New 4.6L stroker build

[lafrad]

I still would think that 40+ psi would be able to get an oil film running decently... the "block" is to the side, not to the direction of travel of the cam.

I keep getting the little thought in the back of my mind that this isn't a problem of oiling, and is a problem of overloading the Cam journals. 4 bearings for 12 valves... Center bearing being the ones dying first (as opposed to the edges that have less oil pressure...)...

was there significant wear on the base circle of the cam lobes? that should be a place where there should be very little wear on a cam that has "few" miles... there should be just a couple lbs of force on the cam when the valve is closed...

[4.whoa]

Have all your cam bearings(that died an early death) wore like that, or just this go-round?

[SilverXJ]

problem of overloading the Cam journals. 4 bearings for 12 valves... Center bearing being the ones dying first (as opposed to the edges that have less oil pressure...)...

But from where? there is no binding.

was there significant wear on the base circle of the cam lobes? that should be a place where there should be very little wear on a cam that has "few" miles... there should be just a couple lbs of force on the cam when the valve is closed...

Nope, the cam lobes are fine. No bent push rods or anything else that would suggest binding.

I couldn't tell or I didn't notice the wear around the oil hole on previous bearings.

[lafrad]

It doesn't need to be binding to cause the problem. Just extra pressure on the base circle, and/or much extra pressure on the actual lifting operation This can be from a couple of things... most easily that I can see is too much pre-load... It might not be enough to hold the valves open, but if there is SO MUCH, there will be a lot more hydraulic pressure on the base circle.

On the springs side... its stock rocker arms? 1.6rr? 1.7rr? spring upgrades? I know you have been together and apart a few times with the same upper end setup... maybe the springs are just too much for the rockers and cam lobe profiles that you are trying to run?

I would find it to be very unlikely that it would be a "bind" situation in any case. That usually causes RAPID failure and/or many catastrophically broken parts. I can only try to suggest that its something that is just pushing through the tolerances of what the bearings can support as they work in a stock fashion.

[SilverXJ]

most easily that I can see is too much pre-load... It might not be enough to hold the valves open, but if there is SO MUCH, there will be a lot more hydraulic pressure on the base circle.

Preload is .030"

On the springs side... its stock rocker arms? 1.6rr? 1.7rr? spring upgrades? I know you have been together and apart a few times with the same upper end setup... maybe the springs are just too much for the rockers and cam lobe profiles that you are trying to run?

Harland Sharp 1.6 ratio roller rockers. Springs are Mopar Performance with 100# seat and 227# open.

[4.whoa]

Just a thought-not sure if it's a good or bad one -you hear alot about chamfering crank journals,it gets more oil in there, WELL.......what if one would chamfer the inside of the cam bearing oil hole(very carefully of course) or put a small "spot "on a cam journal to help pull some oil?? obviously its not been an issue for most, but i fell out of the box i was think'n in

[lafrad]

Could the lifters be "pumping up" hydraulically? How restrictive are the pushrods? how restrictive are the aftermarket rocker arms?

were the rockers installed on any cam that had surviving bearings? What if they are pumping up because they can't get rid of their oil?

[SilverXJ]

Just a thought-not sure if it's a good or bad one -you hear alot about chamfering crank journals,it gets more oil in there, WELL.......what if one would chamfer the inside of the cam bearing oil hole

I am intending to do that to this set.

Could the lifters be "pumping up" hydraulically? How restrictive are the pushrods? how restrictive are the aftermarket rocker arms?

were the rockers installed on any cam that had surviving bearings? What if they are pumping up because they can't get rid of their oil?

The push rods have a .020" hole in them. The rockers have a .080 or so hole in them. The head and rocker arms were on the Titan stroker which didn't have a cam bearing failure.

As for the lifters pumping up I don't know. I doubt it as I don't notice any other symptoms. I always would out to red line with out a problem.

[I6FAN]

I think youv'e found the problem with the rubbing contact. All it takes is a high spot like that to create excessive heat and then the bearing strength decays and behaves as though you have 600 seat and 1000 open spring pressures. Did it rub anywhere else besides the oil holes? I think the rubbing at the oil hole is caused by the tight fitment of the bearing shell inside the bearing journal causing the bearing diameter to shrink causing the bearing to "buckle" in its weakest point; the area of the bearing void of material where the hole is. I think if you can determine if it's too tight of clearence (more than just at the rubbing point), or something out of alignment youv'e got this thing licked.

P1220027.jpg

P1220041.jpg

[4.whoa]

Have you had all these cams treated(nitrated,etc.)? I know that makes them harder, but does it make them bigger???????? If its a coating, then it has to add something,right? Then the tolerances would be tighter.... more resistance.......
I've never had one done ,so I don't know too much about that stuff.

[SilverXJ]

Did it rub anywhere else besides the oil holes?

At the bottom.

I think the rubbing at the oil hole is caused by the tight fitment of the bearing shell inside the bearing journal causing the bearing diameter to shrink causing the bearing to "buckle" in its weakest point;

the buckling was an idea I had too.

You seem to indicate that all the wear started at the oil hole in your image. It didn't while the oil hole shows slight wear, the bottom is where the wear is concentrated. After a while it moves up the sides of the bearing.

Have you had all these cams treated(nitrated,etc.)? I know that makes them harder, but does it make them bigger????????

The only one nitrated was the Comp Cam. Its more of a metal tempering than a coating.

Just to refresh:
1) Comp Cam died
2) Comp Cam replaced with Isky, oil pump and pickup replaced, Lunati lifters, Joe Gibbs oil
3) Failed Clevite bearings #1
4) Thought the cam not being straight was the cause
5) Isky sent another cam, engine cleaned, new bearings all around, Johnson lifters, Brad Penn oil
6) Durabond bearing set fails after ~100 miles, oil pressure dropping
7) Found lose oil pickup on pump
8) Went with Hesco RVOB, Durabond cam bearings, Clevite main and rod, cleaned engine, Hesco lifters, Brad Penn oil
9) Durabond bearing set fails after ~100 miles, oil pressure dropping
10) Find spot where oil pump is being held off block, clean up oil drain back holes, remove timing chain damper, restrictor pushrods, HV pump and new pickup, Johnson lifters, Sealed Power bearing Brad Penn oil, check for binding again with measurements and solid lifter.
11) Bearings die again, this time with much less wear on double miles. Oil pressure was steady at 40psi hot idle.
12) present time.....

[Exos]

I would start fresh with a new block and have it line-bore. And a new crank too. Unless it hapenned with different blocks and cranks?

[I6FAN]

You seem to indicate that all the wear started at the oil hole in your image. It didn't while the oil hole shows slight wear, the bottom is where the wear is concentrated. After a while it moves up the sides of the bearing.

I think it looks like you can see a similar wear pattern in those images as on your newer "rubbing" images at that same point. I can see the start of the burnishing along the bottom edge of the oil holes (everything is upside down). If it is rubbing there the oil coming out of the orifice is protecting it a bit better there than down in the "wearing saddle" where the wear is horrendous which it was probably contacting there also. The tight clearance at the hole blocks the oil, and if it was rubbing down in the bottom too where contact pressures are much higher.....
I've read where you can take an old cam with similar journal diameters, and grind .125" diagonal grooves in the journals. Then relieve one side, and you then have a hand reamer that you can use to flatten-down those high spots by hand turning it. That seems like it would true-up those high spots. I think the overall clearance should rechecked somehow to be sure that it doesn't need more than the high spots trimmed down. Do they even make oversize cam bearings so the tunnel can be re-bored oversize for these engines?
Recap:
-The HV and restrictors did help overcome the tight fit some.
-The oil pressure was good until the bearings tore, and if you would have continued to operate engine much longer the main and rod bearings, in those circuits with torn bearings, would have worn rapidly also. I think you said they looked good, but not great; they were showing something.
-The thinner break-in oil seemed to help, as the 50 weight you used that one time seemed to toasted them real quick (I couldn't believe how quick you were back at square one that time).

I know this has been frustrating for you, not to mention expensive, but following your build thread really has been educational about allot of the details of the Jeep engine! Anyone following this has learned allot.

[SilverXJ]

I would start fresh with a new block and have it line-bore. And a new crank too. Unless it hapenned with different blocks and cranks?

The is the second block. It had the mains lined bored. They were good enough to use as is, but my machinist wanted the bore perfect. This is also the second crank. I sent a spare crank I had to Hesco for them to check it out. It was messy so they ground it .020 under. All teh previous failures can be attributed to oil flow issues outside the cam bearing. This one can't.

I've read where you can take an old cam with similar journal diameters, and grind .125" diagonal grooves in the journals. Then relieve one side, and you then have a hand reamer that you can use to flatten-down those high spots by hand turning it.

I have read that as well. I also read that they can be shaved by hand. I'm going to try to recheck the clearances with a dial bore gage. Was going to use snap gages but they are a joke.

Do they even make oversize cam bearings so the tunnel can be re-bored oversize for these engines?

Yes, in .010" over. However I don't think it needs a cam tunnel bore. The cam still spins fairly easy so its just minor interference.

Recap:
-The HV and restrictors did help overcome the tight fit some.
-The oil pressure was good until the bearings tore, and if you would have continued to operate engine much longer the main and rod bearings, in those circuits with torn bearings, would have worn rapidly also. I think you said they looked good, but not great; they were showing something.

I think if I ran it longer on the engines that were using oil pressure, yes it would have killed the main bearings. At that point the oil pressure sensor was still right off teh oil filter, so who knows what the pressure was at the end of the gallery. On this most recent failure the main and rods look great though. Probably as a function of the HV pump as the oil pressure never dropped.

-The thinner break-in oil seemed to help, as the 50 weight you used that one time seemed to toasted them real quick (I couldn't believe how quick you were back at square one that time).

I'm going with a 10w-30 this time.

I know this has been frustrating for you, not to mention expensive, but following your build thread really has been educational about allot of the details of the Jeep engine! Anyone following this has learned allot.

I've learned a lot. A lot more than I ever wanted to. At this point I don't want to build another engine as this has left a bad taste in my mouth. But I probably will as I now have a really good grasp on everything. But for now I don't care to learn any more and just want to drive the fucking thing.

[basscat]

But for now I don't care to learn any more and just want to drive the fucking thing.

x2 on that!