Looking for thoughts on use of the bigger Autolite 1.21 venturi carb on a mildly warmed over 292.  They are rated at 350 cfm, and were used on the 351 Fords in Mercury and Mustang.  I have been using a 1.14 venturi with 52 or 53 jets the past year and like it.  It has something like a 300 cfm rating. 

IF the smaller displacement Y was overpowered by the 1.21, what would be some of the symptoms?  Past readings of Autolite gurus indicate the Ford carburetors were model specific in application.  Since the carbs arent very tunable,  getting too far away from original application in terms of vehicle weight, transmission, engine, etc. leads to trouble.  But like I said the 1.14 has worked great in an engine which originally came with a little 1.02.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

The most noticeable symptom of too much carburetor is a flat spot during acceleration which is unacceptable to most people. You don't have enough velocity to suck fuel out of your fuel bowl. It doesn't take much between good and not good. Whenever I am pleased with how a component functions, I leave it alone.

Kenneth

Fredricksburg, Texas

I've ran several Autolite's over the years. Both 2100's & 4100's.



On the tired 292, I tried the 1.21 you are talking about. Ran incredible above 2500 to the flatline of 4000 back then. Hell, I think it actually would hit 42-4300 before I'd shift it!



The problems I ran into were that if I drove it real conservatively, like when I was trying to pin down maximum fuel economy over an entire fuel tank it would end up lean fouling several of the plugs. I did end up somewhere around the 52, - 54 jet range for that combo @ 6000ft. Ended up switching back to the 1.14 that was a reman that I removed the goofy "velocity tang" (my made up name for the funny shaped tin piece that sits above the booster when they were trying to use a larger casting on a smaller application.) I also took emory cloth & polished the venturi, cut off one side of the throttle shaft around the blades(like a holley/demon), ground a slimmer flat on the remaining side that houses the threads, & used a draw file to shape the air horn to be just the height & profile of a closed choke blade. After playing with different power valves this performed better than the larger 2bbl did since it was better on the bottom/lower middle.



venturi

Thankyou guys, helpful info as always.  After I redo this 1.21, will try it out for curiosity but it sounds like it wont stay on long.

'63, the mods you did to the 1.14 are very interesting.  I have a 1.08 I've been playing with.  So far the choke linkage, plate and shaft have been removed.  Your cutting down the air horn and polishing sounds like a next step.  It has surprisingly small jets, 47s, and came from an early 70's truck with SBF.  The 1.02 has 46s.  The objective is to get it to perform equal to the 1.14 and have better mileage at the same time.  For the record, the altitude here is 1300 to 1600 feet unless driving through mountain passes.  I assume you used Holley power valves since the Autolites seem to come in One Size Fits All.  What PV was the best choice for your application?  Any trouble with the Holley PVs dumping too much gas?

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.