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MG TD TF 1500 - Rocker arm clearance

Been having a problem with a noisy lifter. 5th back from the front. I,ve adjusted to .012 hot. Noticed that this rocker can "wiggle" fore/aft a bit. I'd like to check clearance and rebuild if necessary.Original engine.
Peter 54 TF
Peter Dahlquist

Peter - I see no-one else has replied, so let me jump in. There are two areas to check with the issue you describe - rocker gear and cam gear. Check the cam issues first, then the rocker. If you have one, put a dial indicator on each rocker and measure the travel as the valve opens completely. You may find a worn lobe or two on the cam. Then take off the side cover and remove the rocker gear. (If your distributor needs rebuilding this is a good time to remove it and send it to Jeff Schlemmer at Advanced Distributor for a thorough service - money excellently spent. I know many owners who report that their cars have never run better than after Jeff has worked his magic.)

If there is sideways wiggle-movement to any rocker, the bushing(s) are worn out, and probably the rocker shaft is worn on the bottom where all the force is applied. This wear causes low oil pressure. You can buy a new rocker shaft and bushings, have the bushings installed and honed to fit, re-surface or re-stellite the rockers, and put it all back together. OR (my preferrence) send the whole shebang off to The Rocker Arm Specialist, and he will do a superb job of rebuilding it all, probably for less than your local machine shop would charge for all the individual steps. Remove and check the pushrods for loose cups and straightness; if a cup is loose it will tap just like a lifter issue. (Keep pushrods and tappets in order - see below.) A loose cup end can be tack-welded back tight, and then check all the shafts for straightness - just the shafts, not the ends. If you need them, I carry NOS Iskenderian pushrods (see mgtrepair.net for my listings).

While you are there, you should check the tappets and cam for wear and galling (keep the tappets in order - I use an egg carton for both, and punch holes in the lid for the pushrods). The lifters can generally be re-surfaced if there is any pitting, dimpling or visible wear - I use Delta Cam; they are very good and very reasonable, although I believe that the Rocker Arm Specialist can also re-do the tappets. You can look down the tappet holes and have someone turn the engine to see if any lobe is pitted or damaged, but it's harder to recognize a worn lobe from above (check with a dial indicator, as above).

I am confident that your tapping issue will be resolved by fixing one (or more) of the above problems. I'm only sorry you have a TF with a relatively inaccessible engine compartment! If you send everything off to be rebuilt, all you will need to order are the rocker stand bolt retaining plates, a new side cover gasket (check the bolts for stretch) and replace the bolts' fiber washers.

When you re-assemble use plenty of Lubriplate engine assembly grease on the cam and tappets, and remember to torque the large rocker stand bolts to 43 foot-pounds, the small ones to 19 foot-pounds (published torque values are wrong). Remember that you will have to break-in the new tappets, if you have yours rebuilt or replace them (Moss has a useful info sheet from Crane on how to do this).

Do let us know what you find out.

Tom Lange
Bar Harbor, Maine
t lange

This thread was discussed on 13/10/2011

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