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MG MGA - Replacing tappet screws

Hi Chaps, I want to replace the tappet screws and nuts on my pushrod A (some of the originals have damaged threads and are hard to adjust properly). I thought this was a simple matter of removing the rocker gear and replacing the screws/nuts on the bench, but the workshop manual says to drain the coolant and loosen all the head bolts before removing the rocker assembly in case the head distorts. Is it possible to change the screws without removing the rockers? I was also hoping to keep the pushrods in situ in case I lift any of the tappets out of their holes. Tips gratefully received!! Adrian B.
A Bennett

I would drain the fluid just so you dont get any contamination under the gasket. But when you lift the push rods just give them a small flick or twist or shake to ensure the cam follower stays in the engine and doesnt lift out. Also store the push rods in numbered holes in a sheet of cardboard so you can return them to the same follower.
DJ Lake

If all you are replacing is the adjusting nuts and screws on the end of the rocker there is no reason to remove the rocker or shaft. The pushrods stay in their holes also. Roll the engine around to the loosest point on one valve. Back off the valve adjustment and push the pushrod off the rocker. Replace the adjust screw and pry the pushrod back under the rocker. Adjust valve and repeat 7 more times.
The top of the screw may be damaged to much to screw it through the rocker smoothly. If so you must grind off the offending edges as to not damage the threads inside the rocker arm.
When replacing the rocker arms you must remove the rocker assenbly. To do that you must remove the head stud nuts. That is why there is a recommendation to drain the coolant. To replace just the nuts and adjuster you don't loosen head nust or drain coolant.
This advise is from memory I will verify in the morning when I am at work where the cars are.
R J Brown

This thread was discussed between 09/03/2008 and 10/03/2008

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