July 26, 2002
This is the set-up as of today
WAY TOO MUCH carburetion
per Jere Jobe.
September 18, 2002
The two '94" carbs on "Souper" as of today are WAY too much for the Model "A's" 200 cubic inches. In fact, the engine runs much better with one carb. I proved it by simply removing one of them and covering up the resulting hole with a piece of plywood.
But, I really want the "look" of a two carb set-up. So for the time being I simply blocked off one of the fuel lines and put piece of sheet metal between the carb and the manifold. (Don't tell anybody.) Now, I'm searching for a pair of "81's" -- the carb used by Ford on its V8-60.
November 11, 2002 - TOP SECRET!
In October I had great fun running Souper in the Newport IN Hill Climb. (Having fun is much more important than proper fuel/air ratios!)
On Saturday morning the car laid rubber off the line and again in second. But then half way up the hill, the engine almost STOPPED! On my second try, I was not quite as aggressive on the throttle, but experienced the same result.
Local experts said it was because of my near-empty fuel tank. So Sunday morning I filled the tank and tried again. Same result.
They start the "official" runs about noon on Sunday, so I figured I'd just park the car and take some pictures. "Where is your car?" asked the officials and they insisted I run again. The car is loud, fun to watch and participants get a nice lapel pin ONLY when they show up at the starting line, so I ran again -- with no better results. I was having fun -- but my elapsed time was embarrising.
On the drive back to St. Louis, I thought about the problem and decided I needed a fuel pump. So I bought one -- a 6 volt in-line model offered by Brattons.
But then I thought some more. I've seen Model "A" powered Pietenpol airplanes fly for hours at high power output levels never required by a car. Piets have gravity-feed fuel systems. Most run Model "B" carburetors. How come they don't have fuel supply problems? They burn more fuel per hour than any Model "A" engine in a car.
My guess is because later Ford carbs were designed to operate with a fuel pump, the orifices in the float bowl valves were made smaller than the "A" carbs. In fact Jere Jobes clearly shows this in his carburetor article (page 88) in Tex Smith's V-8 book (using a drawing copied from a Ford Service Manual.)
He shows the largest diameter to be .129" and the smallest, (the most common) to be .098".
I have a Model "B" carb; its valve orifice is .0875".
Could fuel flow is restricted by these smaller valves in the later carburetors?
If you drill out a valve's passage, you'll mess up the valve seat. A drilled hole will not be round and the valve will leak. So the hole has to be enlarged with a reamer. Thanks to a machinist friend, I now have an 81 with its float bowl valve reamed out to .125".
When we get the rest of the 81 rebuilt, we'll try it on Souper and report back here.
Click to continue.
Grant MacLaren Terry Oberer