Rocker Arms & Rocker Shaft Assembly

[pgp001]

Well they arrived today. And they are going straight back again tomorrow

The bushes were undersize by about .0025" so they would not even go onto my brand new rocker shaft. I turned up a short shaft to try them on to see what size they were, then I used that to hold them in a vee block for measuring squareness etc.
The contact pads were nearly all twisted in the same direction and when set up on a surface plate you can get a 0.015" feeler gauge under one side of the pads. Looking down on top of them some appear to be bent sideways as well.

So they are totally unfit for purpose, how they manage to keep selling these is a complete mystery to me, they have obviously known about the quality issues for years and done nothing about it.

These came in "County" branded boxes, I am guessing they originated from the same place we got Covid-19 from.
I am not normally one for naming and shaming, but I am not a happy bunny.

Phil

[pgp001]

Having had the bad experience with repro forged rockers, I am now looking at a set of sintered ones that I have bought for not much money and in good condition.

I have been giving them a good clean up in my ultrasonic tank, and on inspection noticed that there is an oil hole running from the main bore up the back of the rocker into the tapped hole where the adjuster goes.

Does anyone know what the purpose of this hole is, as it will be just a blind hole when the adjuster is in place.

Thanks
Phil

[philthehill]

The original purpose of the hole was to allow oil to flow to the waisted and hollow rocker adjuster screw and then down the centre of the screw into the cup of the push rod and then down the rod to the cam follower and then back to the sump.
The waisted adjust screw was prone to breaking and BMC discontinued this process when they fitted a non waisted adjustment screw.
Even though oil is not flowing as originally no harm will come to the rocker train because there is no oil is flowing through the oil hole. There is plenty of oil being thrown around inside the rocker cover to lubricate everything.

If you have waisted and hollow rocker adjustment screws I would recommend that they are changed to the non hollow waisted type to remove any possibility of adjustment screw breakage. The screws can be replaced without removing the rocker shaft or rockers.

[pgp001]

Thanks Phil

I have the whole lot stripped down for cleaning and fitting a new shaft at the moment.
It already has the later solid adjusters fitted so no problem there.

The original rocker assembly that I removed from this spare engine has hollow adjusters, so probably another good reason to ditch it as well as the rest of it being well worn out.

Phil

[philthehill]

If the rocker pillars are forged steel keep them as they can be machined to centre the pressed steel or forged rockers over the valve stem tip. If they are alloy put them in the scrap bin.

[pgp001]

Phil

They are certainly not alloy as my magnet will stick to them, they are a slightly different shape to the ones on the old pressed steel rocker assembly. I think these might be sintered as well as the actual rockers themselves.

I guess the old pillars from the pressed steel rocker assembly are forged as there is some evidence of dressing the flash from them with a grinder, I wondered if I should be using those instead of the ones on the sintered assembly ?
They may need the sides locally spot facing in the lathe as they are a tad wider where the rockers sit.

Phil

[philthehill]

There is no advantage in using the sintered rockers with the forged steel rockers. Only those rockers that have a central pivot boss can be recessed into the forged steel pillar. Therefore it is best to use sintered rockers with sintered steel pillars.
Below is a picture of a forged steel rocker pillar being recessed for a forged rocker so as to enable the rocker pad to be centrally placed over the valve stem tip.
Phil

100_2629 (2).JPG (160.66 KiB) Viewed 541 times

And this is the result of that machining:-
Forged rockers and forged rocker pillars

100_2637.JPG (1.24 MiB) Viewed 541 times