I have tried today to line up the engine/crank for TDC. I understand that at the 0 deg mark you could have compression TDC or exhaust TDC. My Haynes book says the exhaust valve will be open if it's the exhaust TDC I'm at, and to rotate another 360 deg to reach compression TDC. When rotating the crank I always seem to end up with both valves at cyl #1 being closed when I reach the 0 deg mark. So I can't tell which TDC I got.

And to complicate it even more, after I had the distributor installed it pointed to cyl #6. So I guess I took it off at the exhaust TDC, because I also understand when cyl #1 is a exhaust TDC, cyl #6 will be at compression TDC.

It's a rebuilt Jasper engine.

Can anyone help me find my compression TDC? When that's done, should I just turn my rotor in the distributor 180 degrees (I guess I could even just unscrew it and turn it)? Or would it just be easier to set the engine at exhaust TDC and leave the distributor at cyl #6.

I would greatly appreciate any insight to my situation. This is a first time doing this kinda work, so my experience is zero.

 

You can leave the dist in to start. Take out #1 plug turn the harmonic balancer over until piston comes up to top. (put thumb over spark plug hole and you will here a pop when it is on TDC or put a pencil in the cyl turn it over until pencil comes all the way up TDC...
Zero your mark on your timing now look at your dist cap rotor should be facing # one tower if not know pull dist and make that happen. Set your timing and you should be good to go.

 

Thanks! So I only hear the pop when it's TDC on the compression stroke, and not on the exhaust (because then the exhaust valve would have relieved the pressure in the cyl), right?

 

I went back down in the garage today and looked at what happened to the valves for every 180 deg turn on the crank. When I installed the distributor (on cyl #6) I was on TDC exhaust. Lucky me! Everything was good to begin with. All I did was turn the crank another 360 degrees to reach TDC on the compression stroke, and checking that the distributor was firing on cyl #1.

The first 180 deg turn the intake valve opened. When I reached 0 degree mark again, I should be at TDC compression stroke. Third 180 degree turn didn't do anything (combustion), while the last 180 degree turn towards the 0 degree mark again opened the intake valve and closed it before I hit the mark with both valves closed.

So what confused me was that I thought at TDC on the exhaust stroke, the exhaust valve should be open. But it isn't. But it opens and closes the 180 degree turn before I reached 0 degree mark and TDC on the exhaust stoke.

Thanks for the help Gad1357! It helps tremendously to get some input.

 

Well, it turned out my timing was off. The car didn't start. I had to reinstall the distributor after reading an article from Alldata. Finding TDC on compression turned out to be a guess when the engine was in. Was hard to turn the engine and also look for TDC on compression. I took the 50/50 chance I had. It then started, but runs a little rough. I'll take it to chevy for a scan and tiing adjustment (I know its automatic, but I want it closer to right timing so it doesnt hav e to adjust itself).

 

You still have to manually set the timing with a timing light after you start it up

 

But my manual and other reearch says the Vortec 350 have automatic timing and that you'd need a scanner (that the dealer has) to check the timing. Though I can't really see why I shouldn't be able to set timing with a timing light. I think I'll leave it for Chevy anyhow since I've never done this and would need a light to even start.

 

yea I read in another thread that you were working on a newer vehicle and that timing is computer controlled and is not adjustable....