Hello Christian and members,

I downloaded the photos and viewed them at your original size:

I read these as outlines of the engine base. I guess some surface pitting caused by
the close contact of an alloy base with the steel rails over 3 or 4 decades.
There is also some pitting from surface rust. I do not see any cracks on this 20" frame.

[Linked Image]

Christian, could you also take a close look at the underside of the rails
to confirm you see no cracks. If you do not see any, but would still like a
second (or third) opinion, then please supply photographs as suggested.

Clutch:
The 5/8 DIA clutch half is HERE.

The 3/4 DIA clutch half is HERE.

The Thrust Bearing is HERE.

Either the Briggs OHV or the Honda OHV are smooth, reliable engines.
Either would be suitable to re-power your application.

Your old side-valve Briggs - by its design - produced more vibrations than
an equivalent OHV. They were very good engines but no match for the new OHV
designs offered today. The main thing is that you re-power with an OHV design.

If your 5/8 clutch is sound, the Briggs would be entirely suitable (and economical).
If you would prefer a Honda, make enquiries as to whether a 5/8 shaft is available
in AUS. The Briggs, as a full-line engine manufacturer, will offer both sizes.

Hope this helps.
---------------------------------
JACK

Last edited by CyberJack; 24/07/15 07:09 PM. Reason: Updated information.