New 4.6L stroker build

[gonridnu]

This is a very unusual situation to be sure.

As noted the main and rod bearings at number 1,3,5,7 (?) share a common oil galley with the cam bearing. As the cam bearing is a "low load bearing" relative to rods and mains you would think they would be burned up too if this were a lubrication issue. Me thinks it is not.

I'm sure you will figure this out eventually but it is terribly unfortunate that you are living the nightmare in the process.

[SilverXJ]

At least one thing is figured out. That knocking sound from the bell housing. I sent a spare crank from a previous engine to Lee at Hesco. He took a look at it and found that the journals were tapered, which would cause the crank to walk back and forth. I have to make a decision if I want to have them turn it 20/20 to straighten it out or buy one of they new cranks... $797 is a bit steep for it though...

As for the cam issue I still don't have a clue. One thing I didn't inspect was the oil pickup tube. Possibly a leak there.

[SilverXJ]

Figured I would throw up some pictures of my beautiful bearings.



I just don't get it. I have rebuilt 3 Jaguar V12 Engines, one Jag V8, and 2 Jag I6 engines. Never have I had this much trouble. I didn't even pay that much attention to the Jag engine assembly and blue printing as I did on the Jeep I6.

I still have no real reason for this failure. I did notice that the oil pickup tube came out of the oil pump pretty easily. I will be replacing that and the pump. I don't know if I mentioned it or not, but the lifters were making sounds like the preload was off slightly, or like they were bleeding down. I understand the cam bearing failure would decrease the preload, but I increased preload to .040" prior to taking these pictures 50 miles later.

Few questions prior to rebuild: Reuse timing set? Anything else need checking?

[omegatron]

Is there a possibility that the cam timing gear is somehow out of balance? Have you used the same timing set with both blocks? Does your timing gear have an off set drilled key for the cam pin to adj timing? Could that be a factor?

[SilverXJ]

Nah... it was used with the comp cam without issue.

[Exos]

Probably not related to your problem, but why did you use 15W50 oil for the breakin? Isn't it way too thick?

[SilverXJ]

Not for break in lube in this weather. If it was the dead of winter, then maybe.

[lafrad]

Have you checked the spring pressures? Is there some wacky chance that the valvetrain setup you have just happens to have some ridiculously strong springs that are just giving the cam hell? Maybe someone sent you the wrong parts?

[SilverXJ]

Mopar Performance and they do spec out at what they should. It can't be the valve train as the same exact thing was run on the 68-231-4 with out failure.

[lafrad]

Well, considering everything else fails, except for that one... maybe that was the exception, not the rule?

[lafrad]

Other 'silly questions'

YOu have checked to make sure the valve retainers and locks aren't bottoming out on the valveseals? That there is no weird binding on the guideplates for the roller rockers (have you tried a setup with the stock, stamped rockers at all?)

[SilverXJ]

Yeah, i checked the retainer to stem seal and there is plenty of room. At least .555" before it bottoms out. No guide plates.

[Exos]

Not for break in lube in this weather. If it was the dead of winter, then maybe.

Still, I wonder if it might be a factor, especially for a new build with tight clearances. All the service manuals call for 10W30. I don't see why it should be thicker for breakin. Anyway, just thinking out loud here.

[lafrad]

What are the consistent things across all these ranges of failures? what parts are the same for each cam failure?

[Bodo]

really looks like lack of oil to the bearings.