Continuation of my 12a rebuild.

Cleaning the front end components I noticed some nicking on the front bearing plate (image), and some concentric rings on one of the washers (if I have the terms correct).

Should the pieces be replaced?

Thanks always.

 

The missing metal is common on 82 and older engines due to their small "low volume" oil pumps measuring in at 12mm. I don't recall what year engine you have, but it's probably an 81-82, right? It's time for you to get some new thrust components and then learn how to set end play. Fun! Also be sure to get a good used or new so called "high volume" oil pump at 17mm. This came stock on all 83-85 12As, the GSL-SEs and several J-spec nitrided R5 12As and 13Bs.
Front Engine Parts, Counterweights, Pulleys

Edit: Ok, so you have an 84. Make sure your engine is an actual 1984!

 

Jeff,
Thanks for the response.
Follow up questions.

1. Where would I measure the 12mm vs. 17mm on my existing oil pump?

2. I have the engine ID number, but I cannot find any useful reference to determine if it is an 83-85 or pre-83 12a. (It was an Atkins re-manufactured.) I did find one thread using the rotor markings F, R and N for 83-85's. I'll check tonight. Is there anything obvious on the exterior which would give me a clue?

 

Being an Atkins build, who knows what year parts they used.

Look for a T shaped heater core tube fitting on the rear iron. This lets you know at least the rear plate is an 83-85.

You already know about the F, R and N for 83-85 rotors.

The oil pump gear needs to come out so you can measure thickness. It just slides right out.

 

Thanks Jeff.

Attached image of rear iron, its 83-85.
On the rotors I did find a faint R, and with some imagination I can almost make out an F on the other. If there ever was an N I cannot find it.
The oil pump measures 17.5mm which is the Atkins "Competition" pump.

(Being totally new to this I take before/during/after pictures. At some point in the hopefully not too distant future, I'll be putting it all back together.)