Switch from Qjet to Holley - Team Camaro Tech
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post #1 of 18 (permalink) Old Dec 7th, 05, 07:11 PM Thread Starter
 
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Switch from Qjet to Holley

Thinking about shelving the Qjet and trying a holley. I have a fairly mild 327, 40 over, 9:1, with performer, 262XE, world 2.02 heads, headers, etc. But I have the cowl air cleaner assembly and really want to keep it. Will the holley housing fit the cowl. The Qjet has a notch on the top to keep it secure, does the holley? And what about the choke? I have the intake manifold set up on the Qjet. Can I get one to work for a holley or would I go electric choke? One last thing, I guess a 750 vacuum secondary would be ideal. Your input is appreciated in advance.
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post #2 of 18 (permalink) Old Dec 7th, 05, 07:26 PM
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Tom
 
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Re: Switch from Qjet to Holley

I would keep the q-jet maybe send it to a carb shop for tuning. I have tried a 750 Holley on my 327 and I couldn't get it tuned properly. I now have a 600 Edelbrock which works much better. I'm tempted to put the old q-jet back on, but it now has a square mounting intake. I would have to use an adapter etc. The problem as I see it is the 750 Holley's have to big of primaries. The 600 is better, but the old Q-jet has even smaller primaries, which will give you better street manners. A 327 doesn't need a 750.

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #3 of 18 (permalink) Old Dec 7th, 05, 07:28 PM
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Re: Switch from Qjet to Holley

I'm a street rodder and my engine rarely sees anything over 6000 RPM. A 750 square bore carb is overkill for a 350 let alone a 327 street motor. At 7000 and 100% VE, a 327 would need only 662CFM. Since you have a fairly mild 327, a more realistic figure for VE is more like 90% at a peak RPM of 5500which would result in 468CFM. The formula I am using (for square bore carbs) is RPMpk * CID * VE / 3456.

One advantage of your Q-jet is that it is a spread bore carb. The primary venturis are nice and small for part throttle cruise and the secondaries are nice and fat for WOT. Don't get me wrong - Holley's are good carbs too, but you'll be trading one set of problems for another. If you get a Holley square bore, don't over do it on the size. Vacuum secondaries are ideal for a mild motor especially with an automatic trans. The choke will most likely be electric.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #4 of 18 (permalink) Old Dec 7th, 05, 10:04 PM
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Keith
 
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Re: Switch from Qjet to Holley

You'll be much happier with the Q-jet if you get it set up correctly for your car engine.Alot of us on the Pontiac side are tossing our holley's and putting properly tuned q-jets back on. They're much nicer to drive and when properly tuned will run just as well as any holley.I personally witnessed a fully worked q-jet out run on an engine dyno a fully race prepped 930cfm holley on a 468Pontiac race engine, plus the q-jet gave the driveability back to the engine.
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post #5 of 18 (permalink) Old Dec 8th, 05, 12:16 AM
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Re: Switch from Qjet to Holley

69rag327

So far we all agree!

Keep the Rochester Q-Jet on and if it is giving you some trouble, either rebuild it or send it off for a calibrated restoration. A properly tuned Q-jet is hard to beat.
I recently had one sent to http://www.smicarburetor.com/. I had Sean calibrate it to my Engine/Trans/Gearing specs. I sure hope it performers as well as it looks.

Before

After


Kurt

Kurt
1969RS 14yrs into it.
383CID Lives
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Cold ones in the fridge. Dam, there gone. BRB
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Getting closer to my goal.
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post #6 of 18 (permalink) Old Dec 8th, 05, 08:03 AM
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Re: Switch from Qjet to Holley

Now that's just beautiful. I think I might steal your after image and set it as wallpaper.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #7 of 18 (permalink) Old Dec 8th, 05, 08:49 AM
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Re: Switch from Qjet to Holley

Is there something wrong with the Q-jet or are you just looking for more performance? A 750 is awfull big for a 327 unless it is a very serious motor. A Q-jet is still the best street carb for just about any combo.
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post #8 of 18 (permalink) Old Dec 8th, 05, 08:59 AM
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Re: Switch from Qjet to Holley

A nice clean carb sure makes that white towel look dirty...
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post #9 of 18 (permalink) Old Dec 8th, 05, 09:03 AM
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Dave
 
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Re: Switch from Qjet to Holley

I ran Q-jets for many years and won a lot of street races with them back in the day (30+ years ago). The Q-jet is a great carb, it just needs to be set up properly. IMO, I would keep the Q-jet and just get it tuned/rebuilt by someone who knows the carb.

Another great thing about a Q-jet is that when you go to race someone, they will typically want a quick look at your engine. Well, the Q-jet is a very innocent looking carb and is much less threatening than a 750 Holley double-pumper. I beat a lot of those Holley-equipped cars back then, LOL. I'm talking 30+ years ago, I know things are different now, but the Q-jet is still a great carb.


camsdad, that's a beautiful "after" pic.

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #10 of 18 (permalink) Old Dec 8th, 05, 09:08 AM
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Wes
 
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Re: Switch from Qjet to Holley

Agree with all the above,..the Q-Jet is the way to go for most anything up to 450 hp.

I have two Holley cars and two Q-Jet cars. I'm constantly tuning the Holley's,..if my Q-Jets could laugh at me, they would. On a Q-Jet, you simply get the right secondary rods and adjust the timing of the opening of the secondaries (both done without removing the carb) and you simply leave it alone. Much easier to tune than the Holley.

If you're going with a vac secondary carb which I'd advise on a smallish SB, there's no carb better than than the ol' Q-Jet. I've got one a healthy 454 Vette,..she loves it!
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post #11 of 18 (permalink) Old Jan 11th, 06, 07:57 PM Thread Starter
 
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Re: Switch from Qjet to Holley

Thanks for the lead in Qjet supplier. They only supply carbs with electric choke. I have the mechanical (intake spring) type. I am tempted to take this opportunity to try the electric. I guess it works better? But my big fear is will it fit under the cowl air cleaner assembly. It is pretty tight under there and want to make sure it will still work. Anybody confirm? Thx
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post #12 of 18 (permalink) Old Jan 11th, 06, 08:06 PM
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Re: Switch from Qjet to Holley

Sean Murphy Inductions sold me a Stage 2 Quadrajet custom tuned for my 383 and it performs flawlessly without any Lean Pop like my previous 750 Holly DP did. I am more than satisfied with the switch to the SMI Stage 2 Quadrajet and would have Sean build me a carb again and again. Sean Murphy use to be the main guru at Jet Performance before he went out on his own. His shop is literally about 1000 ft down the street from Jet Performance. (www.jetchip.com)

http://www.smicarburetor.com/product...9&productID=47

SMI Quadrajet Stage 2 with Edelbrock Performer RPM 6071 with Eastwood DiamondCoat Satin Finish

1969 Camaro - GM 2003 Electron Blue
Beck Racing 383 cu in 465HP Engine - Sean Murphy Inductions Stage 2 Quadrajet
TCI Streetfighter 350 - 3.73:1 Posi 10 Bolt Rear - 12.6 sec qtr mile

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Last edited by Brian Lewis; Jan 11th, 06 at 08:17 PM.
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post #13 of 18 (permalink) Old Jan 11th, 06, 08:15 PM
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Jim
 
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Re: Switch from Qjet to Holley

I had Holley 750 cfm on an Edelbrock when I bought my car, it always smelled rich of gas, stumbled at low rpm. Went back to cast iron intake and Qjet and she purrs like a kitten and goes like a banche. Get the Qjet tuned and enjoy it.

Click..is Jim..former owner of a 69RS-LM1 350/255 - 700r
"There will come a time when you believe everything is finished,
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post #14 of 18 (permalink) Old Jan 11th, 06, 08:19 PM
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Re: Switch from Qjet to Holley

camsdad,

I looked on the website, but did not see any pricing. What can somebody expect to pay to have them rebuild a q-jet. Is there that many varying factors that equate to a big cost variation.

Greg
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post #15 of 18 (permalink) Old Jan 11th, 06, 08:30 PM Thread Starter
 
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Re: Switch from Qjet to Holley

Thanks for the responses. You guys have convinced me to stay with a Qjet. That is why I contacted Sean. By the way, don't quote me but I think he said they cost $325, no core charge. But back to my question... will the electric choke fit under a stock cowl induction air cleaner assembly?
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