I was wondering what a holley/weber progressive 2-bbl carb does to the low end torque vs. a stock rochester 1-bbl. The engine I have is a 1962 235 out of a 1962 1/2 ton that has been rebuilt to stock specs. The truck is a 1954 4100 1-1/2 ton with a sm 420 with a 2-speed rear. I posted a thread a few weeks earlier about running split stock exhaust manifolds on the same application. I wanted to know if these would be wise to run in this application. I live at 4300 feet about sea level and will occasionally climb a 6% grade to elevations of 8600-9000 feet above sea level. I plan to have this truck loaded with my construction tools and may pull a trailer with equipment(i.e. skid steer loader, pickup truck, or tool trailer). I will eventually build a 261 to fit my needs in the future.
Stoveboltkid, My 1948 2 ton with a 235 has a 2 barrel Holley with fenton exhaust headers. I don't know the exact size of carb but it's the bigger size of 2 barrels. Regarding low end torque, there are a few instances (usually hard lugging in third gear) where the velocity of the air going through the carb isn't fast enough to draw in the fuel. Feathering the throttle back a little increases the velocity of air. But normal running through the gears, even heavily loaded, I don't have any problems.
My next carb will be a small four barrel. The primary's are smaller than the current 2 barrel I have now and that should take care of the air velocity issues.
If I remember correctly Tom Langdon told me that the H-W 2 bbl was rated at about 260-270 CFM FWIW. He also told me that running two of these could not be compared to a Holley 4 bbl @390 CFM because of the way the 4 barrels are rated using different parameters. He said it ran better milage than a one bbl but had the extra power of an additional carb available because it's progressive. Now how does that compare to the original Rochester? Sorry, I don't know.
But if I were only running one carb I would want it to be this one I think.
I adapted an Edelbrock 500 AFB 4BBL to my '53 Mack B20 with a 291 flathead six. The original Zenith 2BBL was really too far gone to fool with and I had the AFB on the shelf so I decided to try it. I figured it would be a pig, but was really surprised at how well it runs.
1950 GMC 350 COE powered by a GMC 702 Twin-Six V12 / 4L80E combo.
I love the H-Ws, running a pair on my 261, did have to go up in jet size a bit. Langdon's has linkage, adaptors, air cleaners etc. However I've seen the same adaptors used in Jeeps etc may be found on ebay?
I am running the Carter YF carb from a Ford 300 6 It is a 1953 chevy 235 babitt pounder. The motor will rev up to 4000 rpm under load tough little motor no oil pressure to speak of but runs cool I keep good oil in it. Not wanting to spend alot on this motor will replace with a 270 gmc when thats done but I feel like this motor is going to last a good long time. HEI smoothed out the rpms and starting ability when hot.
