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carburetor choices

gjk5

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I need either a carb rebuild or replace on '72 K5 350. I have called around and everyone wants about $200 to rebuild the Rochester Q-jet, I looked on E-bay and it looks like I could get a Holley or Edelbrock for about that $$. My question is: how much CFM do I want for this application, and is one brand preferable over the others? Just looking for some advice.
 

pauly383

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Jet , I-5 auto, and Edelbrock have good quadrajets. Even in the smaller engines they are capable of flowing 750 cfm. Some big blocks and Hi-Po apps got 850 cfm carbs. I run one from I-5 auto on mine, works great. Hills and off camber don't bother it. In your application its even better as you don't need all the ports and such of the newer carbs. I would request an electric choke for it. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
 

CaveBlazin

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I ran a 600cfm Edelbrock preformer carb w/auto choke and that was on a stock 350. Needless to say it ran Super great with absolutely no problems in the 6 years it was in there. Just my 2 cents
 

Thunder

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Most non Q-jet Edelbrocks and Holley (except Truck avenger) may be cheaper but they will flood out on you if you do any 4x4ing in steep terrain.
Stick with the Q-jet. Try to get yours rebuilt. If yours is orginal you have one of the good pre smog ones. Q-jets are the best carbs for offroading and street use in a Chev truck IMHO.
 

gjk5

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Sounds good, I'm a little wary of ordering a carb off e-bay anyway. I have two '72s (one is a heap) so I may take the carb off the heap and have it rebuilt and switch 'em, I'm planning on switching out the engines when I get some perf. parts for the extra one. Since I have two Q-jets, does anyone know about running dual carbs? What kind of mods are required (probably need new intake man.)? Or is this a waste?

Also just a note, when I talked to the guy about buying these K5's he tells me he has 4 new 33x12.5x16.5 tires to throw in, I looked closer at them and they're 15's, so I can throw 'em right on there!
 

Thunder

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Dont bother with dual carbs.That would be overkill. Big time! The Q-jet will flow plenty of air for your needs. The ones you have are prolly 750 cfm that is more than enough for a 350. Because of their design q-jets only flow what your engine needs. unless the air valve is out of adjustment.
Not sure about the 33" tires on some Blazers they fit on some they need minor trimming on the inside of the front fender. i have a 89 and had to trim about one inch off the lower rear corner of the front fender.
 

84gmcjimmy

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I haven't had any experience with the Q-jet, what is it, and why is it the best for off-roading. Thanks

-Steve
 

GMCLegacy

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Buy a $25 manual, a $30 rebuild kit, carb clean, and a saturday afteroon and rebuild the ole qjet. they arent too bad to do, just take your time and clean everything.

this book was recomend to me by Cybersniper (aka wrathorc), i bought it, and has helped me figure out how the whole carb works.

"Rochester Carburetors" by Doug Roe. The ISBN is 0-89586-301-4

the barnes and noble had it on the shelf suprisingly enough.
 

unclematty

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With all do respect, have you all lost your minds? carbs SUCK off road. throttle body injection is most reliable and relativly inexpensive. take it from a guy who has used both offroad extensivly. tbi rules /forums/images/graemlins/smile.gif <font color="green"> </font>
 

GMCLegacy

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sorry, not much of a wire kind of guy.

a non ARP Qjet with an external choke, fed by a mechanical fuel pump is my choice.
 

Thunder

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[ QUOTE ]
I haven't had any experience with the Q-jet, what is it, and why is it the best for off-roading. Thanks

[/ QUOTE ]
Q- jets are the stock 4 barrel carb that came on most Chevy trucks and cars from the mid 60s on up till they went FI.
Q- jets are good off road because of their center float bowls. When you get these carbs at extreme angles they dont leak fuel down the bore and flood out the engine. They also have very small primary venturies and when tuned right can get pretty good fuel milage in a 4x4.
Many people who know and love these carbs call them "Hillbilly Injection" because they are the closest thing you can get to fuel injection in a carbed US made V8 4x4 truck.
IMHO as far as carbs go Q- jets are the best carb you can run off road.I have adapted them to fords and jeeps with great sucuess also.
Holleys and Edelbrocks/Carter AFBs need quite a bit of modification to run off road at extreeme angles espically on long steep hills.Q- jets will do that just fine right out of the box in most cases.
( holly and edelbrock are now offering modified carbs for offroad but the q-jet is the benchmark carb they are compaired to)
This post is about carbs So i wont get into FI. Which I agree, is far superior to a carb in most all applications.
But if you cant run FI. A Rochester, Jet, or Edelbrock Qudra-Jet is the next best thing. /forums/images/graemlins/thumb.gif
 

gjk5

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Thanks for all of the info, I will take the carb in to rebuild on the running K5 and make do with that for a while. In the meantime the heap has a freshly rebuilt 350 which I am going to pull, put on a stand and work on. I think I will just get parts as I can for that eng. (perf. heads and intake etc.) and maybe look into making that one TBI since I have some time and the yellow one runs OK for the time being.

Also, 33's should fit fine, it's lifted 2.5".


Thanks again.
 
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