Panther M100 head issues

[JFerg]

Pretty amazing coincidence that as I go to pose a question here, the latest query is also Panther related.

Today I went to go out on my Panther.  It wouldn't start, no compression, exhaust valve stuck open.  So I pulled the head off (a pig of a job with the chair on) to discover that what was holding the exhaust open was the valve seat that had dropped out.  I'd had the hardened seats fitted many years and many thousands of miles ago.

What's the group wisdom on getting this fixed?

[R]

Not knowing Panthers intimately, does it have an iron or alloy head ?

A lot of trucks use inserted valve seats.
Any local specialists in your neck of the woods ?

There is such a specialist just up the road from here.
I'd be reluctant to recommend him, he is usually flat strap - and wanting to retire...

P.S. Did your head require hardened seats ?
A lot of britbikes (and old engines generally) can seemingly survive quite happily on standard valves/seats.
Not that I've done vast mileages to test this out ...

But the AAA has done extensive testing in the UK, and found anything run on leaded
had what is termed a 'lead memory', and seemed to be good for 20,000+ miles regardless ...

[cardan]

Same thing happened to me on my BSA Sloper c1980. That was a while ago now.

You need a machine shop that specializes in vintage engine repairs - hard to find these days? So much depends on how much metal is around the seat, and of course whether the head is cracked, but presumably someone can have another go at the insert.

If we were in the UK (!)  I'd say investigate laser welding the head. It's a relatively new technique that seems to be capable of miracles, but I'm not sure if that includes building up seats, but they do mention "heads". http://www.e-m-p.biz/classic-cars/

Leon

[john.k]

Building up valve seats with welded on metal like stellite and bronze is not new ...its as old as internal combustion........twin port Panther heads  are quite thin between chamber and port passages on the exhaust .........I d say another inserted seat of larger OD may be needed ...........This latest 99c Panther I got has a single port head ,but I think the guy I got it off used the motor to restore another.

[R]

No-one has said if these are iron or alloy heads.
Are they welding on cast iron heads

A lot of older diesel engines are iron heads.
The local head guru does trucks as well as vintage stuff,
they are not that different, watercooling and all ...

[john.k]

Cast iron ,and very heavy .

[Rex]

And archaic in design too. Surely any car/bike machine shop offering head repairs could turn up a new seat and insert it properly? Not exactly hi-tech repairs.
Cheapest option...buy another head. Unleaded valve seats was another "end of the world as we know it" scenario from some years back, though in reality nothing was ever going to cause the solid lump of Yorkshire cast-iron Panther head any problems fuel-wise.

[john.k]

heads are so hard to find ,the POC offers a new made one ........havent seen a recent price ,but even in Yorkshire ,prices have gone up somewhat.

[Rex]

Someone was offering one free in the club mag a few months back.