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#21
11-07-2004, 07:15 PM
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OK guys, it was a joke. If you notice, I wrote" well, not really" Im just not as experienced with them as I am with Holley's. My old 78 Trans Am ran great with one for years. Its just when I started getting more into the performance side,(Chevy's and Fords) I stuck with Holleys. Now that im working on my own Ponitac, I want to try the Q-jet. I think I figured it out. It seems I got some dirt or something in the fuel line. Cause i pulled the filter off, and there was alot of debris. I changed it out, and it started up again. Now just for some fine tuning. I'll do that tomorrow.. Thanks to all for the replys. Trust me, I'll be asking alot of questions on how to fine tune it...
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#22
11-07-2004, 09:37 PM
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You'll notice that some people around here take Qjet disrespect as seriously as insulting their mothers ... Come on people, it's a carb!
The absolute best carb I've ever had was a Qjet. It sat on a very warmed over 396 running a plate nitrous system back in 1985. That carb was like fuel injection - it never missed a beat. But some of the worst carbs I've ever had were Qjets after a rebuild. I came to believe that if you had a good Qjet, don't replace it. But the moment it gives you in trouble, in the trash it goes. There are people talented enought to rebuild and tune them, but I'm not one of them. I'm a Holley guy now. My GTO hasn't been started in five weeks, and I know if I go turn the key now, it will fire up and beg me to pull it out of the garage. I know these carbs, so I can make them do things. But yes, they do use a bit more fuel no matter what the conditions .... Mike M
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Midwest Muscle Machines, LLC .... '68 GTO Convertible plus others |
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#23
11-08-2004, 03:44 AM
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We see hundreds of q-jets each year and most of them were "rebuilt" prior to showing up here....with unsuccessful results. To top the lists of problems, most are leaking at the bottom plug(s) right thru the epoxy that was dabbed over them. ALL of them will need bronze shaft bushings. In the past 300 units built here, one carb was within spec on side play at the primary shaft. We insist on bushings as any air that leaks by the shaft at idle/low speeds is a vacuum leak and allows unfiltered air to enter the engine.
A new float is manditory, they often soak up fuel and sink, causing a high fuel level in the carb. The idle tubes should always be removed for cleaning, there will be a lot of debri/dirt in and under them. A quick "fix" in lieu of pulling them is to rod them out with a straightened out peice of .030" spring wire. We vacuum and pressure test all the needles/seats. At least one in 30 will fail the test! We've been compiling information for some time to get a book into print. Goals are to have something out next summer. We've made dozens of trips to the track and dyno armed with Demon and Holley carbs to test back to back against well prepared q-jets. Any of them will make with 1-2 hp and run within about .02 seconds of each other at the track. The q-jets always provide better fuel economy, smoother off idle and are very reliable in long term street use......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#24
11-08-2004, 05:57 AM
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Echoing Cliff's comment about fuel valves or "needles and seats"; we were finding about the same thing until I learned that one of the manufacturer's had eliminated the "staking" procedure to save costs. The last procedure to be done to a fuel valve prior to wrapping is to "stake" the seat.
The enthusiast can obtain the desired result by placing the seat thread down on a piece of wood (so as not to damage the thread), place a check ball into the needle portion of the seat over the orifice, place a drift punch on top of the ball, and whack (highly technical term  ) the punch with a hammer. This removes any burrs from the machining of the seat, and provides a uniform sealing surface.Jon.
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"Good carburetion is fuelish hot air".  "The most expensive carburetor is the wrong one given to you by your neighbor". If you truly believe that "one size fits all" try walking a mile in your spouse's shoes! Owner of The Carburetor Shop, LLC (of Missouri). Current caretaker of the remains of Stromberg Caburetor, and custodian of the existing Carter and Kingston carburetor drawings. |
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#25
11-08-2004, 09:40 AM
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Yeah I think it must be rich but running a pretty much stock 400 with non ported heads and doing mid 12s on Arco gas with a 1.67 0-60 cant be too bad so I just keep running it this way. I live in the NW which can be pretty cold.
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#26
11-09-2004, 05:16 AM
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In addition to what Jon said, we have also discovered that some of the newer needles have a thin film on them, kind of like a protective coating. This must be removed prior to vacuum/pressure testing the assembly. Good tip on the check ball "whacking".....Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#27
11-14-2004, 01:28 PM
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Hey, Cliff. Quick question. I started driving the car. I only got to the end of the block,and the car started dying. It wont stay idling on its own. If I give it a little gas, it will run like a bat out of hell. But it just wont idle. Actually when I first turned it on, it had a little rough idle, but now it will not. Any ideas? Like I stated before. I just did a quick "kit". Any special procedures to cleaning any specific part(s)? BTW, its a 400 6x heads, flat top pistons, Performer intake, HEI, MSD 6a. First thing I checked is a vacuum leak, but didnt find one...
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