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What carb set up will work on the stock intake manifold of a 1955 GMC 248 ?
I plan to do the dual exhaust with the stock exhaust manifold reworked by Kansas Kustoms ,and would like a little more power.

Anyone done this or have any ideas to beef up the stock manifold setup. thanks Bill

About the only upgrade is to go to the two-bbl. Holley-Weber. You have to get an adapter to mount it, and you also need a different air cleaner. Tom Langdon sells them.
http://www.stoveboltengineco.com

The single Holley Weber 2bbl is relatively inexpensive and easy, a few guys I know who did it, including Tom Langdon, reported increased full throttle power and improved fuel mileage, but a reduction in part throttle power due to the carb's small primary throttle barrel.This may not be true in every situation, and some may not mind the trade off.
Carbs on adapters are a crompromise at best.I used an adapter to install a Rochester 2GC V-8 carb on a 261 Chevy 6.The engine was stronger at part throttle, but not full throttle,re jetting made no difference.I suspect the adapter necking down to the one barrel carb opening was messing up the air flow.
So I took a spare stock intake manifold,cut out the area around the single carb opening, made a mounting plate to accept a 2bbl carb.I used a Holley 2300 of around 220 cfm cause their readily available and easy to tune.Now this worked real nice, improved part throttle response,better top end power and better fuel mileage.I'm over simplifing the modification,but it was done with common hand tools , not all that difficult, and others have done it using all sorts of carbs.
Holley 2300 on stock 261 intake
Years ago, racers used to flip the stock intake upside down,cut out the bottom,braze or weld on a plate to accept a four barrel carb.The carb was tilted at a little funy, but it was ok for circle racing.You can also block off the stock carb opening, and weld on two mounting plates , turn the stock mani into a 2 carb set up for cheap money.
This is the fun of these old inline engines, making your own speed equipment like hot rodders did 50 years ago.

The 248 would have originally had some form of Zenith. As Zenith used the same physical size for different internal sizes (CFM ratings); it may be possible to find a Zenith that will fit the original intake with a larger venturi. Zenith 28 size 11 carbs can be had with CFM ratings from about 170 to 220, depending on which venturi is used.

Jon.

Jon,wasn't it the Zenith's that had interchangable ventuis?Or was it Strombergs?
The one main advantage of the Holley 4150's and 2300's is the readily available and inexpensive parts such as jets and gaskets, you can find them anywhere, as well as the carbs themselves are a dime a dozen just like small block Chevy V-8's.

Tony - some of the Zenith designs do feature removable venturi. Stromberg also had some designs with removable venturi as did Carter.

Jon.

Would a 70's 2.8 v6 F@#$ be a good donor? Much of a fight with the linkage?

carbking
the 248 has a zinith with the numbers on it
round tag # 2343632 11965
near base # 174 16B
near top ER4- P3
the 270 has a zenith with numbers
round tag 2194115 1148
near base # 174 1B
near top ER 4-22
248 bolts on front & Back 270 bolts left & right
I think they are 1 barrell wich would be best ? thanks Bill

I am using a Holley / Weber 5200 mounted sideways on one of Langdons adapters. Mounting it sideways with the linkage toward the valve cover made the linkage set up brain-dead-simple. If you set one on that way you'll see what I mean.

I made an air cleaner out of the stock filter and two circa 1980 hubcaps. It turned out really nice. You just trim some of the depth away from each one and drill a hole in the center of the one you want to use for the top, and cut your oval shaped hole in the bottom piece. Take some pieces of 1/4 by 1" flat bar and some 1/4 x 20 x 3" bolts and make a bracket.

At present it has a 132 primary jet and a 140 on the secondary. I have better low end and top end performance as well as a small improvement in mpg. It bogs a little if you jump on it hard at very low speed, but other than that it works great. I have not tried to really fine tune it, because I am gettin ready to rebuild this engine. I may do some mods to eliminate the adapter when I do my rebuild.

I really think that on a stock - mild inline 250 or smaller the Holley/Weber is a very good choice.

Bob

55GMC - you have the numbers reversed. The 11148 is for a 248. The 11965 is for a 270 and is the larger carburetor. The 11965 flows approximately 6 percent more than the 11148.

Jon

CARBKING
Both carbs and intakes are off motors(numbers reversed yea this isn't my first mistake)
the 248 intake manifold #2194002 has 1 & 1/2 " intake carb bolts front & back
the 270 intake mainifold #2194817 has 1 & 5/8 intake carb bolts left & right.
looks like both intakes will bolt on may do as FLEETSIDE try a holley/webber??may not need adapters with 270 intake will see as motor goes back together. thanks Bill