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V-12 Valve Adjustment

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If you are refering to engines with hydraulic tappets they should be "dead" quiet. The tappets do wear a bit over time and the check valves in them get dirty but if they are in good shape they should be quiet with little or no noise. The Ford sevice manuals don't specify an adjustment but when doing a valve grind it's best to check the clearance to make sure the hydraulic plungers don't "bottom out" when the tappet is on the heel of the cam lobe. Generally the clearance between the valve stem and the hydraulic plunger should be between .030" to .070" when pushing down the plunger ( against it's spring) and the tappet at the heel of the cam. The tappet has to be "dry", no oil in it to do this.

There is really no easy way to check clearances on an assembled engine. Noisy tappets are almost always caused by dirt, wear or extremely low oil pressure. Other elements that can cause tappet noise restricted by pass valve or oil filter lines as these items "feed" the secondary oil sytem for the hydraulic tappets.

Some engines have been converted to adjustable tappets but if the cam was not reground with clearance ramps the result was very noisy valve train no matter how careful the valve clearances were set. The '36 and '37 engines came with solid tappets and were fairly quiet.

To change valve clearances on engines with hydraulic tappets requires any of the following: grinding the valve seat, refacing the valve or grinding the stem.

Edited by peecher (see edit history)
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The hydraulic valve train make the lz v-12 a real marvel..My old zefferist friend has

a v-12 named Henry, that is silent; all you can here is the generator brushes...

The valve lifters get pressure from oil pump main feed, which is excessive..volume and pressure..sooooo it is metered down by a little brass valve, poppet thing like an orfice to feed the lifters.....at the end of the lifter tube is a ball and spring...the tighter the spring, the higher pressure for lifters and less left over for the timing gear..The lifters tend to leak or mist and as such create an oilly enviroment for leaky split valve guides ..which in a high vacuum condition, suck this oil into combustion chamber ..and you got a stinkin lincoln.....so...study up..on what you got..and what your trying to fix... fun stuff!

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