I have decided to give up on the Winfield M-C and to try a Carter BB1 on my speedster. The engine has a crossflow Rajo head with the two large 1.7 inch ports, a Model A crank and pressure oiling to the mains and rods. The engine had two of these BB1s with no balance tube when I bought it and it seemed to run pretty good, but that was a short test drive long ago. I want to run just one. I built a new intake manifold for it and reworked the linkage. It seems to run well in the garage, but with load on a test drive it acts like its too lean. Pulling the choke out part way makes it run better. I've concluded that I need to adjust the main jets. Some of them had adjustable jets, but the ones I have don't. Does anyone have a suggestion on how to get this thing to run? I've been told it is not easy to convert it to adjustable jets. I assume new jets are not easy to find. I could drill out the jets I have. That will take some experimentation, since it can't be undone once they are drilled out. I had planned to take it up to Lincoln this week, but that may not happen.
Larry, I can't help specifically with tuning the BB1 but here is some BB1 information from an old Carter Carburetor book that you might find handy. If you can't read it on the forum, pm me with your e-mail address and I'll be glad to e-mail copies of the 4 pages to you to you.
I've read stuff on the net. This is the replacement type with adjustable jets. Doesn't help.
Larry there are several different sizes of BB1's. If the car came with two it is likely that they put in small jets. I have a BBR that runs on a 1.5 BB1 and it is not lean. We have 8.5 to one compression and a counterbalanced full pressure crank, a Joe Gemsa big stuffer cam and ross pistons with Miller tubular rods. Simply get smaller jets.
I've never worked on a BB-1 since they are not brass but I can't imagine it is too hard to make an adjustable jet for it. The main jet is going to screw in from the outside one way or another. It will have a cap for the hole the jet screws in to. I would drill the jet to 3/32nd, drill and tap the passage cap for 1/8 pipe thread, get a 1/8 brass compression fitting with the #8 hole for 3/32nd copper, tap it for #8 thread, put a point on a piece of 5/32nd brass and thread it so it will screw in and out of the fitting. Put a couple 0 rings on the threaded rod, put a knob of the end of it and put it on the carb. That's how I make the adjustable jets for the Zenith HP4S & A series and the HP5A's. Works great.
A couple of thoughts about the bb-1's.
First the fixed jet models were supplied to oe cars and trucks such as the coe Chev and Dodge trucks.
The adjustable jet models were aftermarket replacement models. The next thing you need to know is the size of the inlet fitting. There were 2 sizes. The smaller of the 2 was for a fuel delivery system with a manual pump. The larger jet was for gravity feed systems.
There were other differences such as venture sizes, mounting bolt spacing. There were both cast iron bowls and die cast bowls. The later is a much better carb no rust issues and fuel flows better through these.
I have some 40 bb-1's and I think 19 different configurations