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MG Car Repair/Adjusting valves on new Head 18V


QUESTION: hi Barrie - I removed my old head, and will install the new one with factory valves pre-installed. When it comes to setting valves my assumption is that one would need start with #1 at TDC and the distributor aligned to fire, and then proceed to adjust them in sequence ie 1-8, 2-7, etc..

Wondering if this is correct- and also if there is a good guide out there to follow along ( Haynes only covers adjusting existing valves)

thanks !


The quickest and easiest way to set the valve clearances is to install the new head and tighten all the valves to about .020, turning the engine once so you can set any valves that were open.  You do not need a feeler gauge at this stage, just do it by eye.

Next, turn the engine until two of the valves are fully open.  Set the two that are now fully shut using a feeler gauge.  You can use the "rule of 9" but I just count from the other end of the engine, which makes it very simple.  If valve #1 is open, then the last valve (#8) will be shut.  Third one open, third from the back is shut, and so on.   

Next give the engine a half turn on the crankshaft and you will see that two more valves are fully open.  Repeat the process until all the valve clearances have been set.

I hope this is clear.

---------- FOLLOW-UP ----------

QUESTION: Got it. however - can you advise how to get valves in the correct starting position? Once I lower the new head down to the block, is there a trick to compressing the valves? They are all in closed position, and the pushrods will be in various positions -open \ closed . Will I need to slowly rotate the crankshaft and set the pushrods one by one?

Hi Paul

Assuming that you have changed the head but kept the old rockers, they will usually only need fine adjustment.  For safety you could undo the 8 locknots and back all of the adjusters right off.

First fit the head to the block with no spark plugs, no rockers and a new head gasket.

Torque the head down to 40 foot-pounds as a starting figure.  

Bolt the rocker pedestals to the head.  

You can now adjust 6 of them to approximately .020 clearance.  The clearance is not critical. You will probably notice that two of the rockers are trying to push a valve open.  Leave those two fully retracted.  

Finally, turn the crank through 180 degrees, and adjust the two that were retracted.

You now have a starting position for setting the valves two by two as per my previous instructions.  

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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