Alfa Pages

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

hi all
right - i have just lapped my valves b4 putting the engine back together and basically to check the valves are sealing properly i sprayed some alcohol cleaner down the ports - well anyway some of them slightly leak it takes about 30 mins and then some alcohol seeps through - is this a no go and should i lap some more
cheers steve
_________________
brum brum

markgp4 · Posted: Sat Oct 07, 2006 8:39 pm Post subject:

am no expert but i would think if it takes alcohol 30 mins to seep thro that would be acceptable...
after all a valve is only closed for a fraction of a second..?
(when i checked mine i filled combustion chamber and when nothing came thro that was that... Smile

)

*disclaimer. i am no expert
_________________
make it go faster Smile

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

cheers ears
_________________
brum brum

mt · Posted: Mon Oct 09, 2006 9:12 am Post subject:

No idea what valve lapping is Confused

but...
To me something either leaks or it doesn't, i can't see why there would be a half hour time delay unless the valves are porous and it takes half hour to soak through, or unless after half an hour of continual spraying enough liquid built up to cause a leak, or something changed or moved after half an hour. Or unless it takes half an hour for the evidence of the leak to show (i.e leaks immediately but takes half hour to travel to a visible spot).

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

valve lapping is grinding the with paste so they fit the valve seat properly
when you grind the valves the finish is quite rough - i am hoping when the engine is run they will seat better and therefore seal better
_________________
brum brum

Vecchio Alfisti · Posted: Thu Oct 12, 2006 3:20 pm Post subject:

Common sense tells me that if you have a leak with alcohol at atmospheric pressure, then the same leak will be more obvious at high pressure eg 180 psi or 13 atmospheres and gas. I think that you may need to lap some more. Use the finest paste you can get. Valve seal and ring seal are really the mechanical arbiters of performance. Bang for the buck as it were. Wink

_________________
Alfa 33 1.7 QF I think maybe now I m not so sure

Vecchio Alfisti · Posted: Thu Oct 12, 2006 3:24 pm Post subject:

Forgot to say above that I am no expert! Embarassed

_________________
Alfa 33 1.7 QF I think maybe now I m not so sure

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

i was going to see how much a non lapped valve leaks if its alot i will be happy with what ive done, if it doesnt leak i will lap some more and keep my fingers crossed.
_________________
brum brum

col748 · Alfa Arna Joined: 14 Aug 2006 Posts: 19

hi i work for jaguar so know a little, you should see a ruff area of about 2/3mm around valve and seat same thickness all way round, we don't use cleaner its very thin, find brake fluid best, fill port overnight should be still full in morning, but like you say will bed in when run up.

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

thanx col
just what i wanted to hear because to be honest i didnt want to lap anymore because a - it is doing my head in
and b - if i lap too much i will need new valve seats
thanx
_________________
brum brum

bobbber · Posted: Fri Oct 13, 2006 9:39 am Post subject:

Steve,

Good to hear you're sorting that engine out! Any ideas when you might get it back in there!?

i.e. when MIGHT we see you sprinting up the M6?!

Bob
_________________
Fiat Bravo 165 Sport

stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

soon hopefully but i want to spray all the engine bay first and i`m getting my flywheel lightened plus i`m moving house soon so hopefully 2 - 3 months - fingers crossed
_________________
brum brum