Hello Christian
The rails look fine to me.
I think prd's idea of using paint stripper (rather than sanding) for inspection
of Model 45 rails is a good idea. Perhaps that should be the recommendation
in future cases. Perhaps Mod BB might have something to add there.
FRAME:-
Christian, you've said this machine will get regular use. I made a recommendation for
an OHV engine, not on the basis of reliability, but on the basis of preserving the frame.
I do not believe there is any dispute on these forums that some high work hour machines
of 17" and 20" sizes have in recent times experienced rail failure. We have no reliable data
as to how wide-spread that issue is, or the exact causal factors. Anecdotal evidence is important -
that's all we have at the moment - but the years ahead will give us a better idea.
It is, I believe, a vibration problem, as our Engineer Grumpy has identified. The combination
of rail thickness specification, combined with the vibrations characteristic of single cylinder side-
valve engines is probably the main contributing factor - plus the hours of operation of the
particular frame. This is a new issue, only emerging in the last few years.
It would be easy to argue that the 20" frame is more susceptible to failure, given the longer rails.
The problem is, though, the 17" machine was, by far, the biggest seller. The 20" machines catered
for a niche market of larger residential lawns and lawn mowing contractors. The best advice I
can give is to play safe, and opt for a new OHV engine, that has reduced vibration levels.
ENGINE:-
The old Briggs engines were super reliable. The new Briggs engines are super reliable,
as are the equivalent Hondas. It is really a personal choice here.
The desire to keep the machine in original condition is a good one; but what is in
your favour here is the fact that re-powering requires no modification. Returning
the machine to original spec. could be done at any time. Again, whether you decide
to recondition the side valve Briggs, or re-power is a personal choice.
Hope this helps.
------------------------------
JACK.
p.s. Christian, your excellent photo record of the frame, and the discussion here, will be most
helpful to members and moderators alike.
A big thank you to Mod BB and prd for their contributions.
