Topic: re(over)building my 2.5L question about cams.

[davehall]

I know.  I should just get a V8.  I have read all the post that say this.

*** warning.  wall of text *****

The Goal:
Same problem as everyone else.  It's my daily driver and i hate the slowdown on big hills.  I would not mind a little pep.

Background:
I have Zero experience with this stuff and recently received all my dad's tools.  So I thought what the heck.  I picked up an old 2.5 from the graveyard just to take it apart and maybe learn something.  No reason to mess up my running engine.

Followed the service manual and it came apart pretty easily.  Before I got toooooo crazy, I gave the block to my local shop to have it magnafluxed.  Turned out to be in really good shape.  They are checking the head now.  I think it is gonna be OK as well.

Some decisions have been pretty easy.  It had to be bored just to clean up the cylinders.  We are going to 0.060.  I have no plans to ever rebuild this engine again.  I asked them about grinding the crank to do that off-set thing and rebalancing.  They looked at me kind a funny (like I was crazy) so I have decided to skip this mod.  Probably will end up getting it decked, just because I can.  Just about everything will be new except for the block and head.  I am also 99% certain that I'll have it ported and polished as well.  I'll also put headers on it, cuz it just seems to easy to do with it out and on the stand.  I have the 4.0 TB in waiting as well.

Now for the question section:
there are some cams that no longer seem to be manufactured but are still available.  I have found one site that list 3 and another site that list more.  The first site seems legit enough but the second site is just a forum post.  Trouble is I like the second one better and have no info backing it up.  I would love to do the head / valve-job in accordance with the post, but I'd love to hear from some folks as to the validity.

http://www.pirate4x4.com/forum/showthread.php?t=476130&page=2
actually it is the second comment on this page.  the long one by BCYJ.

At the bottom of that link, it list sorta stage I, stage II, stage III thing.  the cam they are calling for is P4529660.  the valves are available and also the little spacer things, and springs and such.  Has anybody used this cam?  Is this post even close to accurate?  

Here is the link to the more legit appearing cam selection.
http://www.southeastrt.com/catalog/index.php?cat=9&item=602

Yes, I know this is not the best use of my time and money :)

[jfrabat]

I have a .450 lift 256 duration Mopar High Performance camshaft and I am pretty happy with it, although if I had to do it over again, I would probably give the  248 duration one a shot (I have heard it gives a bit more low end torque, as opposed to mine which is more horse power oriented - meaning higher revs).

[davehall]

wow, thanks for quick reply.  hummm..... interesting response.  hp vs. torque.  i think i have heard people talking about this before.  aside from my obvious noobness, I think i see what you are saying.  i do not want to do 90mph in my jeep.  I just want to be able to do 55 mph up a hill.  that does sound more torque-ness instead of HP.

here is a more concise list so folks wont have to sift through those threads.  The first 3 cams I have found on multiple sites, recommending upgrades.  the last 2 cams listed, I have only found in that one post.


P4529656  240-240-24* Duration, .430" Valve Lift, 108 Centerline

P4529657  248-248-32* Duration, .440" Valve Lift, 108* Centerline

P4529658  256-256-40* Duration, .450" Valve Lift, 108* Centerline

P4529659  260-260-44* Duration, .460" Valve Lift, 108* Centerline

P4529660  268-268-52* Duration, .480* Valve Lift, 108* Centerline

[sharpxmen]

if you get a cam you should def get roller rockers or some performance rockers to say the least as the stock ones have less ratio than advertised - check my roller rocker thread in Member's Projects section, on the last page i listed my findings regarding the stock rockers - basically you're supposed to have .424 valve lift but you only get .400 at the most, the 1.7 rockers i got turned that .400 into .460 lift which is quite significant

I could not figure out which thread you were referring to here

http://www.pirate4x4.com/forum/showthread.php?t=476130&page=2
actually it is the second comment on this page.  the long one by BCYJ.

but i am working on getting oversized valves on a spare head i bought at the junkyard (similar to what you're doing to not mess with the on on the Jeep) - 2.02/1.6 vs. 1.94/1.5 stock - i am using SBC valves and require reaming the valve guides to 11/32, intake is no problem at 2.02 but exhaust is really tight at that size (1.6), i'll post updates in my thread once i figure out if it works or not.

good luck finding those cams for sale, i called a bunch of the online stores that have them listed and the answer was they can't get them, hesco might have something similar (ROVB4 part number) and you could also get a reground cam from a place that does that.

Keep us posted.

[jfrabat]

Sharp's got a good point; those cams are no longer so easy to find.  The one I got has been the last one I have seen for sale...

[davehall]

hummm... thought i found those cams for sale the other day.  guess not.  i have looked and they are not there.  the only thing i have found is the P4529660.  judging from the above post and some of the stuff i have been reading in the last 24 hours.  this cam could actually decrease my power on the low end.  good for high revs but maybe not where i'll be spending my time as daily driver. 

what about that saying that knowledge is power.  i'm learning all kinds of stuff.... no more power tho. :)

guess its time to go back and try to understand roller rocker thread.  you are way over my head with that one.  I could not get pics at work.  i'll give it another look at home.

[Jeffy]

The Mopar Purple cams haven't been in production since the early 90's.  Keep in mind that car parts in general have a 10 shelf span.  So that means once model is discontinued, you have 10 years to buy the parts up.  Dealers started liquidating what they had around 2005.  I bought a cam but then decided to sell it.  Looking back, I probably should of held onto it even if I wasn't going to use it.

The alternative is to do what Sharp is doing and switch to rockers.  If you don't want to go through what he's doing then Yello Terra makes some 1.7's that fit but they are $$$.

The main difference is that with rockers, you are only changing the lift.  You can't change the overlap or duration as you can with a custom cam.

[sharpxmen]

hummm... thought i found those cams for sale the other day.  guess not.  i have looked and they are not there.  the only thing i have found is the P4529660.  judging from the above post and some of the stuff i have been reading in the last 24 hours.  this cam could actually decrease my power on the low end.  good for high revs but maybe not where i'll be spending my time as daily driver.  

what about that saying that knowledge is power.  i'm learning all kinds of stuff.... no more power tho. :)

guess its time to go back and try to understand roller rocker thread.  you are way over my head with that one.  I could not get pics at work.  i'll give it another look at home.

i'll try to explain a bit in detail

stock cam has 0.265'' lobe lift, that is how much you hydraulic lifter will move up and down from the base circle to the tip of the lobe (maximum lobe lift that is furthest away from the center of the cam).
also the stock cam is 112deg lobe separation angle, 270/270 intake/exhaust duration and 46 degree overlap

the stock rockers that are stamped steel are 1.6 ration so effective valve lift with the stock cam would be 1.6*0.265=0.424''
unfortunately the rockers are either flimsy or getting worn or whatever and the actual valve lift that you are getting (and i measured it 10 times to make sure) is 0.400''

when you get a perf cam usually it has a profile meant for certain range but you can advance/retard the cam to adjust that as well. It also has higher lift, and various overlap, lobe separation, etc based on what you are trying to achieve. with the roller rockers i was playing i was supposed to get .450 lift but i measured it at .459 which means based on the geometry of the Jeep lifters to rockers you actually get a ratio of 1.73 which is even better. So in this case you would get some benefits of the higher lift but no overlap/lsa/duration just like Jeffy said.

[jfrabat]

The alternative is to do what Sharp is doing and switch to rockers.  If you don't want to go through what he's doing then Yello Terra makes some 1.7's that fit but they are $$$.

When I swapped my rockers I looked for Yella-Terra in 1.7, but could only find them in 1.6.  Still, according to what Sharp discovered, even 1.6 is an improvement, as the stockers bend and deliver more like 1.5 instead of the advertised 1.6 (which the Yella-Terra ones do give you).

These are the ones I ended up getting

Felipe

[davehall]

you guys are incredibly helpful.
  
Sharp, i appreciate the breakdown.  I first read you thread after I had filled my brain with other info.  Diving right in has accelerated my learning curve, but man it can wear me out sometimes.

So at this point, I'm thinking NO new cam.  I really like that rocker arm.  looks like i can just bolt it in there, might do that.  How much do you LUV it?  Would you do it again?  Still gonna gives Sharp a proper read, when rested.

How about new valves, springs vs valve job from shop.  Is there much to be gained from replacing stock?

.... Don't you wish you could go back and delete some things you said earlier, that you now realize make you look silly :P

[jfrabat]

you guys are incredibly helpful.
  
Sharp, i appreciate the breakdown.  I first read you thread after I had filled my brain with other info.  Diving right in has accelerated my learning curve, but man it can wear me out sometimes.

So at this point, I'm thinking NO new cam.  I really like that rocker arm.  looks like i can just bolt it in there, might do that.  How much do you LUV it?  Would you do it again?  Still gonna gives Sharp a proper read, when rested.

How about new valves, springs vs valve job from shop.  Is there much to be gained from replacing stock?

.... Don't you wish you could go back and delete some things you said earlier, that you now realize make you look silly :P

I changed out my springs when I did the cam swap.  Not necessary if you just do the roller rockers, unless you do go with 1.7, I would think.

As for the questions, the only stupid question is the one that's never asked...

[sharpxmen]

the rockers need some mods to make them self aligning (or to be more specific have the shafts aligned between pairs so they don't rotate). the alternative is to use guide plates for the pushrods and you need custom pushrods and custom rocker studs or use ARP 135-7102 (3/8 on the head side, 7/16 rocker side) and drill/tap the stud bosses in the cyl head and possibly (not sure) machine the bosses a bit. If you use custom adapter studs from 5/16 coarse to 7/16 fine thread you can use 9.830 length pushrods or a bit longer - i ordered semi-finished ones that i need to cut but they're not in yet so can't tell you how hard is to get the setup. I don't know the length of the pushrods for the ARP adapter studs, that really depends on the valves and the install height and how much you machine out the stud bosses.

you also need a valve cover spacer as the rockers will hit the internal baffles (same with other Jeep roller rocker kits out there - i think hesco carries them).

[Jeffy]

When I swapped my rockers I looked for Yella-Terra in 1.7, but could only find them in 1.6.  Still, according to what Sharp discovered, even 1.6 is an improvement, as the stockers bend and deliver more like 1.5 instead of the advertised 1.6 (which the Yella-Terra ones do give you).

These are the ones I ended up getting

Felipe

I talked to Yello Tera and they said anyone who currently gets 1.6's can order 1.7's.  I've never seen anyone stock 1.7's either.