Not to start an argument here, but I have tuned carbs for over 30 years. Started with single carb motorcycles and moved on to multi carb motor cycles and cars. My line of work is Industrial control systems, in which cars and plant equipment share many things in common.

The biggest let down of the Holley carb is the fact that the fuel metering system is through a venturi, which is not a linear flow device. All carbs have this drawback, but many of the other manufacturers have linearized the fuel metering by using tappered or staged metering circuit. Holley does not.

I always hear the stories of folks adding a bigger carb and getting a tad more or swapping to another brand and getting better results. So bigger must be better! But rarely do they look at the real reasons why they got better times. The design of the boosters and placement within the venturi are what can make a carb better or worse. The higher end Holleys use dog leg style boosters to get in the flow, the lower ends do not

As I said, Holleys have there place. If you are running down the strip every day then by all means run a Holley as that is what they are good at. If your are driving around town and an occasional run on the track then I would go with the Carters, Edelbrocks or Qjets. They take more time to tune in, but they will do a far better job overall.

 

Dryseals is thinking about it way too hard. If you take your time and have selected the proper size carburetor you can have a fine running engine. I have been tuning carburetors with my wideband for several months now and can tell you that you are able to get pretty close to an optimum fuel curve if you put your heart into it. Especially since you have adjustable air bleeds. Metering rods are not necessary for a proper metering carburetor. While they offer a finer grained enrichment circuit for part throttle driveability a good running holley is hard to beat. It may end up a bit fat at places, but it will run and drive well. I have spent days on end with an AFB and AFR monitor and was unable to get the metering rods where I thought they should be, even with a toolbox full of the right parts.
Every family of carburetor has its advantages/disadvantages. None do it all perfectly, but at least a carburetor is a reactionary device and can think for itself to a degree. When a person specifys "double pumper" they need to realize that its primary focus is competition when you need to know the carburetor is at WOT when your foot is down.
I for one enjoy tuning QJets and AFBs but the Holley 4150 will always be close to my heart and is my personal favorite. I have never been "let down" by the performance of a holley I have tuned on.

 

I'm not trying to put down Holleys, I have several sitting in the shop along with others. Holleys will run a tad fat and thats due to the metering circuit. For the others, I tend to custom ground the rods to get were I want. My primary focus is not to get caught up in a one carb world, they all have their place. If I'm running primarily on the strip, its going to be Holley, thats why I have them. For the street, its a toss up. A finely tuned Qjet is the best, but they sure look ugly.

 

Sounds good. I myself have been working on musclecars since 1974. So I've been at it 31 years or so myself.

The higher end Holleys use an annular booster, not just the dog leg boosters. According to Dave Vizard, an annular booster equipped Holley is the best for all around power on the dyno, bar none. He's used all carbs and the Holleys with annular boosters are the best it gets. The annular booster atomizes the fuel emulsion to a fine misted spray which makes even the most thermal-barrier coated single plane intake manifold responsive at lower RPM's. I believe NASCAR engines use the Holley 830 annular carbs.

I agree the Q Jet is a fantastic street carb, and I've built many of them over the years for myself and friends which have worked superb. However - I have also found from experience the 3310 750 Holley vacuum secondary has worked excellent as well, in fact in higher-HP applications its a lot easier to get the power output with the Holley than the Q Jet. Q-Jets need extensive reworking (ie drilling of passages) once the cam duration goes over about 224-230 @ 0.050" and manifold vacuum drops significantly. Otherwise they tend to run lean and not deliver the power they should.

Overall, in a street/strip application, the 750 Holley vacuum secondary 3310 is pretty tough to beat, even with it's straight-leg boosters. I've run 115+mph while running in the 11.70 range on radials in my street Camaro Z28 with a 3310. It would take a *lot* of modification to get a Q Jet to run that well with my engine set-up.

markinkc69z is pretty much right on the money with his comments about the 4150 Holleys. I agree they are simply a terrific carb once they are dialed-in. They are easy to work on, and tune, and unlike other carbs don't require extensive modifications to make them work properly on a hot street ot strip engine.

We all have our opinions, these are just my own based on experience.

 

I rebuilt the Holley, put the stock size air bleeds in it, new accelerator pumps, 73/81 jets, and it still doesn't feel as powerful as the edelbrock on the top end and it doesn't cruise right on the expressway, if I gun it from a standstill its ok, but if I gun it on the expressway it hesitates. I have my timing at 39 degrees total, my curve gives full advance by 2500 rpm. I am stumped here! The only other recent change to the car was that I took off the bullet mufflers and put on Hooker Aero chamber mufflers, true dual 2.5". Apparently I still need to figure something out with this Holley DP.

 

After driving the car it appears to be running lean. Any help or advice is appreciated.

 

put your car in drive and parking brake applied, check the vacuum from a vacuum source on the carb, the full vacuum port, now from that measurement find a power valve that is 2 inches lower i.e 6.5 inches in drive, need a 4.5" power valve.. also when changing jets, you need to change them in 2 size increments, start over from the beginning and get your vacuum first, then start from the stock jets, do some W.O.T, not feeling it? go up 2 jets, and do it again, and again, and again til you get it, otherwise you are beating yourself up and us answering this question you have.

 

40 degrees of timing? Is it possible that's killing your top end?

 

I always ran between 38 and 40 degrees timing before and it ran good. I have been experimenting with the carb a little each day, I had the 73/81 jets and it ran crappy, just for the heck of it I changed the primaries to 67 and the car wouldn't even make it around the block because it just sputters so I am going to put in size 80 jets in the primary and go from there, I didn't realize how much of a difference a few jet sizes can make but I'm new to holley carbs so I will just keep trying things to see what gets better or worse. Thanks for all the advice guys.

 

To tell you the truth, it really sounds more like your float level is too low. The stock jetting should be producing you good power, tweeking in the extra comes from rejetting. Measuring the floats gets you in the ball park, but I always found that setting results in the fuel level way below the mark.

 

I have sight plugs for the fuel bowl settings and I have the fuel level just at the bottom of the sight plug. I have been driving it with 80/90 jets and it drives nice, but still seems lean, I'm going to go larger and see if I can't pick up some more power.

 

I think your airbleeds are backwards. If you have a primary powervalve your tuneup should be pig rich. If the airbleeds were swapped your main system would be very lean and have a tough time starting up. What are the bleed sizes and is the smaller bleed installed towards the center of the carb? (next to the pump squirter)

 

The air bleeds are 36 in the center 4 and 75 on the outer 4. It doesn't have a bad problem starting, I have to pump the pedal a few times but that is normal with my motor. As I said I am new to Holleys but this is odd because I am running relatively large jets and the bigger I go the better it performs. I am bumping it up from 80/90 to 82/94 to see how it runs. I know that the proform main body flows more air but with these jets this is getting rediculous.

 

Ok, this is strange but it runs even better with the 82-94 jets, I know this is too big of a gap so I need to go with a 84-92 or something but it seems to run better. I have no idea why it needs such large jets to run right? It doesn't bog if I gun it or have any driveability problems now and I haven't seen any black smoke from the exhaust so I don't think its running too rich.

 

I don't get it, somebody help me out here. With 76/86 jets it ran way too lean and bested a mph of 109, with 80/90 jets it ran better, with 84/94 it ran 111 mph and with 88/98 jets which I thought would be a huge overkill it ran the exact same 111 mph. I used the 88/98 jets and it didn't even run rich!!!!!! It didn't bog off idle or show any sign of black smoke. It ran the exact same as it did with the 84/94 jets. 4 runs in a row with jetting between 84/94 and 88/98 were all 12.7 @ 111 mph and all were with a 2.1x 60' time. It feels weak at higher rpm and the only thing I can think of is that my fuel pressure must be dropping or something except for the fact that it doesn't run rich when I first take off.
Any advice or ideas????????????????????