The V8 Owners Forum -

A pair of my Crane roller-tipped rocker arms have been irreversibly damaged as they were not being lubricated. I can see that oil has travelled along the rocker shaft from the oil feed hole end, but there must be reduced pressure as the shaft gets more and more dry and completely dry at the far end.

The two rocker arms atop number 1 cylinder seized on the shaft.

It happened out of the blue without any link to any earlier tinkering beneath the rocker covers which haven't been removed for a year or so.

I can only think that the oil feed hole had become partially blocked.

I wonder if anybody out there has experienced this? My next step is to remove the head and get it cleaned up, spend £800 on a new set of roller rockers hoping that the good clean has resolved it.

Regards
Nicholas

Was there plenty oil pooling in the head recesses?

Not really - it did all seem rather dry around the number 1 cylinder area and of course those rocker arms were bone dry

I replaced a gasket on mine recently, and there was lots of oil floating around. But my engine is high miles, so may have worn shafts - even although the valve train is quiet.

Are the pedestals on the correct way - if not the can block the oil feed holes.

Thank you but I haven't touched the rocker gear other than adjusting valve clearances occasionally.

It just happened out of the blue following a few years of happy running on road and track. I guess it must be a blocked oil feed hole and shall remove the head. Perhaps time to inspect the camshaft and tappets anyway.

Regards
Nicholas

The plot thickens. Having taken off the rocker gear and head, it becomes obvious that the oil feed hole is located at the front. Oddly, it's those front two rockers which were the most damaged. But now I see that all of them have suffered damage to the internal surface. However, there is oil in cavities in the head and sploshed over the rocker arms.

The oil feed hole has been restricted in size on both sides, using small inserts. Bearing in mind this is a Tuscan engine and I have never seen a standard engine, is this restriction normal?

Just to be clear, is the oil feed hole literally the only way that oil reaches the top of the head?

Thank you again for assisting me.
Regards
Nicholas

Some builders fit restrictors to limit rocker oiling this increases oiling elsewhere also, often carried out with roller rockers etc and no not standard, unless its been fitted with hollow push-rods the single front port on each bank to cyl head is the only oil supply to rocker gear

Im thinkin that these are bushed rockers coz they siezed onto the shaft ,I would have thought the oil restrictors would only be fitted to a needle roller pivoted rocker set up as the bush would require some oil pressure to prevent siezure .....much like a big end or main. I think its unlikely that both banks would suffer a blockage at the same time, more likely something common to both, I guess you need to verify oil pressure.....maybe stuck relief valve ?

Yesterday I fitted Yella Terra roller Rockers - the version which slide onto the standard rocker shaft. Just noting that it is imperative that the shafts are fitted so that the oil holes face down and in towards the V. Nevertheless, the rocker arm at the front and the one at the rear, don't get the same strong oiling as the others. Specifically the oil coming out of the little lubrication hole at the top of each arm is not as generous as the other 6 rocker arms - but more than sufficient.

My technical query is this, given the pooling of oil which floods the top of the valves stems, what prevents oil from being drawn into the combustion chambers?
Regards

Just the valve guide oil seals + the fit of the valve into the guide I guess.

Chris.