How to select carb?

[erikoj]

This is not meant to be a hijack thread but how do you tell which carb is on it now and how many cfm it is? I have the same issue here . I want an easy driver that runs smooth and economical Erik

[geezer#99]

Originally Posted by erikoj

This is not meant to be a hijack thread but how do you tell which carb is on it now and how many cfm it is? I have the same issue here . I want an easy driver that runs smooth and economical Erik

Easiest to take a pic and then the debate can begin.

[slikside]

Originally Posted by SS Tim

A quality rebuilt Q-jet is hard to beat for drivibility. Not talking about a cheap parts store off the shelf "replacement" carb but one done by Cliff Ruggles.
http://www.cliffshighperformance.com/

Originally Posted by newmexicosaint

They have a 12 MONTH waiting list!! HOLY COW!!

Originally Posted by Hubscrub

I love Q-jets i bought the book on them by cliff haven't finished it great info in what i've read. My dad always built our Q-jets and they ran fine (40+year technician) never a better carb for power and economy. Saying all that if you want simple edelbrock is more for you i rebuilt the one on my wife's 67 (my first carb rebuild ever) to edelbrock specs, and it runs like a fuel injection engine so simple and also a 600cfm works good on my 350's.

Wow! 12 month wait. I had him put bushings in the baseplate for the primaries about 3-4 years ago. Pretty good turn around time then.

But I bought his book and rebuild kit and did the rest of it myself. Take lots of pics pulling it apart for reference during reassembly. Take your time, and be patient. Follow all of his guidance in the book.

I couldn't be happier. Truck has been running great ever since.

[Bandit130]

Currently installed Holley carb # List-3310-3. Link showing specs.

http://1970mgr.org/_HolleyCarbs.htm

[Maggro]

Anyone know what carb this is by any chance.

Thanks, Mondo

[geezer#99]

Holley 4360.
Quadrajet replacement.
450 cfm.

[dfrank]

Originally Posted by geezer#99

Holley 4360.
Quadrajet replacement.
450 cfm.

Dang, your good. I can only see the front of the carb and don't see any numbers.

[Lattimer]

I went a slightly different direction on my truck and have been very happy with it. I installed a Street Demon 625. http://www.demoncarbs.com/1900.asp
It was easy to set up, runs great. I have decent economy (13 mpg mixed driving) when I drive easy, and a good kick ion the pants when I jump on it.

The carb is basically Holley's redesign of the Carter/Edelbrock design. Very easy to tune, looks nice, works great, pretty inexpensive. I actually bought mine on Amazon. Had it on there for over a year now and no issues.

[Redline novdog]

sounds like you need a bolt on. Like previous hope you checked timing or previous owner didn't pop in a big cam. Weak valve springs carboned up valves.Low vacuum. worn out spark plugs,couple of less than desirable plug wires. If get where I'm goin buy a autoparts store carb and bolt it on.hopefully you hit it.there is more to it than carb.

[Crabass]

Originally Posted by Bandit130

I have a 72 C10 LWB 350 auto. What is the smallest carb can I get for this PU? This is an occasional driver. Not wanting to race. Had PU for 6 mo. Still working to fix up. Currently is a driver, has a holly 750CFM that I do not like at all. Wanting to know what carb would give me good running and performance.

I did a lot of studying on carbs in general and the QJet specifically a while back. My take on the QJ is that it is a really good carb, but relatively complex with a ton of calibrations to specific application, and a lot of things that can go wrong (which is why they have a bad rep in some circles). I agree with a comment made earlier in the thread about avoiding most "rebuilt / remanufactured" ones, especially if they have had the original finish blasted off. They were discontinued years ago and from what I understand many of the parts that might be needed to make one right are either unavailable or really scarce. There are some pretty good alternatives out there (Quick Fuel seems to be getting it right, IMHO).

You didn't mention which kind of manifold is in place, relevant info for your carb selection and desired results.

Search out some carb sizing calculators and run a number of them, I'm pretty sure you will be surprised at the recommended sizing. The right sizing will provide the best metering signal, which translates to efficiency and good throttle response. Too big of a carb makes for sluggish air flow and poor signal.

I'm with the "you're probably over-carb'd" camp.

[bryanw1968]

I agree with the timing comments. Make sure your initial timing is right. Also make sure your total timin is correct. Adjust initial for highest vacuum. I really like Barry Grant carbs. I've had mine since 2004 and haven't had to adjust it since then. For your application id go with a 625 Road Demon.

[Bandit130]

Originally Posted by Crabass

I did a lot of studying on carbs in general and the QJet specifically a while back. My take on the QJ is that it is a really good carb, but relatively complex with a ton of calibrations to specific application, and a lot of things that can go wrong (which is why they have a bad rep in some circles). I agree with a comment made earlier in the thread about avoiding most "rebuilt / remanufactured" ones, especially if they have had the original finish blasted off. They were discontinued years ago and from what I understand many of the parts that might be needed to make one right are either unavailable or really scarce. There are some pretty good alternatives out there (Quick Fuel seems to be getting it right, IMHO).

You didn't mention which kind of manifold is in place, relevant info for your carb selection and desired results.

Search out some carb sizing calculators and run a number of them, I'm pretty sure you will be surprised at the recommended sizing. The right sizing will provide the best metering signal, which translates to efficiency and good throttle response. Too big of a carb makes for sluggish air flow and poor signal.

I'm with the "you're probably over-carb'd" camp.

Truck has an Edelbrock Performer EPS Intake Manifold. Has an ACCEL HEI Super Coil 140003 distributor.

[geezer#99]

But what's your initial timing?

[Lou Boffa]

Curious guys, why not a 2 bbl Rochester -well rebuilt?

[Crabass]

Originally Posted by Bandit130

Truck has an Edelbrock Performer EPS Intake Manifold. Has an ACCEL HEI Super Coil 140003 distributor.

Decent manifold, but if you plan to keep it you won't be running a QJ (or any other spreadbore) unless you stick an adapter in between.

The timing chorus has a valid point. Pretty much the golden rule to make sure your ignition is spot on before you go diddling with the carb. For that matter, you might want to check your cam timing and balancer timing mark accuracy before you bet your butt on any observed ignition timing numbers. In what condition are your timing chain and harmonic balancer? How many miles on those components?

Way back when, I had a buddy "accidentally" discover he had horribly bad plug wires, after he had replaced the carb without curing the problem (rough running/ misfiring). New wires did the trick.

Don't you just hate it when a simple question bogs down into such complication?!

[imjeff]

Originally Posted by Lou Boffa

Curious guys, why not a 2 bbl Rochester -well rebuilt?

Two barrel carbs big enough to work have primaries that are bigger than on a four barrel. Big primaries equal lower velocity and efficiency.