'98 Cam Upgrade, Worth It?

[xjrobert]

Hi Gang,

Been around a while with XJ's and have relied on this forum for some do's and don'ts....

I'll keep this as short as possible.
Many years ago I had a '94 XJ that had a tired motor. I tore it down and just threw some rings and bearings in it. Along the way I had a custom grind done on a cam and LOVED it. I gained quite a bit of grunt for pulling me up the long hills on the highway.

My buddy has a '98 XJ that has a knock so we're rebuilding a motor I had sitting around as a spare. I suggested a cam upgrade to him.

When he went to the machine shop the guy there said not to bother.
He said with the '98 being OBDII the gains wouldn't be as noticeable as with me with the '94.
He also said that there would be a lot more drive train noise with the different cam.

What are the thoughts here?
On a '98 4.0L with a header, 2.5" pipe back and a CAI, is it worth a cam upgrade?
Are the gains there and what about noise?

Thanks,

Rob

 

[cal]

There are certainly gains to be had, and noise would be a result of doing things wrong?

I'd call Russ at Bishop-Buehl and ask his opinion, he can also make cam suggestions and probably get you one of the better deals.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Fax (626) 967-7836
Cell (626) 673-2203
Email [email protected]

 

[dan1977p]

The noise will depend on the cam but usually it's only the motorcycle guys who complain about more noise. If the cam opens the valves higher, they will come down with more force making more noise. It gets even louder if you do a valve job with stronger springs. If it's so much louder that you can hear it from inside the cab, I would think there is an issue on the install but I haven't done a cam on a 4.0 yet so I don't have first hand experience in the change.

 

[DieselSJ]

You have to be VERY careful with camshaft selection on these. They are very sensitive and it is extremely easy to kill your low end power with too big of a cam or something that doesn't have the correct lobe centers. IMHO, there is much more to be gained with a mild head port than with a cam.

As for noise...the correct length pushrod will keep things from being mechanically noisy and the speed at which the valve seats itself is 100% dependent on the shape of the lobe and not the spring pressure.