Cm871 valve cam part number mystery

[dhirocz]

So, after loosing the good fight that I got drug through the mud with for 4 months, I'm left to myself to fix my truck. No other good options. On top of that I'm about to loose my loaner...because I 'should have' fixed it by now even though my rolling junkyard of a loaner truck has spent most of it's time as a dealer decoration.

...and in accordance with my great luck, I found a leaking head gasket and a liner leak on my 871 to go along with the cam I have to fix. No avoiding it now, it needs some work here. Heads gotta come off. You know what that means... 685k miles on it.

I have enough to buy parts and tools. That's it. Fortunately, I'm very mechanically inclined.

I'm finding alot of different part numbers for isx valve cam. 4298626, 4059331, 4298629 to list a few.

I'm finding references stating that the cam from a 2250 fits an 871 and others. I'm having a hard time swallowing that but I might be wrong.

I also know there was a revised camshaft with wider lobes I believe, which would also require a change in rocker arms if I'm not mistaken. A call to Cummins gives me the typical idiotic shrug of a response aside from 'they fixed the cam issue, buy a recon'. Uh, no.

I don't know if these are parts number changes, actual newer compatible revisions or whatever. I know I found an 8629 NIB Cummins cam for $600 but won't buy it unless I know for a fact it'll work right. I don't need to confuse the ECM.

Anyone care to enlighten me? I've got a 2010 cm871. Valve cam is toast, among other things.

[AussieISX]

(06-27-2017 )dhirocz Wrote:  So, after loosing the good fight that I got drug through the mud with for 4 months, I'm left to myself to fix my truck. No other good options. On top of that I'm about to loose my loaner...because I 'should have' fixed it by now even though my rolling junkyard of a loaner truck has spent most of it's time as a dealer decoration.

...and in accordance with my great luck, I found a leaking head gasket and a liner leak on my 871 to go along with the cam I have to fix. No avoiding it now, it needs some work here. Heads gotta come off. You know what that means... 685k miles on it.

I have enough to buy parts and tools. That's it. Fortunately, I'm very mechanically inclined.

I'm finding alot of different part numbers for isx valve cam. 4298626, 4059331, 4298629 to list a few.

I'm finding references stating that the cam from a 2250 fits an 871 and others. I'm having a hard time swallowing that but I might be wrong.

I also know there was a revised camshaft with wider lobes I believe, which would also require a change in rocker arms if I'm not mistaken. A call to Cummins gives me the typical idiotic shrug of a response aside from 'they fixed the cam issue, buy a recon'. Uh, no.

I don't know if these are parts number changes, actual newer compatible revisions or whatever. I know I found an 8629 NIB Cummins cam for $600 but won't buy it unless I know for a fact it'll work right. I don't need to confuse the ECM.

Anyone care to enlighten me? I've got a 2010 cm871. Valve cam is toast, among other things.

The 4298626 is the new pn for 4059331. It has the wider lobes on the intake and exhaust (now same width as the jake lobes). You don't have to change rockers to suit if you choose not too . The information regarding the same cam used between 871/2250 is correct , in fact the Australian cpls they use the same valve cam in the cm570-2250

[dhirocz]

Ok...so where does this 8629 fit into the equation?

I wasn't sure if maybe there was a different cam for an isx600 or something like that.

What about rocker arms? Any way to identify by pn which rockers go with the wider cam?

[AussieISX]

There's probably half a dozen different cams among the cpl's, you need to get the the one that suits yours obviously. Maybe this helps in relation to levers https://quickserve.cummins.com/qs3/pubsy...l?q=02t3-1

[Brock]

Cummins does say you need to change the rockers when updating the wider lobe cams, I remember going through this when I did mine.

That doesn't mean you need too but rather just that Cummins says you need too..... it's this reason why I bought a used cam.

[AussieISX]

Based on the information in the literature I posted the link too , I can't see anything to say the older narrow levers are not compatible with the newer wider cams, it states the new wider rollers are not backwards compatible with the old pn narrow lobes

[Rawze]

(06-28-2017 )AussieISX Wrote:  Based on the information in the literature I posted the link too , I can't see anything to say the older narrow levers are not compatible with the newer wider cams, it states the new wider rollers are not backwards compatible with the old pn narrow lobes

My own opinion is that if you go with older rocker levers on the new cam, then in the future, say in another 500k miles, if you have to replace one for any reason, the older ones may no longer be available. Now the trouble lies in the fact that you have lobe wear pattern the matches older rollers and suddenly installing newer wider rollers on an old cam that had shorter ones may become an issue.

Just my own thoughts on it. If I owned it, I would update all of it or stick with the older style if I could instead of playing mix and match. You never know what the future might hold.

[AussieISX]

Very valid points, I have a couple of good sets of the narrow levers to fall back on in the future but budget permitting I'd love to upgrade to the improved rollers