Tweet
Not sure if it's suitable for air-cooled, but we have occasionally hard-chromed and ground stems of NLA valves. Then honed out the guides. This is for engines (pre-1914) with no guides. Just cast-iron. They did that back then. I suspect that hard-chrome would work fine in air-cooled engines. But I've never done it myself.
We used a company in California called something like Electro-chrome and Grinding. It's in Rancho Santa Fe. You can google it. They hard-chrome and then grind the stems. They will grind to your spec. and work to Tenths. The stuff comes back in 2 weeks or so and it's superb. Not even that pricey. Then again, it's pricier than buying new guides and Indian Valves (which I did not long ago for my '38 Chief). So there is not much point in doing that. But if you get into bikes for which parts are unobtainable, it's an option. The folks out in Rancho Santa Fe, Ca. LOVE working with old car folks. Most of their stuff is oil rig and aerospace... industrial stuff. But they are gear heads out there and will treat old car and bike stuff like it's a treasured religious icon.
But there are ways to address worn stems/guides without sleeving.
That said and IMHO, if new parts are available, processes like hard-chroming are either not economical or run an element of risk that makes the process not worth the trouble. For us, it's a process of last resort, but it is also one that has successfully let us save/repair some engines that, otherwise, would have required extremely expensive parts made (blocks... new valves from scratch, etc) or reassembling with some wear remaining, which we really don't like.
I agree that sleeving guides is not a great idea. Even worse is the old process of knurling guides. I see that All the Time on engines that people rebuilt cheap back in the '60's and '70's. Usually in cars that have been parked... since the '60's or '70's when the 'rebuilt' engines failed rapidly and the cars got parked by frustrated owners.
This is a bit of a tangent, but it is a good rule of thumb that "barn Finds" went into that barn for a reason! Very few people parked perfectly good vehicles for no reason at all. Yes, it happened. They died, went off to war, forgot it was there, got a better bike/car/tractor/whatever. But most of the time, things that got parked... have some mechanical issue or flaw that caused them to get parked. And there's always a story that is far more interesting than "It broke and grandpa was too lazy/poor/itinerant/incompetent to fix it." It's always something fun and new owners want to believe fun stories! Finding and fixing the flaw that "parked" a machine generally prevents expensive damage from surfacing when you start up a machine without properly recommissioning it. Most of these old machines will fire up with spark, gas and oil (add water to some...). But the risk inherent in that first startup is huge!! Investigate, clean, lubricate, measure... do it all before starting the engine! Even though it is time-consuming and for impatient guys like me... no fun at all. (well, it is fun.. but not as fun as that rush you get with a first startup after 50 years sitting. I'll never get tired of that moment...)
The net of all this is that there are always shortcuts. And, personally, if I don't have time and $$ to do it right once... I certainly don't have time and $$ to do it badly twice! As Sir Henry Royce said "The quality remains long after the price is forgotten."
Anyway, sorry for the rant off into the ether of an over-caffeinated breakfast.
Cheers,
Sirhr
We used a company in California called something like Electro-chrome and Grinding. It's in Rancho Santa Fe. You can google it. They hard-chrome and then grind the stems. They will grind to your spec. and work to Tenths. The stuff comes back in 2 weeks or so and it's superb. Not even that pricey. Then again, it's pricier than buying new guides and Indian Valves (which I did not long ago for my '38 Chief). So there is not much point in doing that. But if you get into bikes for which parts are unobtainable, it's an option. The folks out in Rancho Santa Fe, Ca. LOVE working with old car folks. Most of their stuff is oil rig and aerospace... industrial stuff. But they are gear heads out there and will treat old car and bike stuff like it's a treasured religious icon.
But there are ways to address worn stems/guides without sleeving.
That said and IMHO, if new parts are available, processes like hard-chroming are either not economical or run an element of risk that makes the process not worth the trouble. For us, it's a process of last resort, but it is also one that has successfully let us save/repair some engines that, otherwise, would have required extremely expensive parts made (blocks... new valves from scratch, etc) or reassembling with some wear remaining, which we really don't like.
I agree that sleeving guides is not a great idea. Even worse is the old process of knurling guides. I see that All the Time on engines that people rebuilt cheap back in the '60's and '70's. Usually in cars that have been parked... since the '60's or '70's when the 'rebuilt' engines failed rapidly and the cars got parked by frustrated owners.
This is a bit of a tangent, but it is a good rule of thumb that "barn Finds" went into that barn for a reason! Very few people parked perfectly good vehicles for no reason at all. Yes, it happened. They died, went off to war, forgot it was there, got a better bike/car/tractor/whatever. But most of the time, things that got parked... have some mechanical issue or flaw that caused them to get parked. And there's always a story that is far more interesting than "It broke and grandpa was too lazy/poor/itinerant/incompetent to fix it." It's always something fun and new owners want to believe fun stories! Finding and fixing the flaw that "parked" a machine generally prevents expensive damage from surfacing when you start up a machine without properly recommissioning it. Most of these old machines will fire up with spark, gas and oil (add water to some...). But the risk inherent in that first startup is huge!! Investigate, clean, lubricate, measure... do it all before starting the engine! Even though it is time-consuming and for impatient guys like me... no fun at all. (well, it is fun.. but not as fun as that rush you get with a first startup after 50 years sitting. I'll never get tired of that moment...)
The net of all this is that there are always shortcuts. And, personally, if I don't have time and $$ to do it right once... I certainly don't have time and $$ to do it badly twice! As Sir Henry Royce said "The quality remains long after the price is forgotten."
Anyway, sorry for the rant off into the ether of an over-caffeinated breakfast.
Cheers,
Sirhr
Comment