Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: LairdScooby on February 18, 2016, 12:59:33 AM

Title: XJ 4.0 cam, lifters and timing chain renewal - much of a job?
Post by: LairdScooby on February 18, 2016, 12:59:33 AM

Pretty much as the subject really - i'm thinking of renewing the timing chain as there's a bit of noise from it sometimes at idle and if i'm going that far into the internals, i may as well change the cam and lifters too.

So the big question is..............

............is it a seriously big job or relatively straight forward? Also if i go for anything other than a standard cam, what would be a good cam to go for to get a bit more low end/mid-range grunt?

Thanks in advance!

Title: Re: XJ 4.0 cam, lifters and timing chain renewal - much of a job?
Post by: Delk on February 18, 2016, 05:41:07 AM

Its not hard but a lot of work. If you change the caM everything comes off the top and front. Head, dizzy and damper.

Mopar did a good replacement cam. I have a Comp cam in mine because i needed to bleed off some of the compression from the stroker. Crane cams are gone but they had a reputation for failures anyway.

Timing chains usually last forever in the 4.0. There are some better ones but not sure if its worth it.

Years ago i was dealing with some people in the stroker world about roller cams. Imanaged to modify and fit some roller lifters from a Mopar V8. The problem was you need a good billet cam and the production costs were huge and the need did not justify it. I see 505 Performance has roller cams on sale but i dont know what they did or if they last.

Title: Re: XJ 4.0 cam, lifters and timing chain renewal - much of a job?
Post by: LairdScooby on February 18, 2016, 10:02:02 AM

Thanks for that - i had hoped the head wouldn't have to come off to do the cam. Maybe i'll just do the timing chain if needs be. I need to put a strobe on it to see if the timing is wandering about too much, if it's not then i'll go for the "if it ain't broke....don't fix it" approach.

Title: Re: XJ 4.0 cam, lifters and timing chain renewal - much of a job?
Post by: Delk on February 18, 2016, 12:10:54 PM

The lifters will not pass the head so it would have to come off.

For interest on roller cams.
http://www.jeepstrokers.com/forum/viewtopic.php?f=5&t=105&sid=174078b311cc7f9a29db8d0212388414

Title: Re: XJ 4.0 cam, lifters and timing chain renewal - much of a job?
Post by: LairdScooby on February 18, 2016, 01:22:04 PM

The last cam change i did that wasn't OHC was in a Rover V8 - heads can stay on but inlet manifold and valley gasket had to come off. Then the lifters come out upwards.

Interesting arguments about the roller lifters - i don't plan on going anywhere near wild enough to need them but reading between the lines, with the right shape/profile/ratio the roller rockers could turn a standard cam into a full race cam. OK, slight exagerration but it seems there's potential there to get more from a standard cam using roller rockers than normal flat ones.

I did have a sticky tappet but have cured that using about 3/4 litre of Dexron II in with the engine oil. I think my "timing chain" will bear a bit more investigation before i decide to change it.