GZMS Vacuum Pump Technical Notes

1. 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.


2. 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.


3. 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.


4. 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.


5. 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.


6. 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.


7. 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.


8. 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.