HELP PLEASE!!!Need to find TDC with no regular indicators

[zdude1967]

Here is the situation: Engine was rebuilt the cam timing chain gear is not the standard with the notch, the car doesn't have a timing tab and the dizzy has been set wrong so how do I find TDC with tis situation. Can I remove the valve cover, rotate the engine by hand until I get one of the pistons to the top of its stroke. Then rotate that one through its 4 cycle stroke until i find the pattern of intake opening at the top of the cylinders stroke, closing until exhaust valve opens coming up exhaust stroke and find the 1,53,6,2,4 pattern of this  then rotate the engine through to  go back to # 1 and set it at TDC. I may not be explaining this clearly but I would be happy to further explain. Basically there are no indicators to determine where the engine is so I am a bit lost.BTW - I am using a chopstick to feel the piston reach the top of its stroke through this process

[jonbill]

The dizzy and the cam sprocket can never tell you where TDC is.
You can buy or make a tool like this to find tdc,
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F192244689624

then make a pointer to record it.

You don't need to worry about cam position etc. Tdc is tdc, twice a cycle.

[Zed Head]

You're going to need a proper timing tab and matching damper pulley to get the engine running right.  Maybe just get the parts that you'll need so that you don't have to get all twisted up using other methods?  What happened to the tab and damper pulley that came with the engine?

Not clear why you need to find TDC either.  For most of engine assembly work you really just need to be close.  Your chop stick method could even work.

[zdude1967]

I need to find TDC because I replaced the oli pump and now it wont start. I believe this is because it was not at TDC when I installed the oil pump. The tab was replaced with a tab for early model 74 260z -this car is a late model and the damper never pointed correctly at the tab . In the past I made a mark on the damper when I put it at TDC. The damper was rebuilt recently as it was separating, so the mark is gone. I want to work on this today, if I rotate the engine by hand and find a piston at the begining of its travel closest to the spark plug then as it goes down see the intake open , close at bottom and stay closed until heading up for the exhaust stroke can I then keep doing this until I find it doing this through the proper firing order then identify #1

[jonbill]

If you get piston #1 at the top, and both cylinder 1 cam lobes are symmetrically up, then you're at tdc between compression and power strokes and you can time the distributor spindle.

 

 

[Zed Head]

I haven't been keeping up with the names of the people whose threads I post in.  But I'm pretty sure that I already mentioned that the position of the oil pump does not really matter for starting.  I think you have 2 or 3 threads about the same problem, right?  You should just stick with one thread.

Here's a couple of things.  #1 is always #1.  You don't have to find it, it's the first one at the front of the engine.  Take the valve cover off and rotate the engine until the two cam lobes point up, but slightly off to the driver's side (the engine is tilted jonbill, you knew that...).  That will put #1 very close to TDC.  Then use your chopsticks and get the piston as close as you can to the top of the bore, if you don't have any of the correct tools. Then mess around with the oil pump and the distributor drive quill (shaft) until the tang looks like the picture that siteunseen often posts.  Your other picture was way off.

Then with the piston still at TDC, reinstall the distributor and put the rotor on.  Find the distributor cap terminal that the rotor points at.  That is where your #1 plug wire goes.  Install that wire then install the rest in counterclockwise order, 1-5-3-6--2-4.  Make up a tab of some kind so you can use the damper mark for timing, ypu need to know at least close to where zero is.  Even if it's not exactly at zero, you will be able to adjust the timing to about 5-10 degrees before zero.  It should start.

Just one way to try...

[zdude1967]

Thanks for the information. I set up TDC the best I could . The car starts however a few issues and questions. First question is when the piston is at the top of its stroke using the chop stick highly technical tool the piston remains stationary as the crank is hand turned for just a bit before starting to move down for the power stroke. So is TDC when the piston first reaches the top of its stroke or is it prior to starting to come down for the power stroke, or or somewhere in the little bit of rotation I can get by hand in between those two points.That was the question now the issue- in trying to time with the timing light I advance the dizzy as far as it will go and it is not advanced enough- it is about 6 to 8 degrees BTDC. The car needs additional advance as it stalls. What would be the reason that I turn the dizzy as far as it will go and it is not enough. What is a solution for this. Would using the point that the piston first stops moving up to TDC allow the dizzy to give a bit more advance. 

Thoughts anyone 

[Zed Head]

What type of distributor does it have?  Might be that the distributor has been changed but the base was not.  Are the engine and distributor the matched set it came with?  

[Mark Maras]

  TDC is halfway between when the piston stops rising and starts dropping. There's a few degrees of crankshaft rotation while the piston isn't moving.

[zdude1967]

Mark-thanks. I used a bit after the piston stopped raising and before it started dropping so I would guess I am close

 

Zed head- Dizzy is a stock replacement from motorsports, I bought a few years back. I cannot recall if it came with a new base. Also it has the crane xr -700 ignition module which requires a different piece to be put under the rotor that comes with the crane module.Is it possible that when the engine was rebuilt since they did not use the Nissan cam gear (the one with the numbers and the v notch) is it possible that they set the chain up one tooth or something off and would that create the situation I am having with being out of advance

[Zed Head]

Ignition timing and cam timing are separate.  It's a concept that many people have problems with.

The fact that the engine starts means that you are very close.  One thing you might try, just to see how close you are, is to take the lockdown screw out completely so that you can turn the distributor to get the timing that you want.  After you reset the "zero" using what Mark said.  At that point you might find that resetting the oil pump drive quill by moving the oil pump one tooth over is the right thing to do to get the distributor back to whee it is in the adjustment range.  So, we're back to the oil pump, but it's all about the drive quill.  

But, it might still be that you could solve your problem with a different distributor base.  Hopefully though, since it starts and you've been through the process a few times, you have a feel for how the ignition timing works.  You're very close.  If it runs well, you might just lock it down at 8 degrees and leave it for a while.  8 degrees is actually in spec for some engines.  I think that my 76 has 7 degrees initial as spec.

[Patcon]

There should also be a secondary adjustment screw that might get you some more room. It faces down on the other side of the distributor base. DON'T break it off