Incorrectly machined cylinder block deck surfaces caused by necessary factory machine tolerances and production line inaccuracies have long plagued the automotive machinist. These errors create a number of problems, which can be address with the BHJ BLOK-TRU

The BLOK-TRU is a precision machined fixture which has a true 45 degree angle machined off each side of it's 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.

When the BLOK-TRU is set up all angular dimensions can be corrected.


Most problems caused for the deck height being uneven are, uneven deck clearances, poor intake manifold fit and sealing. We have seen deck height vary for side to side as much as .007 thousandths, and as mush as .010 thousandths from front to rear. The BHJ BLOK-TRU kit will correct this problem and square up the block to the correct angularity.

The BOR-TRU is specially designed for cylinder bore location on semi-finished factory cylinder blocks. These blocks have rough-bored holes which must be accurately aligned before the finish boring operation. The BOR-TRU can also be used on any stock block when a sufficient overbore will allow correction of out of position cylinders.

The BOR-TRU Kit is the only commercially available fixture that enables the machinist to quickly and accurately locate the cylinder bores over the correct crankshaft centerline. When properly installed, the BOR-TRU references from the rear main surface or rear main thrust surface (depending on block configuration) as a zero datum for front to rear positioning of the fixture on the deck surface. In addition, it spaces the bores at the correct center-to-center distance from one another. BOR-TRU option will only apply to block desiring an over bore of .040, 95% of the production blocks will not clean up at .030 due to the poor level of factory production machining.