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MG MGB Technical - How do U adjust valves 'warm'??

The last time I adjusted the valves (last year) I followed the directions for doing them cold.... opps, I have a 1979 MGB and they should be set at 13 warm.

So the question is this: how do I keep the valves warm enough while I adjust them?

If I go for a ride and drive about 30 minutes first, pull plugs, valve cover... will the valves stay warm enough? Doing this in an unheated garage, hope next week if we get a day about 50 degrees.

Any tips or ideas? Looking forward to your replies.

Don
1979 mgb roadster

Donald Wheeler

Go for a run for about 20 mins, take off the cover and then take some of the torque off the nuts, start the engine and set the clearances with it idling.

There is a lot about this in the archives.
Iain MacKintosh

Oh and Donald, wear an old shirt and be prepared to scrub the engine down afterward. The oil does get around.
As Iain said, lots of info on this in the archives.
Lewis

I found that if I am careful adjusting them cold when warm they were all pretty much spot on. Last time I did it I just had to tweak one slightly.
Simon Jansen

Its not too much of an issue hot or cold wth a standard head.

The valves and pushrods have about the same coefficient of expansion as the head and block (perhaps a fraction more).

Easiest way to check this is to set them cold or warm, and check later after a run.

Different for alloy heads, expansion aluminium is greater than that of steel / cast iron.

Valves can be adjusted while running. Its messy, frustrating, and can badly damage your feeler guage if the rocker tips are even slightly hollowed.

Cheers
ian F
Ian Fraser

Donald,

I do not like that procedure as it ruins you 0,015in feeler gauge. And it is messy but good for dry skin.

A static adjustement is more than adequate.

JGC
Jean Guy Catford

Donald. Take the car for a drive, sufficient for the cylinder head temperature gauge to show the engine warmed up. Drive into the garage. Remove the rocker arm cover. Adjust the valves as per the order in the factory workshop manual/Driver's Handbook. They will do fine.

Have used this procedure for something over 38 years now and have never had a problem with it.

Les
Les Bengtson

Yes, provided that the rocker pads are perfectly flat it will be OK but that is seldom the case and in addition it allows you very quickly locate the noisy rocker and sort it out. Never use a good set of feeler guages, keep an old set for this. Running clearances are much more accurate, my GT idles almost completely silently at a .015" running setting
Iain MacKintosh

For the last 30 years I have warmed the engine to operating temperature and set the lash with the engine not running. The valves stems will expand more than any other component in the valve train since it gets the hottest, thereby closing the lash. The exhaust expand more than the intakes.

I use the "go/no go" method. I use two feeler gauges, in your case they would be a .014 and .016. The lash is set so the .014 gauge is loose and the .016 would not fit or be extremely tight.

These are the methods I have learned from racing the MGB for 30+ years.
Glen Popejoy

I use the same go and no-go feelers like Glenn, but 15 thou is the *cold* figure. Other than helping you stay warm on a cold day I don't see any advantage in setting them hot. For several years I had a problem getting a repeatable clearance, until I discovered that at the regular 'rule of nine' adjustment point the clearances on some valves were still changing. Now I adjust these slightly to one side or the other of the strict 'rule of nine' point, where they are no longer changing. Not only can I get repeatable clearances now but it is also a bit quieter.
Paul Hunt 2

Hey, thanks for all the replies. As I am a "little" slow on how "fast" I could work on setting the valves, I'll go with doing them at 15 (using the go-no go method) and doing them while the engine is cold.

I really don't mind a little tappet noise, just want to make sure they are set close enough to spec's.

Plus, I always wear old clothes... I tend to make a mess....

Spring is coming! See you on the road, wave, when you go by!

Don 1979 MGB
Donald Wheeler

Ian F., et al - I have the aluminum alloy head as well as a performance cam. The clearance specs given by the cam manufacturer is .017. I do not recall if that is to be set cold or operating temp. I did set the clearances at opertaing temp at .017 and that did quiet the valve train.

I like the idea of the "go/no go" method outline by Glen. Next time I will use that procedure - thanx

cheers,

Gary :>{D
gnhansen

This thread was discussed between 03/03/2006 and 12/03/2006

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