GZMS Vacuum Pump Technical Notes
- GZMS vacuum pumps are
designed to have oil pass thru them, and require oil for lubrication of the
wipers at the vanes. Experience has shown that synthetic oil yields a longer
pump life. A dry pump will wear out prematurely due to friction between the
Rulon wipers and the carbon fiber vanes. GZMS vacuum pumps are warranted for
one year with proper use. If a pump is returned that has been run dry, any
warranty is void.
- GZMS products are
installed and used by others, no warranty is made as to use of products as
regards performance or safety. Motorsports are inherently dangerous, the user
of GZMS products assumes all potential or real risk of using those
products.
- GZMS vacuum pumps should
be run with a pulley ratio of .5 to .75 (small crank pulley, large pump
pulley) with a maximum pump rpm of 6000. GZMS Sportsman vacuum pumps are
successfully run at higher RPMs, however, this is not recommended. GZMS
manufactures a street option for our vacuum pump kits.
- Net vacuum in a wet sump
drag race engine should not exceed 15" hg max at maximum rpm. Many engine
builders recommend 10" to 12". Dry sump engines can be run at 20" hg or more
net. Check vacuum on the dyno or at the track. Install a vacuum control valve
if you exceed recommended vacuum level.
- GZMS pumps are
manufactured in our shop. After assembly each pump is tested on our pump dyno
at 3500 rpm (sportsman pumps), 2500 rpm Pro pumps and 1900 rpm Super Pro
pumps. During testing Red Line racing oil is run thru them so when you get
your pump you will see "blackened" oil at the inlet and outlet ports. This is
normal and due to break in process. GZMS vacuum pumps all show the test
vacuum and date tested on the part sticker on the pump. This is the test
value at the test rpm noted above.
- The vacuum your engine
will make is dependent on the amount of blow by it generates and any air
leaks it may have. No two engines are identical.
- Trouble shooting: No or
low vacuum? Check for leaks, pressurize the engine and listen. Engine must be
TOTALLY SEALED. Check pump by removing hose from engine and running at up to
5000 rpm. Check for suction Hook a vacuum gage hook it up directly to the
inlet of the pump and check test rpm. If it measures 4" or more less than
test value, the pump may need refurbishing. Check for Belt Slip. Check the
VCV. Inspect inlet hose for pinching closed.
- Low oil pressure can be
caused by inadequate oil return holes to the pan. This causes higher vacuum
in the upper part of the engine than in the pan, which will reduce oil
pressure as oil is "pushed" by the pressure differential. Oil held up in the
upper portion of the engine due to small oil returns will cause oil
starvation. Solve this by adding an air line from valve cover to lower
portion of engine.
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