Is this relevant on newer 4.0’s ? It’s a 98 grand . I see many do this to older engines but trying to get mine smoother and better wondering if this is worth the effort ?
thanks
Ant

 

Sorry I can't give a direct answer BUT I did this on my 73 Nova with a 350 to help narrow down a issue on it and I will say no difference. Even got the adj rotor button. Maybe on a race car where every little bit matters it may. EDIT... I did is actually distributor phasing but should be same thing pretty much. From another XJ forum..
https://naxja.org/threads/distributor-indexing.1159556/

 

Hey, that's my thread.

Anyway, mine is a Renix so the indexing procedure is different. The Camshaft sensor in mine disintegrated so I swapped out the distributor. Initially, I just timed it, and bolted it in. Ran fine. Crusier54 pointed out the TSB (for Renix) so I redid it according to the TSB. That's the process you see in that thread.

Ignition timing is not adjustable. If the distributor indexing was off, it might cause misfires or even a crank/no start due to the rotor pointing at the wrong plug.

 

LOL...Didn't even think about looking at the poster.

 

Appreciate the replies , I’m thinking it’s relatively easy and can’t hurt so why not ✊

 

No big deal checking. HOWEVER, make sure you use the correct procedure for a '98. The link above is for an '88 (Renix). Later models use a different method.

I realize that the 4.0 is basically the same in a XJ, YJ, ZJ, but there are still differences in other areas. Since you have not been very specific about your current running condition, other than not smooth enough for you), you should consider posting in the GRAND Cherokee forum to make sure you get replies most appropriate. There's a chance your issue could lie elsewhere.