Oil Pump Cover Plate Assembly

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Oil Pump Cover Plate Assembly

Post by Mick D »

Hi

I've developed an oil weep from the oil pump rear cover plate which I wish to eliminate, (in the probably fruitless search for a leak free engine :roll: ). The gasket I used during re-assembly was very a thin paper one sealed with Wellseal

I also re-assembled the cover as I had found it, knowing this was not in accordance with the parts list but see comment below re countersinks:
Oil Pump Cover.png
I realise that the parts list indicates all four attachments should be bolts, (000591), which I believe to be 3BA, can anyone confirm this size and even better give me the under head length?

I'm also confused by the fact that the cover plate attachment holes are countersunk whereas the bolts are not, resulting in a poor fit, is there a reason for this, have I got a 'wrong' plate?

I am considering fabricating another plate from aluminium alloy and without countersinks which I will install with four bolts and a slightly thicker gasket - does anyone have a cover plate lying around that they could accurately measure for me please?

Regards Mick
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Pharisee
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Re: Oil Pump Cover Plate Assembly

Post by Pharisee »

The bolts are 3BA x 5/16" but they are not normal hex head bolts. The head has a shoulder to fit the counterbore in the pump end plate.
The part number is 000591 and they are available from AMOC Spares.
pump plate screw.jpg
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Stuoyb
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Re: Oil Pump Cover Plate Assembly

Post by Stuoyb »

The plate has the recess (not countersunk) to match the bolts

http://www.amoc-parts.com/store/catalog/000772.jpg
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Oil Pump Cover Plate Assembly

Post by Mick D »

Thanks Guys

It all makes sense now - I'd convinced myself the plate was countersunk :oops:

Regards Mick
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