October 24, 1961
Bulletin No. SB-876
Carburetors
SUBJECT: High speed nozzle - float chamber to venturi.
40 h.p. RD(L) thru RDS(L)-23, (1961).
Figure 1 illustrates the difference between the high speed
nozzle used in the subject engines, #307166, with the new one,
#308956, used in carburetors on the 1962 - 40 h.p. engines.
The only difference between the two nozzles is an increased
length of one quarter inch (1/4") for the new nozzle.
Although designed for the 1962 - 40 h.p. engines, the new
nozzle can also be used on those 1961 engines which do not
develop the recommended full throttle rpm even though com-
pression is satisfactory, and the magneto, spark plugs and
carburetor are properly adjusted and function correctly.
Where these conditions exist on the subject engines, and
provided also the rpm loss is not caused by, (1) excessive
carbon and/or petroleum gum, (2) an incorrectly propellered
engine, (3) induction system leaks, etc., installation of
the new nozzle will correct this rpm deficiency.
While nozzle 308956 can be used in 1961 - 40 h.p. engines under
the aforementioned conditions, it does not supersede nozzle
307166. Neither should it be installed until such time it has been definitely determined
that full throttle rpm loss is not the result of some other malfunction such as those
listed in the preceding paragraph. Before installing the new nozzle, be certain that
condenser #580422 has been installed, (refer to Service Bulletin #SB-861, subject (a).
If, after having checked these and other possible
causes, low full throttle rpm continues to be a
problem, install nozzle 308956. Installation is a
relatively simple operation.
1. Remove the float bowl from the carburetor.
2. Unscrew high speed nozzle 307166 indicated
by the arrow in figure 2.
3. Replace with the new nozzle, #308956.
4. Reassemble float bowl using a new bowl gasket.
JOHNSON MOTORS
W. W. DeWees
W. W. DeWees
Service Department
WWD:eb
NOTE: Post on your RD (40 h.p.) index.