Basic cam/crank timing?
 

My son and I are reassembling his 4.0L Jeep straight six - while I have read numerous texts, and think I understand the process, it seems too simple ... would appreciate an assessment of whether or not we've got it right.

We turned the crank to TDC where the #1 piston was at the top of its stroke, then put crank pulley and timing chain cover temporarily on - did fine rotation to align at 0 degress on the cover. We then rotated the camshaft to the point where both intake and exhaust were closed (based on watching the lifters) and this put the cam sprocket into position for dots on both the cam and crank sprockets to point directly at one another. We then removed the sprockets and installed the timing chain on them such that the dots were pointing at one another when all slipped back together.

Now, I think we did more than needed, but in the end, as long as the sprocket dots point directly at one another while the crank is at 0 degrees (TDC) it means we are timed correctly, right? Is it possible for it to not be timed correctly if the dots are pointing at one another while the #1 piston is at TDC based on the way I described it, above?

I know this sounds a bit silly - but, I can't figure out how to screw it up since cam rotates once for every two crank rotations - no matter where you start, as long you position the crank where #1 piston is TDC, and dots align, you're all set, right?

Thanks!

JEEP !!!!!!!!!:eek: :eek: :eek: :eek: :eek:

Okay...Phew....The #1 intake and exhaust should be closed, as you said to align
the cam to the crank with #1 piston at TDC too.

This is supposing, the distributor rotor is also pointing to #1 plug wire too.
Turn the engine over with plugs out, BY HAND, two revolutions before you go any futher...... this will tell you if you have engine interference anywhere.

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Thanks, dk!

Don't have head on it, yet ... will certainly spin it by hand when get head on it ...

Thats not an interference engine. And cam timing is almost always that simple on american stuff.
Can you imagine the fit a german engineer would have if you suggested they set cam timing like that. Deetah that is way to simple!

Omegaman,

Thanks ... it just seems so simple that I could screw it up!

Have set it and up and now dots on sprockets point straight at each other when #1 is at TDC - anytime #1 is at TDC, right? ... jeez ...

Every second time #1 is at tdc. First time dots are together, second time dot on the cam is on top because it revolves at half the speed of the crank.