Correct Holley Carb Size

[Emo69SS]

I'm looking for a little guidance before I purchase a new carb. I have a 383 stroker, vortec heads, rpm performer manifold, Comp XE 268 camshaft, 700R4 trans and currently an Edel. 600cfm carb. The car is really falling down (not living up to it's potential) at WOT and I'm fairly certain that the carb size is the problem. The current carb is the one that the engine builder used and I haven't been happy since day 1. I am certain that I want to buy a Holley. I spoke to the tech guys there and they suggested either a 650DP or the 670 Street Avenger. Some of the carb comparison articles I've been reading such as one in Chevy High Performance indicate that the fuel monitoring in the Holley's is so good that the 750 was their choice in the test on a Smeding Performance 383 stroker. Any input would be greatly appreciated. I would rather base my decision on real owner experience than what a math equation says I should have for a carb. Thanks!

Eric

[HILROD]

I personally think a 750 holley would be great. I like vacuum secondaries. A double pumper can be trouble to tune especially with an auto trans. FRANK.

[zbugger]

The 750 would be a good choice. If it's a street car, try the vacum secondaries. If you drive it occasionall, such as on weekends, the DP would be fine. You could also check out the Barry Grant Speed Demon carbs. I hear they're pretty good.

[ProdigyCustoms]

Your 600 is killing you. not only is it small, but those Edelbrocks make no power. Smooth as glass, just no power. I know there is a big vacum secondary craze right now, and there is some tuning possible, but I have yet to see one that can touch a DP. Out of the box, a 750HP will be a bad boy for your motor.

[toofun]

I think it is safe to say you'd better go with the 750 holley. YOu could go with the Mechanical secondaries, but by the sound of the input here, I would go with the Vacuum secondaries to stay on the safe side. Hate to say I told you so about the 750 but............TOLD YOU SO!! Hey gotta bust your balls EMMMMMOOOOOOOO!!!!!

Call me at work

[Emo69SS]

Thanks for the input everyone. I figured the answer was going to be the 750 but just wanted to hear it from the experts. The car does and will spend 99% of the time on the street and it has the auto trans so the vacuum secondaries are probably the way to go although Prodigy is right that there is nothing better than the throttle response out of the mechanical 750DP.

TooFun, thanks for busting my balls but can I remind you how the 600 got on there in the first place........ I'll call you at work Thursday morning

[Emo69SS]

OK, the carb size has been established. I now need opinions about 2 specific Holley carbs I'm looking at. The first is a 4160, 750 cfm, model # 0-3310S, vacuum sec., etc. The second is a 4150, 770 cfm, street avenger, model # 0-80770, vacuum sec., etc. My questions are:

1. Is the 770 too much carb for the engine?
2. The 770 has 4 vacuum ports(pcv, power brake, spark, accessories) and the 750 doesn't specify whether it also has the 4 vacuum ports. I'm sure this is a stupid question, but should I be making my decision around the vacuum ports?

Does anyone have any opinions about either of these carbs specifically or opinions about which carb would be the best choice? I'm not aware of what the benefit of the Street Avenger Series is versus the Universal product line that Holley offers. Any information would be appreciated. Thanks again!

Eric

[WELTERRACER]

Vacume carbs only give as much fuel as the engine needs.. Thats why they work so good..

THe 770 is a great carb and will work awsome on your car.. Vacume secondarys work way better on street cars with Auot trannys.. I found out the hard way..

BTW.. my sbc with a vacume secondary 750 ran 12.80s with a 2500 stall and turbo 350 pulling 1.80 60foot times with street tires.. LIKE I SAID THE VACUME SECONDARYS WORK GREAT

[Rick Dorion]

And then there's the 700 DP

[gmachinz]

I vote for the 750 vacuum secondary Holley as well. I use one which I've gone through extensively. You can pm me for specs but basically, I had a weak upstairs until I went through it. You will still need to tune the heck out of it out of the box. I experimented with various springs-they determine at what manifold vacuum reading they will open-allowing more fuel (also why there is always a slight hesitation when you mash it-it's supposed to do that.) and found the plain one worked the best. And, I installed a 50cc pump kit (no sense in going with bigger jets, nozzles only to keep with the stock 30cc pump kit on it) to ensure extra fuel upstairs, went with progressively larger jets, squirters and nozzle sizes, too. For throttle response, you want to keep with the dog-leg boosters-the 90/degree ones offer less than ideal response for the street and are more suited for competition use as in the DP line. Finally, I would swap to a secondary metering block and remove the metering plate that is on it now-that way you have a little more tuneability with respect to jet changes for the secondaries. Oh, and I kept with a 6.5 power valve. You may want to change yours based on manifold vacuum present-I run about 16-18 inches @ idle. Long and short of it is I have a $150 carb with about $150 worth of mods I did myself. It works great for me. You may want to think about using an A/F ratio gauge w/a three wire (think 1996 Chevy 1/2-ton truck )O2 sensor for added tuning ability. I stay in the 13:1 range and for my combination it has worked out great at all RPM ranges in my SB-very consistent fuel delivery. I also use a Holley regulator set at 8 psi @ idle and it creeps to around 11-12 @ full throttle under load. -Jabin

[Emo69SS]

Welterracer-
Thanks for the input. I seem to be leaning more toward the 770 at this point. Only concern I have is that I am not oversizing the carb on the 383 stroker engine. What do you think about that point?

Eric

[Emo69SS]

Rick- That was my original plan, but I want the vacuum secondaries and with the DP you get manual

Eric

[Emo69SS]

G-
PM sent

[WELTERRACER]

770 isnt too big for that engine.. 383X6500rpms=2489500 devided by 3456=720CFM carb...

I run a 750 on my 355 spinning 6500rpms.. and works awsome.. bigger motor needs bigger carb..

[Kevin@W2W]

In my experience the Edelbrock carbs are good for cruisers. If you want performance stick with a Holley or a BG.

The 770 avenger is a very good carb for that motor and will not be too big due to the vaccum secondaries.
One thing to consider is the avenger comes with a few extra goodies that the 3310 does not.
Like, the quick change cover for the secondary spring and a few other things.

Personally I have always had very good luck with the 3310 and the 770 over the years when I don't use a Barry Grant.

Good luck

[SatisTraction]

talk to a pro about it

http://www.pro-system.com

his are the best

[383]

I run a 600cfm Edelbrock on my 383 stroker with Edelbrock rpm package all the way, but since i´am never satisfied i bought the Holley 3310 750cfm carb but have not put it into place yet.
If you want i can keep you all posted on the result.

[vanzuuk1]

383 , Ive got the 670 avenger on my 383 and it runs good but I dont have much to compare it to. Let me know If i should experiment with something bigger when you install yours.

[Emo69SS]

I ended up buying the 770 Street Avenger but haven't intalled it yet. I just got my new TV setup because I have a 700R4 so I'll get it in soon. 383, I'd be interested to hear how you make out. I'll post my results also. Thanks to all who helped out!

Eric

[CAMAROBOY69]

I agree with everyone here about the 750 Holley.
I am running the 750 Holley Double Pumper 0-4779C with manual secondaries on my 383 with cast iron heads. And it runs good enough to get me into the mid 12's. 12.66 to be exact. Yes cast iron heads too.
I started out with an Edelbrock 600 and what a joke. Just starved the engine to death and never ran correctly so I bit the bullet and bought the correct carb. I also fouled plugs every 2 weeks until I put the 750 on.
For the record I was never into Holleys until I bought this carb! Now I am a believer.