Advanced
Valve Train Technology For Kart & Jr. Dragster Racing
Gokart
parts and Jr. dragster parts for Briggs & Stratton™ racing
engines from
Go-Parts ™
If you have any questions concerning installation or proper use
of your new Go-Parts™ products, call us toll-free at 1-800-976-9376.
Cam cards and
application sheets are also available by calling Go-Parts™'
tech line toll-free at 1-800-976-9376.
IMPORTANT:
Take the time to make sure that your camshaft is
installed
and clearanced
properly.
The following
instructions are designed to help you properly measure your Go-Parts™
modified class camshaft. It is a necessity
for you to properly and accurately measure the camshaft as it is
installed in the engine to insure proper performance. All measurements
taken can be verified against Go-Parts™ cam card and application
sheet.
Go-Parts™
Complete Camshaft Degreeing Instructions For Briggs & Stratton™
5 HP Engines
"Degreeing
a cam" describes the process used to verify that a cam is installed
properly and aligned to the crankshaft as the engineers intended.
Several methods can be used to degree a camshaft, Go-Parts™
explains the "Intake Centerline Method" below. It's quick,
easy, and accurate.
Note:
Remember that your goal is a hi-performance racing engine, it is
in your best interest to follow these instructions. By not following
these simple steps, you may reduce horsepower, efficiency, and the
performance of your engine.
Note:
You can not degree a cam accurately without a
degree wheel
, a
dial indicator
, and a fixture to hold the dial indicator.
-
We
will assume at this point that you have installed your camshaft,
that the cam gear timing mark and the crank gear timing mark
are aligned, and that both valves are closed. (If the marks are aligned and a valve is open, you need
to remove the camshaft and rotate it 180 degrees)
-
Install
a dial indicator for checking the height of the intake valve
lift. (Always use a checking valve or
a new valve when degreeing a cam to insure the absence of valve
lash)
-
Rotate
the crankshaft to TDC (top dead center) and install a degree
wheel on the crankshaft. Then install the degree wheel pointer
aimed at the zero position of the degree wheel and also align
the zero position of the dial indicator to the indicator’s
needle as a reference point.
-
While
facing the flywheel side of the engine, rotate the crankshaft
clockwise until the dial indicator reads maximum lift and reset
the indicator to zero.
-
Rotate
the crankshaft counterclockwise until the dial indicator reads
0.100”
-
Rotate
the crankshaft clockwise until the indicator reads 0.050”.
-
Record
the degree wheel reading.
-
Rotate
the crankshaft further clockwise until the indicator rises to
maximum lift and back to 0.050”.
-
Record
the degree wheel reading.
-
Add
the two readings from the degree wheel and divide by 2 to find
the intake centerline for your setup.
Example: 156 + 46 = 202, 202/2 = 101
-
Compare
your intake centerline to the intake centerline listed on your
camshaft's spec sheet. (The numbers should
be the same although ½ degree either side is an acceptable variance
due to crank gear and various other engine tolerances)
-
If
the numbers do not match, there are a few possible reasons:
-
you
may be reading the degree wheel incorrectly, degree wheels
have the low number on the right and the high number on
the left. Re-check your degree wheel readings.
-
you
passed a specific point on the dial indicator and backup
up a bit. Doing so may introduce errors. You must start
over, do not pass a point and back up.
-
the
camshaft has been installed incorrectly, re-install the
camshaft and try again.
-
the
crankshaft gear’s manufacturing tolerances are at or
beyond high or low limits. Gears are available that have
multiple timing locations for making adjustment to correct
or modify the way a camshaft aligns with a crankshaft.
| STOCK
CLASSES ONLY
Make Sure Your Stock Class Camshaft Meets WKA/IKF Profile
Limits
Improper measurement
or installation in stock classes can result in disqualification
in post race tech inspections and may cause improper engine
performance. |
-
With
the degree wheel and dial indicator still in place,
rotate the crankshaft to TDC.
-
Rotate
the crankshaft clockwise until the dial indicator reads
0.050" lift and record the reading on the degree
wheel.
-
Continue
recording the degree wheel readings at 0.050" lift
increments until you reach maximum lift and record it's
reading.
-
Keep
rotating the crankshaft and record the readings at 0.050"
increments as the valve closes until it is back to 0.050"
of lift.
-
You
should now have a list similar to the following:
Example
Lift
0.050"
0.100"
0.150"
0.200"
0.233"
0.200"
0.150"
0.100"
0.050" |
Degrees
3 BTDC
12 ATDC
31 ATDC
56 ATDC
Maximum Lift
36BBDC
10 BBDC
10 ABDC
29ABDC |
|
Your
Readings
Lift
0.050"
0.100"
0.150"
0.200"
0.______"
0.200"
0.150"
0.100"
0.050" |
Degrees
______ BTDC
______ ATDC
______ ATDC
______ ATDC
Maximum Lift
______ BBDC
______ BBDC
______ ABDC
______ ABDC |
|
-
Perform
these steps for the exhaust valve as well as the intake
valve, then compare your readings with the ranges in
the WKA/IKF Tech Manual to reveal potential inconsistencies
and avoid disqualification.
|
-
Once
you have the correct intake centerline reading, you are finished
degreeing your camshaft and will want to set the
valve lash
.
-
If
you can't get the correct reading for your camshaft, call us
toll-free at 1-800-976-9376 for assistance.
|
