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Old 08-15-2002, 09:11 AM
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Post Qjets Ain't they great

Got really fed up with my Qjet not running right and not getting those tree hugger caps of the idle screws. Took the carb off, again, and decided to grid the base of the carb and pop the caps off from behind. Worked like a charm. I pulled the needless and one was worn. I tried exchanging them with needles from another older carb but they have different threads. Much finer on the new carb. I shot some carb cleaner in the holes, cut slots for a screw driver in the back of the needles and adjusted them to 4 full turns. They were set to 2 1/2. Reinstalled and it ran great. Had a nice smooth idle although not as smooth as the older carb but has great power and runs great.

I also installed my pcv system which might have made it run a little rougher than without.

It was running so good that I decide to steam clean the inside since I had no idea how bad the carbon is inside. The guy I bought if from was a real liar about everything on the truck so when he said it was rebuilt with flat top pistons, I had no reason to believe him. I got the engine warmed up and slowly poured water down the carb. I used about a quart reved the engine as I poured. It ran a little rough afterward but after I took it out on the road it smoothed right out real nice. Got it back, let it cool and it started right up first time everytime.

I still think that when set up right a Qjet is hard to beat for a road car.

Thanks Dave for the info on the 3 1/2 turns I probably would have set it back to 2 1/2 or 3. I figured with the fine threads but shorter needles I was safe to go with 4. I will probably fine tune it later.

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Old 08-15-2002, 09:45 AM
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Does this "steam cleaning" procedure really work?
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Old 08-15-2002, 10:00 AM
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ok i have never heard of doing the water thing like that but i too would like to know if it works good and if there is a chance of hurting the engine doing this thanks
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Old 08-15-2002, 10:34 AM
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Never heard of using water but they make a solvent to pour into the carb, kill the engine with it and let it soak. Start up a little later and blow the garbage out. I used it once a long time ago, don't remember the name of the product. Don't know if it did any good but didn't do any harm. One caution: do it at night 'cause it clouds up the entire neighborhood!!
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Old 08-15-2002, 10:43 AM
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I have been working on a Corvair for a couple of years and have spent a lot of time on the Corvair forum. This is a standard recommendation for cleaning carbon out of an engine. The idea is that it creates steam in a hot engine that loosens the carbon that then goes out the exhaust. The Corvair runs at about 350 degrees so it is pretty effective in making steam.

I have seen other people recommend this proceedure on "standard" engines as well. I figure give it a try it couldn't hurt. I did this with a tank type sprayer when I first got the truck and it seemed to smooth up the idle right after I did it.

Keep the revs up and spray in the water with a garden sprayer until you have put in about a quart. Take it out for a good hard drive (the fun part) and your done. Someday when I need to pull heads I will try this just before I pull them. Some people recommend putting in a little alchohol.

I'm not sure this is a good idea on computer controled cars. It will probably mess up some sensor.
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Old 08-15-2002, 11:18 AM
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Dumping water down the carb while the engine is running is one of the best ways of getting rid of all that nasty carbon...
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Old 08-15-2002, 12:11 PM
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.......and cracking a ring. This is one of those things that many people do and never get into any trouble but.......one out of every 1000 or so crack a ring doing this, pouring any liquid down the carb is an invitation to disaster. Yea I know people have been doing it for years but every engine I've torn down needed bead blasting to remove the carbon from the piston domes, I doubt the water gets very much out. Mostly the black you see coming out of the exhaust pipe is the soot that has accumulated in the muffler, not carbon in the engine. I hate to be a party pooper but......This is like the "don't ever put a battery on concrete" wifes tale that never seems to die. I wouldn't do it - ever. A good hard run on the highway will unfoul the plugs just as efficiently.

In case your wondering where the battery fairy tale came from, they used to make battery cases out of glass and the were much heavier than they are today due to the heavy plates. Ever try to put a 150 pd chunk of thin hollow glass down gently on concrete? It would be kind of like trying to put down a full fish tank.
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Old 08-15-2002, 12:12 PM
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hey, neat trick. 4jaw-if thats an old wives tale how come it seems like every time i pick up a battery that i left on the garage floor it's always dead? i know plastic is an insulator so ?

[ August 16, 2002: Message edited by: bullheimer ]</p>
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Old 08-15-2002, 12:30 PM
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If spraying water down the carb is bad then why are people installing water injection. I am not talking about dumping a gallon of water down the carb of a hot engine. I am applying a controlled spray of water in more of a heavy mist.

I agree that a cold liguid suddenly applied to a hot metal part like a ring could crack it. Theoretically the water becomes steam as it enters the combustion chamber so it is never really a cold liquid.

4jaw Thanks for the history of the battery on the concrete. I always wonder where these things come from. I remember jar batteries but didn't know they used glass batteries in cars.
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Old 08-15-2002, 12:49 PM
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Hey Mertz; Glad to hear you got the old Quadrajet working. I got mine fine tuned, although it is a little hard starting when cold but I still think it is the best carb for street use. I never heard of putting water down the carb but I have learned a lot on this site about new things. Only thing that bothers me is that you see a post a sometimes never hear from the guy again. I wonder if he didn't do himself in??? Dave E Shank
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Old 08-15-2002, 03:31 PM
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I hope I don't sound preachy but after seeing hundreds of motors apart including mine I don't think anything can prevent carbon buildup. Your right about water injection working wonders on high compression engines, I have used it myself with excellent results. Guess what, those engines had the same carbon buildup as any other I had built. This leads me to believe that water has no effect on reducing carbon buildup.

If done carefully I don't think it really hurts anything but the potential of causing real harm if you inadvertantly kill the engine with excess water and the cold water hit a hot ring.....you get the picture. The same goes for those pour in combustion chamber cleaners, I have yet to see one that works better than plain old diesel fuel poured into a cold engine with the plugs out and cranking it with the starter.

Just my opinion.

BTW if you want a clean engine, switch to alky.....zero deposits in the combustion chamber but lots of condensation in the oil. <img src="graemlins/drunk.gif" border="0" alt="[drunk]" />
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Old 08-15-2002, 03:41 PM
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Like I said I have never taken one apart after doing the water thing so I'm sure that your experieince has more clout than my speculation. I can say that the truck did run better after I did it but that might not have been due to a reduction in carbon.

As for the Corvair, there is documented proof that it works in this high temperature engine. There are hundreds of Corvair nuts like myself that have done it with great success. They are built to run hot. The concern and warning is alway that if your doing it and you kill the engine you'll never start it again.

Thanks for all the comments. I always learn something here. I looked into water injection and found an interesting site. <a href="http://website.lineone.net/~dave.cushman/mannject.html" target="_blank">http://website.lineone.net/~dave.cushman/mannject.html</a> This might work for those on a budget that have detonation problems. Might improve gas milage too.
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Old 08-15-2002, 03:54 PM
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While on the topic of pouring stuff down your carb, I remember way back when I was still in school pouring trans fluid down the carb and smoking out all your neighbors. Anyone else remember doing that. I think if I can still remember it was supposed to clean your valves or something, I just liked the smoke. Used to have to drive the car around the block a few times when done.
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Old 08-15-2002, 05:52 PM
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i know this is a hotrod forum but qjets are the best for offroading too. small primaries and a central float boal make for good off idle throttle response and less stalling at severe angles.
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Old 08-15-2002, 06:54 PM
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I've done the water trick too.Had a 305 w/ 200,000mi on it held the rpms up slowly poured water down it,it stumbled blew a black soot cloud out ran better for a littlr while.Don't think I'd try it on any of my good motors though.
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