Edelbrock 600 cfm vs Qjet#7041250
May 5th, 2011, 08:42 AM
#5
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Location: Phx, AZ
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Both will work very well, the Q-jet is a larger carburetor with smaller primaries, much larger secondaries. It should get better mileage if you can keep your foot out of it. Good luck, there.
If you go with an E-brock/Carter Afb carb, look at moving up to a 750, your'e usually giving up 20 Hp on a 350 upper rpms, using the 600.
Jim
Last edited by Warhead; May 5th, 2011 at 08:46 AM.
May 5th, 2011, 04:00 PM
#6
Completely agree with Jim.
Smaller primaries on the Qjet will result in better mileage. A lot of people don't know how to adjust the timing of the secondaries and that is often the problem. there are several books on the subject of performance and standard rebuilds, fun reading if you like that sort of thing
Qjets are more complicated than Holleys but not significantly so IMHO...
Smaller primaries on the Qjet will result in better mileage. A lot of people don't know how to adjust the timing of the secondaries and that is often the problem. there are several books on the subject of performance and standard rebuilds, fun reading if you like that sort of thing
Qjets are more complicated than Holleys but not significantly so IMHO...
May 6th, 2011, 08:53 AM
#7
Where were you in '72?
Join Date: Nov 2009
Location: Ottawa, Ont
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Check out the King of Qjet Cliff Ruggles site, he has lots of go fast parts and advice for the Qjet.
http://www.cliffshighperformance.com/
http://www.cliffshighperformance.com/
May 6th, 2011, 10:49 PM
#8
Just put on a Brand new 650 Edelbrock (AVS Thunder series) on my motor (last week), and found this to not be true. I have a more agressive cam, headwork, much higher compression, etc. than the motor in question and the 650 did not run better than the 600. Cannot imagine how much worse it would have been trying to run a 750. I ended up ordering another 600 CFM and the car runs fabulous. I certainly do not loose 20 hp using that carb at upper rpms. Not sure where you're getting that exact number or why. Also, Edelbock clearly states on their website ( tech section..tech video..before you start..begin at 40 seconds into video) not to use a 750 on a motor such as the one in question, because that carb is for "very highly modified larger cubic engines, for real performance use only." I over-carbed my engine and had to go back..performance gain after bolting on of the 600 was instantaneous ( Full disclosure of set up w/ 600: I did use one stiffer step up spring, one size smaller metering rod, and bumped the secondary jet from an .095 to an.098, so it is not in its "stock" configuration).
Last edited by 71 Cutlass; May 6th, 2011 at 11:17 PM.
May 7th, 2011, 03:17 AM
#9
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Location: Brazil Indiana
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this is always a never ending subject but here is my input, i believe the Q jet is the better carburetor, even Joe Mondello and Jack Merkel both have said this is true for most street engines and backed up by the dyno. the biggest problem i see with Q jets is that they are so old and tinkered with so much that most people can't get them back to the correct settings. not to mention the other problems that have developed over the years like internal leaks, bent shafts, misaligned butterflies and that list goes on. these problems will not get fixed by most any do it yourselfer. for the price of a new aftermarket carburetor you can have someone like Sparky's carburetor service rebuild your Q jet to new condition and to your exact engine specs. an off the shelf aftermarket carburetor will be a one size fits many. a properly built Qjet will last many years without having to touch it in any way. i am not an expert, just another opinion among many on this subject.
May 8th, 2011, 09:15 AM
#10
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Location: Phx, AZ
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Just put on a Brand new 650 Edelbrock (AVS Thunder series) on my motor (last week), and found this to not be true. I have a more agressive cam, headwork, much higher compression, etc. than the motor in question and the 650 did not run better than the 600. Cannot imagine how much worse it would have been trying to run a 750. I ended up ordering another 600 CFM and the car runs fabulous. I certainly do not loose 20 hp using that carb at upper rpms. Not sure where you're getting that exact number or why. Also, Edelbock clearly states on their website ( tech section..tech video..before you start..begin at 40 seconds into video) not to use a 750 on a motor such as the one in question, because that carb is for "very highly modified larger cubic engines, for real performance use only." I over-carbed my engine and had to go back..performance gain after bolting on of the 600 was instantaneous ( Full disclosure of set up w/ 600: I did use one stiffer step up spring, one size smaller metering rod, and bumped the secondary jet from an .095 to an.098, so it is not in its "stock" configuration).
The butt dyno always lies, Chrondeks don't lie. When we switched, I first thought we went 3 tenths slower, the ET slip said over 2 tenths faster.
If you like the way it feels, by all means keep the smaller carb. It will probably get better mileage too.
Jim
Last edited by Warhead; May 8th, 2011 at 09:18 AM.
May 8th, 2011, 08:22 PM
#11
Just making an apples to apples comparison b/c before my motor was modified to it's current form, it was virtually the same as the one in question in this thread (71 and 72 350s) , and the dyno showed no loss in HP due to air/fuel at higher rpms using the 600 carb.
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
Last edited by 71 Cutlass; May 8th, 2011 at 08:24 PM.
May 8th, 2011, 08:42 PM
#12
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Join Date: Apr 2011
Posts: 2,703
Just making an apples to apples comparison b/c before my motor was modified to it's current form, it was virtually the same as the one in question in this thread (71 and 72 350s) , and the dyno showed no loss in HP due to air/fuel at higher rpms using the 600 carb.
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
Motor = Electric
Engine = Combustion
May 9th, 2011, 08:40 AM
#15
"Motor" is what a lot of the old timers called "engines" back in the day. Joe probably did it many times himself. Thus the birth of titles such as "Motor Trend" magazine...boats use "outboard motors"..this list goes on.
Last edited by 71 Cutlass; May 9th, 2011 at 08:47 AM.
May 9th, 2011, 08:56 AM
#16
The guy who did my engine work and tuning used a Holley 600 cfm. It's what he prefers and he knows them forwards and backwards. The car runs great and dialed in really good.
If I were to do it myself I would use an Edelbrock because they are easy to use.
If I were to do it myself I would use an Edelbrock because they are easy to use.
May 9th, 2011, 02:54 PM
#17
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Join Date: Mar 2008
Location: Phx, AZ
Posts: 1,012
Just making an apples to apples comparison b/c before my motor was modified to it's current form, it was virtually the same as the one in question in this thread (71 and 72 350s) , and the dyno showed no loss in HP due to air/fuel at higher rpms using the 600 carb.
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
What car(motor) did you have at the track that you had a 600 CFM carb on that you found out could be using a 750?
That will still not hold true for every 350 because every comparison is apples to oranges.
look at moving up to a 750
Run the one you can afford, and the engine likes best.
My Opinions
Jim
May 22nd, 2011, 11:18 AM
#19
Just used Cliff's Stage I Q-Jet rebuild kit on my 403 with mild cam. I'm also using his electric choke. It runs so smooth I can't believe it. The issue is that Q-Jets run off vacuum, and with a mild cam the carb is starving for vacuum to run the primaries correctly. Cliff's modified idle tubes allow the carb to be on curve for tuning. My 403 runs like FI, nk.
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