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MG MG Y Type - Polished rockers

Attached is a picture of how my rockers will look when I'm finished.

I know the engine won't perform better and the will be invisible, but I just think it looks good.

Willem vd Veer

and another

Willem vd Veer

Hope they look as nice after a couple of hundred miles in hot oil Willem ... or you will be off your rocker!!
Paul Barrow

I'm sure they will tarnish, but surely less dirt will be able to cling to the highly polished surface?
Willem vd Veer

Very nice Willem but be careful you dont invest too much in a material object...there's a balance to these things ...I have to keep reminding myself...God first, neighbour and myself...than Y types ha ha ! We are all a work in progress in these matters.
D MULLEN

Hi Willem,

Cant wait to see the con-rods and crank!

Rob
Rob King

Hi Willem,

for sure they look much better and I've thought about polishing those things (casting marks on crank, con rods) as well - but then it came to my mind that there might be a reason for such a surface.

Beside the cost factor producing them there seems to be the reason that oil will stick much longer to a rough surface than to a polished one.

Maybe a member with more knowledge can clear this?

Anyway - nice job!

Regards
Manfred
M. G. Schulz

No Rob, I won't do the conrods and crank for the same reasons Manfred has in mind.

The conrods on highly tuned race-engines are polished (always in longitudal direction) to reduce the risk of breaking, but I don't trust my own polishing efforts to risk them on such important parts. The rockers are much less vulnerable.

I would love to do the cranckshaft because it is the ugliest piece of casting I've ever seen, crudely ground off for balancing at the factory. But again I'm afraid of doing damage.

In David Vizards' 'Tuning the A-series engine' a chapter is dedicated to polishing and lightening engine parts. For the cranckshaft that involves several machining and hardening processes and I'm not prepared to go that far.
Willem vd Veer

Rough surfaces both hold oil/lube and give more surface for heat dissipation. Paul
Paul Gaynor

Hi Willem, very nice indeed. But it reminds me of a friend of mine some time back who purchased a very large expensive Dining Room table. Very ornate, heavily carved built of solid English Oak with ten seats. When showing it off to his father, the father replied "Yes son, it is very nice, but the food you eat at it will still taste the same"
The food he ate at it still did taste the same but he still has the table and he is still very proud of it. As you should be of your rockers.
Terry
T J Ciantar

Nice job Willem
I'm a great fan of shiney engine internals, there's something special about knowing they are in there and you put them there
AND if it sadly blows apart at least the bits left on the track look special -- well better than rough old cast stuff eh.
Cheers Willy

Years ago, building Chev speedway engines we polished everything , even the inside surfaces of the block
It really helps the oil drainage back to the sump where it needs to be at racing speeds---------
William Revit

'Off your rockers' springs to mind ha ha but each to his own I suppose and if makes you happy and does no harm go for it!.
D MULLEN

Villem, you should put a glass window in the valve cover!
Art Pearse

Interesting anecdote: there is a neat little aircraft museum in Arizona, halfway between Williams and the Grand Canyon. One of the displays is a Japanese plane that crashed in New Guinea circa 1942. The plane and the land it is lying in was extracted from the island and sent to the museum. The planes' engine components are visible because the top
cover is missing,the crankshaft is overhead and the cylinders are down below. All the parts had been beautifully polished at the factory and most were still very shiny despite more than forty years exposure to the elements at the jungle crash site!
S.R. Barrow

The polished internals of several aircraft engines I've seen on display are in fact the inspiration for this folly.
Willem vd Veer

I think some of you may be missing the point of polishing. In the case of the rockers, polishing the leveraging parts, will remove any roughness where a crack might start. Furthermore and stresses are evenly distributed with a polished surface. I'm not sure polishing the shaft bosses is worthwhile because they are quite robust and unlikely to crack in this area (I'll bet somone proves me wrong).

In my present XPAG, I have indeed polished tbe rods to a mirror finish for reasons outlined above.

I have gone to meticulous care to balance everything. The small ends and big ends have been matched end-for-end using mandrels and two pan balances. I played the "shell game" with the bearings, wrist pins, pinch bolts, rod bolts, pistons and piston rings 'till I got each rod assembly the same as the other, all within .1 gram.

All rotating parts - flywheel, clutch, pulley and cranksshaft have been dynamically balanced.

Needless to say, my engine is very smooth.

Gord Clark
Rockburn, Qué.
Gordon A Clark

You only need to polish the internal components and balance everything if you intend to race or drive your MG very hard. For average daily use it achieves less than you might imgaine in my opinion. I rebuilt my YB engine at home - had it rebored locally, fitted new pistons etc and had the crank reground to +60, cleaned up the c/head..this was back in 1989 and only recently I took it all apart again (mind you it had done less than 20,000) and only had to fit new big end shells, the mains being fine. I did not balance the flywheel or crack test the crank or polish anything but then I dont drive the YB hard. The head was dismantled and valves reground etc. I fitted new rockers and a rocker shaft as the old one was a bit past it in even in '89. The old push rods were fine and only one cam follower needed replacing with a spare one I had. Cam shaft was OK with not too much wear on it.The timing chain assembly which I had fitted in 1989 seemed fine too. I also used a new old stock cork seal for the rear crank and currently have no leaks. New core plugs were fitted and water ways cleaned out etc - it runs fine..most of the problems I had over the years were down to needing a distributor rebuild. These engines are simple, tough and really dont need pampering unless you intend to thrash it...but if it makes you happy to go to these lengths that's fine. You can spend a fortune rebuilding an XPAG if you want but being a tough little unit it is not really necessary - its just an old OHV engine - nothing complicated about it at all despite what MG specialists charge to rebuild them. Mind you if you have spent a lot of money on the rest of the car and have the money and are a perfectionist it does makes sense not to skimp on the engine. Mind you if something drastic does happen to mine I promise to own up !
D MULLEN

David,

As I said earlier, the polishing is a bit excessive in a road car, although I agree with Gord that it reduces risks of cracking.

Balancing however is very benificial to our cars. Especially because it is just an old OHV engine.

I'm on a rather tight budget with this overhaul, but I am going to invest in having all rotating (crankshaft connected) parts balanced. At some time a new crankshaft was fitted and I fitted a new clutch assembly. God only knows what other parts are not factory fitted.
With so many differently sourced parts in one assembly, it pays to have it balanced as a whole and the engine will be much smoother as a result.
Apparently you can let a fully balanced engine idle at 450 RPM (you shouldn't, but you can), an unbalanced engine will stall or run very rough.
With a balanced engine you can also have the flywheel lightened, making the engine much livelier.
Willem vd Veer

This thread was discussed between 10/06/2012 and 17/08/2012

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