Getting Holley's 670cfm TBI Through a Scout's 2bbl Manifold

By: Mike Deschamps

Why not just use a 4bbl manifold? A 2bbl manifold gives better air flow for a 2bbl TBI (throttle body injection) unit and you don't have to spend $350 for a 4bbl manifold. This page gives instructions on how to get the most from the Holley 670cfm TBI.

What you will need:

• Drill press
• 2" Hi-Speed steel hole cutting saw
• Dremmel tool with lots of cutting disks
• Drill bits
• Threading taps
• J.B. Weld
• 1/4" steel plate
• Thread cutting oil
• Shop magnet or speaker magnet
• TBI base gasket
• Patience

What to do:

• Remove your intake manifold. Note of caution: IHC intake manifolds are heavy. My bathroom scale says the intake manifold from a 345 weighs just over 70lbs.
• Set up the drill press with the hole saw and set the spindle speed at about 100rpm (mine would not run that slow, so I had to drive it with a 1/2" hand drill).
• Set the intake manifold on the drill press so that it will cut bores out as shown below. The left side of the manifold is about 2 1/2" thick and the saw will not cut all the way through. Cut as deep as you can. Use the dremmel tool to cut out enough scrap so that the saw will cut through the rest of the way. The actual finished hole size is about 2 1/16".
• Cut out a piece of steel in the shape shown below. Take a wire brush or something and scuff up the area where the steel plate will be added and make sure it is clean. Use enough J.B. Weld so that when the plate is put in place there is a complete bond. Use a good flat magnet to hold everthing together until the J.B. Weld has cured.
• Since you now have full size bores, you can use a sharp knife to cut the reducing part of the TBI base gasket out.
• Use the TBI base gasket as a guide to mark the new bolt holes. Drill 'em an' tap 'em.
• Take compressed air or the garden hose and get rid of all of the metal filings.
• Put it all back together and enjoy how it starts and idles perfectly without ever touching the gas pedal.

This page was made by Mike Deschamps with WebDesign 1.3