Thanks, Capt, looks like I got away with it then...even the valve stem seals had been consigned to scrap at this point.
I should just add, for anyone reading this thread in the future, that the valve guides will rust if you give the head a good wash/rinse without making haste of the drying process! I fortunately noticed this within hours of rinsing it off and got to it quickly with the hairdryer and a wipe of oil.
How’s the job going Stuart, I know the bike is outside so given the weather I don’t expect you have done much on that but have you made progress with the head/valves other than a clean?
As you say, all outdoors, so dodging the weather is the greatest issue...even the wind is a pain with everything opened up. I’ve managed to switch out the double-spring clutch with a later single-spring issue, though I can confirm that after 29k none of the inner springs were broken. I’ve got a week off from tomorrow morning, so plan to get the valves lapped in and back together for shim adjustment within the next day or so. I’m not quite sure about the most efficient way of replacing the shims, because a number of them were not measurable, making it a case of (I’m guessing) putting an undersized shim in until there is a gap to measure and calculate from? I’m thinking there must be a simpler solution...I’d really like to avoid the number of times I’ll have to remove the cams with that ‘solution!’ I might put it to the group later? Take it easy out there, Stuart
You’ll lose a small amount of clearance anyway by lapping the valves in so if you had any that were wide they will come back towards spec for you but I believe most were very tight or had no clearance at all so you have a tricky job on your hands. I’m wondering if it’s possible to set the head up before refitting it to the engine. You’d be able to work inside and you wouldn’t need to set the cam chain tensioner every time you wanted to turn the cam to check another cylinder. I’ve only ever done the valves on a head on the engine but providing you can turn the cam so it points away from the valve and stays there I should think it’s possible.
Yes, nearly all the inlets were tight, and I definitely plan to finish the head indoors. Fortunately there’s a purpose-built lug on the cams so they can be turned insitu with a spanner
I know it won’t please a lot of you to still see carbon on a rebuilt head project, but it’s the best I can do without using a whole load of chemicals and rinse aids. The first four valves are ground in with a 1-1.5mm seal (hope that’s enough, I was afraid to go further)...it’s feeling good to be constructing rather than destructing The inlet valves have nipped in really tidily. However the exhaust valves are leaving an imperceptible peck or two until magnified by phone, when they seem massive...do you reckon I should try and grind them out (marked in red circles)? They are literally 10th of a mm wide and deep - I fear it could make a really wide ‘band’ to cut them completely out...there must be total 1mm of material sealing in and around the ‘pecks,’ what’s your thoughts?
According to google the ideal seat width is 1/16th (1.58mm) for inlet and 3/32 (2.38mm) for exhaust. What are they at present? The exhaust seat needs to be bigger than the inlet for heat transfer. I wouldn’t worry too much about a small mark, concentrate on getting the seat as smooth as possible, it’s easy to get a bit of grit stuck and end up with grooves all around the seat. Regularly lift the valve off the seat as you turn it backwards and forwards and don’t apply too much pressure, let the paste do the work. Looking good, only ten more to go.
Interestingly when trying to find your Google info. I came across the info (which I failed to spot before) from the Triumph T595 workshop manual, which gives the below details, and stating these figures for both exhaust AND inlet valves?? I also found lots of information in keeping with your post too...all very complicated this overhaul stuff
I realised after I’d posted that it was probably way out of date given it was in 16ths and 32nds and may not apply to modern engines with better engineering and materials. You probably won’t be able to control to much degree what size seat you end up with, I’d just concentrate on a nice smooth finish.
