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post #1 of (permalink) Old 09-27-2004, 12:51 AM Thread Starter
 
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Q-jets how to make them work etc.

Ok here we go...... First phase..





Ok first off this is the 895 cfm truck type carb... See arrow (1).. The extra ring the arrow points at is ONLY on the 895cfm carb. The 850 does not have this.. (2) there is a small fuel filter and a spring in behind the fuel inlet. Throw it away use a inline these are JUNK don't flow and clog easily. (5) this actuator(or whatever you want to call it) needs to go the rod etc pitch them also.. (3) these are your secondary mettering rods. Pull them out and spray the holes out real good with carb cleaner. (4) screw is how you lift that whole assembly out.


Hmm ok lets see here...



Ok... (1) looks alot like this thing has backfired a few times a very thourough cleanup is deffinately in order.. (2) the twist-tie on this thing really indicates its junk pitch it. (4) make sure there isn't much play here because if your main throttle shaft has alot of play its not worth messing with. Common problem on these things. A little play is ok but if its really flopping around use it for a parts carb. (3) these are your idle mixture screws. run them all the way in counting how many turns each (so you know where to put them back) then pull them out and clean the hell out of em. Blow the idle circuit out with an air hose. There our about 50 million little holes and passages in these carbs and a little clog can couse big problems.. Thats all I can think of for now. Whenever norm posts the other pics I will see what else I can do. Wish I still had one laying around I'd tear it down take pics and show some tricks on putting one back together..


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post #2 of (permalink) Old 09-27-2004, 11:09 AM
 
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Re: Q-jets how to make them work etc.

895!!! My God man. Why on earth did I find it on a 305 boat engine? Is the way you gage cfm different with the Qjets? I mean on a Ford smallblock you don't want to exceed like 600 with an AFB or Holley.Anyways Here's more pics. This post is cool as hell man. You got me believing in these things again. Every Mechanic hot rodder I know will choose one of these over any other type of carb. The secret is knowing what needs to be done. So Edlebrock's version is worth getting? I'll be tearing this down piece by piece so you can enlighten the rest of us Jake. Thanx again. I'll just post the links so that you can show the overview. [img]images/graemlins/smile.gif[/img]
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post #3 of (permalink) Old 09-27-2004, 11:11 AM
 
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Re: Q-jets how to make them work etc.

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post #4 of (permalink) Old 09-27-2004, 11:11 AM
 
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Re: Q-jets how to make them work etc.

[img]images/graemlins/cool.gif[/img] [img]images/graemlins/cool.gif[/img]
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post #5 of (permalink) Old 09-27-2004, 11:13 AM
 
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Re: Q-jets how to make them work etc.

[img]images/graemlins/cool.gif[/img] [img]images/graemlins/cool.gif[/img] [img]images/graemlins/cool.gif[/img]
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post #6 of (permalink) Old 09-27-2004, 01:04 PM Thread Starter
 
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Re: Q-jets how to make them work etc.

The reason they ran such a large carb on smaller engines is the way the secondaries work. A q-jet has fairly small primaries so its not To much carb for small engines just driving around. The secondaries are kinda like 4bbl on demand system. They open as the engine load/rpm demands more performance.(thats how they are supposed to work thats why they arent a real popular performance carb) For instance if you had a stock 4bbl on with no air cleaner and your hood off and watched the top of the carb when you stepped down on it. the secondary butterflys on the bottom are all the way open but as engine rpms increase the airdam on top starts opening as it opens the secondary metering rods increase the ammount of fuel. In most cases you would never see the air dam on top kick all the way open which would equal 895cfm. Now if you disable this system when you step on the gas you get 895 cfm when you want it NOt when it thinks you need it. I will download the pics and post more info tonight when i get home from work.
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post #7 of (permalink) Old 09-27-2004, 01:12 PM Thread Starter
 
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Re: Q-jets how to make them work etc.

If you don't mind Norm post one of the choke(left) side. I'd appreceate it.
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post #8 of (permalink) Old 09-28-2004, 12:24 AM
 
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Re: Q-jets how to make them work etc.



This pic was in my post that started the pics. This is all that was on it. I attached a choke cable to this side to get it to start.
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post #9 of (permalink) Old 09-28-2004, 05:28 AM Thread Starter
 
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Re: Q-jets how to make them work etc.



Ok..(2) this is wheere you adjust the preload on your accelerator pump(1). The hole it is in now is for the most gas when you step down on it. Which is most likely where you will end up running it you will just have to play with this when you get the carb on. Somthing else I will mention is the acc. pump and the float are 9/10 times the problem with a malfuntioning q-jet expecialy one that has sat around. The old accelerator pumps are almost always bad, and will cause all kinds of problems. Also somthing else about the secondary metering rods I was talking about earlier. You can swap them out smaller rods and get more gas larger rods=less gas. Somwhere I saw a calibration kit with an assortment of metering rods but they are a dime a dozen in peoples scrap carb piles and junk yards. Almost every q-jet out there had diffrent sizes of secondary metering rods so there are alot of choices out there if you really want to dial it in after you get the basics taken care of. Will post more tommarow I had to work over 3rs so I am off to bed.

[img]images/graemlins/givemebeer.gif[/img]

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post #10 of (permalink) Old 09-28-2004, 12:21 PM
 
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Re: Q-jets how to make them work etc.

Teach me how to overide the butterfly. [img]images/graemlins/smile.gif[/img]
I put that wire on there to hold the plastic vacuum thing on. It's one of the things you said I could scrap. You are being a huge help here. Thanx alot. I was still having problems with the carb crapping out in some steep areas. Any tips to keep that from happening?
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