....So the XPAG is noisy, like all the other ohv engines of its day. The side-valve engines had fewer gaps between its camshaft and valve, and it was all buried down the side of the engine, so little 918cc Morris Eights sounded like sewing machines. The XPAG, coming from the Morris family of engines, had a thin pressed steel rocker cover that can almost act as a sounding board, and it did not prevent noise from getting out. The simple fact that an ohv engine changes the direction of its actions through 180 degrees from the cam lobe to the valve stem does not help.
Wear will cause the tip of the case-hardened camshaft lobe to wear, and this eats away the underside of the tappet, eventually causing it to concave and break up. The tappet also gets a lot of thrust in the direction of rotation of the cam, so it wears its hole oval, (you can get oversized +.010” tappets, many Gold Seal engine have them already). The oval hole with its sloppy tappet is a major cause of clatter, and no amount of adjusting the gap will cure it. It is very like piston-slap, but at half-engine speed. The ends of the push rods work loose, and cause more noise. But the item that is easy to change and will remove lots of excess noise, is the rocker shaft. It gets very badly worn on its under-side with the action of the valves and camshaft shoving upwards twice each cycle. It is also the last place to get any oil on starting up a cold engine.
There are lots of other culprits under the bonnet that cause noise, a very powerful one is any carburetters that have no air-filters fitted. Pancake air-filters do little silencing of the intake-air, and that is why the Y saloons have a large intake ‘silencer’ above their single carburettor. The fan will roar away at speed, its very inefficient flat-spade like paddles bashing the air stupid as it pulls it through the radiator. Worn and cold engines will display piston-slap if run at too low an rpm in gear. This will mostly disappear once everything warms up to its running temperature. A badly worn camshaft lobe will make a sound like a diesel engine idling, and has fooled some into thinking a big end is on the way out. A worn timing-chain will clatter about at idle.
j'ai toujours fait ,et entendu,qu'il faut faire les réglages a froidJidé de Grasse a écrit :une question bête au sujet du jeu culbuteur/tige.
Pour moi le réglage se fait à froid afin que à chaud, avec la dilatation du métal il ne reste quasi plus de jeu afin d'optimiser la levée de la soupape.
Du coup je suis étonné des valeurs données par xavier. Il reste 5/10° de jeu à chaud ? pas étonnant que ça claque non ???
merci d'éclairer ma lanterne
et ça ,date pas d'hier 0.38 c' est pour une B à froid.0,38 à froid?, on est 1/10 en dessous de ce qui est préconisé par le manuel à chaud (0,48)
My opinion est qu'il est peut être encore temps de sauver les soldats soupapes en adoptant un réglage correct.xavier60550 a écrit :bonjour à tous,
La personne qui m'a vendu la MG TD et qui en possède une autre totalement restaurée m'indique qu'il est réglé à 0,30 et qu'il roule déjà depuis un bon bout de temps avec sans aucun problème.
Your opinion?
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