I have a 71 Chevelle with a 350 engine. Right now it has a 600 Holley (vac. sec.) which is shot. I want to replace the carburetor, but I just don't know what carb to use.I'm just a simple weekend mechanic, so suggestions are much needed, as to what carburetor to use . The engine has a Torker ll intake,a mild cam(fireball?).Thanks for the HELP! Tom

I have a Holley 600 vac. sec. on a 327 in my 64 with an Edelbrock Performer RPM. It works great I got em' from summit with that intake package for 200 bucks.(You know the one with all the parts plus an open element summit air cleaner)that is if you have a summit catalog http://www.chevelles.com/forum/wink.gif You might also want to look at the Edelbrock performer carbs or the Carter AFB's. Get a summit catalog if you don't already have one at www.summitracing.com (http://www.summitracing.com)
Good Luck, Steve

Go with a 750cfm with secondary vacuum. The 600 will run out of air/fuel at high RPM ranges.

Mark

If your running a spread-bore manifold, I would suggest Edelbrocks Q-Jet. They are costly, I just paid under $400 for one from Summit. I have a 396 on my 69 El Camino and it has lots of get-up and went, and that's with a 273 rear end.

Tom;
It doesn't mater what they say -size does matter. With a 350 and a mild cam you don't want a large carb. A large carb may make more HP at high RPM but your mild cam will already be done. A large carb won't give you a smooth power flow on the street at slow speed. Stay with a 600 or 650 cfm vac. secondary carb.
Gary R

I have recently installed a Carter AFB in place of an old Holley on a 327 in a '72 Chevelle and found it to be a good installation. The cost is under $200 and the car runs well. The tuning manual that comes with it is pretty good and it is easy to change the metering rods for tuning for the street. I will probably do this swap again.

Thanks for the suggestions ! . Out of the carbs mentioned, Holley,Edelbrock and Carter . What would be the easiest for me to adjust(tune).The simpler the better for me. Thanks again Tom

I recommend the AFBs for the street. They are easily tuneable and can be made to idle really well. Part throttle tunability is very easy as well.
I have used Holleys, Q-jets and AFBs over the years and find the AFB the simplest of all for every day drivers.
Bill

I'll stay clear of this one on which brand.
All I can say is they are all good. It's your preference. I know what mine is though.

Mark

Tom,
On this topic I definitely agree with Gary R. A 350 does not need anything more than a 650cfm on it. I find that a 600 is a good carb. As for the brand, it really depends on what you prefer. If you want simplicity, then Holley is your best bet, due to the fact that it has the least amount of parts in it, and it is easiest to rebuild. However, it is the biggest pain in the ass because you constantly have to tune the damn thing if you decide to romp on it and race around. A Rochester Quadrajunk, on the other hand, is a great carb, WHEN IT'S PUT TOGETHER CORRECTLY. Once you tune it, you can walk away and forget about it. The problem is that it has about 1,000 parts in it, and rebuilding one is a headache and a half; I know this from first hand experience. I have a 795cfm on my 79 L-82 Vette. I know what I said about a smaller carb on a 350, but it came from the factory like that...why I still don't know. I hear that Edelbrock makes a good repro of the Q-Jet, but I have never tried it. The choice is really yours. Good luck on your decision.

I suggest going to the websites for the carb manufacturers. Several have technical data and charts to assist in selection try www.holley.com,www. edelbrock, www.carter.

too big is a much more common problem than too small. Don't be tempted to go too big.

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I feel that a 650 would be more that enough for a 350. I put a brand new Carter AFB on my 70 El Camino and it started right out of the box and its a good looking carb.(I have a friend that put a Edelbrock on a 57 chevy with the same results. Summit does have some good prices without a dought. If you buy a new manifold the Edelbrock performer will not bolt up to the Carter AFB without an adapter block.

[This message has been edited by LIGHTWAVE (edited 11-12-98).]

A buddy of mine has a 62 Bel Air with a 350 in it. He has a dual plane manifold, and a mid range comp cam. He has the Holley 600 CFM vac, sec. carb, but changed the secondary metering plate with the metering block kit. He uses 68 jets in the primaries and 78's in the secondaries. This gives the motor plenty of pull all the way to 6000 RPM. The block swap was drop dead simple, and it works really well.

Tom, I agree with several of the above in that it really is your own preference. I personally like the Edelbrocks or Q-jet. Both are fairly easy to tune and will keep the tune which may be important to you. I have several carbs for sale now from 750 Holley DP, Q-jet, and Holley 600 w/vac sec; all in good shape but in need of rebuild and pretty cheap!
E-mail me bcurrent@csu.org if interested
BC

What does "shot" mean for the carb you have. A Holley "trick kit" is less than $40, and takes less than two hours to rebuild even if you are a total bonehead. Unless yours is truly "shot" like a cracked base plate or something, rebuild it. I have picked up used holly 1850 600 vac sec at fleas and swap meets for less than $15. They are almost never "shot", just need a rebuild.

Contrary to my own earlier belief, I have to agree with COPO on the size for your application. Last summer I substituted a Holley 600 for the 750 on my 350/350 (3.36:1 rear gear w/ 4spd)and it ran absolutely great, right up to 4800 rpm. Beyond this point it fell apart. I put the 750 back on and the problem was gone. I agree the 600 was noticably better at low speeds but overall the 750 does a better job.

I am running a holley 600 cfm model 4010 on my 350. I am running a mild cam (about 230 duration @.050, about .480 lift) headers, 2-1/2" exhaust, stealth intake, dart sportsman heads, 4.10 gears, automatic with a 2500 stall. The motor pulls hard all the way to 6500 rpm. I did quite a bit of tuning, changing primary and secondary jets, secondary vacuum springs, timing, and so on until I got the response I wanted. On the dyno I had a perfect fuel/air ratio all the way through the rpm range.

Perhaps some of the other folks disappointments with the 600 cfm carbs were because they did not have a soft enough secondary spring or the right jets for the motor. This has to be right no matter what brand or size carb you pick.

Like a previous post suggested, maybe a trick kit and some tuning and the carb you have will do just fine.

As far as the condition of your Holley, if the throttle shafts are worn, there are a couple of places which you can order a bushing kit, and new shafts, to fix them. Brad Urban's Carburetor Shop is one. I was going to use one of their kits, until a friend was cleaning his garage, gave me a bunch of Holley stuff, including a brand new primary shaft, with grooves in it, which in itself will cure vacuum leaks. (This is referred to as a labyrinth seal). I don't know where he got it, but it looked like a factory piece. Just a thought. Darren

Quick note on sizing. Most carbs are prety much self regulating with engine demand opening the secondaries by air flow (AFB) or vacuum (Holley) or lack of it (Q-jet). Problem is that when the butterflies are less than full open the airflow is not through the venturis smoothly making it hard to get the mixture right on consistantly. Ideal in my opinion would be about a 625 CFM AFB with electric choke and a strip kit for tuning. tom