Page 1 of 2

Question on rockers...

Posted: Tue Jun 12, 2007 4:07 am
by jackkelleher
I'm dismantling my engine in situ, and just removed the cylinder head. I've just taken the rocker assembly to pieces, and the rod in the centre is, through time wear, unevenly blackened, and this residue will not come off with simple cloth cleaning. It means slight ridges on the rod, as well... Should I clean it off? If so, how? Will it be bad if I do, since it rather offends aesthetic sensibility (silly, I know, since it'll be hidden under a rocker cover, but still... :wink: ) and I would like to anyway?

Posted: Tue Jun 12, 2007 7:32 am
by bmcecosse
It's worn (shining) where the rockers have been rocking - and not worn (black) where there were no rockers. New shaft required - and possibly new bushes in the rockers themselves - although usually the wear is on the shaft only.

Posted: Tue Jun 12, 2007 4:00 pm
by jackkelleher
Oh, it's that way round, is it? All right, thank you. The bushes on the rockers look ok to my untrained eye, just the shaft that is pretty worn... Oh, and the balls on the rockers are worn on the lower halves (where contact is made, I suppose.) Should I replace those too? Oh, and the pads on the other ends of the rockers... But apart from that there doesn't seem too much wear.

Posted: Tue Jun 12, 2007 5:11 pm
by bmcecosse
Sounds bad! The 'balls' will be fine, and the pads you can stone flat - with a carborundum stone. But you do need a new shaft. Must be loads of Mini parts places out there (where exactly are you in USA ?) who will do you a shaft.

Posted: Mon Jun 18, 2007 6:12 pm
by jackkelleher
I suppose there will be... I'm in New Jersey, and in an area where loads of people have classics... There's a garage in the local town has a few Astons, a big Healey and a TR3 at the moment... Needless to say I'm covetous of that place!
I've now stripped out the rest of the engine, apart from crankshaft (I didn't take the block out of the car) and I have a few questions on wear in other parts of the car. Pretty raw deal- so far as I can tell tappets, camshaft bearings, big ends, pistons and rings, and plenty more will need replacing... :o But I'm going to start a new topic for those. Watch this space!

Posted: Mon Jun 18, 2007 6:13 pm
by jackkelleher
Oh, by the way, the pads have indentations of about 1 mm. Is that really bad?

Posted: Mon Jun 18, 2007 8:04 pm
by Packedup
jackkelleher wrote:Oh, by the way, the pads have indentations of about 1 mm. Is that really bad?
It's definitely not good.

Sounds like it's time for new rockers.

Posted: Mon Jun 18, 2007 9:04 pm
by bmcecosse
Yes - that's pretty bad - but could be sorted. Only worth it though if the bushes are unworn - otherwise sounds like a complete new rocker shaft assembly is the way to go. Camshaft bearings are impossible for the 'home mechanic' to replace - don't even think of it! Just noticed - your engine is 948 and therefore only has a camshaft bearing in the front position - the other two journals just run in the cast iron block! It's not impossible to renew that one bearing - but v difficult - don't attempt it.

Posted: Mon Jun 18, 2007 9:30 pm
by jackkelleher
Yes, I noticed in the manual it was most adamant about taking it down to my local BMC garage... Not quite so easy these days :)

Posted: Mon Jun 18, 2007 9:33 pm
by bmcecosse
It is possible to get new bearings - and I suppose to fit it if you make up the right tools - but then it needs to be 'line reamed' to size and in perfect alignment with the other two locations - which on the 948 are just the cast-iron block material !! Not for the home mechanic I fear.

Posted: Mon Jun 18, 2007 10:25 pm
by jackkelleher
No, indeed, especially an inexperienced one like me. Pity my first engine job turned out to be quite such a job...

Posted: Tue Jun 19, 2007 7:38 am
by bmcecosse
But i'm sure that front bearing will be fine - post up some pics of the damaged parts for us all to see !

Posted: Wed Jun 20, 2007 5:12 pm
by jackkelleher

Posted: Wed Jun 20, 2007 8:28 pm
by bmcecosse
The rocker pads are bad - but could be stoned back to flat (actually slightly curved) surface. the rocker shaft needs renewing. These big-end shells look fine - not to be reused, but as an indication of the crankshaft health I think it will be ok - probably won't need regrinding.
You DO need 4 new pistons and rings (1098 engine type) - and a full new set of bearing shells for the crankshaft, and a new rocker shaft. And I need to know more about the timing gear - can I have pics of that - and the timing cover please ?

Posted: Thu Jun 21, 2007 5:26 pm
by jackkelleher
New pics are up! Check the same url...

Posted: Thu Jun 21, 2007 7:03 pm
by bmcecosse
You can stone the rockers back to good as new using a carborundum stone with a little olive oil. may take a while - but think of the job satisfaction!

Posted: Fri Jun 22, 2007 8:55 am
by Dominic
I'd personally use a thin engine oil, or 3 in 1 rather than a vegetable oil such as olive oil... I'd prefer to save that for culinary purposes! It also tends to go gummy in time, clogging the pores of the stone.

Posted: Fri Jun 22, 2007 10:31 am
by bmcecosse
Official recommendation from my Toolmaker ! Personally - I agree - any thin oil should be fine, just don't do it dry!

Posted: Fri Jun 22, 2007 5:58 pm
by jackkelleher
Well, I have large supplies of both, so I'll go for it with the 3 in 1... Does the olive stuff work better with some crushed garlic thrown in? My rockers'll be scented nicely... 8)

Rocky Rockers

Posted: Thu Jul 12, 2007 10:19 pm
by tufty
My Moggy Motor had the same problems. :( I refaced the pads the same way. You will notice the ball end of the adjuster has a hole in it this to lubricate the push rod. If you cut a spare rocker in half you will find there are two galleries inside the pressed arm one going to the adjuster one going to the pad. Oil is supposed to feed from the rocker shaft out through the hole in the bearing and into the gallery. What happens is the gallery gets bunged up with carbon if the oil is not changed regularily. I boiled my rockers in Caustic Soda in an old pan whilst the wife was out :o Squirting oil in bearing proved the galleries were clear. Next myth you can change the bearings in pressed steel rockers but you will need to ream the new bearing to fit your nice new shiny shaft which is harder than it needs to be when you find that that new sparkly shaft is not parallel but is with in MOWOG limits. Because you live in a sensible country imperial bearings should not be hard to find. Here in Blighty the EU are trying there damdest to put us off the road with tripe about Metric threads etc. I build Model Steam engines for a living so the engineering part is simple for me, and should be possible at any small machine shop in your area :D