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MG MGB Technical - Rocker arm life expectancy

What is the average life expectancy of the faces of the rocker arms? I have a 79 B with 75,000 miles that I am about to replace the rocker shaft on but was wondering approximatley how much longer I had before I might need a whole new (remanufactured) rocker shaft/arm assembly. I realize there is no pat answer to this and it will depend on how the car has been cared for but was wondering what was the experience of the group.
Frank

Just get the existing rockers refaced to take the depression out - a light touch on a fine grinding wheel is all that is required - keeping the original profile.
Chris Betson

Frank,

I searched high and low for a machine shop that would reface my rockers in this area. I couldn't find one. It seems they used some sort of special jig to maintain the curve on the faces. And no one has the jig anymore.

I fixed one of mine with a file and didn't see any problems. But then I had a valve job done within a year and replaced the whole assembly at that time. I was afraid my 'repair' would side load the valve and damage the stem or guide.

The machinist didn't mention that anything was oddly ruined on that valve. But then everything was pretty well worn out.

FWIW,

Matt K.
Matt Kulka

Frank-
You said it best: "there is no pat answer to this and it will depend on how the car has been cared for". That being the case, take a hard look at the faces of each of the rocker arms. If all you see is a wipe mark, you're OK. If you can see a groove, scrape the end of your fingernail over it. If you can detect it that way, you'd be wise to just go ahead and replace it now. Unless you have a gunson's Clickadjust tool, setting the valves to proper clearances is almost impossible with that groove present.
Steve S.

Delta Camshaft of Tacoma Washington will reface rocker arms for you at a reasonable rate (they also do a great job on cam shafts). Their address is:
Delta Camshaft
1938 Tacoma Ave. S
Tacoma, WA 98402
(800) 562-5500

Cheers - Dave
David DuBois

David, Can Delta cams rebush MG rocker arms? I asked because I bought a reconditioned rocker shaft assembly, the rocker contact faces were reground with a rather course grinder. You could run your finger nails over it and feel the grind marks. I installed it on the engine I was rebuilding and it made lots of unwanted noise. I removed the shaft and hand polished each rocker with emery cloth but still couldn't get all the grind marks out but is is a lot quieter. The grind marks were prependicular to the rocker arm movement so they made a noise as they opend the valves due to shear action of the rocker on the valve stem. I hope "shear" describes what I'm trying to say.

I bought the rocker assembly from a supplier who buys all his parts from the UK so I'm reluctant to buy another one unless I can look at it before buying. I have a spare worn rocker assembly and it may be best to rebuild it.

Regards, Clifton
Clifton Gordon

This thread was discussed between 16/10/2002 and 17/10/2002

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