Holley question

[Keith Tedford]

Eric, I am a big fan of the Quadrajet as well. Our '72 Lemans had a '70 455 with a 230 degree by .480 lift cam, headers, and a '69 Ram Air III Q'jet. That car was much smoother to drive than our L78 Chevelle, made considerably more power as well, and gas mileage was about 4 mpg better to boot. I plan on buying a wide band O2 sensor to better tune the carbs. Some people see fairly big gas mileage improvements, basically because the carb was so far off in the first place. Being retired now, I thought that I would have all kinds of time to play with this stuff. Not so. I don't know how I had time to go to work and get the stuff around home done too. A common lament. I'm keeping you in mind when I get the 4346 from our 427 restored. Our mild 350 el Camino has a 4010 Holley. Starting is excellent and it drives fine but gas mileage is not all that good. I'm afraid to take it apart because I don't know if I can even get a rebuild kit for it. At least it gets me down the road the way it is. I have a q'jet of the shelf that will probably get a rebuilt and a home under the hood.

[ORIGLS6]

I had heard the Q-jets were difficult to work with/rebuild, so I tried the Holley spread bore. Bad decision. Afterward, I rebuilt the QJ and reinstalled it on my Corvette. I've told many people since then that I'm evidently too stupid to know that I can't do something because it turned out fine. I've rebuilt a number of them over the years and always (knock wood) had success.

Smaller primaries for economy; HUGE secondaries for performance.
Limited tuning capabilities

But overall, I'll take a QJ over a Holley spread bore 10:1.

[Salvatore]

"Limited tuning capabilities " Not so Dennis. They have a lot of potential for performance. But the original style Holley is the easiest and most quickly rewarding for the street scene and any bracket classes you would run on the strip. A lot of class racing requires a Q-jet. That is when it gets a little tricky. Just call Eric!

[ORIGLS6]

OK, I'll give you that. Maybe I should have said "more difficult to tune when compared to the 4160 series Holleys",............... at least for me.

See you Friday?

[VintageMusclecar]

Dennis;

The QJet actually has a bigger window of tuning potential (for part throttle/street style use) than a Holley. Where people get into trouble with a QJet is when they take the same approach to installing/tuning one as they would a Holley, i.e. the "well, all Qjets are the same, so it should run fine" mindset. Problem is, neither the QJet nor Holleys are all created equal, and if the wrong carb is plopped down on the wrong engine...you know what happens next.

The fact that most Holley tuning is accomplished via jets, power valve, and squirter selection whereas the QJet has a much more sophisticated range of adjustments in as far as jets, metering rods, power piston springs, secondary air door tension spring, secondary air door vacuum break, etc. is where people start to get confused. It's actually very easy to get in over one's head when trying to tune and modify a QJet, which I am quite sure is the reason the QJet has earned such colorful euphamisms as nicknames over the years, such as "Quadrajunk", "Quadrabog", and a few others I can't repeat on a family-oriented forum.

If you're building a non-stock hotrod and want to use a QJet, starting with a compatible core will get you 90% of the way there more often than not. It's when you try to put on a QJet designed for a `67 California smog 327 on a hot 454 that you run into problems. (I actually encountered that exact scenario recently!) Had you started with a QJet off of...say...a early `70's 454 passenger car, or even a late `70's to mid-`80's 454 truck, you would've been much better off.

OK, I'm done blathering about carbs for now.

Eric

[427TJ]

[ QUOTE ]
OK, I'm done blathering about carbs for now.

Eric

[/ QUOTE ]

I find it fascinating. Beats the heck outta' the morning paper!

[ORIGLS6]

[ QUOTE ]
the QJet has a much more sophisticated range of adjustments in as far as jets, metering rods, power piston springs, secondary air door tension spring, secondary air door vacuum break, etc. is where people start to get confused. It's actually very easy to get in over one's head when trying to tune and modify a QJet.........

[/ QUOTE ]

Nuff said! I'll leave that to you guys.

[Keith Tedford]

Keep on blathering. Those of us who play with carbs a little are always interested in learning more.

[Salvatore]

[ QUOTE ]
OK, I'll give you that. Maybe I should have said "more difficult to tune when compared to the 4160 series Holleys",............... at least for me.

See you Friday?

[/ QUOTE ] Friday it is!