Vacuum Pump Setup

Vacuum Pump Setup

If your MADCAP RACE ENGINE is equipped with a Vacuum Pump please read this entire sheet!

Install a vacuum gauge on your engine. Remove the 1/8-inch pipe plug located on the back of your valve cover. Then screw in the appropriate fitting that allows you to use your vacuum gauge.
If you are working on a brand new engine or one you just got back from MADCAP for a freshen, MAKE SURE YOU HAVE ADDED OIL. Start your engine and check the timing, make sure all cylinders are firing. Take a vacuum reading from your gauge.

On your Post-Dyno inspection report that came with your engine you will see the max vacuum setting. We have tried to set your pump to the proper setting. When altitude changes so can your vacuum reading. We recommend your vacuum gauge be located where the driver can safely monitor during a run down the track. Engine Vacuum is a great way to monitor how your engine is performing.

If vacuum is not within specs on your sheet, you can adjust by following these simple instructions. Or Call us. 1-800-349-8590

Unscrew the cap on the Vacuum Regulator located on your Intake Manifold, in front of the distributor. BE very careful, this may be warm and there are some small parts involved. After removing the cap, remove spring and plunger. To INCREASE Vacuum add a small washer under the spring assembly. To LOWER vacuum remove a small washer from under spring assembly. Screw cap back on valve, make sure O-ring is in good shape and clean. DO NOT OVER TIGHTEN.

You may find your engine runs better with more vacuum. Be VERY CAREFUL. If you run more vacuum than the max we recommend SEVERE INTERNAL DAMAGE may occur.

You are looking for your gauge to increase as you run or to reach a reading and stay steady.

During a run; if you notice the pressure decrease slightly as RPM increases or if you see a Rapid Spike in your reading this is a sign of Detonation. (This is bad) Retard your timing before making any more runs.

If your vacuum suddenly drops and does not recover this may mean a pump, pulley or belt failure or a massive air leak due to a blown seal or gasket. In some cases this may also indicate internal engine damage. The first thing to do is check for an air leak. Remove your gauge line; then cap the hose that goes from your pump to your breather tank. Blow compressed air into the fitting where you removed your vacuum gauge. BE VERY CAREFUL. DO NOT blow too much air; it takes very little pressure to check for leaks. After putting air into the valve cover plug the fitting with your finger and LISTEN for any air leaks. Get some help so you have people on the bottom (oil pan) and both sides of your engine. Any air leak at all can make a BIG difference. The most common place is valve cover gaskets. Repair air leak if you find one and then re-start your engine and check gauge reading.

If you hear no vacuum leak then you must remove the spark plugs and perform a leak down test on your engine.