1966 cyl head oil feeds ?

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
Locked
Dubbsy
Posts: 43
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

1966 cyl head oil feeds ?

Post by Dubbsy »

Hi, I'm In process of restoring my cylinder head, no real issues, but found a badly pitted exhaust valve, so changing this. I'm keen just out of interest to understand how the valve guides / stems are lubricated if at all. I'm aware my head is a late one with the blanked oil feed adjuster, but can someone enlighten me on how and where oil is fed to the guides , it seems the inlet is not fed with oil but the exhaust is ?. Pics attachef
IMG_20220311_193447.jpg
You do not have the required permissions to view the files attached to this post.
Red Gauntlet
Member
Posts: 173
Joined: Wed Aug 19, 2020 11:22 am
Location: Dorset UK

Re: 1966 cyl head oil feeds ?

Post by Red Gauntlet »

The exhaust is fed from the little cup drip fed from the rocker cover 1st pic, the inlet is via a slot like you can see on the exhaust guide in the 3rd picture. The guide has a slot milled down the side and a groove machined in the periphery half way down with a small hole entering the centre drilling of the guide, if that makes sense. Caveat, some inlet guides don't have this slot so rely on splash fed oil from around the valve spring gradually lubricating the valve stem, it is pulled down under the vacuum of deceleration. It is always good practice to remove and replace guides when you have the head stripped as the oilways are nearly always clogged up with carbon and other debris. Replacing the exhaust guide, make sure the milled slot is downwards like in the 3rd pic it will tend to smoke otherwise.
Dubbsy
Posts: 43
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

Re: 1966 cyl head oil feeds ?

Post by Dubbsy »

Thanks, on my head the little cup in the 1st picture is sealed so cannot feed oil to the exhaust, i.e the casting is made to have no hole, is it possible this was a late change ?
Red Gauntlet
Member
Posts: 173
Joined: Wed Aug 19, 2020 11:22 am
Location: Dorset UK

Re: 1966 cyl head oil feeds ?

Post by Red Gauntlet »

Ah, yes there were many changes, it's a very late head, the exhaust valve will be fed from that slot at the base of the guide, I expect they worked out there was plenty of oil trapped in the coil valve springs to feed that guide. Even more reason to replace the guide if there is any doubt that the oilway has become clogged, a seized exhaust valve at speed is a real bear...
Dubbsy
Posts: 43
Joined: Thu Dec 02, 2021 4:07 pm
Location: Bedfordshire England

Re: 1966 cyl head oil feeds ?

Post by Dubbsy »

Thanks, I just checked the exhaust slot and ts nice and clear through to the inner guide. The inlet is an inigma though. As you can see the adjustable feed was deleted, but the guide is totally smooth inside with no groove or feed hole, so no chance of a feed of oil that way. Seems that the oil feed to inlets wad completely deleted? Is it that it now relies on splash feed around the stem? I can't locate anything on this but I'm also sure I read or heard about the late inlets having no direct feed
Red Gauntlet
Member
Posts: 173
Joined: Wed Aug 19, 2020 11:22 am
Location: Dorset UK

Re: 1966 cyl head oil feeds ?

Post by Red Gauntlet »

You need very little lubrication on the inlet, the fuel acts as a lube and the inrush of air keeps the valve relatively cool as well, the guide is normally cast iron so has a certain amount of natural lubricity anyway.
Locked