# Bad timing, bad valve, bad luck



## ghart3 (Oct 24, 2011)

Just finished Root & Vandervoort model hit n' miss.
After much cranking it started for first time and reved up then a stop with a bang.

Valves are held on with a nut and the nut came loose on intake valve and was inhaled into cylinder. Ding, Dang why did it have to wait until starting to come loose. Bent valve and gouge cylinder.


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## Groomengineering (Oct 24, 2011)

Ouch! :redface2:

Is there room above the valve nut to crossdrill and fit a 'safety' cotter?

Jeff


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## MachineTom (Oct 24, 2011)

OUCH!! Sorry for your loss. Since your going to mak a new valve, scrap the threads make a shallow groove, a solid C shaped ring, and a valve retainer that captures the C ring. Millions of engines have run that way. Threads on an engine valve, not a good idea IMO.


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## Catminer (Oct 25, 2011)

Oh my that's gotta hurt, apparently cotter pins are important.
Good luck with the repairs.
Peter


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## ShedBoy (Oct 25, 2011)

Bit o bad luck there, must admit I have never liked the idea of threaded valves. I am a fan of the captured C ring idea. I hope the rod, piston and head survive. 
Regards
Brock


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## CMS (Oct 26, 2011)

Dang man!!! That BITES!!! You could also use a second nut as a jam-nut, then tied together with some small wire. Not much room for this method on the small scale of the models but have seen it done on larger equipment.


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## Swede (Oct 26, 2011)

Hopefully, all you'll need to do is make a new valve. The cylinder bore ding should hone or polish out, and the engine should still run... fingers crossed.

And the notion of a nut to retain the valve, as mentioned, not the best idea, unless it is like an aircraft castle nut that can be cottered or safety-wired in place.


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## ghart3 (Oct 26, 2011)

Wasn't all bad luck. The gouge in cylinder cleaned up and little if any loss in compression also no damage to valve seat.  Only had to make new valve. 
 Looking at pictures of full size engine they did use double nuts.  Plan on using something like small cotter pin for insurance and not waiting for taking apart for cleaning and painting for fixing nut to valve.


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