See also 77-85 Oil Pump and Parts (app.) Dims Below

Brand:
Circle Seal
Manufacturer Part Number: P106-376
Patent #3626977

77-E83 Chamfered Feed Gerotors
(can also be used on L83-85 oil pumps). ¹⁾

77-E83 Chamfered Return Gerotors
(can also be used on L83-85 oil pumps). ²⁾

Seal 1

Seal 2

Note: All dims are taken from a used pump and should be viewed as approximate measurements only.
The only intent is to show general measurements.
✔ Specs from the FSM are shown with a checkmark by them.

✔ The bushing to shaft clearance is .0005“ ³⁾
(both bushings below are out of service limit)

Brand: Circle Seal
Manufacturer Part Number: P106-376
Patent #3626977

A small rod was inserted into the check valve to measure the plunger travel which is app. .0845”

App. .002“ difference in diameter was noticed between the top and bottom of the hole in the check valve.

77-E83 Chamfered Feed Gerotors
✔ Each gerotor set has an inner and an outer piece and both of these should measure the same in thickness. ⁴⁾
(Ea second pic below):

✔ Maximum wear limit between the inner and outer gerotor set is .004” ⁵⁾

This is the most common way to measure how high the feed gerotor sits above the rim of the cover (as in the FSM). ⁶⁾
Generally, the straightedge is stood straight up across the flat gerotor surface and a feeler gauge is inserted between the straightedge and the cover.
Measurements should be taken on at least four sides to verify that the cover isn't warped.
✔ The dimension between the top of the feed gerotors and the lip of the cover should be between .001“-.011” ⁷⁾

However, if the straightedge is not flat on the bottom edge, it will allow the leading edge of an oversized feeler to partially get in it which may lead to a false reading.
Laying the straightedge on it's side will also work it is not bent.

A dial depth gauge is a little more tedious.
First, set the gauge on the gerotor top,
Zero the gauge once you're sure it is flat and square
Then move the gauge so the depth rod falls on the cover area

A depth rod on a caliper is more difficult to use.
You have to rock the base of the caliper square on the gerotor top while holding it tight and drop the rod on the cover.
It's easy to rock it out of square with the gerotor.

77-E83 Chamfered Return Gerotors
✔ Each gerotor set has an inner and an outer piece and both of these should measure the same in thickness. ⁸⁾
(Ea second pic below):

✔ Maximum wear limit between the inner and outer gerotor set is .004“ ⁹⁾