LaverdaIan
Hero member
Hey thanks Red. The old stick and paste method huh.. reckon I'll get B1 on that duty. Good clue as to drill method also. Will get into it and let you know if we've got problems.
Ciao
8)
Ciao
8)
Montjuic head job
- Thread starter LaverdaIan
- Start date
Dellortoman
Hero member
- Location
- Tasmania, Australia
I've found the suction cup and stick method to be pretty hopeless. Most of the time the underside of the valve head is too rough for the suction cup to stick any longer than about 2 turns of the valve. And you need good grip to turn the valve against the friction of the grinding paste.
My method (sorry, I don't have any photos) is to use a variable speed drill via a flexible coupling onto the valve stem.
Mount the head in a vice with soft jaws and insert the valve with grinding paste. Make sure the valve guide is oiled. Then find a short length of fuel hose and push it over the top of the valve stem. Poke a drill bit into the other end of the hose and then grab the drill bit in the chuck of your power drill. Hit the drill switch while pulling the valve onto its seat. The hose has to be a reasonably tight fit on the valve stem so you can pull against it. If you can't get enough pressure on the seat without pulling the hose off the valve stem, try using a smaller hose or a spring type hose clamp on the valve stem (I don't reckon you'll have room to fit a worm drive clamp). Alternatively, you can push on the valve head at the same time. A greased pointy stick works well.
You can let PFC off the punishment duty. But if the object of the exercise is punishment rather than valve lapping, maybe you can think of another use for the greasy wooden stick
Cheers,
Cam
My method (sorry, I don't have any photos) is to use a variable speed drill via a flexible coupling onto the valve stem.
Mount the head in a vice with soft jaws and insert the valve with grinding paste. Make sure the valve guide is oiled. Then find a short length of fuel hose and push it over the top of the valve stem. Poke a drill bit into the other end of the hose and then grab the drill bit in the chuck of your power drill. Hit the drill switch while pulling the valve onto its seat. The hose has to be a reasonably tight fit on the valve stem so you can pull against it. If you can't get enough pressure on the seat without pulling the hose off the valve stem, try using a smaller hose or a spring type hose clamp on the valve stem (I don't reckon you'll have room to fit a worm drive clamp). Alternatively, you can push on the valve head at the same time. A greased pointy stick works well.
You can let PFC off the punishment duty. But if the object of the exercise is punishment rather than valve lapping, maybe you can think of another use for the greasy wooden stick
Cheers,
Cam
Jotaman
Hero member
- Location
- Verrierdale, Qld
Cam - there is no way we need alternative shed punishment proposals - thanks ever so much for caring though.
I do agree though, if the seats/valve are flogged: the paste is next to useless, however i do believe a vigourous (make this shit end) man can provide a decent seal if the cuts are still ok: i like the drill option though
Looks like it'll be back to fighting Max over the blast Cabinet :'(
Cheers
Peter
I do agree though, if the seats/valve are flogged: the paste is next to useless, however i do believe a vigourous (make this shit end) man can provide a decent seal if the cuts are still ok: i like the drill option though
Looks like it'll be back to fighting Max over the blast Cabinet :'(
Cheers
Peter
Hand lapping the valve seats is often a waste of time on used, worn seats. These are, more often than not, far too wide and usually bowed, thus compromising sealing properties. Add to that a bit of wear in the guide, and the freshly lapped seat will quickly deteriorate to the state it was before.
Freshly cut seats and ground valves CAN be lapped to complete the seal, but modern-day seat cutting methods have made the procedure almost obsolete. A well-ground valve will seal perfectly in a seat cut for example on a Serdi head servicing centre, usually no need for lapping.
Cam,
When re-using used valves, after grinding their seats and determining them servicable, their heads are cleaned up in the lathe with a piece of emery. The suction cup then works as it would on a new valve.
I hand lap the valves only to check they seal on the entire, freshly cut seat surface, a couple of turns is enough to ascertain this.
Even easier and quicker is to use engineers dye...
piet
Freshly cut seats and ground valves CAN be lapped to complete the seal, but modern-day seat cutting methods have made the procedure almost obsolete. A well-ground valve will seal perfectly in a seat cut for example on a Serdi head servicing centre, usually no need for lapping.
Cam,
When re-using used valves, after grinding their seats and determining them servicable, their heads are cleaned up in the lathe with a piece of emery. The suction cup then works as it would on a new valve.
I hand lap the valves only to check they seal on the entire, freshly cut seat surface, a couple of turns is enough to ascertain this.
Even easier and quicker is to use engineers dye...
piet
LaverdaIan
Hero member
Thanks fellas for all of that..PFC, you're out of a job.. :-*
BTW.. anyone know what PSI read I should get from a compression test on the Monty. Did one yesterday, and got an even 100 over both pistons, but I keep getting oil leaks from the base gasket..which I've replaced twice now..
Thanks again guys
Ian
BTW.. anyone know what PSI read I should get from a compression test on the Monty. Did one yesterday, and got an even 100 over both pistons, but I keep getting oil leaks from the base gasket..which I've replaced twice now..
Thanks again guys
Ian
