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RV cam in 180k mile motor?

Well I mean 180k is a lot of miles...I would not recommend changing out the cam to something w/ more performance. You have to look closely at the scarring that takes place w/ those factory parts in there and changing it to something w/ more performance may cause a lot more problems than you need. Though I think that if you just take it easy and don't think its a dragster after you replace it, you should be okay. If your going to go through all the time to put a cam in it, why not take the pistons out re-ring them and hone out the cyllinders, as far as I know you should be able to do that w/ the engine still installed..
this whole time I'm assuming you want to do this w/ an XJ by the way
 
if you are going to do a cam, go ahead and do a set of rings while you are in there. you already have to take the head off to replace the lifters.

at that point you are not too far from doing all your main and rod bearings, and RMS, oil pump, oil pan gasket and valve cover gasket, oil filter o-rings...
 
Have him pull the rod and main caps one at a time and check for wear. If they're all good he should have no problems with a new cam. If there's much wear I wouldn't do it without a rebuild.
 
I've done some performance mods to other motors so what I say is really just based on that experience.

I think that if he is putting an RV cam in to get a little more performance while driving around town and some towing then it should be fine. If he begins to think that he is Speed Racer, then he needs to save for another bottom end while he's playing with this one.

Also, he is not going to get all that the cam would offer in a fresher block.
 
Doing a Camshaft is not the same level of fun or money as doing a fluff and buff job on the existing assembly.
And if you are even thinking of a fluff and buff on a 181K engine, then, just pull the block and do it right the first time with a whole rebuild.

Also, an RV Cam is not going to be an earth shaking experience for the existing rotating assembly as RV Cams are set up for low end torque; something that a stock 4.0L has in abundance anyway. Since changing a Cam does not affect the compression ratio, concerns about lower end longivity are not an issue.

Unless the stock Cam is junk, I really doubt you'll see much performace gain. However, if you just want to have fun, this sounds like an interesting weekend project. Let us know how it went :cheers:

Ron
 
if i were gonna add a cam to a motor with that many miles i would replace the valve springs. the old stock worn out ones may float and cause alot of problems
 
Thanks for all the input guys!

Zuki-Ron said:
Unless the stock Cam is junk, I really doubt you'll see much performace gain. However, if you just want to have fun, this sounds like an interesting weekend project. Let us know how it went
cheers.gif


Ron
Click to expand...

The only reason he's looking into it, is because he's gotta do the lifters anyway and saw a good deal on a "cam kit" (cam, lifters, head gasket, etc).

Thanks again,
Billy
 
I just did a ring job on the 95 while I was waiting for the head from the machinist--it'll take you an extra 2 hrs or so while the head is off. Cams won't change the static compression ratio, but they do affect the dynamic compression ratio(less overlap, compression builds sooner).
 
JeepFreak21 said:
Thanks for all the input guys!



The only reason he's looking into it, is because he's gotta do the lifters anyway and saw a good deal on a "cam kit" (cam, lifters, head gasket, etc).

Thanks again,
Billy
Click to expand...

you have to take the radiator and everything out of the way to yank the cam out in chassis, so if he is prepared to do that, go for it
 
I would not hesitate to add RV cam with matching lifters/springs to high milage motor.
Cylinder pressure is likely going to be a bit higher, but, I'd guess he's putting an emmissions friendly daily driver cam in it, so I'd not be concerned.

If you are doing the work yourselves (free labour) then ya, I'd go ahead and put new rings, rod and main bearings, oil pump and rear main seal.

fwiw, I put an rv cam (springs/lifters) in a 200k '78 Pontiac 350... no issues arose out of that deal, and those motors are not as tight or long lasting as the 4.0's are.
 
IF your going to do a cam-please at least replace the valve stem seals.The cam will more than likely have a higher valve lift which in turn will go past the wear spot on the valve stem-end result it will burn oil and/or smoke.
 
I hate "old school" cam terms,I used to sell(many times over and over again) a 3/4 cam(it was a cam with some of the lobes cut off)!Stick with stock,it will save you alot in the long run
 
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