Drag Racing Online - Project 4-Link pg.2 Vol. IV Issue 11 November 2002

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Here is a nice view of the one-inch drive spindle. This is a Barry Grant unit, but all of them are similar. They usually attach with a longer harmonic balancer bolt and have an 1/8-inch keyway to secure the pulleys. Note the MSD crank trigger wheel clears everything.

I already have the standard 1-inch drive spindle mounted to the crank snout so I will be using pulleys from Moroso that are designed to be slid over the 1-inch spindle and retained with the 1/8-inch keyway. If you have a regular harmonic balancer with pulleys bolted on, Moroso has several sizes and styles available for almost every type of engine. In my case we will use the 4-inch V-belt pulley part #23523. If you have a high RPM engine (over 8200 RPM) you probably should use the 2.5-inch pulley (part #23520), as this will slow the pump down a little bit.

We have opted for the new Relief Valve, part #22639, that goes into a valve cover as well. This will prevent creating too much vacuum. In some cases excess vacuum, over 15", can cause excessive wrist pin wear and exhaust guide wear because the oil is actually pulled off these surfaces. The relief valve is the best way to prevent that problem.

On Project 4-Link the only problem I encountered was having to relocate the alternator mounting plate about a half-inch to the rear to make room for the vacuum pump pulley. The complete installation only took three hours and all I have left to do is put the fittings in the valve covers. That should be easy as the holes are already there and all I need to do is use a #12AN bulkhead fitting in the valve cover and assemble some hose from there to the inlet port on the pump and run a 12AN hose from the outlet port to the Moroso breather tank, part #68811. This tank I will mount where draining it will be convenient. On my friend's carbureted alcohol dragster he can drain about half a cup of moisture after the first warmup and about a cup of liquid after a day of racing.

Maintenance to the Moroso pump is simple and should be performed on a regular basis. As with most performance parts you will get the best results if you take care of the equipment as the manufacturer suggests.

The Moroso 3-Vane Racing Vacuump Pump (part # 2264)) with the 5-inch V-belt pulley attached.

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