Great Planes Super Sportster (original) - Manual (Page 29)

Figure 2
AND
HAYES MOUNT
Now let's figure out how far back to move the firewall from the normal 2-cycle position. We have already
figured out for you the "A" distance of the Sportster 20 (3-5/16"), the Sportster 40 (3-3/4") and the Sportster
60 (4-1/8"). The chart also takes the spinner used into account. If you use a different spinner than mentioned,
just measure the backplate depth and add that distance to one of the above measurements, depending on
which model you are building.
Distance B
(length of your
4-cycle engine and
mount
SPORTSTER 20
B
B
B
SPORTSTER 40
B
B
B
SPORTSTER 60
B
B
B
Minus
—
—
,
—
—
—
—
Distance A
(length of 2-Cycle
engine/mount and spinner
back plate)
3-5/16" (CB Spinner)
3-5/32" (Dubro Spinner)
3-7/16" (Goldberg Spinner)
3-3/4" (CB Spinner)
3-29/32" (Dubro Spinner)
3-7/8" (Goldberg Spinner)
4-1/8" (CB Spinner)
4-9/32" (Dubro Spinner)
4-1/4" (Goldberg Spinner)
Equals
=
=
=
=
=
x
?
(Distance to
move firewall
back)
?
?
?
?
?
?
?
?
?
Chart 1
29