GAS ADAPTERS (COMBINATION GAS
GASOLINE)
E n g i n e s having s t a n d a r d g a s o l i n e c a r b u r e t o r s a r e m o d i f i e d t o a l s o u s e g a s e o u s f u e l s t h r u the
a d d i t i o n of a g a s a d a p t e r p l u s -t h e n e c e s s a r y g a s p r e s s u r e r e g u l a t o r y e q u i p m e n t . The g a s a d a p t e r i s
i n s t a l l e d on
a i r i n t a k e s i d e of the c a r b u r e t o r . The a d a p t e r c o n s i s t s of a
a n d g a s j e t -
a r r a n g e m e n t with a n e x t e r n a l m a i n f u e l ( l o a d ) a d j u s t m e n t a n d u s u a l l y a n i d l e f u e l a d j u s t m e n t . S e e
F i g u r e 12- 2
a n d F i g u r e
f o r i n i t i a l s e t t i n g s . The c o m b i n a t i o n s y s t e m m u s t a l s o
include f u e l shut- off v a l v e s in both g a s a n d g a s o l i n e l i n e s t o f a c i l i t a t e switching f r o m one fuel t o the
o t h e r .
G a s O p e r a t i o n : B e f o r e switching f r o m g a s o l i n e t o g a s , d i s c o n n e c t t h e a u t o m a t i c choke l e a d w i r e o n
e n g i n e s equipped with e l e c t r i c choke. T a p e end of l e a d w i r e t o p r e v e n t grounding t h e n p r o c e e d a s
follows:
1.
C l o s e g a s o l i n e shut- off valve ( u s u a l l y l o c a t e d o n f u e l f i l t e r ) . Open g a s valve in g a s f u e l
l i n e .
2.
D e p r e s s g a s p r i m e r (if s o e q u i p p e d ) then s t a r t e n g i n e . Use Step
3
if f i n a l a d j u s t m e n t s a r e
n e e d e d .
Allow engine t o w a r m up t o n o r m a l operating t e m p e r a t u r e s . Move t h r o t t l e c o n t r o l t o
n o r m a l o p e r a t i n g s p e e d a n d
engine u n d e r l o a d . L o o s e n locknut t h e n move load a d j u s t -
m e n t i n u n t i l engine. s t a r t s t o slow down f r o m l e a n m i x t u r e then b a c k out on a d j u s t m e n t p a s t
the p o i n t w h e r e engine s p e e d p i c k s up then s l o w s down a g a i n f r o m
m i x t u r e - - l o c k
a d j u s t m e n t a t point halfway b e t w e e n
a n d l e a n s e t t i n g s .
engine r u n s u n s t e a d y a t
no l o a d , i d l e s p e e d s , m o v e idle a d j u s t m e n t s c r e w i n o r out t o a t t a i n s m o o t h e s t idle.
Gasoline O p e r a t i o n : R e c o n n e c t e l e c t r i c choke l e a d (when u s e d ) t h e n s h u t off g a s valve and open g a s o -
l i n e valve. If e n g i n e i s s o equipped,
g a s o l i n e s y s t e m with p r i m i n g l e v e r on f u e l pump. S e e
Gasoline C a r b u r e t o r i n Section
4
if a d j u s t m e n t i s needed.