Engine Overhaul


 Dave Groh and his staff of A&P certified mechanics specialize in overhauling Continental W-670s and Wright 760s (Whirlwind J-6-7s).  There is a lot of work done as part of a Yesteryear overhaul that you might not get other places.  All engines are line bored with new bearing liners, and every part is inspected and measured to ensure that it meets the new part specification and not just a serviceable limit. 


 click each image for full-size

This engine is ready to begin disassembly for overhaul.
  After thorough cleaning and flushing out of all oil galleries, the old bearing liners are machined out of the case.  
The bearing liner has been removed and the hole has been made true in preparation for a new liner.
The new bearing liner has been installed in the front case half.
The new bearing liner is now in the main half.  This case is almost ready to line bore.
The bearing liners are line bored to size with the case assembled in order to run perfectly true to one another.
With the case line bored together to spec, the crankshaft will turn perfectly straight.
The case and accessories have been masked off, primed, and are now ready for paint.
  Power case after paint.  This high quality durable paint has a great finish.
The masking material is being removed from the case.   The accessory case after painting.   Accessory case after assembly.  All limit measurements have been checked and noted.  Those measurements come with your package of overhaul paperwork.
Accessory case ready for installation.   Crankshaft with hard chrome repairs.   Lining up crankshaft with V blocks and dial indicator.

Crankcase assembly set into the rear power case.

Another view of the crankcase assembly.

Bearing spacer installed on the crankshaft.
Case halves assembled.

The engine is ready for the cam ring to be installed.

Cam ring installed and gasket in place for attaching the accessory case.
Cylinders being cleaned and measured out for limits inspection. First stage of repairing broken off cooling fins.  These are now ready for grinding and finishing. Second stage of the fin repair after grinding and shaping up the fin.
Valve seats are ground to appropriate limits, valves are ground and lapped to seats, and cylinders properly honed. After valves are lapped, all cylinders are leak tested to ensure a complete seal at the valves (80/80). Cylinders primed and ready for paint.
Cylinders painted with a high quality acrylic urethane paint.

Cylinders are beginning to go onto the engine case.

All exhaust stacks have the old liners machined out and new liners installed before going onto the cylinders.
After overhaul of the accessories and magnetos, they are installed onto the engine. The assembled engine.

Preparing the engine for testing.

The engine has been installed onto the test stand and is closer to its first start.

Engine undergoing a series of tests to ensure proper operation.