Valve Stem Lubrication

[SimonBrown]

Hi All,
I’m after some advice on tight valves with my 4.2 engine that was rebuilt 6 years and about 2000 miles ago.
I have been having concerns over excess tappet type noise, only when cold, above 1500rpm, which disappears after 4-5 minutes running. The engine runs well with good compression and I have checked valve clearances.
How can I ensure the valve stems are adequately lubricated?
Has anyone any experience with any Molyslip type additives, or fuel additive to try and help ease off any valve tightness?
I am trying to avoid having to remove the head because the engine runs so well when hot, but equally wish to avoid a stuck valve with risk of other damage.
I would have fuel additive would be better because I cannot see how an oil additive would lubricate the valves.
Thank you
Simon

[Gfhug]

Simon, which sort of fuel additive and what would you expect from it? Esso E5 is well worth using as it is reputed to have no ethanol in most parts of the country and is closest to what the cars ran on in the 1960s.
What oil pressures are you getting at start, after a few minutes, at higher cruise revs and at idle when warm?
Also what are the cam tappet clearances on your engine? The later 4.2 in the S2 had different cams with larger clearances which can make the engine sound very tappety when cold.
All this may help the more experienced to answer your question better.

Geoff

[abowie]

I can't specifically help, but if you have one of those braided cam oiler pipes fitted rather than the original rigid pipe ones I would change it.

The braided lines are smaller in diameter. We had one on a client car which had tappet noise. We changed it back to the standard line; problem solved.

[SimonBrown]

Hi Both, Thanks for the responses
Inlet valve clearances all around 10 thou. I only use Esso 99 unleaded, plus Millers additive.
The noise only occurs over 1500rpm when cold, is an excessive clatter and disappears completely after 4-5 minutes running. If the revs are limited to below 1500rpm there is no noise.
Oil pressure is 60lb plus when cold, only dropping to 50lb on tick over when hot. This has been confirmed with a wet gauge.
The oil feed pipe to the cams is the original type and there appears plenty of oil to the cams.
I feel the valves are running tight in the guides and closing slowly when cold above 1500rpm. There is no misfire.
I am wondering if something like Slick 50 or Molyslip in the oil would help lubricate the guides and gentle use will ease them.
Appreciate your help
Simon

[Gfhug]

Simon, as above what are the correct clearances for your engine? 4 inlet, 6 exhaust for early engines. 12-14 inlet and exhaust for later engines with different profile cams.
10 isn’t correct for either.
Also can’t see any reason for additive when using Esso premium, happy for others to correct me.

Geoff

[SimonBrown]

Hi Geoff,
My engine number is 8682, 6 engines before the change of valve clearance (8688), so the correct clearance is 12-14 thou.
I can’t see a clearance of around 10 thou is likely to cause the clatter heard only when cold?
I do think it is a guide clearance issue diminishing as the engine warms.
Happy to send you a video of the noise from start up if that helps
Appreciate your knowledge
Simon

[mgcjag]

Hi Simon....did you have valve stem oil seals fitted on your rebuild....typicaly there wernt oil seals so lubrication is from above.....a start would be to to remove cams and check for tight valves. ..i havent done it but assume you can by pressing down on the valves.....at the same time you can get your gaps in spec and readjust the timing chain which can make a lot of noise. .....adding an oil additive as a first step isnt going to hurt and then at least youve tried it.....Stevr

[Gfhug]

Simon, you say yours is before the change, therefore should be 4 thou inlet surely not the 12-14?
But as I said before with the later cams they do sound tappety on first start.
But please check which cams you actually have. 10 instead of 4 would be noticeable imho.

Geoff

[Allrand]

Hi Geoff,
My engine number is 8682, 6 engines before the change of valve clearance (8688), so the correct clearance is 12-14

After the change the clearances increased to 12-14, so shouldn't yours be 4-6 thou?

[SimonBrown]

Just checked original chassis plate and clearance should be 4 thou, my mistake, sorry.
I will check which cams are actually fitted before going further
Thanks

[PierreW]

And?