New 4.6L stroker build

[SilverXJ]

Now the next question.. could that possibly cause enough binding to kill the cam bearings but not damage the rest of the valve train?

Oh yeah.. I have no problem moving the valve in and out of the guide, I can feel play (have no way to measure) and rotate it. Of course that is with the head cold.

[I6FAN]

But would a non concentric valve seat cause wear to that extent? I would think it would only be when it gets near the seat.

I saw something somewhere on this that says if valve seat to guide run-out is excessive, it will show up on one side of the tip end and should show something likewise on the opposite side, down on the head end of guide.

[Exos]

lateral play of the stem, when valve is just begining to open, should be no more than 0.003".

[SilverXJ]

I took a better look at the valve seats. Holding the valve with just finger pressure I saw some light past the seat on one of the exhaust valves. I took it to my new machinist in Danville and he took a look at an intake valve as well. It showed a lot more light through than the exhaust I had looked at. So it needs a valve job, possibly a few guides and he would like to install spring locators under the springs. Still I don't see how the problems in the head could cause the cam bearing wear... although the head has been the only consistent thing on all the engines and hasn't been checked (except for bind) until now. Weirder things have happened.

In the mean time I am working on a screen that will attach to the main girdle to remove air from the oil.

Also, some other projects I have been working on: http://www.jeepstrokers.com/forum/viewt ... =24&t=2375

[I6FAN]

Still I don't see how the problems in the head could cause the cam bearing wear... although the head has been the only consistent thing on all the engines and hasn't been checked (except for bind) until now.

Yea, it seems like "sloppy" guides would make it easier for the valves to be pushed down.

You have checked a lot of dimensions and set-ups that you have had on your failed bearings. How about a process in the build; something that is getting done incorrectly, and keeps getting done that same way each time. Did you have your blocks thermally cleaned? There was a thread over on Speed Talk about thermally cleaning blocks, and someone had an issue like yours, although a Ford V8. What happens is the block is heated to 500 to 600 degrees for x amount of hours and then must be sllooowww cooled (usually in the furnace). If it's taken out early, the block can warp and distort. The cam would spin freely in the block, but the middle bearings were always ruined on the same surfaces. I thought that sounded a lot like your situation, and the length of the I6 block could worsen warpage. I looked back at some of your earlier data on deck clearance, and it looked like as you got to the middle of the block the slugs had less clerance, and as you move from the center cylinders outward the deck clearances increased. If the rods were resized I would think they would be "closer" than that, or is something warped about the block?

[SilverXJ]

Yea, it seems like "sloppy" guides would make it easier for the valves to be pushed down.

Or the guides and/or seats could be introducing some form of wobble that could be causing an issue.

How about a process in the build; something that is getting done incorrectly, and keeps getting done that same way each time. Did you have your blocks thermally cleaned? There was a thread over on Speed Talk about thermally cleaning blocks, and someone had an issue like yours, although a Ford V8.

Yes I had read that thread. Cam bearings falling out and the like. But no, the block was never thermally cleaned. It has always been one of those heated spray cabinets. Besides my thread on Speedtalk I lurk a lot over there.

I looked back at some of your earlier data on deck clearance, and it looked like as you got to the middle of the block the slugs had less clerance, and as you move from the center cylinders outward the deck clearances increased. If the rods were resized I would think they would be "closer" than that, or is something warped about the block?

IIRC the machinist said the rods were slightly different sizes and he didn't want to cut more off than necessary just to bring them all to the same length. That and the crank wasn't perfect, which has been rectified. It wouldn't be the block out of square on that issue because the crank tunnel was checked (by 2 machinists and the ones that did the line hone) and the deck surface is flat.

There is either some kind of binding issue which hasn't been seen yet, but it would have to be something that bound when opening the valve and not when its closing. If it bound when closing I would think I would have a noisy valve train. Or an oil issue, which I can't fathom where it would bleed off at and still have great oil pressure and no damage to the other bearings. Or... maybe the cam for some reason is bouncing around in the block, wiping the oil off the bearings in the process.

Theoretically the oil pump and the grind on the flat tappet cam should suck the cam into the block. However, it was either the 4.2L or the early 4.0L that didn't have the spring and pin in the crank bolt. That was added later, I assume to address some sort of issue. Also, there is a AERA document on a knocking sound being made by the cam if the the pin and spring were omitted during a rebuild. And I do have a knocking sound, but i am running the spring and pin. Maybe the more aggressive valve train is over coming the spring and causing it to walk in and out.

[SilverXJ]

All the intake valves are pretty well damaged. The exhausts fared better. Going with SI Stainless swirl polished valves for a 5.9L. The are only .01" larger in the head and .005" shorter in OAL than stock ones. He hasn't gotten to the guides yet.

[SilverXJ]

I am fairly certain that the knocking noise was coming from the cam moving in and out of the block. We had a Ford Galaxie come into the shop with a knock that was very similar to the sound my engine was making. It wasn't present when cold, but would come about once heated up and had about the same rythm as mine. The only difference was that the sound on the Ford was louder. Tore down the timing cover and the cam thrust plate was eaten up, allowing the cam to move in and out about 1/8".

The spring and pin setup on the 4.0L would let it move nearly 1/8" with finger pressure. So it could have been moving quite a bit.

But what would cause it to move? Just the stronger valve train over coming the spring or a symptom of another problem?

And would the cam moving in and out cause cam bearing wear like this?

[Exos]

I have almost the same setup as yours.... no cam bearing failure signs after 200000 km. So the cam riding the block is not an issue, me thinks.

[SilverXJ]

But the cam isn't riding on the block.. its bouncing in and out of the block.

[SilverXJ]

I got the head back about two weeks ago. Replacement guides, new swirl polished stainless intake valves (for a V8 Magnum engine, SSI valves iirc $11), spring cups, spring seat height corrected, 3 angle valve job. Yeah, it was pretty screwed up.

I was going to use DWG's timing cover cam thrust mod and had it installed in a cover. However, I was planning on adapting a roller cam button from a chevy. I had this nagging feeling there was something that interfered with the cover. Sure enough the serpentine belt goes right in front of the cam. So I an using a stock cover with with a solid steel pin. Like the stock setup but no spring and .005" end play.

I am also working on a windage tray built off the main girdle. I almost forgot to cut a spot for the dipstick tube. I'll throw up some pics later.

So, for this round the changes are: coated cam bearings, solid cam thrust setting, re worked head and a windage tray. After this I will be 100% out of things to try.

[Muad'Dib]

I would be afraid that a solid rod would eat the timing cover faster or all at once... Wouldnt a stronger spring be a better suit? Then there is still some "give" but its stiffer than stock.

[SilverXJ]

Its still steel on aluminum or magnesium or what ever it is. and if I went to a stiffer spring and it was able to hold the cam in the block it might see even more of a force. The pin used also has a much smother surface than the stock pin.

[Muad'Dib]

It was just a thought... just didnt want anything nasty to happen

[SilverXJ]

Something bad happen? To my stroker? Never!