Project Car Tips and Tricks

The Holley conversion kit...        read full caption The Holley conversion kit comes with a metering block, gaskets, seals, a longer fuel transfer tube, and longer bowl screws.

The first step is to drain...        read full caption The first step is to drain the fuel from the secondary float by pulling one of the lower bowl screws. Next, remove the remaining three screws and yank the secondary bowl. The gaskets like to stick, so we use a stiff gasket scraper and a small hammer to leverage between the float bowl and the main body. Also pull the fuel transfer tube.

Holley Metering Block Conversion
All Holley carbs are not created equal. Holley's more affordable line is referred to as 4160-style carbs that come with a metering plate in the secondary side. These carbs are easily identified by the lack of a thick metering block between the secondary float bowl and the main body of the carburetor. The advantage of a metering block in the secondary side is that these blocks allow easy metering changes with changeable jets. Holley makes a simple 4160 to 4150 conversion kit for most any 4160 model 600-cfm carb and even for the budget 4160 version 3310 and 0-80508S 750-cfm carbs. Because of the large number of carburetors these kits cover, they do not come with main jets. This means you'll have to do some research first to find out what main jet you need. You can do this by looking up your carb number in the Holley catalog and referencing the metering block number. The catalog will also convert that number into a main jet. Our 600-cfm Holley required a pair of 70 main jets.

The secondary metering plate...        read full caption The secondary metering plate is attached with special clutch head screws. If you don't have a clutch head screwdriver, you can make a reasonable facsimile by grinding down the end of an old screwdriver until it fits inside the clutch head fitting. Remove the metering plate and the gasket. Scrape any torn gasket material.

Screw the new jets (ours were...        read full caption Screw the new jets (ours were No. 70) in the metering block and then place the new gasket and metering block on the carb main body, along with a new bowl gasket on the pins on the bowl side of the metering block. Put a small amount of petroleum grease on both ends of the new fuel transfer tube, install the tube seals, and insert the tube in the float bowl.

Now install the float bowl...        read full caption Now install the float bowl with the longer bowl screws. Remember to install those small gaskets on each bowl screw to prevent a leak. Tighten everything up and reinstall the carb on the engine, check for leaks, and you're ready to run.