Spect for the rocker gap on inlet and exsort vouls

Valve lash is the end of the rocker arm and the valve stem clearance between. When the engine is running, due to the thermal expansion and contraction, if there is no gap between the rocker arm and the valve stem, rocker arm swells, the top valve open, the impact of engine power and economy. Engine valve clearance will be different, usually when the car is cold, the intake valve 0.08-0.10MM, clearance exhaust valves 0.10-0.12MM Car Diagnostic Tool

look at rocker arm for bends or to tight. spect all when you damage one it puts undo stress on others could have more than one bent rod. make sure all arm are coming up and down, by watching rocker while rotating engine. un hook distrubor line to keep from running while checking it

valve cover? when was the last time it was serviced. sounds so far like a burnt valve.

12th inlet 15 exhaust will do it

your not setting lifter gap,
your setting rocker arm gaps!

MOTORCRAFT Part # SP420 {#BSF42C, BSF42CF4}
.044" Gap
this gap has been he same for years, who told u 0.26"?

Advice, call Mazda dealership, mechanic or autozone.

Hi,
The method of adjusting the tappets is the same on most engines that don't have hydraulic tappets.
The gap between rocker arm pad and the top of the valve stem is important for several reasons - to allow for expansion of the metal, to ensure that the valve is fully closed when needed, and to ensure the smooth running/timing of the engine.


The rocker cover gasket or oil filler cap leak eventually over a period of time and the top of the engine gets in a right mess, like the one shown here.
Remove the filler (series have a 7/16" bolt in the side of the cover to retain the filler)
The heater hoses are held by one of the three acorn nuts that hold the rocker cover on. Remove the center nut, and then slacken the 10mm pinch bolt enough for the pipe support to be removed.
Remove the other two acorn nuts and alloy washers, then the rocker cover will lift away.
Each tappet should have a locknut and slotted thread - you will need a 13mm ring spanner and blade screwdriver.
Starting at the front of the engine - turn the crankshaft by way of the crank bolt until No2 valve is open. The camshaft lobe for No1 is now out of the way and the tappet for it can be adjusted. Undo the locknut a couple of turns - if the threaded part turns as well, then keep it still with a screwdriver.
Insert the right thickness blade in the gap between the rocker pad and top of the valve stem and turn the tappet thread until the blade is slightly pinched. Keep the screwdriver dead still and tighten the locknut.
You may find that the tappet gap will close too much when you tighten the locknut. If that happens, then re-set the gap, allowing for this. Work through all 8-tappets, making sure that you set the correct gap for the valve - inlet or exhaust. Once done - clean around the top of the head, the gasket faces, and the rocker cover inside and out. Sticky gaskets are very handy.
Refit the cover, use new alloy washers on the three studs, and re-attach the heater hose clamp.
For pictures you can refer to: http://forums.lr4x4.com/index.php?showtopic=8023

Thank You for contacting Fixya.com

If your engine has a (reasonably) tall, blue rocker cover it'll be a chain driven camshaft. If you have a relatively flat, black rocker cover then you probably have the Z series engine which is belt driven. If the belt/chain has jumped a tooth the ignition timing will be a mile out. Be sure to disconnect the vacuum advance pipe when checking the ignition timing, especially with the Z series engine. If you have the blue rocker cover, that engine was prone to inlet manifold gasket failure & the spark plug colours should confirm/eliminate that. Gap the points to 20 thou/0.5mm. The white lead connects the points to the outside of the distributor & then on to the coil.