Harris Engines has just purchased from the USA , BHJ’s Blok-Tru engine block Blueprinting Fixture
which is used to correct improperly machined deck surfaces commonly caused by factory machine tolerances, production line inaccuracies and blocks previously machined.
This precision-machined fixture has a true 45-degree angle machined at each side of its own centerline. The Blok-Tru Index Plate, when installed on the cam-crank centerline of the block, is
then referenced to roll over and correctly index the block into position for the resurfacing operation.
Top engine builders across the USA rely on the Blok-Tru to provide the level of accuracy necessary for today’s performance requirements.Common issues improved after using the Blok-Tru include:
Twisted Blocks: On a twisted block, it is necessary to choose a point on the deck surface to use as a reference point for set-up. As a result, you may be compounding the out-of-square condition.
Uneven Deck Clearance: Deck clearance often varies between the top and bottom edges of the piston due to the deck surface not being at 90 degrees to the bore. On race engines where deck clearances are held on the verge of piston to head contact, any discrepancy in deck angle means lost compression.
Poor Intake Manifold Fit: This condition is usually blamed on the intake manifold. However, if the included angle of the deck surfaces is not 90 degrees or if the top of the block has the incorrect angle, the manifold may not be at fault.Block Deck-Height Measurements: The Blok-Tru is marked with the height from the crankshaft centerline to index surface. A simple measurement from the block deck surface to the index surface of the Blok-Tru plate, added to the Plate’s marked dimension gives you the deck height.