Cylinder head with issues..

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T Batnes
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Re: Cylinder head with issues..

Postby T Batnes » Thu Jan 30, 2020 10:27 am

The easiest solution is often not so obvious Nev, thanks for the advise. I'll give it a go, run a tap in the rocker box threads and get the head bolt landings even. Will measure the guides to see if they need to be swapped. How much wear can be allowed on the guides? Another cylinder head, that was doing fine when in use, had a valve teller lateral play/movement of 0,2mm(8 thou) on the inlet valve and 0,4mm (16 thou) on the exhaust valve, measured with the valve at full lift from the seat, and in the longitudinal direction on the head (most wear).
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

john.whiting
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Re: Cylinder head with issues..

Postby john.whiting » Thu Jan 30, 2020 12:11 pm

Its funny to think that only a couple of years ago a cast iron head with broken bosses would have been thrown in the scrap without a second thought....I dont know how many Triumph and BSA A10 iron heads I swapped for ally ones and tossed ..Used to be when you restored a bike ,you had another worth of spares you put together and sold ,and then a third bike s worth of reject stuff that you took to a swap as a "basket case".

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T Batnes
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Re: Cylinder head with issues..

Postby T Batnes » Thu Jan 30, 2020 12:13 pm

Reagarding brazing, anyone tested brazing with TIG on cast iron? Saw this on YouTube, looks easy... https://youtu.be/xQN_yz-4Hhg
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

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Re: Cylinder head with issues..

Postby nevhunter » Thu Jan 30, 2020 9:24 pm

Combined valve guide and stem wear.. is what you are seeing.. The inlet can/should have very little and the exhaust needs a minimum of nearly one thou per 1/8" of stem diameter. They wear oval (fore and aft). due to the rocker action. I certainly would not be spending a lot on this head but chucking two guides in and doing the seats is par for the course.. Once done, they should last for quite a while with the enclosed rockers. Nev

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T Batnes
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Re: Cylinder head with issues..

Postby T Batnes » Fri Feb 28, 2020 10:27 am

Here goes, the head with issues now has new guides, cut & grinded valve seats, squared off bolt landings and a fresh coat of black cylinder paint. Ordered a guide reamer from Woodwards in US to ream the inlet guide which was too tight, and was a bit p.... off when I found that the reamer took out 1.5 thou more than it should... is that even possible, what's the point of an exact dimension on a reamer if it takes out more than specified...?
So the new inlet valve has a lateral play measured on the teller edge of 6 thou/0,15mm... I reckon it will work for quite a while anyway, the cylinder head I took off the bike had 8 thou/0,20mm play on the inlet valve, and the engine worked well with no blue haze or hick-ups.
20200228_112604.jpg
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

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Vincent.vanGinneke
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Re: Cylinder head with issues..

Postby Vincent.vanGinneke » Fri Feb 28, 2020 10:55 am

:D Build to last !

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T Batnes
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Re: Cylinder head with issues..

Postby T Batnes » Fri Feb 28, 2020 11:14 am

Haha :D , I just saw that one now! Quite coincidental, I just took a brochure in my office and threw under the head to save the shelf from any marks or scrapes... even says "Built to perform" on it :lol: 8-) Let's hope both are true in this case!
20200228_121327.jpg
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.

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T Batnes
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Re: Cylinder head with issues..

Postby T Batnes » Mon Mar 02, 2020 7:23 am

20200301_141916.jpg

Sunday supper 8-)
Ariel W/NG '40 "Bitzer", Triumph Thruxton '04, IZH-49 '56, Tempo Standard 150 '54.


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