pre '49 G80 valve guides - circlips?

[g80csp11]

there are oversize guides available so its possible that you purchased +.001 +.002 etc. that will close up the gap when fitted
nothing wrong with either part just the wrong parts I suspect
each time a guide is removed it takes a small about of head material with it

check what you ordered , ptions to ream to size or replace
don't be tempted to ease the valve stem !

[hatrack]

They are:
014510 ex valve guide
017019 in valve guide
As listed on the club spares scheme.
With no mention of over sizes.

[Rob Harknett]

It is strange there is no clearance at all valve stem and guide bore the same. The valve needs some clearance. I am sure in this case when hot. Which is why I hinted at the valve some how creates a clearance when hot. Perhaps due to more heat getting dispersed from the guide via head fins.??? If I have had a sticky valve I have cleaned and pushed it up an down the guide a few times using fine grinding paste, it soon seems to clean up and stop sticking. I may have been doing wrong using that method to clean up a sticky valve stem of carbon.

[Rob Harknett]

They are:
014510 ex valve guide
017019 in valve guide
As listed on the club spares scheme.
With no mention of over sizes.

Sizes of valves and guides to suit them can be found in trade catalogues, with bore and stem the same dimensions = no clearance at all.
http://archives.jampot.dk/technical/Pis ... e_1939.pdf
wrong era for post war machines but note and compare valve stem and guide bore sizes are the same dimensions.

[g80csp11]

valve should not be tight and I forgot that oversize guides are usually only for aluminium heads , sorry to mislead you
will valve stem go in from
n either end
could be that they have closed the diameter by bad fitting technique

I have a 46 that I replaced guides and valves and they are certainly not tight in guides

[hatrack]

They go in from either end.
The engineer fitted them, and the inlet that I was able to grind in was perfectly aligned. So no real reason to expect heavy handed methods.
The valves will slide up and down the guides but need slight pressure. On all the other bike engines I have worked on over the years (except more modern ones with valve stem oil seals) the valves would just drop out if not held.
As the previous owner had trouble with the exhaust valve seizing, and had it reamed to a generous 4.5 thou clearance, I am concerned.
But then he was the one who didn't think the oil feed to the ex valve was necessary. (see my other thread)
Reading through the Bernal Osbourne/Temple Press 1939-55 book (a mine of information!) I found a suggestiion of reducing the flow of oil to the ex valve guide, to minimise the likelyhood od seizuer due to carbon build up on the stem.
So I am faced with multiple choices.
Not a happy situation as I am fettling the bike for the 2018 Giro d'Italia and don't wantr to be embarrassed by seized valves on the way there or half way around the event.

[hatrack]

Got the valve guides nudged into place.
1/2" inlet guide protruding into rocker box.
5/8" exhaust guide protruding into rocker box.
Circlips removed.

[hatrack]

Having seen Hamlin's in Bridgwater recommended on other threads, I took the head to them this afternoon. A brilliant place!
They took time to discuss the matter and reamed the guides out by 2.5 thou, creating a lovely easy sliding fit, and they lapped the valves in, all while I waited, for a tenner.
Head going back on this evening.

[Pharisee]

Having seen Hamlin's in Bridgwater recommended on other threads, I took the head to them this afternoon. A brilliant place!
They took time to discuss the matter and reamed the guides out by 2.5 thou, creating a lovely easy sliding fit, and they lapped the valves in, all while I waited, for a tenner.
Head going back on this evening.

Nice one... good to go then. I thought the Giro d'Italia was for bicycles... Are you sure they'll let you in? !!

[Rob Harknett]

Hope all goes OK now and the bike behaves on the 2018 Giro d'Italia event.