Timing belt help, cam phase?

[eager pace]

Went to put the belt on, one cam gear jumped. Tried to turn it a couple times to get it lined back up, jumped some more. I can get it lined up, and I can hold it in place or be more careful about bumping it. But how do I know it’s in the right phase?

 

[DBULL]

Could it be the cam lobes are making it jump?If that’s the case,locking it back in position shouldn’t be a problem.

 

[eager pace]

yep. I have it back in position, but I don’t know if it’s in phase or 180* out with the crank.

 

[medtro]

Check the mark position on crank pulley.

 

[eager pace]

Check the mark position on crank pulley.

Crank didn’t move. It’s lined up but the cam rotates twice for each crank rotation so it could be out of phase.

 

[medtro]

Crank didn’t move. It’s lined up but the cam rotates twice for each crank rotation so it could be out of phase.

How did the cam rotates twice with crank not moving?

Yes, crank pulley mark will tell you if you are out of phase.

 

[eager pace]

How did the cam rotates twice with crank not moving?

Yes, crank pulley mark will tell you if you are out of phase.

I rotated it

I have it back together. Belt is all lined up. Made two crank rotations, everything seems good.

 

[eager pace]

I rotated the engine by hand a couple revolutions, didn’t feel any binding or issues in the valve train. Cranked it with the starter real quick, all good again. Fired up just fine.

The cams rotate twice for every crank revolution so with one being off I had a 50/50 shot of it being out of phase. Maybe I got lucky, maybe my checks worked.

 

[medtro]

The cams rotate twice for every crank revolution so with one being off I had a 50/50 shot of it being out of phase. Maybe I got lucky, maybe my checks worked.

Are you saying you can rotate the cam sprocket 1 full revolution with the crank not moving?

On my engine, crank rotates twice for each cam revolution.

 

[Rebus Knebus]

On my engine, crank rotates twice for each cam revolution.

Same here. And since the intake stroke is the same as the firing strike to the crank (same with compression/exhaust) the OP’s 180 degrees out of phase is still in phase so it works either way, no luck involved.

 

[eager pace]

Same here. And since the intake stroke is the same as the firing strike to the crank (same with compression/exhaust) the OP’s 180 degrees out of phase is still in phase so it works either way, no luck involved.

Oh gotcha, so I had that backwards. So then why is everyone so concerned with not moving the cams while doing the TB? If they move just line them back up.