Noise From Tappets And Extended Cranking For Starting

If it sounds like no compression it would be sensible to check them using a cylinder leakage test after checking the belt and timing.

There is a rare condition engines with hydraulic valve lifters, tappets, cam followers can suffer from - tappet jacking. This happens with a cold engine and an abnormally high oil pressure (temporarily stuck relief valve) and the hydraulic lifters can fully expand and hold the valves open.
Usually the engine briefly starts and then immediately stops and then refuses to start again. Often the situation cures itself after an extended period of cranking...

There is another rare condition where carbon is shed from the pistons en mass, much of it becoming trapped under the valve seats, again this usually rights itself after adding Redex or similar to wet the cylinder components and valve seats to produce some residual compression.

Swings is a word I have not heard applied to engines since the days of the cranking handle. I assume you mean the engine cranks but will not start?

I am not familiar with your particular engine but it is sometimes problematic starting a freshly assembled engine that has been partly reconditioned. Fully reconditioned engines that have been built rather than merely assembled usually present few problems because everything is new and correctly adjusted.
The word "reconditioned" means many different things to different people...

A newly-built engine is often down on compression and a diesel needs good compression. It also needs a good cranking speed. If the engine is an indirect injection engine it is necessary to have an efficient set of heater plugs or to provide copious amounts of hot air into the intake. This helps with direct injection types but isn't absolutely necessary. Careful manipulation of an ether spray at the right time can be great help when starting the latter type of engine for the first time.

By far the biggest problem is bleeding the fuel system. Even when a good supply of air-free fuel is reaching the injectors it can take a considerable amount of cranking before a reliable injection is achieved and the engine begins to fire. This time is shorter with common-rail diesels and a great deal longer when fitted with a hydraulically governed DPA type injection pump.

A starter motor should not be operated for more than 10 seconds and then rested for around 10 seconds. This avoids over-taxing the starter and the battery and connections...
If it really won't start I suggest you revisit the valve clearances, valve and fuel timing and compressions.

In the case of hydraulic valve lifters, I prefer to fit them unprimed and find them a lot less trouble that way. If I am refitting used valve lifters I ensure they are emptied before reassembly to avoid one or more of them holding a valve from it's seat and reducing compression. Another possible trouble is tappet-jacking. With new bearings and oil pump the oil pressure can be high even at cranking speeds. If the valve springs are weak the oil pressure can cause the hydraulic lifters to open the valves a little.

compression pressure is read at cranking speed with throttle wide open. For petrol engine it is 155-165 psi hot dry with an allowed variation of no more than 10% between adjacent cylinders and around 175 psi hot wet (OIl injected to seal rings)
For a diesel engine it can be 550 psi -650 psi hot dry at cranking speed with the only engine being test while running being a detroit diesel 2 stroke
There is no compression reading done at rpms as it is meaningless

please add more details to your issue> like does the car engine run when you hit start ?

Okay, you have to set the number 1 cylinder at TDC of its
compression stroke, and then drop in the distributor so the rotor is pointing to the #1 spark plug wire tower. This should start the car, then you could set the timing to spec with a timing light.

There are two TDC's of a cylinder- the compression stroke and the exhaust stroke. To find the compression stroke, take out the #1 cylinder spark plug. Put your finger over the hole. Now either turn the engine over by hand (with a socket on the crankshaft pulley-turn clockwise), OR have a helper bump the starter over in as short bursts as possible. As soon as you feel pressure on your finger- stop turning- the piston in #1 is rising on its compression stroke. Now check the timing pointer or scale by the crank pulley. Turn the engine slowly on over until the notch or mark on the crank pulley is right on the zero degrees mark on the scale. This is TDC of compression stroke-the piston is at top of travel in the cylinder. Put the distributor in so the rotor will be pointing to the #1 spark plug wire.

wrong ignition timing
timed to the exhaust stroke instead of the compression stroke (180 degrees out )

First off, ether is not the way to go at all! You'll end up messing up the piston rings with continuous use. Also with using ether engines tend to get "addicted" to it (its the only way they will start after some time as the rings get burnt and compression under normal cranking isnt enough)

The fact you can start the engine on ether means fuel prob isnt the problem. I would have said the problem was probably your pre-heating system and to check your plugs, wiring and fuses for the pre-heating system but the fact hot start doesnt work either doesnt make sense.

How long have you been using ether? If it has been for an extended period then I have a feeling the piston rings might be shot and full compression cant be reached during cranking and the ether just kickstarts your engine into starting. Any smoke out the tailpipe?

I would still check the glow plugs.

Hope this helps in some way

If engine has all compressions
Check for spark while cranking,
Fuel pressure at key on.
and enough batery voltge at cranking is very important

well the 4 things that you need for an engine to run are fuel, spark, compression and air. so i would focus on compression and air. If you cant do this by yourself then i would take it somewhere somehow adn have it looked at

crankshaft sensor may be going bad