Cam bearing failure x2.. help...

[SilverXJ]

So what do you think happen

Seems like something must have been wrong. I be worry if I didn't see anything wrong.

There is nothing in the measurements that show anything obvious. I was really hoping that I missed something in the valve train binding, but even with solid lifters there was plenty of room. When priming the engine last time my machinist was surprised at how fast the oil came up to the rockers. He wanted me to go back to stock lifters. I was planning on it because the stock lifter I have is very different internally from other lifters for this engine. So I ordered a single Mopar Performance and OEM lifter to compare the two. I got them and I was quite disappointed because they obviously changed the design at some point in time and now the lifters are just like any other after market lifter.

My machinist's theory lies in the fact that the lifters I have used in the past for the two bearing failures (Hylift/Johnson, and standard brown bag lifters) were different from the stock ones. Thus he thinks that the lifters were sending too much oil to the top, not enough to the bottom... or just enough to keep the mains and rods happy but not enough for the cam bearings.

He also had another theory that the major damaged happened in the first few minutes of running the new engine in. Because of the extra oil to the top that the cam bearings didn't get enough oil during priming and during the first few minutes of running. Last time I primed it for 20 minutes and there was oil pressure the whole time, albeit from a gauge positioned right after the oil filter (that has been fixed). This time I will also plug the pushrods while priming to send the oil to the bottom end. Combined with restrictor pushrods.

Another thing is that 70% of the people with strokers built themselves have installed a high volume oil pump. Their thinking is extra insurance. However, several manufactures of crate strokers install high volume oil pumps. Including Mopar's own stroker. Maybe there is something to that.

[Dodge Freak]

I didn't reread the full thread, its late. But on Mopar stock lifters on the la motors, 318-340-360 the oil for the rockers comes up by the heads. Lifters come two ways, the mopar way-or use to-had a solid disk to be used with solid pushrods. What I am using now but I have used the ones with the oil hole for the pushrods and notice no problems..well my rod bearing did weld itself to the crank after 8 long season.

Yeah I would run a high volume pump, all 340's came that way...and the factory used a small oil pan.

[SilverXJ]

Anyone have a suggestion for what size restrictor in the pushrod? My machinist suggests .020" because I have roller rockers, but I'm a little worried about that size due to the fact that the oil also cools the springs.

[BrazilianZ28Camaro]

I'd get the .020" pushrods.

Can you imagine the hot oil at 30psi flowing through it?

Well , there are twelve pushrods and a lot o of oil flowing up top.

My two cents,again.

[CHT]

So it feeds the lifter gall then then onto the main, flowing passed the cam bearings. So why is limiting the push rod going to fix it?
(I understand less bleed off points)The main is after the cam yet they arent getting hurt are they? I still think you need to coax oil into the cam bearing area. Either that or the cam bearing journal is being turn the wrong way when manufactured. The pics look like starvation wether it be from tightness or plainly not getting enough oil, your mearsurements show it not to be tight so......

[SilverXJ]

Yes, that is how the oil flows. The mains and rods don't look perfect, but nothing like the cam bearings. Everything else checks out, so I don't know. It doesn't make 100% sense to me, but I'm no expert. However, being that the oil does get up through the push rods rather quick and a lot and everything else checks out it is making more sense. I told Clay Smith to make sure that the cam journals are polished in the correct direction and they said it was. I don't know how I would be able to check that though. They said that everything else on the cam checked out.

One other interesting thing is that I have found 3 other people that had cam bearing failures similar to mine. Their mains and rods didn't look terrible as well. One of the failures was from a clogged oil pickup, one was from a damaged oil drive gear, but the last happened a few weeks ago and hasn't been investigated yet.

[SilverXJ]

On the oil pickup on the pump. Its a press fit. I was considering soldering it on or JB welding after its been pressed in. Good idea or not?

[Malvn]

I would Weld the oil pick up in place Only after I have it in the right place

[SilverXJ]

Oh yeah.. I know I have to align it first. However I don't weld.. any alternative way that doesn't require a weld?

[Greg West]

I suggest checking which direction the cam was rotated when the cam journals were polished. I had the same problem on a 4.0L Jeep race engine. If the cam is polished in the wrong direction, the lay of the cam journal material will scrape off the cam bearing material leaving just the steel cam bearing shell. This can happen during 15 minutes of cam break-in running time. I had this happen twice before finding the root cause of the problem.

I was told that some cam companies polish 6 cylinder cams backwards because many 6 cylinder engines use two gear gear drives (6 cylinder Chevrolet's for example) so the cam turns backwards in the engine.

[SilverXJ]

How do I go about finding which way the cam was rotated? Just ask the company?

What company made the cams on the race engines you had? Any details on the engine as well?

[jimjamm65]

SilverXJ, ALWAYS weld any press-fit oil pick-up into the pump housing. if you don't weld, take it to someone who does.

[SilverXJ]

Is it to be just tack welded to hold it on, or a full around weld for a seal? The pick also has a bracket that bolts to the pump itself, about 4" from the press fit.

I've actually never heard of anyone doing it on a jeep 4.0L oil pump, but have heard about it on other pumps.

[Greg West]

I ran the Jeep In Stock Eliminator. I had used Lunati, Crane and Comp Cams. I suggest you take the cam you ae planning to use to a shop the grinds and polishes cranks. Have them polish the cam in the proper direction. A shop that grinds crankshafts should be aware of this problem because it can happen on cast iron crankshafts as well. The cams I ran were stock eliminator type cams with flat noses and aggressive profiles. Spring pressures were quite high. After the cams were polished correctly, I did not have any more problems with cam bearings.

[jimjamm65]

SilverXJ, i usually weld a bead 3/8 to 1/2 inches long at the point of easiest access. no need to weld all the way around, and on some combinations impossible. a "tack" will not hold much, if anything. also, you may at some point want to separate the two, so it's easy to use a small cut-off wheel and cut the weld, saving the desired part. J-B weld is good stuff, but not in this application.