Model A & B

Ford Garage

Kwik-Way Boring Bar Locating Fixtures

Babbitt Main Bearing Align Boring

Pictured above is a pair of Kwik-Way main bearing align boring bar centering fixtures positioned on the pan rail and bearing saddles of a Model A engine block. These fixtures are used to properly locate the boring bar centerline for machining the poured babbitt main bearings for the Model A and B crankshaft.

The fixtures have (near) net locating pin holes for various Ford blocks including Model A, Model B, early flathead V8, and Fordson tractor. There is a front locating fixture and a rear fixture which are similar, but different.

The locating fixtures are used to precisely center the 1-1/4 inch diameter main bearing boring bar in the bearing saddles, and place the boring bar centerline at the pan rail datum plane.

The Kwik-Way fixtures can also be used to position the LEMPCO boring frame on a block, instead of using the LEMPCO camshaft bore locators. Both Kwik-Way and LEMPCO use a 1-1/4 inch diameter boring bar.

The main bearing boring bar itself is supported by the adjustable Kwik-Way boring bar bearings and support bridges.

The bar locating fixtures are removed after the Kwik-Way bar bearings and support bridges are fastened in place, and then the bearing caps are bolted to the block for subsequent align boring of the cast babbitt.

Shown above is the boring bar rear locating fixture positioned in place and pin-located to the main bearing cap bolt hole.

Shown above is the boring bar front locating fixture positioned in place and pin-located to the main bearing cap bolt hole.

When used on vintage Fords, the Kwik-Way boring bar locating system relies on the integrity of the pan rail datum surface, and on the position of the main bearing cap bolt holes.

The Kwik-Way boring bar locating fixtures do not 'know' or account for the location of the camshaft directly, or make use of the camshaft bores, or utilize a false cam for alignment.

The scan above is from the Ford block drawing, showing the datum hole at the rear bearing saddle. The corresponding hole at the front bearing saddle is also designated as a datum for block machining.

The concept of locating the main bearing boring bar independent of the camshaft centerline position is a little bit unintuitive in a non-timing chain engine like a Model A, but Ford did originally use the main bearing bolt holes as the net datum features for all subsequent critical block machining operations as shown above, so it follows the original production method.
Check your measurements before cutting!

Visit the links below on Ford Garage for more information about establishing and maintaining proper crankshaft and camshaft timing gear engagement and clearances.


More related information on Ford Garage:

  1. Model A & B Camshaft to Crankshaft Gear Alignment
  2. Model A & B Proper Crankshaft and Camshaft Positioning
  3. Model A & B Tobin-Arp Main Bearing Boring Bar Fixtures
  4. Model A & B LEMPCO FSU Main Bearing Line Boring Machine
  5. Kwik-Way Line Boring Machine Operating Instructions
  6. Kwik-Way Line Boring Machine Parts List
  7. Model A & B AER Insert Main Bearing Data & Instructions

December 2009