Valve lifter not working + worn valves/rocker ?

[Amb3611]

Hi all, I have now noted that my valve lifter is not working on my 1960 350 lightweight model 8. After removing the rocker cover I have noted quite a lot of carbon build up around the exhaust side of the cover (as pic) I have also noted a groove in the exhaust valve stem face and rocker arm (further pics), Could the carbon build up be due to worn valve seal or is it more likely a valve stem issue? also I take it I will need to replace both the exhaust valve and the rocker arm Although I am struggling to find a replacement arm? The valve lifter does appear to be moving the rocker arm so I don't understand why it would not work ,tappet clearance appeared ok etc ? Any advice appreciated.

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[SPRIDDLER]

Hi all, I have now noted that my valve lifter is not working on my 1960 350 lightweight model 8.

Has it ever worked?

Could the carbon build up be due to worn valve seal or is it more likely a valve stem issue?

There isn't a seal as a component but relies upon a close fit 'twixt valve stem and guide, and obviously between the valve head and its seat. Possibly a bent valve stem or build-up of carbon on the head end of the stem making it stick and/or preventing full valve closure.

also I take it I will need to replace both the exhaust valve and the rocker arm

Yes, and possibly the valve guide.

Although I am struggling to find a replacement arm?

AMC Classic list pre-loved ones on page 5 in the link below.
(I've found them a b*gger to fit on a H/W engine and guess that the L/W would be much the same. Before dismantling make a note of the relative positions/angles of the lever at the pushrod end and the worn lever).

http://www.amcclassicspares.com/Secondhand%20Spares.pdf

[g80csp11]

certainly id look at the valve guide and valve , as excessive wear will lead to exhaust gas past the guide
you will see carbon deposits on valve stem and excessive rocking of valve in the guide
let everyone know what you find

[Amb3611]

Thanks Both I will remove head as soon as I get chance and asses properly. I think I may just replace both valves and guides any way ,exhaust valve wear does not look good on the rocker face etc. I still can't understand why the valve lifter wasn't working though? Once I get the head sorted I will try it with the pieces on the bench.

[SPRIDDLER]

Going back to you very first post from last July............

Hi all, I have after a few years without a bike decided to take the plunge and get myself a small project. I have a 350 model8 1960. It has already had some “playing with” so I’m not surprised may have a few issues.

I'll take a wild 'off the wall' guess at the problem and say that in view of the several issues you've had with it who knows what has happened before you got it. It could have the wrong zorst valve which has a stem that is too short. The top of the valve stem looks as though it has been hammered by the lever, perhaps because with a too short valve stem the pushrod couldn't be adjusted/extended enough to obtain the correct minimal gap which would also account for the damage on the nose of the lever. The lifter may not work because the too short valve stem means that the lever doesn't sit high enough for the valve lifter to make contact with it in order to push the valve open.
You haven't said whether you've had the engine running but it may be that the valve guide has migrated too far into the combustion chamber, holding the valve slightly open.
Or none of the above, but they are things to check.

[SPRIDDLER]

Going back to you very first post from last July............

Hi all, I have after a few years without a bike decided to take the plunge and get myself a small project. I have a 350 model8 1960. It has already had some “playing with” so I’m not surprised may have a few issues.

I'll take a wild 'off the wall' guess at the problem and say that in view of the several issues you've had with it who knows what has happened before you got it. It could have the wrong zorst valve which has a stem that is too short. The top of the valve stem looks as though it has been hammered by the lever, perhaps because with a too short valve stem the pushrod couldn't be adjusted/extended enough to obtain the correct minimal gap which would also account for the damage on the nose of the lever. The lifter may not work because the too short valve stem means that the lever doesn't sit high enough for the valve lifter to make contact with it in order to push the valve open.
You haven't said whether you've had the engine running but it may be that the valve guide has migrated too far into the combustion chamber, holding the valve slightly open.
Or none of the above, but they are things to check.

[SPRIDDLER]

I know little about L/W engines or their valves but I've just had another fantasy which may provide food for thought for the L/W cognoscenti.
Could it be that the PO was a bit of a bodger and perhaps unknowingly he fitted a zorst valve from an early H/W engine? These had shorter stems because a hardened cap was fitted over the end of the valve stem. This might account for the decomp lever not activating the shorter valve and also the damage to to the end of the stem.
(I really should get out more )

[Amb3611]

I have found a number of issues since I purchased it last year. In fact I have only managed one short 1/4mile journey before the brakes failed. The engine ran quite well but is very Smokey. On start up it’s as though the engine has just been rebuilt. (Clouds). It may well be that the valve has been altered which would make sense with clearance etc. I intend swapping both and new guides and rockers so hopefully will solve it. I must admit the wear is very excessive and different to the inlet valve.

[SPRIDDLER]

I have only managed one short 1/4mile journey........... The engine ran quite well but is very Smokey.

As indicated by the carbon in the rocker cover, so it'll be interesting when you've checked the valve and guide when you've got the head off.
Don't mean to do the granny/eggs stuff but heat the head 180deg Gas 4 until it spits back when you spit on it and drive it out into the combustion chamber. Use a puller (threaded rod, washers, nuts) to pull in the new one in the reverse order.
If the new guide has an oil drilling/groove make sure it aligns with the feed hole in the head. ( Not sure if that applies to the L/W's guides).

If you don't have one you can probably find the factory workshop manual in the link here........

http://archives.jampot.dk/book/Workshop_manuals/

[Amb3611]

Thanks Spriddler, to be honest I never thought of using the oven to heat up the head . After now removing the head It appears there is some previous damage to the piston (although rings were replaced but not piston ?) and the exhaust valve guide does have excessive play. The exhaust valve has not been seating properly at all. dry fitting the valve lifter etc appears to show the excessive wear to all components may be the cause of it not functioning correctly. Can you tell me ,does a new piston set come complete with gudgeon pin? as that too seems to have some wear. Little end looks ok.