me!
|
| posted on 11/3/12 at 09:05 AM |
|
|
Valve lapped?!
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.
|
|
|
|
|
batteredoldsupersport
|
| posted on 11/3/12 at 09:12 AM |
|
|
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?
|
|
|
jollygreengiant
|
| posted on 11/3/12 at 09:42 AM |
|
|
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
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
|
|
|
Wheels244
|
| posted on 11/3/12 at 10:06 AM |
|
|
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
+1
While you've got it in bits why not go the extra mile and make it as good as you possibly can.
Just my opinion of course - it's your head 
|
|
|
perksy
|
| posted on 11/3/12 at 10:16 AM |
|
|
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]
|
|
|
me!
|
| posted on 11/3/12 at 11:18 AM |
|
|
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!
|
|
|
Ben_Copeland
|
| posted on 11/3/12 at 11:37 AM |
|
|
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]
Ben
Locost Map on Google Maps
Z20LET Astra Turbo, into a Haynes
Roadster
Enter Your Details Here
http://www.facebook.com/EquinoxProducts for all your bodywork needs!
|
|
|
MikeRJ
|
| posted on 11/3/12 at 12:19 PM |
|
|
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?
The purists would never consider using coarse paste; all this does is recess and widen the valve seat. If the seats are pitted they should be
properly re-cut.
|
|
|
mark chandler
|
| posted on 11/3/12 at 01:14 PM |
|
|
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
|
|
|
Dave Ashurst
|
| posted on 11/3/12 at 03:18 PM |
|
|
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]
|
|
|
snakebelly
|
| posted on 11/3/12 at 03:26 PM |
|
|
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
|
|
|
Dave Ashurst
|
| posted on 11/3/12 at 05:03 PM |
|
|
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
...and the head may need a valve seat insert (?) 
|
|
|
mad-butcher
|
| posted on 11/3/12 at 05:30 PM |
|
|
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
|
|
|
Paul Turner
|
| posted on 11/3/12 at 05:44 PM |
|
|
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.
|
|
|
me!
|
| posted on 11/3/12 at 09:31 PM |
|
|
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!
|
|
|
paulf
|
| posted on 11/3/12 at 09:41 PM |
|
|
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
|
|
|
paulf
|
| posted on 11/3/12 at 09:47 PM |
|
|
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!
|
|
|
AndyGT
|
| posted on 11/3/12 at 10:40 PM |
|
|
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.
nothing is impossible
everything is possible
|
|
|
.jpg)
