Morning LCB.
Could you have a quick gander at this and let me know if I have gone far enough with the twiddle stick and lapping compound- I've not done this
before!
Pre lap:
Valve pre lap
Post lap:
Valve post lap
Valve seat:
Valve seat post lap
A bit of pitting on the valve but other than that I think it's ok?! Comments please!
Thanks.
I'm no expert but it looks OK for a country job. The purists would have you lapping with coarse paste till the pits were out, then fine to finish. What difference this makes I don't know. To performance, none, but longevity, who knows?
quote:
Originally posted by batteredoldsupersport
I'm no expert but it looks OK for a country job. The purists would have you lapping with coarse paste till the pits were out, then fine to finish. What difference this makes I don't know. To performance, none, but longevity, who knows?
quote:
Originally posted by jollygreengiant
quote:
Originally posted by batteredoldsupersport
I'm no expert but it looks OK for a country job. The purists would have you lapping with coarse paste till the pits were out, then fine to finish. What difference this makes I don't know. To performance, none, but longevity, who knows?
No pits = better gas-tight seal = better combustion and bhp per cylinder.
Simples, shnick
Worth spending time and getting it right imho
Check the condition of valve seats in the head
Mark around the edge of the valve with black marker and let it dry
when lapping you should see a nice even line around the valve where its lapped in nicely to the valve seat (use the right grade/s of paste)
When they are all finished check they drop down the valve guides under their own weight and don't bind
For a final check you can then fill the chambers with parafin or WD40 to check seal
Make sure all is nice and clean and all the grinding paste is removed
This is an XE head that the valves were lapped and then left over night with WD40 in the chambers to check seal
[Edited on 11/3/12 by perksy]
Right oh, in for a penny, in for a pound. I'll get the coarse paste out and get rid of those pits. I may be some time!
The valve clearances will be well out after this I suspect, if anybody has the tool for removing blacktop shims with the cams still in I would like to
borrow it! Unless there is another way?
That XE looks ace!
I always put my valves into a battery drill, run them with a scotch bright pad. Gets all the carbon off.
You can do the same with the swivel stick too... if you can keep it on the valve long enough
[Edited on 11/3/12 by Ben_Copeland]
quote:
Originally posted by batteredoldsupersport
I'm no expert but it looks OK for a country job. The purists would have you lapping with coarse paste till the pits were out, then fine to finish. What difference this makes I don't know. To performance, none, but longevity, who knows?
I,m lazy, dump the swivel stick in the first instance, drop of oil down the guide the use cordless drill on the valve stem and pull the valve back
into the head.
Just finish with swivel stick
It doesn't look quite right to me. From the photo it looks like you've gone a bit too far; recessed the valve into the head, changed the
seat angle and ground a step into the face of the valve.
I hope I'm wrong.
D
[Edited on 11/3/12 by Dave Ashurst]
have to agree, on close inspection it "looks" like youve mabe taken a mill of the valve face, if you have i fear that valve may be scrap
quote:
Originally posted by snakebelly
have to agree, on close inspection it "looks" like youve mabe taken a mill of the valve face, if you have i fear that valve may be scrap
just a slight explanation on dave ashursts and snakebelly's comment, if you grind it in too far you can get to the point were under heavy load
the valve will pull right thru the seat, seen it done quite a few times when I was racing
tony
As MikeRJ said most experts I have spoken to over the years would never use coarse paste. They normally argue that if they are that bad they need new
seats or recutting.
They would also say that you must completely strip the head before using any abrasive paste and thoroughly clean it afterwards. Any paste that is left
in the guides, followers, cam area or oil ways will quickly wreck the head or worse.
Crumbs, I don't know how strong you lot think my wrists are, but I don't think I removed that much metal! I'm pretty sure it's a
shiny ish/exhaust covered metal + phone camera thing. I'll post some 'profile' pics soon for you lot to have a gander at. I had already
done the exhaust valves before seeing the latest comments, so they've now been done with course paste to remove the pitting, followed by a round
or two of fine. Hopefully I haven't made a total hash of it, but I'm reasonably confident (?!).
The head is completely stripped, and will be throughly cleaned when I've done the inlets. There seems to be loads left on the valves, but
I'm no expert (clearly!) so I'll leave that to you lot when I get some pictures up! The valve seats seemed ok, it was a touch of pitting on
the valves themselves. If that makes any difference?!
Thanks for your help!
He would have a few blisters on his hands if he had lapped it in that much, I have refaced valves on a grinder and it takes ages to remove much even
then.Maybe the valves were already a bit recessed due to wear or the carbon left on them gives a false impression.I always put valves in a pillar
drill and clean up with a wire brush and emery cloth prior to lapping them in.
Paul
quote:
Originally posted by snakebelly
have to agree, on close inspection it "looks" like youve mabe taken a mill of the valve face, if you have i fear that valve may be scrap
They will be fine, it is OK to use coarse paste if you haven't got the means to grind the valve faces on a valve seat grinder, it just takes a
lot longer and is liable to leave more stray paste to be cleaned up before reassembly.I used to work for a company that did lots of engine work and
have ground in hundreds of valves over the years.
Paul
quote:
Originally posted by me!
I had already done the exhaust valves before seeing the latest comments, so they've now been done with course paste to remove the pitting, followed by a round or two of fine. Hopefully I haven't made a total hash of it, but I'm reasonably confident (?!).
The head is completely stripped, and will be throughly cleaned when I've done the inlets. There seems to be loads left on the valves, but I'm no expert (clearly!) so I'll leave that to you lot when I get some pictures up! The valve seats seemed ok, it was a touch of pitting on the valves themselves. If that makes any difference?!
Thanks for your help!
When I do this I make sure the inlets are 100% and nothing less. If the exhausts have LIGHT pitting it is fine. If the inlets are not done right
that will upset the tune of the engine much quicker than the outlets.
I agree with Ben, clean off all the carbon from the valve necks and stems.