rbNW

First time poster and first time working on a 3vze- 92 forerunner, but not my first engine rebuild.

I changed the head gaskets and cannot figure out how to set the passenger side cam to TDC. I have the timing marks on the metal plate and the market on the sprocket but if I line it up, the lobe on cam shaft hits the valve and won't fit into the head. If I rotate the cam 45 degrees either direction, it drops in fine, but then the timing marks are NOT lined up for TDC. I asked friend who has rebuilt a lot of these engines and he said he has never seen it. Everything else I have read said you cannot screw up TDC if you line the two marks up. On the driver side the two marks line up at TDC with no issues. I tried rotating the engine 360 degrees to see if I was on an exhaust stroke for TDC, but that didn't help anything. I also tried turning the cam 180 degrees away from the TDC mark and have the same issue.

My only thought is that perhaps the PO installed the cam sprocket wrong (which I don't think is possible). I have the timing belt marked onto the sprocket in 2 places, so my thought is to try to get it as close as possible to these marks and hope...?

Any help or advice greatly appreciated- I am trying to get this thing back together today...

scope103

Then line them up.

At TDC, the valves on #1 are closed, but that's not necessarily true for the other valves. To line up the cam, you have to turn it against a small force.

The 3VZE is a "non-interference" engine, so you can turn the cam 360° with the crank at TDC; the valves won't hit the pistons. So you can safely "rock" the cams to get them properly onto the timing belt.

rbNW

Got it! Don't know why I couldn't figure that out on my own... I was thinking that since the driver side cam dropped right in at TDC, then the passenger side would do the same- but I understand the non-interference aspect of the engine- so it makes perfect sense to install them however they fit into the head and then rotate the cam sprocket to TDC and then install the timing belt.

Thanks for the help! If I missed something obvious in my reply please correct me- otherwise assume the problem solved... until I hit the next one!

Appreciate it,
Rob

scope103

Just so you know, if you have an interference engine, you can rock the crank a few degrees away from top dead center. That lowers the pistons and you can do what you want with the cam.

Subaru engines, which are interference, set up the timing belt 90° away from TDC to assure all the pistons are clear of all the valves. There's nothing magic about TDC; you just have to have marks the crank and cams where everything is consistent.