help me choose a carb

[84c20]

I have an internally stock 350 with a comp cams cs 252h-10 .425 lift 206 duration, 1.5 roller rockers, long tubes, low rise manifold, hei. I'm mainly going after torque but i still want it to be drivable on the highway. I have a brand new edelbrock 750 but i think that might be too much carb for this engine and hurt performance. I was also told edelbrocks dont atomise well and to get a holley. What cfm range should i be looking in?

[TandocTools]

I just put a Edelbrock Thunder AVS 650 (#1806) on my stock 1975 350 and I was expecting to have to do some tuning, but I was pleasantly surprised that it is running perfectly right out of the box.  I will fine tune it some more when my brakes are not so scary, but it was nice to have it behave so well without any real work!  I had a Holley on my last C10, but I couldn't tune it so I replaced it with a 600CFM Edelbrock which also ran right out of the box!  I recommend them without reservation!

[Grim 82]

I have run a 600cfm Edelbrock, and currently run a 600 Holley, and both are good, but if I had it to do over again I would have spent about the same amount of money and got a q-jet from someplace like SMI carbs.

[84c20]

what makes a q jet better?

[Captkaos]

For what you have, 600cfm is plenty and the 750 is WAY more than what you need.

Q-jets are great for daily drivers and gas mileage due to their small primaries, and will give you all the power you need.

[Grim 82]

I didn't say it was better......

but it has small primaries and big secondaries, so it's easy on gas but can really make power when you need it. I suggested someplace like SMI because they will set up the carb to match your motor and intended purpose, which is better than generic setting out of the box carbs. The main reason I personally would have chosen a q-jet is because it would have saved me alot of headache trying to get the right geometry for the TV cable on my 700r4.

[eventhorizon66]

*Small primary venturi and high gain boosters that help it atomize fuel very well at low throttle, resulting in excellent throttle response and mileage

*HUGE secondaries that support great deal of airflow

It can be a turd if it's not tuned or rebuilt correctly, but do it right and you'll have a superior street carb.

http://www.amazon.com/Rebuild-Modify-Rochester-Quadrajet-Carburetors/dp/1932494189/ref=sr_1_1?ie=UTF8&qid=1290621625&sr=8-1

[VileZambonie]

The nice thing about the Edelbrock (Carter/Weber) design is they are very easy to tune and you can make many changes very quickly. The AFB (aluminum four barrel) or the AVS (Air Valve Secondary) which allows you to manually adjust the secondary circuit on the engine but both decent carbs. The Edelbrock 750 out of the box will be set up way too rich for your essentially stock engine but you can buy a calibration kit for your 1407

http://www.atlanticspeed.com/productcart/pc/viewPrd.asp?idproduct=4583&idcategory=114

[84c20]

whats better mechanical or vac secondary?

[ohio hab]

600 Holley with vacuum secondaries. Vacuum for street, mechanical for strip. 750 like stated in a previous post, too big for a basically slight modified engine IMO.

[84c20]

Would this be a good match and still have some room left for future upgrades? http://www.holley.com/0-80457SA.asp

[Grim 82]

I run that same carb right now, only not the aluminum one. I found the Edelbrock (1406) to be easier to adjust and tune, but the throttle response and idle quality of the Holley beats the Edel every day of the week and twice on Sunday. I know this all depends on how it's set up and tuned, etc., so before WW3 starts let me reiterate, that's just my personal experience. However, I got better mileage with the Edel, but I have more power with the Holley.

What intake would you put it on, and what are your future upgrade plans?

[84c20]

The intake manifold is an edelbrock 2101, eventually id like to get a set of dart heads and raise the compression to maybe 10:1

[Dr_Snooz]

I had high hopes for my Edelbrock. I bought it to replace a very tired and worn out Q-Jet. The Q-Jet had vacuum leaks, missing bolts, bent internal parts, worn out linkages and the secondaries wouldn't open, but it ran and idled well enough. The swap was basically a bolt on, but I still spent a lot of time and additional money modifying the stock vacuum lines and fuel line and air cleaner mount. I also bought a calibration kit and followed all their instructions for tuning. Unfortunately, none of the tuning combinations can get the thing to run anywhere nearly as well as it did with the old worn-out Q-Jet. Which is really disappointing. I even bought Edelbrock's A/F Ratio meter to get it dialed in perfectly. Oddly, the mixture is so far out of whack, the meter doesn't register anything. And no amount of tuning can bring the mixture into range. I have some more tricks up my sleeve, but I'm beginning to think that poor performance is just part of the fun of owning an Edelbrock. I'd say learn from my mistake and avoid these things.

[78 Chevyrado]

From my experience, all 3 carbs, edelbrock, holley and q-jet are all good.  They have little quirks about them that should be the deciding factor.

IMO  Edelbrocks are the simplest overall.  Easy to tune, easy to swap jets and such, no lower body gaskets to go bad, and there are plenty of tuning parts available for them, like jets and rods, etc..  when I change my jets in the carb on the truck, I pop the top cover off and all the fuels sitting right there in the bowl, not a drop drips anywhere, and I install the new jest right in the inch deep gasoline, pop the top back on, 6 or so screws and 3 linkages and I'm dow the road again.  and all the ones I've had don't need constant tinkering.  I set mine and forget it except for the climate change every 6 months or so.

Holleys are always said to give you more power overall.  I think they do, but its not too much.  I think this is so, because there are just SOOOO many parts available for them from everywhere,  and they seem to be a bit more tunable, overall.  I don't like having to drain the fuel to take off the fuel blocks to change jets and such, and that there's a block on front and back as the back one is a paint to get to on the vehicle.  I don't know how the newer ones are, but the older holleys if you ever had a carb backfire, you had to get a new power valve.  I think they fixed this in the newer carbs though, am i right guys? 

Q-Jets will get you the best mileage when you keep your foot out of it, because of the small primaries make lots more air/fuel velocity which is good.  They are as good and tuneable as the other carbs, IF you know how to do it.  There's not a a lot of tuning parts readily available for them and most people just ditch them automatically, so most don't know what they can do.

For me, which I want Economy and Reliability (set it and forget it)  I pick a Q-jet as 1st Choice and the edelbrock as 2nd.

Stick to 600CFM or less  higher CFM carbs have larger throttle bores that allows more flow, but cuts down the velocity which is what you need for normal street driving.  The 750 will work, but won't be near as responsive, and will get worse fuel mileage. 

The CFM calculators on the net say that for a 350, with a volumetric effeciancy of about 82%  that will run to 5,000RPM  only needs  420 to 450 CFM.  In all actuality the 500CFM carb would be more what you need, but may be too responsive/touchy.   I had one on a 350 before and  the gas pedal was too touchy, it ran REAL good and nothing about it was a dog, but you almost couldn't take off easy from a stop light.  <that was a pain trying to do anything on dirt.  So I have a 600cfm on mine and I like the feel of it, overall.