Did I bend my valves?

[mboyko2000]

This is the first time I've tackled installing a new head. So I tear it down and it put back together to the point where I put the timing chain back on. I get the timing chain on however I got the exhaust sprocket off by 1 cog (didn't know it at the time). I then turned the engine 720 degrees to check it and I noticed it didn't quite line up and was off by 1 cog. So the question is did I destroy my new head's exhaust valves?

I suspect the valves did come in contact with the cylinder because there were a few points that turned a little harder than when I put the chain on correct. I figured it was just the compression cycle that was causing the stiffer turning, but having never done this before I had nothing to compare it to. Anyway just looking for your thoughts on my situation.

2.3L DOHC 1993 Grand Am GT

Thanks,
Michael

[catback23]

Depending on how you turned the engine it is possible, the thing to do now is to pull the head and check. Compression test would be easier but better to have a visual inspection if possible.

[mboyko2000]

I certainly could tear it apart again, however If it can be checked without doing that I'd prefer that becaus removing the timing housing is a HUGE pain. Also if this is done will my head bolts and gaskets be reusable since the engine has never been heated up?

Thanks,
Michael

[mboyko2000]

The two ways the timing could have been changed are either the exhaust valves were closing early or closing late. The latter being the potential damaging operation upon rotation. Is there information a mechanic can look up to determine how many degrees of clearance the exhaust valves have normally? If the valves did hit the cylinder is it going to be automatically bad?

Michael

[gm-andy]

Just so you know, that engine has timing holes. When everything is lined up properly, there are 2 holes below each sprocket, exhaust & intake. a 5/16 or 8mm bolt should slide in and out very easily. If restitance is felt, there is a problem. That engine just has no clearence for any mistakes in timing. You might have damaged the engine. I would try the compression test, removing everything again is way to hard.

To get it retimed properly, is to have the dots on the crankshaft sprocket facing straight up and cam sprockets dots straight down. Bolts (2) should slide easily into guide holes as mentioned above. This is the timed postion. If its not lined up, remove chain and turn crankshaft sprocket 90 degrees clockwise with bolt on crankshaft that you removed. Turn cams to the timed postion. Turn the crankshaft COUNTERCLOCKWISE until its lined up again. Put on chain, and check with pins again. If they slide in and out easy, turn engine by hand 2 full turns clockwise. You should feel no resistance. Remember to pre oil chain.........

Good luck

[mboyko2000]

Yes, I know about these 2 timing holes and used them. I am not quite sure how I managed to get the timing off. I suspect either the chain wasn't fully seated on the exhaust sprocket and slipped to the next links while I started to rotate the crackshaft or there was slack in the chain between the exhaust and intake sprockets and I didn't notice. I'd bet on the first one. Needless to say I'm very disapointed in myself. I'll update the thread once I find out if the valves were damaged or not.

Michael

[mboyko2000]

For those of you interested in the outcome of the motor... It appears like I lucked out. I fishished putting the motor together and all appears to be working well. I went for a 150 mile drive today without noticing any problems. The engine sounds very good.