New 4.6L stroker build

[the_wrench116]

sweet thanks for the pics good luck with the rerebuild.

[seanyb505]

This thread never gives me hope of having a decent running stroker.

[lafrad]

I think this particular Jeep is cursed. There are plenty of examples of nice running 4.xL strokers running around.

[SilverXJ]

Yes, there are plenty of strokers driving around with my problems. Besides basscat (iirc) and maybe two others this is the only other cam bearing failure I have heard of. And I don't understand what about my particular combo makes it like that. Sure, oil is probably bleeding through the rockers. But I have never heard of this problem before with anyone using this combo.

[lafrad]

Have all of the cam failures been in the same *block*?

[SilverXJ]

No, two different blocks. One had a comp cam in it prior to a failure

[Bodo]

Did you make the proper sacrifices to the HP gods before break in?

There's some bad joojoo going on there

[I6FAN]

You may have explained this already, but the first photo on page 20 shows some peculiar indentations, which would be on the "camward" inside of the block. What are they? They almost look like there has been some previous catostrophic failure inside of there at some point? Also, there is a hair line indication on the lifter bore roof; between the cam bearing bore and the lifter bore. I also see some kind of grind point at the bottom edge of the cam bearing bore (top in photo)? Just curious what these are? Were these blocks Magnfluxed? How are you procurring these blocks, and did you do the tear-downs? Check me on this: Your wanting to restrict down to .040" from .088"; 79% reduction, and the factory restricts ~55%; .064" from .095". Your present setup restricts only 17%; .080" from .088". Seems like to keep it apple-to-apples you'd want .059" unless your wanting to go beyond what the factory does? I know I have alot of questions here. This whole thing has got to be discouraging for you...hang in there!

[SilverXJ]

You may have explained this already, but the first photo on page 20 shows some peculiar indentations, which would be on the "camward" inside of the block. What are they? They almost look like there has been some previous catostrophic failure inside of there at some point? Also, there is a hair line indication on the lifter bore roof; between the cam bearing bore and the lifter bore. I also see some kind of grind point at the bottom edge of the cam bearing bore (top in photo)? Just curious what these are? Were these blocks Magnfluxed?

For some reason I only see up to page 12. No 20. If you like you quote the image. However I remember seeing some rough machine marks on the block near the cam. I am not sure but they may be marks from the factory removing material.

How are you procuring these blocks, and did you do the tear-downs?

First one I got from 1bolt on here, the second one from a salvage yard. I didn't do the tear down either time.

Check me on this: Your wanting to restrict down to .040" from .088"; 79% reduction, and the factory restricts ~55%; .064" from .095". Your present setup restricts only 17%; .080" from .088". Seems like to keep it apple-to-apples you'd want .059" unless your wanting to go beyond what the factory does? I know I have alot of questions here. This whole thing has got to be discouraging for you...hang in there!

The largest restrictor push rod is .040". Besides the smallest hole in the stock setup is .064", its also at an angle from the pushrod hole, so there isn't always a direct path from the push rod to it at all times. Plus roller rockers don't need as much oil as the stock rockers.

[I6FAN]

I was late last night, and I didn't have enough time to put it together, but this is what I was referring to:

cb1.jpg

[I6FAN]

What is the procedure for cam bearing fitment and installation. I didn't know until recently that there where precision bearings avaialble; I previously thought cam bearings for these engines where oversize units that where installed in aligned bored bearing bores, and then Finished In Place (FIP) with a reaming operation. With precision bearings, is there any preliminary bore machining or any machining of the bearing after install?

[SilverXJ]

The dents are just casting imperfections, the crack is flash bounce and I don't know what that grinding mark is. I assume it was done at the factory as I didn't do it nor is it a failure related item.

The bearings are just drove in. Make sure the oil hole is aligned and they go in square. I don't know of any other bearings for the 4.0L that aren't that style.

[SilverXJ]

This is the plan:
1) Use restrictor pushrods, .040" size. The top is still getting a lot of oil.
2) OEM lifters... maybe... They are $$$. I ordered one to see if it is in fact the same as a stock one or if they changed their design. The stock lifter is quite different from every after market lifter I have seem.
3) Remove timing chain snubber and mounts on cover. The chain has 1/4" of play from a flat edge. Maybe the snubber is taking up the slack and tightening the chain down. It would explain why the rear most cam bearing shows the least wear. Hesco recommend the snubber removed, but I couldn't get a solid answer as to the reason.
4) High volume oil pump with cam gear oiling line... still a bit uncertain about the HV pump, although Hesco said it can provide extra oil to the cam when idling. http://www.jeepstrokers.com/forum/viewt ... hilit=.026
5) Relocate oil pressure sensor to rear of block like on TJs and WJs for a better reading of oil pressure. Use original oil sensor location for cam gear lube line.
6) Check cam gears for run out, which could tighten the chain
7) recheck cam bearing clearances
8) recheck valve train for bind.

I'm not sure about the whole oil bleeding down though the top theory, but it had been proposed by a few people. However, it also could explain that persistent knock... i.e. not enough oil passing to the thrust surfaces. But again, I am not the only person running this combo, but I seem to be the only one with cam bearing problems.

Valve train binding... I don't remember how many times I have checked it using measurements, checking valve springs, and a solid lifter with regular springs. Nothing bound up.

[basscat]

Silver,

I have talked to 505 once since losing my cam bearings. He suggested that in higher temp climates, I should run the HV oil pump but it should be modified to limit the upper pressure to 60 psi. I didn't have time to get into the specifics and will have more questions after we get into the block this coming week. For instance, my machinist wants to know if we need to open up the oil drainback holes or be concerned with modification to get oil back to the pan when using the HV pump. In addition to the blueprinted pressure limited HV oil pump, 505 also said he had teflon coated cam bearings for me to try.

FYI, my 97 TJ's oil pressure sender is at the oil filter instead of at the rear of the block.

Just passing along a little info...

[SilverXJ]

I'm not modifying anything on my head at the moment. But I am also going to be running restricted pushrods. If you have your head completely apart it would be easy to do some work on it.

I'm going to try to pressure test the pump myself... piece of plexi over it with two holes drilled in it. One for the drive one for the exit, plugged with a pressure gauges. I'm not paying what Hesco or 505 wants for a blue printed pump.

I wonder when they put the sender at the rear of the block on the TJ.. probably in 99 or 2000.