I own an 84 TA with a 4bbl HO. Does anyone know what the CFM rating on this carb might be? And, would this be enough to power a 350 SB to any real degree? Thanks all.

 

The carb is good for about 750, except that the factory put a little extra tab of metal to keep the air valve from opening all the way, which limits it to somewhere between 550 and 600.

Grind the little tab off and it should be fine, as far as its size (WOT performance) goes. Whether you'll be able to get it to work right at any other time besides WOT depends on things like what cam you are using.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Thanks.

 

what's "WOT"? I just want to keep it street and emissions legal. Thanks again.

 

wide open throttle when you bury the pedal to the floor

 

Thanks mean.

 

RB, you sure about the tab? He said he has an HO, which may not have that limitation built into it.

For what it's worth, GM has the ZZ4 conversion kit that would work for your car (if you have auto tranny). They provide everything needed to put the car into the 13's, and they don't give you a new carb.

Another point: I'm running a 750 Edelbrock q-jet on my 396. That's enough to feed it, and their other q-jet is a 795 cfm (have one of those on the van).

So, yes, your stock q-jet is enough to power a 350.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

Whats the zz4 convertion kit????

 

GM Performance Parts part number 10185077. A 355 horse ZZ4 engine and a bunch of parts, including: air cleaner; fuel pump, regulator, even the brackets & bolts to mount it; transmission upgrade pieces; full exhaust system; lower control arms for the differential; ECM & PROM; and rods & hanger for the q-jet. Costs about $4400 plus tax & shipping from your local friendly GM dealer.

 

Oh, yeah, emissions legal to boot.

 

Thanks a lot five7kid. I'll have to look into that... and yes, I do have an automatic.

 

Five7: The HO has it too... I've become rather familiar with one of those over the last 15 years or so...

The thing that is hardest to do with the late-model Q-Jets has to do with the way the carb is built. There are a couple of orifices critical to part-throttle opration that are buried deep in the fuel bowl, and drill bits of the right (small) sizes but also long enough to reach down in there are very hard to find. But then, there are also some passages that lead to some of these orifices, that are too small to flow what they need to for really premium driveability; and there's not enough metal in the casting to drill them out without risk of breaking through which of course turns the carburetor into garbage. So the carb is capable of supporting a certain level of performance, but no more, no matter what you do, apart from WOT. And I don't know about you, but to me while WOT is important, on the other hand the car's behavior the other 99.5% of the time is significant too.

Again, BTDT. I have a 400 in my formerly HO-equipped 83, and I gave up trying to get it to work after a couple of years of frustration. It always ran lean at idle and part throttle, no matter what I did; it used too much gas as a result, and tended to run hot on the highway.

Also, if you keep the carb, you have to keep the ECM; and if you do that, you have to keep the distributor too. All in all, that collection will provide an extremely restrictive upper limit to the engine's performance, that I know of no way to overcome. The ECM is really crude being GM's first attempt at a computer-controlled vehicle, just think back if you dare to what a PC was like in 1984 (or actually 1981, when that kond of ECM was intriduced), compare that to today's, and you'll have a good idea of its relative sophistication.

The carb calibration part of that "kit" used to be available as a separate part #. It might still be, I haven't looked for it lately.

What are your goals with your 350?

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"So many Mustangs, so little time..."
ICON Motorsports

 

RB, the reason I ask is two-fold:
1) My '86 LG4 opens all the way.
2) I'd heard that was one difference between the "earlier" LG4's & L69's.

I definately know what a full-open q-jet AV looks like - been working with them for over 30 years. I just have never seen one with limited opening like everyone talks about. But, I skipped from about '77 to '86, and this current one is the only CC q-jet I've dealt with.

Someone posted the calibration kit p/n a couple of months or so ago.

 

The goals with my 350 is daily driving, no real competitive racing, and about 230-250hp. That's all. Oh, as well as half decent gas mileage (12-15mpg)and passing emissions. I get about 15-18mpg with the 305, so I'm guessing 12-15 would be a reasonable assumption with a 5.7L. With these goals in mind, I simply would like to know if I can achieve this keeping the origional carb, computer, and emissions electronics, ect... Oh, I plan to have eimissions legal shorty headers put on the block as well. Thanks for all the info thus far too. I appreciate it.

 

You're on the way there. Check the tech articles for getting the most out of your q-jet.

 

Would the swap work WITHOUT any modifications on the carb, electronics (outside of a chip), ect...? I'm on a limited budget, and I would just like to get the engine in without worrying about any other nit-picky mods to the things stated above that's all.

 

It will work, but to get the most out of it, you'd need to do the stuff RB said. Take a look at the tech article, most of the stuff is "free".

 

Buy HP Books 014 - Rochester Carbs. That and the tech articles would be more than enough to get you comfortable with the minor mods you would need to do for the 250 - 300 HP range.

I ran as fast as 13.18 with the computer carb on a 408 in a 3700 lb car with driver,, 2400 stall - about 325 horse to the rear wheels - 380 or so at the fly wheel. I had no driveability problems. Swapped to a 750 Holley and mechanical advance distributor,, and had to tune,, tune,, tune,, and buy a 50cc pump, adjustable metering plate, and quick change vacuum spring kit,,, to get it to run a 13.06. I thought I had made a big mistake in swapping it out. Actually if I had to do it over again,,, I would have left the computer carb on that combination.

 

OK, that's all I needed to know. Thanks people.