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Author Topic: Petter A 1944 cylinder head stud size  (Read 92 times)

billybongo

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Petter A 1944 cylinder head stud size
« on: October 09, 2020, 03:59:07 PM »
Hi everyone, I'm new to tis forum having just purchased a Petter A. (My first stationary engine.)
It came in with no compression whatsoever. On stripping I found the exhaust valve badly bend and not seating at all.
Anyway that has now been straightened and reground following which I have heaps of comp'.
My question is what size are the short cylinder head studs, as one has been crossed in its time and another seems way to short, so obviously I'd like to replace them.

Any help would be very much appreciated.

 

cobbadog

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Re: Petter A 1944 cylinder head stud size
« Reply #1 on: October 10, 2020, 10:57:36 AM »
Gday Billy and welcome to the forum. I have no idea what size the studs are but what I would do is remove any offending studs then measure the height of the head and add extra for the thickness of the nut. Now on some engines you also need to add extra as it may also hold on the rocker cover.
Be careful removing any old studs, I use a stud extractor that is used in conjuction with your 1/2" drive socket set and it can be used to fit the new studs if you feel you need to have them very tight. Check the thread pitch at both ends of the stud. Sometimes they use a coarse thread in the block and finer on top but not always. Any nut and bolt shop should be able to supply you with the Whitworth stud/s you need.
Good luck with it and I'm glad it was a simple fix with it being a bent valve. Make sure it runs in the guide freely and does not stick anywhere. If it does buy a new valve they are not expensive but a hole in the piston can be.
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