Ok, help me out here.

I have a 93', with a later style OPTI, XE 230/236 Cam, and a Cloyes Double Roller.

Please correct if I am wrong in my understanding.

I must position the cam gear and crank gear dot to dot.
Cam gear - 6 O'clock
Crank gear - 12 O'Clock

Cam Dowel Pin - 3' Oclock
Crank Key Way - Around 1 to 2 O' clock.

Piston 1 should be at TDC, and both exhaust and intake valves closed (rockers at their highest position). This is the part where I am confused. What postion will both rockers be on piston 1?

I need to know what to watch out for. Can I put in something wrong? Do both cam and crank gears only go one way?

By checking the rocker position when piston 1 is at TDC is a good way to check if cam is grounded incorrectly or dowel pin installed at wrong hole?

Please let me know!!!
Muchas Gracias!!

 

Everthing you got is fine. When people talk TDC, "most" mean on the compression stroke. The 6-12 dot thing actually puts the "REAL" TDC at #6. I believe 6-12 is the TDC for #1 between the exhaust and intake stroke not the compression stroke. (Someone jump in here if this is incorrect) The deal is; because this is were overlap occurs on #1 it is harder to adjust rocker arms here. You want to be sure that both valves are closed before you adjust that cylinder.

Jeff D.

 

Ok, cool but I am not adjusting valves at this point. I need to have information as a failsafe to make sure that my initial timing is correct.

For example, just because my dots line up at 6 and 12 does not mean my cam timing is correct. I want to eliminate any possibility that my timing is off.

Take this into consideration, if I line up perfectly at dot to dot, but lets say my cam is grounded incorrectly or the dowel is on the wrong location, my cam timing would be off 180 degrees? Please correct if I am wrong.

So this is why I need to know what everything will look like to verify that I do have correct cam timing chain alingment.

So if everything lines up dot to dot (6 to 12), cam dowel at 3, crank keyway at around 1 and 2. Where should both the intake and exhaust rockers (valves) be at either piston 1 or 6.

If they are suppose to be closed at 1, but are really open, then something is wrong at the cam or dowel pin regardless if the my dots line up right?

 

I dont know if it makes a difference but I did mine like the GM manual said too. Install timing chain dot to dot with pin at 3 o clock with #1 at TDC. Then rotate the assembly till both dots are at 12 oclock and pin is at 9 oclock and install opti. Worked for me.

 

OK, if you already have the cam in the engine and want to set your intial timing, what you need to do is go ahead and drop in a couple of lifters and pushrods for the#1 cylinders, put the rockers back on (no need to set valve lash right now, they just need to be snug at this time). When the mark on the crank gear is at 12 and mark on the cam gear at 6, you should be at TDC on the compression stroke on #1, which is what you're looking for. The valves on the #1 cylinder should be in the closed position, i.e. the tip of the rocker on the valve is at its highest position. You can also make sure the timing mark on on the harmonic balancer is at zero.

Another way you can check if you put the cam in correctly is to turn the crank while observing the valve closure sequence. Obviously, you will need to have all the lifters, pushrods, and rockers back in, and the timing set installed. Go ahead and loosen the sparkplugs so that you don't have to fight against the compression when turning the crank. The first position you are looking for is TDC on the #1 cylinder. If the both the valves on #1 don't appear closed with the timing marks lined up as described earlier, the cam is obviously off the mark and needs to be put back in so that both valves are closed when the marks line up. Once you get the #1 cylinder right, turn the crank 90* clockwise. This will bring the #8 cylinder to TDC. Make sure both valves on #8 are closed. To check the rest of the cylinders simply turn the crank 90* clockwise only each time and check the cylinders in the firing order 1-8-4-3-6-5-7-2. If you have been following the process, you have already checked #1 and #8. Move on to #4.

Ideally, the best to dial in your intial timing is to degree the cam. Using the method above will at least get you to the point where you have an idea of where you are with your cam timing.

Good luck!!

 

Yeah, 88IROCZ28 Did you notice a helicopter flying around about 100 feet all around your town a few months ago. That was me. I was there for about a week. Man, did the people their get pissed. I was doing work for AEP and the power grid there. Anyway, isn't 12 and 12 TDC for number 1 on the compression stoke?

Jeff D.

 

Thanks guys, I now understand what I am looking for, but I guess we have to come into an agreement of which pistion is really at "real" TDC (on the compression stroke)

Right now the engine is fully assembled, valves adjusted. I only the timing cover off, because I am trying to make sure.

So to review, (please correct me) When cam gear at 6 and crank gear at 12, crank keyway between 1 and 2, cam dowel at 3 I will be at "real" TDC on piston 1 and both valves should be closed.

Right?

So if I turn the crank and additional 90 Degrees clockwise and I will be at TDC on piston 8 with both valves closed and so on. As long as I follow the firing order and only turn 90* the cylinder next on the firing order should be at TDC with both its valves closed. Right?

Please confirm guys, this is really appreciated. My car has sat for almost 1 year.

 

This is wrong. Crank at 12 and cam at 6 is #6 TDC. If you think it is #1 and you try to adjust valves with the 90º method, they will be all screwed up. 12 and 12 is #1 TDC.

Look at the back of your vented opti. There are indicators that tell you when the dowel is at #1 or #6. Notice with the dowel at 3 o'clock, the opti says #6 and at 9 o'clock it says #1. Remember you are looking at a mirror image representation of the front of the cam, because it is the back of the opti.

When the crank gear dot is straight up, the keyway is at 1:30.

If you are worried about the cam being manufactured wrong, you need to degree it. Procedure can be found on Comp Cam's website.