Does the Datsun h20 engine found in the forklift from the 1980's bend valves if the chain breaks ?

I'm not positive but I don't think any engine with a timing chain rather than a timing belt will bend valves if the chain breaks.

yes broken timing chain can and will damage an engine do not run vehicle until repair is made
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Nissan Forklift Engine parts guides TIFFIN PARTS

Pull the distributor and check if the gear on end of dist. shaft is attached. The roll pin holding the gear may have sheared off.

If it is not the distributor, check the timing chain still works.

The 4 cyl and V6 engines both use a chain. They should not be interference engines.

No you don't always bend valves typically with 4 or 6 cylinder engines are equiped with free floating engines that when the chains or belts break it allows the engine from creating greater damage to other parts of your engine

at the dealer we rec them at 100k,,,,even if its not noisy or anything,it is a constant wear and tear item and the chain is no bigger or stronger than a bicycke chain,,,,they stretch and can break,and if the tensioner breaks or releases tension,its as bad as the chain breaking,either way the pistons will hit the valves and bend the valves,,,,also the timing chain guides are plastic and wear out,i would rec doing it,,,,but do the guides (2) front and rear and the chain,the tensioner,and lower crank sprocket and cam gears,,,,,if the car is in good shape and youre gonna keep it do it,,,if not,,,risk it and let it go,it may never break,,,but i would do it

With a new motor most likley. When a timing chains break pistons tend to collide with valves which can punch holes in the pistons or bend/ break valves. Usually at this point it is more economical to replace the engine than to actually fix it.

http://forums.nicoclub.com/zerothread?id=428078

Here is a link to a Datsan Fourm hope this helps

This car has hydraulic lifters( tappets} therefore should not adjustment, you probably have a bad or weak lifter. But, in any case you have to remove the valve covers to make the adjustment. You will see the adjustable bolt on the rocker arm. rotate the engine until the valve is all the way to the top, [no tension on the valve spring] then place a feeler Gage in between the rocker arm and the valve stem, adjust the rocker arm until the feeler Gage is snug but not tight. Do this with each valve. Check the book for the correct Gage to use but I think it is a .018.