Rockers

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Rockers

Postby Billy Opel » Mon Mar 25, 2019 7:56 pm

Hello!

This is my first post here.
Hope to get some help from you all.

I have a Matchless G80 -1948.
Last summer there was a ”knocking” sound from the engine, and after taking off the head/rockerbox, I noticed that the pushrods had knocked into the rockerbox casting.
(Bottom side of oilchannel.)
This I think is because of worn rockers, and me adjusting pushrods too high.
Earlier last summer, when I adjusted the pushrods, they apparently got too long and so they finally touched the casting.
I ordered new rockers but they are longer and also the splines do not match the old ones.
The dealer says he only has this type of rockers for matchless, and that the records show no other type of rockers. Because these new rockers are longer, I see they do not match the holes for the pushrods.
The valve side rockers also seem wrong considering angle against the valve.
My question is:
Are there different types of rockers for Matchless engines?

I do not know how to post pictures.
I have pictures that would help explain.
Maybe someone can tell me how?

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Re: Rockers

Postby Andy51 » Wed Mar 27, 2019 7:56 pm

There are at least 2 types of rocker arms (4 if you count inlet and exhaust) - long types for heavyweight singles and shorter for lightweight. A known performance dodge back in the day was to use the lightweight (shorter) pushrod side rocker arms as this gave more valve lift; I have done this on my 18S - the splines are identical. This slightly altered pushrod angles and could cause the pushrod to rub against some repro pushrod tubes. Given the age of your machine, who knows what mods have been carried out over the years? Always expect the unexpected when you start dismantling a 70 year old machine! Andy

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Re: Rockers

Postby Billy Opel » Wed Mar 27, 2019 8:09 pm

Ok. Thank you for the info.

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Re: Rockers

Postby Duncan » Thu Mar 28, 2019 8:10 pm

There are sketches in the parts book, do yours look like these on page 11?
http://archives.jampot.dk/book/Spares_lists/1948_M_Spares_List_CL8.pdf

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Re: Rockers

Postby Billy Opel » Fri Mar 29, 2019 10:05 am

Yes, they look just like the ones called FE-59 and FE-60.
The new ones I ordered was longer and dealer says it’s the only kind of rocker he has for Matchless.

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Re: Rockers

Postby clive » Fri Mar 29, 2019 9:40 pm

The lightweight ones look identical, just shorter.
clive
if it ain't broke don't fix

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Re: Rockers

Postby ajscomboman » Sat Mar 30, 2019 9:16 am

clive wrote:The lightweight ones look identical, just shorter.


Tut, tut,Clive! L/W rockers don't look like the H/W ones, the L/W have a cut off squared nose when compared to a H/W with it's rounded pointy tip leading to the pushrod pimple. That's what makes them instantly recognisable as L/W ones, plus as you mentioned they're shorter.

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Re: Rockers

Postby clive » Sat Mar 30, 2019 4:46 pm

:oops:
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