Hia all.
As you all were so helpful in sorting out my previous problems, I was hoping to be as lucky with my latest one.
Hopefully it is a simple question.
I am attempting to restore my old 1970s/1980s Qualcast Suffolk Punch lawnmower.
Does anyone know what threads Qualcast used for their nuts and bolts when they originally assembled the lawnmower?
I have been told they could they be BSW UNC BSF UNF or Metric? All of which people have said they use.
To aid the restoration I intend to buy a Tap and die set and want to ensure I purchase the correct sort.
Many thanks in anticipation.
Stan Mutch.

I can offer you a complete one, everything present, if you want.

Never got round to adjusting the carburetor and unused for five years.

Peter
Many thanks for your kind offer but the thing is, I feel I must renovate grandad's mower, it keeps his memory very much alive, so it's not a replacement I am after.
As always I am amazed at the generosity of people on this site.

Stan

I think you can eliminate metric.

If you take a sample of the bolts to a small Engineering concern, they will offer it up to a thread guage which looks like a small fan made up of hacksaw blades! They should sort out your problems.

Personnaly I'd go with Whitworth. Cheers, Tony.

Morning Vfstan, it might be as well to buy yourself a thread gauge, just incase they used a mixture of threads on the mower.

They sell them on ebay and they don't seem that dear.....

I think I would expect a 1970s Suffolk Super Punch to have both UNC and UNF. They use AF spanner fittings.

Flywheel nuts are left hand thread.

From 1979/80, Punch 30DL and 35DL etc. They had the then new A98 aluminium engine which brought with it some metric...only for the engine though. Early of these A98 engines had some semi self tapping 6mm metric set screws and often pulled threads in the aluminium block casting...a job then for a helicoil insert.

The exhaust stub 1/4" nut can get seized...often a job for a nut splitter to then preserve the stubs thread.

I don't recall ever having to clean up many threads whilst working on these mowers generally...although they were a lot newer back then....


Clive.

Clive
(The lawnmower Guru)

Many thanks for your very informative answer, which as always is exactly what I needed in order to make a decision on the correct choice of a taps and die set.
You have such a wealth of knowledge, not only on lawnmowers, you should be on the radio or TV as a pundit par excellence.
Once again the man dun good.

Regards

Stan

Best see if I'm right though first...

Clive.

Clive,

Further to the above ie (correct nuts and bolts)
Regular readers will not be surprised to read that 'Clive the lawn mower guru' was spot on with his summations.
They are confirmed by yours truly as UNF and UNC nuts and bolts.
Well I have used UNF/UNC taps and dies to clean up the threads on the Suffolk Punch.
Once again a major dollop of 'respect ' to Clive.

Regards

Stan