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what carb are you running on your 454-468 bbc?

89K views 63 replies 31 participants last post by  71 chevy 
#1 ·
for a street/strip car?

how much power are you making, and how is the low end/top end response.

also would like to hear from those who tried several carbs before finally settling on one.
 
#3 ·
800 DP Mighty Demon w/annular boosters,and I LOVE IT !!!
Guy
 
#5 ·
I have run both a 750 vac and an 850 dp with annular boosters. Since I have a TKO 5 speed I can really test the low speed response. The 750 is smoother at low speed but the 850 is not bad either. No lack of driveability with either. I can lug the engine down to 1200 rpm in 4th gear and it won't stumble. BTW my cam is a 236/246 @ .050 flat hyd. The 850 will overpower the tires in third gear when opening the secondaries. I also run an Edel RPM intake which helps build torque. No track times yet.
 
#6 ·
Holley 850 cfm double pumper. Not sure I'll stay with it, I have had several problems with the power valve.
 
#7 ·
Currently using a 800 DP with Proform body on my 463. I had a 750 VS, but the 800 was good for an honest 50 hp on the dyno. I haven't driven the car on the street, but with a 150 shot it was good for a best of 1.607 60', and an 11.61 1/4 mile. No bog or hesitation out of the hole off idle either. Turbo 400, 4500 stall, 4.10. This is with a Performer intake and a 1" spacer.

I really like the 800.
 
#13 ·
Currently using a 800 DP with Proform body on my 463. I had a 750 VS, but the 800 was good for an honest 50 hp on the dyno. I haven't driven the car on the street, but with a 150 shot it was good for a best of 1.607 60', and an 11.61 1/4 mile. No bog or hesitation out of the hole off idle either. Turbo 400, 4500 stall, 4.10. This is with a Performer intake and a 1" spacer.

I really like the 800.
WHAT THE $#@#%

50hp????? this is a huge increase . what other carbs did you try, and was the 750 tuned?
 
#9 ·
so 7 out of 7 favor a carb with mechanical secondaries . HOW interesting. running a 770 and I think its choking my top end. I think I'll change to a 800 or bigger double pumper.
 
#10 ·
I like the 950 Hp's they work quite well too. One thing I don't like about them, they have no vacuum fittings. They do only flow 830 cfm, the 800 double pumper its more of a street carb. A regular 4781 850 double pumper, they are like a fire hydrant, you don't want one of them. How much gear and converter are you running?

Dave
 
#14 ·
Dave, I would tend to differ on the 850's. My 4781 850 DP is lean and mean because it is tuned properly.

I think you meant it flows like a hydrant...nice analogy, :D . Anyway, if you have a lower rpm converter or smaller cubic inch motor you can lose carb signal with an 850 DP, but it would work well on any 454+ motor as long as it is tuned properly and matched to the rest of the combo. the 4779 750 DP is a great carb from 396 to 454 as well.
 
#11 ·
On my .030 over 454, I tried to use a 750 Holley, but I would have had to drill the butterflies to get it to idle. So I moved up to the 80531 Holley 850 as used on the ZZ502's, and it was perfect. AWESOME throttle response. It is still on it today, ready for another Chevelle. On my 496, I went with a Speed Demon 850 for more flow.
 
#12 ·
before anyone starts throwing big carbs on their motors you need to check the manifold vacuum at Wide open throttle. If you have more than .5" of vacuum at WOT than you are a candidate for a larger carb. Get a buddy to hold the vacuum gauge while you open her up for a few seconds. If you are bottomed out at zero vacuum, don't waste the money on the larger carb. Ok to spend it on HP main bodies, thin throttle blades and screws etc.

Also, before we start comparing carbs and saying which one is better than the other, you will need to ask yourself an honest question...Were both carbs tuned to the potential they had ??? to get apples to apples comparisons.

There is a lot more in the carb tuning than many know. A tuned 770 will out run a box stock 850 DP any day of the week.

Case in point....Ran 10.50's 126 mph on an very tuned 4781 DP with the choke horn still on with a single plane intake. A direct swap to a tuned 1000HP and it was good for about .08 and 1 mph with the contoured venturis and thin throttle blades and flathead screws.

So what's that 600 HP in my Monte ??? maybe 650 HP...
I know my Chevelle motor made 475 with the same carb

Put that carb right onto my low budget "LS-5" 462 motor with an RPM dual plane intake and it made 436 HP..with proper jetting that came out to be significantly staggered it ended up at 475 HP after a dozen or so pulls on the engine dyno...same carb
 
#15 ·
There is a lot more in the carb tuning than many know. A tuned 770 will out run a box stock 850 DP any day of the week.
but will it outrun a tuned 850?


dave427, what is so bad about the 4781 850? thanks
 
#22 ·
I use a BG 850 Sports Claw (yes it had shavings in it brand new :().
Sometime later I sent it back to BG to have them convert it over to annular boosters.

Runs like Fuel Injection on my 468" with an Air Gap dual plane. Crisp and responsive.

I have a smallish UltraDyne Hyd roller: 233 @ .050 .626 lift 109 sep single pattern.
 
#23 ·
I have a mild 461 with low compression, an Isky 270 cam, high rise intake, headers, 2000 stall TH 400, and 2.73's out back. Oh yeah, peanut port heads. This is a torquey street engine. Max rpms's about 5500.

I had a Speed Demon 750 on it for two years. While the Demon was never sluggish, going to an Edelbrock 650 cfm AVS woke the engine up. The smaller carb was far more appropriate for the rpm range and stock converter and highway gears. One way to think of it is that 100% of the 650 cfm carb fits into the 5500 rpm range, whereas only about 80% of a 750 cfm carb would fit into the same range -- the top 20% of the carb would be wasted.

The Edelbrock pulls much harder down low, in the middle, and up high. I haven't yet run out of top end as with the 2.73's I'd have to be going about 145 mph to get above 5000 rpm's.

Make sure that the carb is appropriate for your engine.
 
#29 ·
I don't have a 454 yet but it's in the works. I have a 750 quickfuel on my 408 now and I love it. I'll probably keep my blocks and get an 800 or 850 for my new 454. if your going to run a lot on the street and only have a max of about 5500 a double pumper with annular booster would fit very nice.

I love my double pump. If you set up the pump shots right you can just nail the secondaries and it's just instant tire smoke
 
#30 ·
3310-2 750 cfm holley vacuum secondary's on my 468 low 12's, 12.12 at 112- 113 mph in a 4100 lbs plus car.

770 carb should be plenty for a street driven 468 in most of the cases, people need to learn how to tune there combo instead of being parts changers, see this all to often, the guy at the race track with several different carbs and all they do is change parts not knowing what is in them or really what it does.

this is where you get claims of this carb was a second faster then that carb and so forth.

i think the key here is to tune your combo not change carb out, 770 should be just fine.
 
#31 ·
3310-2 750 cfm holley vacuum secondary's on my 468 low 12's, 12.12 at 112- 113 mph in a 4100 lbs plus car.

770 carb should be plenty for a street driven 468 in most of the cases, people need to learn how to tune there combo instead of being parts changers, see this all to often, the guy at the race track with several different carbs and all they do is change parts not knowing what is in them or really what it does.

this is where you get claims of this carb was a second faster then that carb and so forth.

i think the key here is to tune your combo not change carb out, 770 should be just fine.
Im more concerned about seat of the pants throttle response than anything else. how about the guys picking up 50 hp and lower ets by going dp. have you run your current combo with a double pumper?

Ive got the afr perfect I dont know what else I could try on this carb to make it run any better.
 
#34 ·
Let me add my $.02 here, as I have more experience with this than I care to admit. I have multiple carbs here on the shelf: a 750 vac sec, 950HP, and a 850DP.

For just a street car, occassional strip, you cant beat the 750/770 vac carbs...they are just so smooth and work damn good, and the price is right. But, if you have some gear, as in 3.73's +, I think you may find that your car will like the DP's.

When I had the 454HO/M20/3.31/28" tire there was no difference between a 750dp and the 770, they both hit the rear tires about the same. Fast forward to a 550+hp 454 and 3.90's, the DP's gives me the best seat-of-the-pans feel when getting into the secondaries. In 2nd gear, the engine has to spool up and the tires gradually start to break loose with the vac sec. The DP will bust 'em loose when I just plant it. Now, I'm wondering if I had slicks on if it would truly be faster with the DP...that would be the true test. I would guess that a car with a DP would '60 better all things being equal. Even though the DP hits the tires harder, I run the vac sec on the street just for its overall smoothness. I would love to run my 950HP on the street, but the thing is a gas hog in a huge way. Believe it or not, the 850 DP runs excellent and relatively clean for a carb that gets such a bad rap...maybe cause this is a newer version. If I didnt have this 750vac I'd probably run the 850.

Bottom line, be honest with your intentions of the car, and carb accordingly. For street and occasisonal strip, you just can't go wrong with the 750 vac sec on just about any motor.


Or, you could do what I do...but a bunch of used carbs on ebay, try 'em, and keep what you like the best. I liked the 750 vac sec and 950HP so much, I kept both :D

 
#36 ·
But we need to to try a DP at some point in your life ;)

Take my 950HP when you hit the track next time and see if there's any diifference.
 
#37 ·
Just for illustrative purposes, fella here AK69 think it was had a 454 or 468 or something running 11.4x's, this was with a Prosystems 1000HP I believe. The track was gonna ban him b/c of no cage. He put is "trusty" 770 Avenger on there to slow the car down. Now the car ran 11.55's.

Not too shabby.
 
#39 ·
anyone have an old 750-800 double pumper they want to sell cheap?
 
#40 ·
I have a Pro System 950 HP. Stock bore 454.
 
#41 ·
well I just picked up a 4779-9 750 dp so I'll do some back to back tests and see if the double pumper wins the seat of the pants test.
 
#45 ·
question to all running a holley double pumper. which pump cam are u using?
 
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