JeepCoMJ

my '97 xj 4.0 has a bad cam on the number 6 lobe.

I have a '96 used cam in good shape with no scoring/scratching that I could put in.

obviously new lifters. I've already got the lifters, head gasket, head bolts, intake/exhaust gasket, push rods, and necessary rockers to replace the bad ones.

Would you guys use the used cam, or would you go ahead and buy a new one. and if I'm buying a new one, I certainly am not putting a stock one in it....so what would you suggest? keep in mind i'm trying to increase mileage and power, as much as possible.




history on the jeep...I built this motor a year and a half ago, it sat on an engine stand for a year, got installed in the jeep (at the time my old room mate's), and then my room mate moved out with 2 days notice, and didn't do the break-in oil changes. one month later, he beat the **** out of it off-road and blew the head gasket.
I grudgingly did the head gasket for him.

3 months after that, he beat the **** out of it again illegally wheeling, got stuck, beat up on it to get out, and drove home with a real bad lifter tick.

i told him to stop driving it, not even to start it, until i could look at it. he did not listen. then got drunk on St. Patrick's day, drove it, got it impounded, couldn't afford to get it back, i bought it from the impound lot.


Thanks

Pat

djb383

I'd go with a new cam and throw the roommate and old cams away after I broke/bent one of them over his head. LOL The '96 cam may look good and it may still be good but without accurate measurements, u don't know if the lobes are possibly a little short from wear (still smooth but less lift).

Now here's a cam.

its_deer_not_jeep

correct lol you always wana get your cam and your crank shafts checked if they are used (i only use new cause they could have a crack or w/e)

JeepCoMJ

Cam lobes are in spec.

I'm not buying a new cam unless its non stock and meant for more torque....just not worth the money to me. I'd also consider a renix to 95 cam as they are better then 96 and newer.

JD Cravin

where can I get that cam?

Cherockee

There are lots of contridictions on the internet, and you'll find just as many people say the new dual patteren cam is better than the older ones.

Just keep in mind, if you buy ANY cam that is not factory spec you will have to replace the valve springs also, maybe even the rockers.

IMO, the stock dual patteren cam is the best choice, unless you have the coin to replace the valve train and make the necessary improvements to the intake and exhaust so you actually see gains from a higher performance cam.

JeepCoMJ

I always build 4.0's with a 99 and up intake manifold, and i can't recall having put one together with anything less than the cheapo stainless ebay header...

that said, this jeep got a stock used cam and was running great, until the new owner of it traded it for some rednecks monstrosity of a "linked" (read that as POS) renix xj on full widths.

djb383

Go to your local library and check out a book or 2 on camshaft dynamics/design.....it's all about the numbers. It's a myth that valve springs MUST be changed when doing a cam change. Sometimes u do, sometimes u don't. If the new cam's lift, the existing valve springs coil bind rate, the rocker arm ratio stay within close spec of the existing cam, the existing springs, etc should be good to go. BUT, if anything is changed from the cam up thru the valve train, valve train geometry must be re-checked to be on the safe side. The books explain how to use those dial indicators and do the valve train geometry.

JeepCoMJ

eh. I pulled the lifters out of the jeep that the "new" cam came out of, did a real quick top point micrometer check on all of the lobes, checked for scratches on the bearings, cleaned it, and put the lifters in on the lobes that they came off of in order. jeep didn't make a sound.

was going to put new parts in it, but ended up deciding to sell it and the new owner didn't want to spend the $$$ on new parts. it ran absolutely fantastic when done.