I have a 95 z28 and I'm trying to get the timing done but every time I get both dots lined up on the crank and cam gears on the compression stroke. And when I turn the motor over I get compression out of #1 cylinder when the dots are both at 12 o'clock. Tried this multiple times with both dots lining up and still with get the same result with having compression with the dots not lined up. What am I doing wrong or what is messed up with my cam or anything else ? Been working on this thing forever just need some answers please! Thanks!

 

Everything works off the cam. Ignition fires off the cam and the valves work off the cam and it turns half the speed of the crank. The crankshaft and pistons don't know whether they are at 0 or 360 degrees. If you put the crank mark at 12 and the cam mark at 6, then put on the chain, it will be right. Or if you put the crank at 12 and the cam at 12 and put the chain on, it will work, too, because they will line up at 12 & 6 when you turn the engine around 360. Understand?

If you get confused, you can put in a couple pushrods and watch them go up and down and figure out where your compression stroke is. Your valves probably aren't adjusted at this point so you might not be getting the normal intake and exhaust valve opening to make the compression seem like it is at the right time.

 

So your saying if I get the crank dot at 12 and the cam dot at 6 so they are lined up. And when I turn the motor over and get compression out of #1 cylinder and the dots aren't lined up the motor is still in time? And I have both valves adjusted on # 1 cylinder so don't think that is the problem. I thought the dots should line up whenever I get compression out of the number one cylinder but I guess I'm wrong? Let me know and thanks for some ideas

 

It doesn't sound right from what you are saying, but what are your valves doing when you have the dots at 12 & 6?

Is it a new cam? Or one that you ran before?

 

When the dots are at 12 and 6 then when I start turning the motor over the intake valve opens and pretty sure that's what it's supposed to do. But when the dot on the crank comes back around which should be exhaust stroke the number one cylinder puffs air out again. Everything is stock just took apart to put a new timing chain on.

 

It should look like this

Which direction are you turning the engine?

 

Yup that's how I'm lining everything up. Whatever way it turns when I turn the key. Clockwise I think

 

Stock replacement timing set? Also you can compare the marks and keyway and the dowel pin hole to confirm your parts are Ok, then if they are, you probably got it right and nothing to worry about.

 

Yes sir everything is stock in the timing territory and yes my crank key way and the pin on the cam is exactly like your picture. Like I said I figured I was lining everything up correctly just dunno why I'm getting compression out of number one when the dot on the cam gear is at 12 o clock ya know. Guess I'll put it back together and see if it runs?

 

Well your exhaust valve probably isn't opening very far and if you have the spark plug out, then its going to blow a bunch of air out of there when the piston goes up again. It's kind of hard to evaluate if the only way you can turn it is with the starter motor. Best way is with a crank socket (not crank bolt). Then you can ratchet it around and see what the valves are doing.

 

Hmmm ok. So should I just line the dots up AGAIN lol and I should be good to go then correct?

 

Dot to dot is tdc compression stroke of cylinder #6, both dots at 12 o'clock is tdc cylinder #1

 

Oh I thought It was the other way around lol.

 

Everyone gets it wrong, that's the main reason guys starting rebuilt carbed SBCs have the distributor 180 out at first

 

Ok well thanks for the info!!!