It’s true that many of the Racing Chiefs seem to have been changed over to a single carb and stock manifold arrangement, but as you mentioned in your document, this was done mainly to make the motor more user-friendly.
I do not believe there was any reason for Lockwood to install a single carb on a 92BR at the factory. The dual carbs would have been what the racers wanted in order to achieve best performance.
The racers would have had the dual carbs with air horns and progressive sliding linkage, as well as a special angled adapter at the base of the tiller arm mount in order to allow the tiller arm to be canted at an angle so as to clear the port-side carburetor/air horn assembly. The Service Chief used a two-blade prop that was 9 inch X 14 pitch, where-as the racers used a 9 X 15 or 16 pitch. The Lockwood Ace and Chief props have the diameter and pitch stamped on the hub, check yours to see which one it has. Probably 9 X 14, it’s the most common one.
Racers also had aluminum rods from the factory. You can check yours by pulling the intake and carb off and looking in through the ports. If its still got aluminum rods in it, and the crankcase isn’t welded anywhere, consider yourself blessed, but I don’t recommend that it be run it that way. It yours has bronze rods, it’s been modified by more than just changing the carb and intake… and that modification is considered an upgrade, the bronze rods are stronger. It is common to find a Racing Chief with a welded crankcase and bronze rods installed. The aluminum ones didn’t stand up too well, and when they came apart, well let’s just say it didn’t make a pleasant sound and didn’t paint a pretty picture…..
Oilers – it seems that some 92Br’s have shown up with Lunkenheimer No 2 Figure 1300 oilers installed….. but I think to be 100% correct, it needs to have Michigan Lubricator oilers on it that are identified with the number X48A4 stamped on the outer rim. I have one of those oilers on my 92BR, still looking for the other, they are every bit as rare as sensible Presidential candidates on Super Tuesday…
92Br’s used the Ace magneto and flywheel, it is smaller in diameter and lighter in weight than the service flywheels. I think the only other difference between the racers and the service motor, aside from the obvious cylindrical gas tank that only got installed on the 92BR, would be the size of bearing in the crankcase, and the crankshaft was drilled different to get more oil into critical spots.
Hope this helps.
Best,
T2
.
