKTOM]

I seriously doubt you'll feel anything in the seat of the pants dyno by changing carbs. That's still a heavy car and if it's working perfect now that's a beautiful thing.

Tom

 

[Bee1971]

I agree with some of the posts about your combo , especially with the flow of those heads

Apples to Oranges

Going from a Carter AVS 630 CFM to an Carter Competition 750 CFM to an Edelbrock AVS2 800 Annular was like

My 383 / 432 kept wanting more and more and

Honestly it was night and day difference on the street


YOU SAID - I like to spend money

My question is

What Holley 850 made today comes with Annular Boosters ??? especially for a street car , so what brands of Holley are you looking at

Thanx

 

[sc440]

Atm

 

[sc440]

Not sure about the there annular but there 850 down leg is 1.390 Venturi and and 1.75 throttle plates. My 700 is 1.312 primary and 1.375 secondary with 1.688 throttle plates

 

[Bee1971]

Atm

ATM ?

Yes , you will
definitely need an ATM when buying a Holley LOL

 

[sc440]

lol atm innovation the guys that started quick fuel and sold it to Holley the make them in bowling green KY