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73-87 Chevy _ GMC Trucks => Performance => Topic started by: sbx22 on August 29, 2011, 10:49:43 pm

Title: Which carburetor would you choose?
Post by: sbx22 on August 29, 2011, 10:49:43 pm: So I have a crate engine sitting, waiting for me to pick out a carburetor for it. It's a 350 mild street. The builder recommends the Holley Street Avenger 670 cfm. According to the calculator on summit racing, they are recommending 474 cfm for street, 613 cfm for racing. 670 is much more than this obviously, the 570 would be in range. If you were me, would you follow the calculator method or choose what the builder recommended? Thanks.
Title: Re: Which carburetor would you choose?
Post by: chevymanrob on August 30, 2011, 06:17:10 am: if it were me i would go with a standard 600 vac holley. parts are everywhere and cheap! the 670 wouldn't be overkill either. maybe call up holley and get a tech rep to just be sure?
Title: Re: Which carburetor would you choose?
Post by: muddpuppy01 on August 30, 2011, 06:11:17 pm: if you go with a bigger carb you may have to jet it down but you will also loose thottle response vs a smaller carb. I would run a 600 as well.
Title: Re: Which carburetor would you choose?
Post by: VileZambonie on August 30, 2011, 07:19:06 pm: Quadrajet or EFI
Title: Re: Which carburetor would you choose?
Post by: 1979C20 on August 30, 2011, 07:21:45 pm: Quote from: VileZambonie on August 30, 2011, 07:19:06 pm
Quadrajet or EFI
X's 2

I love the qjet.
Title: Re: Which carburetor would you choose?
Post by: str8bloc on August 30, 2011, 08:45:49 pm: loved edelbroc,k started to read up on the qjet and the qjet is the shoot.great gas milage and performance
Title: Re: Which carburetor would you choose?
Post by: 1980c10 on August 30, 2011, 10:06:03 pm: I have a mild built 350 in my truck with the 670 Street Avenger
specs are;
mild cam
flat top pistons
vortech heads
edelbrock vortech dual plane intake
holley flotech headers
balanced rotating assembly
proform dist.
dyno tuned and run 393 hp @ 5400 rpm and 432 tq #4300 rp
I re-jetted the carb with slightly larger jets front and back to keep up with the engine.
I have the best throttle response I have ever felt with any vehicle, (better than late model trucks)
I also get range of 15-21 mpg depending on my driving
My engine was also run with a 770 Street Avenger and pulled the same numbers with out of the box jets
you will get better throttle response with the holley and it is much easier to tune and maintain
That is my opinion many others here and elsewhere will hype up the q-jet and its not a bad choice but the holley can do better; it all comes down to tuning and setting it up right which is a lot easier with the holley.
mpg gains are about tuning and proper combinations
Also the builder should know his engine combo what performs well on them (In theory)
Title: Re: Which carburetor would you choose?
Post by: sbx22 on August 30, 2011, 11:30:58 pm: Well, I ordered the 670, on its way here! ;D Anyway, I have a qjet from the old motor that was pulled. I can always rebuild that one and swap it on whenever right? I have a dual-plane edelbrock performer that can mate with both square/spread bore. Thanks for all the input, much appreciated.
Title: Re: Which carburetor would you choose?
Post by: JohnnyCanuck on August 31, 2011, 09:10:13 am: I like sticking with the qjet, no adapter plate, and you can buy them rebuilt if you don't feel like doing it.
Title: Re: Which carburetor would you choose?
Post by: 1980c10 on August 31, 2011, 06:58:51 pm: You can run either carb on that intake.
Title: Re: Which carburetor would you choose?
Post by: Grim 82 on August 31, 2011, 08:41:21 pm: I like my 600 Holley because it's easy to work on, but I would recommend a q-jet and original brackets for somebody that was running a 700r4, and anybody whose main goal was fuel economy.
Title: Re: Which carburetor would you choose?
Post by: westsidek20 on September 01, 2011, 03:49:35 pm: What would be the "mods" needed on a Qjet to get performance?