General Category > Quadrajet Carb Talk and Tips
Float level and other Qs
Cliff Ruggles:
Warping isn't really a big deal provided that you have a good fit between the parts.
I checked our books back in January and we had 12,900 work orders since going full time here in 2003. That's how many carburetors have been thru our shop, but all were not full rebuilds, some will have been here just for bottom plug repairs, correcting issues with them, coloring/plating work, etc.
It is rare to find one that doesn't show some warping across the front due to tightening of the long bolts to the intake. We simply make sure the fit between the parts is good. In 99 percent of the cases where it wasn't we correct it my running the front of the airhorn across a bench mounted belt sander for a few seconds. We then check the fit and continue this process until the top is slightly flatter than the main body.
We also use much better gaskets that are .015" thicker and good to go. I actually have one of the good unwarping tools and have used it a few times on carbs that were excessively warped. It will pull the main casting back as well as flatten the airhorn.
I still don't see a little warping as a problem and it woln't be provided the builder take the steps needed to make sure the fit between the parts is good and the gasket used is effectively sealing things up.
As far as the Quadrajet having a bad reputation it is well deserved for the early models as they are pretty much HOPELESS for high performance work. The early plunger inlet valve models (1965-66 and some early 67's) are difficult if not impossible to use for high HP applications.
Even the improved versions thru 1968 and any later variety with the early hinge pin location have limitations when it comes to using them on engines making big power in really fast cars.
By 1969 they had sorted out the issues with the early units which included moving the hinge pin location to provide superior leverage for a smaller float on the N/S assembly. They also added POE for the secondaries and got rid of the weighted air door design and used the pull-off to keep the flaps from whipping open too quickly going to full throttle.
They also had the idle bypass system in place by 1969 which is far superior to drilling the throttle plates for big camshafts.
Even with all the improvements folks had been removing factory Q-jets and tossing them aside for aftermarket carburetors thinking they were improving engine performance when in most cases they were not......Cliff
Cliff Ruggles:
Seldom mentioned in conjunction with this topic are how many excellent factory intake manifolds hit the scrap pile in favor of aftermarket aluminum ones. Just like the excellent factory carburetors the engineers spent a lot of time with intake manifolds to make sure they provided the best power production over the engines potential RPM range, good idle/off idle characteristics, and efficiency in the "normal" driving range.
Sure you'll read all sorts of advertising about ditching the stock intake for something better that will make more power, but about all that happens in 90 percent of these scenarios is that you remove some weight from the front of the car and kill off some low end power while shifting power to higher rpms where the engine doesn't spend much time.
I get a LOT of attention if/when I take my car to our local track and make a few runs with it. Last time I went there on a Friday night "test and tune" it was really hot/humid. In full street trim on DOT's I ran low 7's at 96mph and never even cooled the engine down. Yep, drove it right off the street, dropped the air pressure in the rear tires to 18psi and started making runs. I made 5 runs about 20 minutes apart all in the 7.18-7.24 second range (1/8th mile), aired the tires back up and drove the car home. In staging folks were coming by to check out the combination since I was running WAY quicker than the street cars in attendance and faster than a good percentage of the full race cars that were there.
The look on their faces when they spotted the factory intake and Q-jet sitting on it......PRICELESS!.......Cliff
Macadoo:
Thanks for the info and great stories, Cliff. I've read through these posts a few times. The wife and I just got home from a 3 day weekend at Route 66 Dragway so your last anecdote really hit home. There was a car show in conjunction with the races and, yet again, I had to defend the quadrajet (even though I'm still working on mine and have the Holley on the motor). Of course now everyone is all about EFI. Which would be great if I could afford it, I suppose.
I've hand-milled the base plate and main body so that all three parts fit pretty darn close. I can't feel any movement with the gaskets in place. I'v gotten the circuitry and idle tubes tuned to the recipe #2 specs and will start assembly soon. For right now I'm using parts I had laying around or gleaned from the other carbs because I want to see if I have any air leaks before ordering jets and rods. The gaskets (for this particular carb) are in fine shape but I'll probably replace anyway. I've installed 49B rods and #77 jets (a bit rich for recipe #2, I think) along with a G-hanger ans either the short tip CS rods or the long tip CV rods. Again, just until I know the carb isn't going to leak air.
It was a good weekend at the races and we brought home 2nd place for the GM A-body category. I haven't won an award in years so that was a nice surprise. :)
Macadoo:
Oh, and yes, I scrapped the stock EGR intake for an aluminum Edelbrock. Rookie mistake, maybe, but I don't think my back could manage a cast iron anymore, lol.
Macadoo:
Hey Cliff, based on my engine/cam specs, which power piston spring should I try first? I have all these parts from last summer, when I just started to look into all of this (but before I bought your book). I've never been able to get it to idle good enough to get a decent vacuum reading.
Cam: .512 in and out, 227/233 @ .050, 110 LSA
CR about 9.8:1
Dual 2.5" exahaust
Cast iron Heads ported and polished
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