Oil Diverter (Bypass) Valve

Oil bypass assembly – Engine oiling is the most important item in your engine build. Many builders have gone to great lengths to improve flow such as opening up existing holes, blocking or restricting flow, higher volume pump, etc. BUT, they have missed one of the most important items. Since the ’60’s this aluminum bypass has remained unchanged – until now! On a stock engine, this is the check ball assembly under the rear main cap. For racing it is removed in favor of the aluminum diverter without a check ball. The aluminum bypass drops in the existing hole and diverts ALL oil to an external filter.  One negative is that current models restrict oil flow by as much as 50% if one of the legs joining the top to the bottom rotates to partially cover the .500 hole in the block leading to the oil filter. Due to the action of the oil flow this was the case I found most often in my engines. Even if a leg does not block the hole in the block, oil is still restricted by about 20% since the inside diameter on some drop-in units is as small as .406. If the holes in the pump, block and cap are .500 diameter, why not take advantage of the added volume?  My bypass will flow the equivalent of a .492 diameter and will not rotate. I have also included a 10-32 tapped hole in the bottom for easy installation and removal. Since 1972 I have been using a modified version of this bypass and have NEVER lost a bearing due to oil starvation.     Patent pending.

Please Note: This item deviates from “stock” and it is YOUR responsibility to install it correctly.

Note: If installing in an aluminum block please call me prior to ordering.

When ordering please specify .500 or .625 holes on oil filter pad.


P/N  D01       Oil Diverter/alignment and installation tools, plastic storage box.       $  39 + shipping *

P/N  D02       Extra Oil Diverter                                                                                 $  17 + shipping *

P/N  D03       (2) Extra Oil Diverters                                                                          $  30 + shipping *

P/N  A01       Extra 1/2″ alignment tool   $8.50

P/N  A02       Extra 5/8″ alignment tool   $8.50

Call for quantity discounts.

* Actual shipping charges only – no additional charge for packaging.