I would think the 2bbl is a little more simple than a 4bbl. The Motorcraft 2bbl is freakin awesome some models approach 400 CFM, and I learned from old school AMC Jeep guys that they can run upside down for a little bit. The Motorcraft 2bbl is one of the best carbs ever made. I can see why people would want a 2bbl in place of a 4bbl when the only choices are Holley, Edelbrock, and factory spreadbore carbs. I personally went with a Q-Jet, but it's probably more work to install than a Motorcraft 2bbl.
Aaahhh the Quadrajets.....I was told awhile back that such a carb might be a good one for me. Does anybody know the cfm ratings I should expect to have from a Q-jet say, off of a chebby 4.3 (they did put Q-Jets on those right?), or a 305, or maybe a 350?
Any QJ set up for small block engines up to 350 is fine. The overall cfm is mostly irrelevant since 95%+ running is going to be on the primaries and the secondaries should be adjusted to restrict opening at low engine speeds otherwise the bog monster rears it's ugly head.
You can make any quad good-as above mentioned. I had one on an old Buick 3.8L with the 4.1L 4-barrel intake. Had to rejet a bit- was jetted for a 307 Pontiac- and you REALLY have to tame the secondaries. Look for real lean secondary rods and leaner hangers and don't leave the spring adjustment loose. The 3.8L w/ a 350C turbo could average 26 mpg's hwy and had good bottom end. Some of the 2150's can be used on the 4.3L also. This is a good caburetor- esp. if the Quadrajet intimidates you.
Anyone w/ some carb background can do the 2150. For offroading, there's an extra spring on the float assembly which puts upwards pressure (a little) on the float so that the bowl stays about right. My ford 300 motor has a 2150 sideways on it. W/ the extra spring I've only been about 60 degrees w/ it w/o a sputter.
The quad, on my Dodge truck, also easily does this. Neither truck is for offroading though. These angles are from taking the kids to some remote swimming hole or collecting firewood.
Harte3 or anyone else with the knowledge, I have a question for you. Im new to carb'd engines and looking to get alittle more out of the 300. I found a quadrajet 4bbl with a 700cfm to go with my clifford intake. Is the 700 cfm to much?
Thanks for your help
Basically no...when properly adjusted. The only time it is too much is when opening the throttle like WOT and the secondaries are not properly adjusted...they open too soon and the bog monster appears. I myself like the spread bore concept. Small primaries for economy and driveability and the toilet-flusher secondaries for the Exxon contribution moments. Qjets appeared on smaller engines like V6's and sb V8's especially for marine applications so they do work on small cid engines like ours. If one can't find a Qjet in good shape at a reasonable price,
Holley currently makes a spread bore Qjet replacement...650 cfm with vacuum actuated secondaries that are adjustable with springs like any other Holley. IIRC the PN is 80555C and the model is either a 4165 or 4175. One of those models has mechanical actuated secondaries usually not recommended for the street but, IF (operative word is IF) one can educate their foot to the operation of the mechanical...like not too heavy too fast...it can work quite well too...IF...
As previously stated, the q-jet can be adjusted for about anything. I've personally used the Q-jet on an old Buick 3.8L motor and gotten good bottom end, respectable passing, and good fuel economy. You need to make sure the throttle shaft is bushed- or at least- not leaking. If it's after '74 or so, don't worry about the secondary wells. The secondaries will need to leaned (w/ rods AND hangers) but alot is done w/ an allen and tweeker.
Also, DO NOT use the phenolic float- brass ones are $8.00 and will not saturate with all the crap they're putting into gas as "experiments". If you are using the fuel pump off the engine, get a pressure regulator -$18.00 at Checkers, and put the pressure at 3. The rebuild specs for the float are a bit high. You should be able to set the float 2 or 3 16ths LOWER. Not knowing what altitude you're at, I cannot recommend a power spring.
If you've got the Quad, I'm really interested w/ how it acts on a 300. I intend to do the same thing this Spring. Seriously, PM me if you have questions of setting it up- they are easy once you can take the top cover and gasket on and off.
Has anyone tried a Weber 32/36 DGAV/DGEV progressive 2bbl on a 300? A Holley version (5200, IIRC) of this Weber came standard on Pintos and the like, and the Formula Ford racers, using the 1600 Ford "Kent" engine (old Ford Fiestas and such) have used these carbs for decades. It's a nice piece, too small for a performance engine, but it draws about 320 cfm at 3.0"Hg, and for a stock-cam 300 truck installation that's never going to be revved very high, it ought to have excellent throttle response. Ideas??