Quadrajet guys out there? - Page 2

ThumperZ28 · 07-03-2012, 03:22:18 PM

a Q-jet would be excellent for your application...

and as for the heads...try porting them to get more flow out of them...

Cmatt1605 · 07-03-2012, 03:23:42 PM

Quote:

Originally Posted by Damon

Better yet, a Weiand Street Warrior intake (also available as a Summit house brand intake). It's the direct competitor to the improved Performer EPS, but is available with a QJet carb flange. Link:

http://www.summitracing.com/parts/SUM-226008/

I mean, seriously. How can you argue with a new, modern computer flow-modeled performance aluminum intake with a Qjet carb flange for $119? The days of paying $25 for a used (abused) base-model Performer intake at a swap meet and then have to heli-coil all the stripped out bolt holes just to use your QJet carb may finally be over! And I certainly wouldn't spend good money buying a new copy of the old-school Performer when you can have this better intake instead for less money.

Plus it's made by Weiand which means if you ever want to put a Holley carb on it the rear vacuum port on the intake won't try to occupy the same space as the carb's rear fuel bowl, like an Edelbrock intake will.

If you step up to a Performer RPM-class of intake then it's just the opposite on Qjet carb flange availability- Edelbrock has one available, Weiand doesn't.

thanks for all the suggestions! I currently have a RPM Air-Gap intake with a cowel induction hood, will i see any negative results with using an adapter plate? or will i be better off getting a new intake for it? i am trying not to spend TOO much on my engine, it already has a mild cam, the air gap intake, mallory unilite ignition system, and headman headers. if need be i can get a new intake just figured i would ask. after the buildup i will be sure to post a thread about it with a dyno chart of before and after

Pfrederiksen · 07-03-2012, 04:23:00 PM

The adapter plates are pretty lousy.
You should be able to sell your air gap as it seems most people are going the other way anyways (spread bore to square bore)

P

Cmatt1605 · 07-03-2012, 04:27:20 PM

yeah true, how much do used air--gaps sell for? like $180? its only been on there about 8 months? probably has about 3,000-4,000 miles on it.

hhott71 · 07-03-2012, 06:27:13 PM

Quote:

Originally Posted by Cmatt1605

well the edelbrock was on the car when i bought it, the last owner had no clue how to even hook up spark plug wires properly, let alone tune a carb. i basically had to rewire the entire interior and under the hood to fix the hack job he did, and do a lot of work to get it runing right, the carb is the only issue i keep fighting.

i have found mixed things on the QJET but i have also found that they give decent MPG's?

and the eddy is a square bore not a spread, has 2 floats, the QJET has 1, and 2 fuel bowls vs the 1, and mechanical secondary vs vacuum.

but i am NO expert, just stuff that i have found on the internet

The Q-Jet and AFB are both mechanical Secondaries.
The AFB uses a weighted air valve to choke the secondaries. The AVS and Q-Jet use a vacuum / spring counterweight to choke the secondaries.

Cmatt1605 · 07-03-2012, 06:44:13 PM

Quote:

Originally Posted by hhott71

The Q-Jet and AFB are both mechanical Secondaries.
The AFB uses a weighted air valve to choke the secondaries. The AVS and Q-Jet use a vacuum / spring counterweight to choke the secondaries.

learn something new every day

thanks for the info!

Damon · 07-03-2012, 07:27:21 PM

I'm not a big fan of using adapeter plates to put a QJet on a squarebore manifold. Better to just swap it out for a Performer RPM QJet.

For future reference- I always buy the QJet version of an intake, if it's available. Adapting a Holley onto it no problem. The other way around is new intake time.

Cmatt1605 · 07-03-2012, 08:18:14 PM

Quote:

Originally Posted by Damon

I'm not a big fan of using adapeter plates to put a QJet on a squarebore manifold. Better to just swap it out for a Performer RPM QJet.

For future reference- I always buy the QJet version of an intake, if it's available. Adapting a Holley onto it no problem. The other way around is new intake time.

looks like that will be what i will be doing, will prob be selling the intake i have after this weekend when i get the motor taken apart.

Wynder · 07-04-2012, 06:17:40 PM

You should make nice power with that Q-Jet. AND it will give you very respectable mileage (iffin you keep yer foot out of it!). One very important tuning tip is getting the secondary air valve tuned right. All the "Quadrabog" guys out there never took the time to tune the air valves. They let them come in (open) way too early and bogged the secondary fuel signal, too much air into the engine without corresponding fuel mixed in.

You'll have to run the car and spend time dialing in the air valve setting until it feels right for your combination. Start with them pretty loose (easily tipped open) and run it, get the inevitable bog, tighten some more, run it... See the progression? When it kicks you in the ass under power when the secondaries come in without hesitation or bog you've gotten it correct.

You'll be surprised how stiff the air valves will have to be when they are correctly set. All the past "high school heroes" set theirs (if they messed with them at all) WAY too loose "cuz I want four barrels flowing right NOW!" and bogged the hell out of their motors, and immediately (and incorrectly) blamed the Q-Jet, giving a respectable carburetor an undeserved reputation. Tune it right, and you'll have a great street combination. Enjoy!

Air_Adam · 07-04-2012, 08:05:49 PM

Once you understand how they work, they are a really good carb. Very versatile. The only issue I have with them, and it really only applies to race/very high performance applications, is that the fuel bowl volume is quite small compared to the other performance carbs, like the Holley 4150/4160, so having the fuel bowl run dry at WOT can be a problem if your fuel pump is not up to the task. With the Holleys, there is enough fuel bowl capacity front and back, that an inadequate fuel pump can be compensated for to a certain extent. This just simple doesn't exist with the Qjet, as the fuel bowl is so small, and there is only one (the Holleys have two). Removing the plastic baffle inside the bowl helps, but only so much.

But this really only applies to race/very high perf applications, it is rarely if ever an issue on a street car, especially with a small engine like a 305. Use it on your engine, get it tuned properly, and be happy.

Cmatt1605 · 07-05-2012, 03:38:10 PM

thanks for all the info everyone! i have a deal lined up so that i can get one either this weekend or next week. I have also ordered the Cliff Ruggles book on the Q-Jet so that I can get a full understanding on how it works for the rebuild of it.

Air_Adam · 07-05-2012, 08:38:02 PM

Best bet for one that will work well with the least work is to find one that was originally on an engine thats the same size as what you're using (ie. 305 carb on a 305, 350 carb on a 350, etc)

Then things like the air bleeds, etc, will all be pretty close "right out of the box"... just do a little minor tuning and you're good to go.

Cmatt1605 · 07-05-2012, 09:20:11 PM

well the one that i have lined up to get is off of a 76 grand prix motor. do you think it will take much to get it set up for a 77 305?

Air_Adam · 07-05-2012, 10:05:41 PM

Aside from the tuning problems (and ya, since most of those had a 400 or 455, it will take quite a bit of tuning and recalibrating to get it right) you have another problem - Chevy Qjets had the inlet facing towards the passenger side, Pontiacs had them facing straight forward. This can cause problems running fuel lines on a Chevy motor.

Look for one off a 305 Chevy - it will be the easiest and most trouble free for you, and it can't be hard to find something with a 4bbl 305, they are everywhere.