Setting timing on 93 trans am

[jpatty15]

Doing a cam and heads install on my LT1. Got the Cam installed and when I put the timing chain back on I made sure the timing marks lined up correctly but I didn't check to see if #1 cylinder was top dead center. Is this something that I needed to do? or is justing making sure the timing chain marks line up good enough?

[cardo0]

Installing the timing marks with the cam gear at 6 o'clock and the crank gear at 12 o'clock actually puts the #1 @ TDC but on the exh stroke. The #6 cyl as also at TDC but ready to fire on the power stroke. The correct position for #1 @ TDC ready to fire is with both gear marks at 12 o'clock position.
If u choose to degree the cam then u need to nail the #1 TDC with a piston stop and use a wire for pointer on the block pointing onto a degree wheel - another topic itself.

But u could find TDC on #1 to place the crank hub (no crank key to position it) casting mark on to mark it as TDC #1 - as with the stock position - sorry i can't recall where that hub casting mark points to. But the crank snout, hub and dampner are all "zero balanced" so it won't hurt a thing if hub is not pointing correctly.

Just a few things u should understand,
cardo

[cocobolo95]

If you have timing mark on cam gear at 6 o clock and timing mark on crank gear at 12 o clock, cylinder # 6 is at tdc on firing stroke. For cylinder #1 to be at tdc on it's firing stroke, you would rotate crankshaft 1 full turn. But this is not necessary as the type 1 splined opti you have in your 93, has a small key way on it that fits into a matching key way on the cam gear.

shbox.com has pics of timing marks and of type 1 opti drive mechanism, and how it fits on his site.

[shoebox]

I'm sure you are the one who emailed me this question.

Here is the response I emailed back:

If you lined up the cam and crank gear dots vertically close together, you would automatically be at #6 TDC. If they were both vertically aligned at 12 o'clock, you would be automatically at #1 TDC. Either way is correct and proper. When the crank gear dot is at 12 o'clock, both the 1 and 6 pistons are at the top of their travel. The cam position determines which one is at TDC for the intake or exhaust stroke. You should be fine.

[DUDBIRD113]

If i rememmber on my build with my lunati chain it would only go on one way. So i didnt have to find tdc. Just align marks n go.

[jpatty15]

Thanks for the responses. So the cam dowel is in the pin hole on the timing chain and the timing chain marks are lined up. So should it be in time or could it still be out? I just don't remember making sure #1 or #6 was at top dead center when putting the timing chain back on.

[jpatty15]

So would you guys think I need to take the waterpump, opti, and timing chain cover back off and check before I get it put all back together?

[shoebox]

If you lined up the dots on install, you need to do no more.

[jpatty15]

So no matter where any of the cylinders are as long as I lined up the dots on the timing chains then it should be ok? Just afraid that I needed to have #1 at top dead center and timing marks lined up. When I took the timing chain off the dots were not at the 6 o'clocl and 12 o'clock, and when i put them back on i put them at the 6 o'clock and 12 o'clock position without looking at the cylinders.

[shoebox]

I don't know if you are just not reading what has been posted or what, but the dot on the crank gear corresponds to where the pistons are. Again, crank dot at 12 o'clock = 1 and 6 pistons at the top of their travel. You can look at pistons or the dot. Same result.

[jpatty15]

I think I understand what you are saying but I don't think I am explaining what I am asking clearly enough... When putting my cam in I took the timing chain off and when I took the timing chain off the dots where not at 6 and 12. I installed the cam and does the cam rotate freely for me to put the cam dowel into the timing chain with me putting the timing chain on with the dots lining up at 6 and 12? I can't remember if I had to turn the motor manually to get the cam dowel to line up with the timing chain for me to install the timing chain with it lining up at 6 and 12. If I did have to turn the motor to get the dowel to line up with the timing chain then it should have put the pistons where they needed to be for me to get it lined up. I believe from what you are saying I had to turn the motor to get the bottom crank to be at 12 and when i done that it put piston 1 and 6 exactly where they needed to be and then i just put the timing chain on the cam dowel and bolt it down at 6 o'clock.

[jpatty15]

sorry for the confusion. This is my first time pulling it apart and putting it back together. Also could I be 180 degree's out? If thats possible is there a way for me to check without pulling the timing cover off?

[shoebox]

It might be confusing when you are not used to dealing with it. What position it was in when you removed it all does not matter. To line the dots up, you will most likely have to move both the crank and the cam. You can look at the cam timing animation on my website. It shows where the dots are for every time the plugs fire. You can see that they can be aligned vertically twice. At #6 TDC, they are together. At #1 TDC, they are both at 12 o'clock. Either way synchronizes the cam and crank. The reason the dots together method is usually specified is because it is easier to visualize.

As long as you lined up the dots, you are good to go. If you still have the heads off, you can easily see where the pistons are in relation to the crank position (and keyway). If the heads are on, you might have to use a straw poked into the spark plug hole to help verify.

[Racy Roadmaster]

This is more intended for the young "patty",but questions like this used to
really play with my mind when I was a young lad. First off I think everyone explained this well. But to ease pattys mind,here it is stated another way. AS long as you have the dots lined up either facing each other at (crank at 12 and cam at 6) or (crank at 12 and cam at 12) then
you cant do anything wrong with your cam timing. Especially since your opti can only go in one way,unless you gorilla it, that is. So relax by your explination I think you are fine. Now a whole other ball game comes into play if and when you decide to degree your cam in and or change your
ignition timing from the stock spec. But for your first entry into engine
modifying you are fine. I hope this helps. ed

[95 Firehawk]

I think you are getting caught up with the position of the timing gears in relation to the crank and cam. You can't install the gears the wrong way so there's no reason to verify TDC once the dots are aligned. As mentioned, you would have needed to turn the crank and cam to get them to line up if you removed them with dots not aligned.

In other words, you cannot have the crank at 12 o'clock and not have #1 and #6 at TDC, and cam at 12 o'clock has valves on #1 closed (between compression and power stroke), whereas 6 o'clock is #6 at the top of the power stroke.