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Discussion Starter #1
I am about to replace the head on my 83zx nonturbo, this is going to be the first time I do so. Question, How do I set the #1 piston to TDC? I have a manual and it says to do that, but not how. Also, if you guys have any other tips please let me know.

Thank you,

Santana
 

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Discussion Starter #3
I know I have to set is to TDC before i do the swap but how do I do that?

Thank you,

Santana



Post Edited (Dec 31, 10:00am)
 

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You cant just count on the timing indicator, you have to make sure its at tdc on the compression stroke.
Take spark plug off number one.
Disable ignition by pulling off ignition coil wire to distributor.
Place finger over spark plug hole.
Have someone bump the engine over very slowly with the key just in short bursts at a time.
When the piston comes to tdc on compression stroke you will feel it blow your finger out.
Stop turning the engine with the key.
Your timing pointer should be close to ligned up with the zero mark. You should be able to move the crank pulley with a large socket and breaker bar to get it to match up with the zero mark. Once you have it at the zero mark you should be able to confirm that the piston is all the way up by placing a screwdriver in the hole. If the piston is up you will feel it. You can also confirm that your pointer and pulley are accurate by moving the piston while holding a screwdriver against the piston. It should travel upwards up until right before tdc, once it starts to go down you know you have gone too far.
Once your at tdc on the compression stroke, your valves for that cylinder should be closed and your distr rotor should me matched up with the #1 wire on the distributor cap.

Also, Removing all the plugs makes turning the engine by hand easier.

Hope this helps, have fun...
 

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What is TDC on the compression stroke? (long)

BTW what manual do you have?

first an animation from howstuffworks.com - Internal Combustion

then from my favorite book, "How to keep your Datsun-Nissan Alive: a manual of step-by-step procedures for the complete idiot"


Step 1: What is Top Dead Center (TDC)?
TDC is when a piston is at the top of its stroke. All six of the pistons in your engine reach TDC twice in the four strokes of their cycle--on the top end of the exhaust stroke and the top of the compression stroke. For now we're only concerned with #1 piston.

Step 2: How to Find TDC.
To find this position you need to rotate the crankshaft and align the timing marks on the front crankshaft pulley with the stationary marker on the timing cover. But wait! That pulley mark will come around twice during the full four cycles of each piston, so you have to get the right one. The timing marks pass when #1 piston is at both TDC of its compression and exhaust strokes. Compression stroke is when both valves are closed and the spark plug fires. This is the one you want.

How you rotate the crankshaft depends on what tools you have. The easiest way is with a remote starter(pics) and a 27mm or 1-1/16 in wrench. Using the remote starter you use the starter motors power to get the crankshaft position close to TDC. Then with the wrench you can turn the crankshaft pulley bolt to line up the pulley and stationary marks precisely.

Manual transmission people can push the vehicle while it's in fourth or fifth gear on flat ground. This way the wheels will move the crankshaft via the drivetrain. In any case cranking the engine is easier if the spark plugs have been removed.

Step 3: Other Reference Points to Find.
There are three ways to determine if you are in fact at the TDC #1 cylinder compression stroke: 1) noting the camshaft position; 2) noting the distributor rotor position; or 3) putting your thumb over #1 spark plug hole to feel for compression. By using two of these methods as well as aligning the stationary indicator and crankshaft pulley you'll certainly find the TDC #1 compression stroke.

The crankshaft method: You'll have to remove the cam cover and watch the position of the two frontmost lobes on the shaft. At TDC (compression) the lobes on L-series engines are pointing up like rabbit ears.

The distributor rotor method: You'll have to remove the distributor cap. But first identify where #1 spark plug is--the frontmost one. Follow this wire over the engine to the distributor cap. Mark the side of the distributor housing. Now remove the distributor cap.

When the crankshaft's at #1 TDC compression stroke, the distributor rotor should point almost exactly toward the mark you made on the side of the housing--the position of the #1 spark plug wire. On all L-series engines the rotor tip is obvious; it's the end with the metal tip.

If the crankshaft pulley and stationary marker are aligned but the rotor position is 180&#186 opposite your mark on the housing the engine's at TDC exhaust stroke and you'll have to rotate the engine 180&#186 to reach TDC compression stroke. If it's not anywhere near the mark the distributor driveshaft may be incorrectly installed.

The thumb over #1 spark plug hole method: You'll have to remove at least the #1 spark plug and have a remote starter or an assistant to crank the engine. If you crank the engine from the ignition key you'll have to ground the coil wire so that the engine won't start.

It also helps to have the distributor cap off to observe at what position the rotor points when you feel for compression. If the cam cover is off you can also look at the #1 cylinder camshaft lobe's position as the cam turns.

Put your thumb over the vacant #1 spark plug hole and if all is clear crank the engine. When #1 piston is on its compression stroke (upward) you'll feel a lot of air pressure against your thumb, the rotor will be nearing the #1 markpoint, and /or the camshaft lobes will be pointing where they should be--away from the rockers.

You'll also feel this pressure if you crank the engine manually, but not as much.


Post Edited (Jan 1, 10:42pm)
 

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There should be a notch on the edge of the crankshaft pulley, and a pointer bolted to the front of the block to correspond with same.

Remove #1 cyl spark plug, turn engine over in the normal rotation direction, preferably with socket on crankshaft bolt. (not with ignition key---)
With your finger over the spark plug hole, you'll feel air compressing against your finger.......this is the compression stroke.

At this point, watching the pointer and notch, bring the notch under the pointer and stop........this should be TDC. (be sure about this part, cuz the notch lines up in two spots, and the other spot is 180 degrees off,,,,,go around twice if you have to,,,)

To further be sure, check the rocker arms for the valves on #1 (I assume you have the cover off by now) and make sure that neither one is tight under the cam lobe.

I don't know if it applies to your model, but the earlier engines required you to block the timing chain so the tensioner wouldn't fly off***,,,,,,,,,,,,you don't want this problem, and I hope somebody else can confirm if you have that style or not.

***Get that question answered before you disengage the timing chain.

Offhand, why RU removing the head?
 

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Well,,,,,,,I guess we got that one covered from several angles...... :)

Another ?

If your manual doesn't give some basic info on this subject, you need a better manual ! !
 

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Sure you wanna tackle a head swap?

Be sure to wedge the timing chain tensioner BEFORE you remove the old head. Otherwise the project will get bigger than a simple swap...

Good luck.
 

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Hopefully he has got it now.
 

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to get to TDC just take a piece of paper and make it into a plug for the first cylinder and crank the engine (via starter) slowly until it will fire (the plug should pop out like a champain cork) then insert the screwdriver into the hole and hand crank until you creach the top (it is on compression stroke at TDC) have fun.
 
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