How to set cylinder #4 on tdc?

Mxgrds

Mxgrds

True Classic
Uno turbo 1.3. All marks aligned. That is on flywheel, camshaft pulley and crankshaft pulley. But I am not sure if it is it is aligned for the compression stroke for cylinder #4. The could as well be aligned for #1?
How do I know which cylinder is in it’s compression stroke?

I can see the camshaft lobes of #1. Pointing both upwards is comprssion stroke?
 
When I bought my X i foolishly just yanked all the wires, cap and distributor with out checking to replace the 20 year old bits. I assumed it would be set to TDC on 4 but the previous owner had it on #1. Thank god these things are non interference motors. Took me a while to figure out that the PO had it 180 out. It was running before 180 out but I replace the cam gear with a billet one and put it back factory specs.
 
1 and 4 are at TDC.

1 is at the top of compression for ignition. 4 is at the top of the exhaust stroke.

Turn it a full revolution and now 4 is at ignition and compression.
 
Mxgrds said:
I can see the camshaft lobes of #1. Pointing both upwards is comprssion stroke?
Click to expand...

If by "both pointing upward" you mean the spring is not compressed at all on either valve, then most likely it is on the compression stroke. However, if it is between the exhaust stroke and the intake stroke, the piston could be at TDC and both valves open slightly (exhaust valve closing and intake valve opening - in overlap, in other words). Since most valves have overlap, I think it's safe to say that if the piston is at TDC and the normal valve lash clearance can be felt on each valve, then you're on the compression stroke.

If you have the ability to rotate the engine, that's the safe bet. When the piston is coming up and no valve has moved for about 180 degrees of crankshaft movement, that is the compression stroke. That's what I look for.
 
so of I umderstand it correct. If the lobes of cilinder 1 pointing downwards (i can see through the oil fill hole), that means cilinder #1 is not on the compressie stroke, but #4 is.
 
Mxgrds said:
so of I umderstand it correct. If the lobes of cilinder 1 pointing downwards (i can see through the oil fill hole), that means cilinder #1 is not on the compressie stroke, but #4 is.
Click to expand...

Yes, if you are at TDC and cam lobes on #1 are pointed down towards the shim and spring, then it is at the end of the exhaust stroke and about to start the intake stroke. As Karl said, this means the #4 piston is also at TDC, and is 2 away in the firing order (1-3-4-2). Since it is a 4 cylinder engine and there are 4 cycles in a 4 stroke motor, then the #4 cylinder is 2 strokes away from where #1 is. So #4 would have to be at the end of the compression stroke and about to begin the power stroke.

...................................#1 position........#4 position
................................... V ................ V .......
Suck....Squeeze.....Bang......Blow....Suck.....Squeeze....Bang
 
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