Motor typ 4 GE

[vjachym]

Good day
I have a VW T2b year of manufacture 1978 with a type 4 GE engine. I would ask for advice. I made the engine, including new hydraulic tappets and camshafts, and after the engine has been installed, I don't know what clearance I should set when the valve clearance is not to be adjusted because they are hydraulic. But even in the factory, they probably had to set some basic will. Can someone please advise me?

[Wildthings]

You have to have the piston at TDC compression for the cylinder you are setting the valves on. You need to loosen the nut for the adjusting screw and back the screw off until you have lash and then turn the screw back in slowly using just your fingers until the screw just touches the end of the valve stem, this can be very subtle. Now turn the screw in two full turns and tighten the nut.

If you try and adjust your valves at TDC exhaust your adjustment will be way off, so it is very important to get the crank in the correct position.

If your lifters are 100% full of oil it can help to do the two cylinders on one side and then run the engine for a few minutes before adjusting the other side. It helps to have the engine no warmer than 40°C when adjusting the valves so you don't burn yourself. Lifters tend to pump up faster when using a thin oil like a 5w30, and like a synthetic oil to keep them clean.

If your lifter have very little oil in them there are tricks to getting them to pump up.

[vjachym]

thank you for the info
the engine is completely oil-free, the camshaft and the peeling tappets have been changed. should I tighten two more turns after touching the shaft?

[Wildthings]

The adjusting screw runs against the end of the valve stem. You initially create slack in the system by backing the screw off and then without applying any pressure that might compress the lifter you turn the screw in until it just contacts the end of the valve stem again. This point can be fairly difficult to determine if you use a screwdriver to turn the screw as it can be barely perceptible so just use your fingers. After contact you turn the screw two more full turns.

If you did not fill the lifters with oil it can take a long time for them to fill up and your engine will be very noisy until they do fill.

[SGKent]

what is your native language?
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[germansupplyscott]

Two turns of preload (2 turns past) contact is too much on a new engine where the lifters will be new and should easily pump up and hold pressure.

With a new engine I recommend 3/4 turn past contact as an initial setting. Start the engine and let it get fully warm. You will hear if the lifters are not pumped up. The noise can be a bit disturbing but it's better to have a loose lifter than too tight. Allow the lifters to fully pressurize and the engine will quiet down eventually. Let the engine cool and check clearances again.

A good condition hydraulic lifter engine will almost always run very nicely with 3/4 turn of preload and in most cases it will run better (than 2 turns) because the valves will be fully close. 2 turns of preload can and does permit the valve to never be fully closed, as well it encourages cam wear due to constant firm contact between cam and lifter.
_________________
SL

[Wildthings]

[babysnakes]

[ratwell]

[airschooled]

Be aware, some new hydraulic lifters do not have the same internal dimensions as original lifters. I spoke with a handful of engine builders, and the average spec they used was 3/4 turns preload.

Call the manufacturer of the lifters and ask what they recommend.

Good luck,
Robbie
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[Abscate]

[ratwell]

[germansupplyscott]

[Wildthings]

[ratwell]

I'm going to posit that the 3/4 turn adjustment advice is originating from Web Cam which recommends one half to one full turn using their lifters:

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'78 Westfalia CDN
'76 Doublecab
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[vjachym]

I'm from Czech Republic

[Wildthings]

The load on the lifter doesn't change with the adjustment as Scott seems to claim, the load is determined by the valve spring specs and the force needed to accelerate the mass of the valve train when the valve is being opened. The preload has nothing to do with this, excepting less preload means the lifter has more oil in it and is a bit heavier adding to the opening force and the amount of preload causes a slight change in the rocker geometry.

What the preload does is determine how much wear you can have in the valve train before the piston in the lifter bottoms out at one end or the other of its travel. The wear of the valve against its seat is going to be pretty small, maybe 0.001" over 20-30K miles, while the wear of the lifter against the cam is apt to be many times that, same with the wear of the adjusting screw against the end of the valve stem. The lifters start out with a crown of maybe 0.020" and by 100K miles will have a dish in the wear face of some 0.020" or maybe more and the valve stem may have worn about 0.010" as well. This wear would total around 0.050" while if the preload is set at only 3/4 turn you can only tolerate 0.030" of wear before you have no preload any longer. Yes I am not taking the rocker ratio into account here, nor am I taking the effects of a loose valve seat into account, as once a valve seat starts working the heads have very few miles left in them.

It seems that people who claim that low levels of preload are all you need also are often the same ones that claim the hydraulic valves need to be adjusted frequently. This is kind of a "well duh" moment. Since using less preload defeats the reason for having preload in the first place then yes, frequent adjustment would be needed when the preload is decreased.

[babysnakes]

[ratwell]

[germansupplyscott]

In my experience hydraulic lifters should be adjusted to no more than 3/4 turn preload. '78 - '82.5 hydraulic lifter aircooled engines have the worst cam wear of any aircooled engine. Because I specialize in Bay Bus parts and repairs I have taken many of these apart—and it's not close. You (Ratwell) ask basically "how does this 'over-preloading' affect how the engine runs?" My answer is "The engine runs better with 3/4 turn" (try it) Sometimes empirical knowledge has value. I analyze things in abstract ways sometimes, sometimes your fingers and nose and ears are pretty good at analyzing.

"Wynne's Engine Tune Up" is an excellent product to free up lifters that otherwise won't pump up, maybe engine has had dirty oil in it or lived a hard life. It's never failed for me to quieten a noisy hydraulic lifter engine. Oil should be drained after using it.
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SL