Steve Underwood

Have you knurled out your guides?

Larry

iTrader: (4)

Several reasons guides gall or wear prematurely. One little spec of sand or dirt during assembly, improper lubricant, lack of lubricant, incorrect valve too guide clearance, improper geometry causing too much side loads on the valve stem.

If it has done this before did you replace the valve or valves? One little dimple on an old valve would gall or prematurely wear out a guide. The valve stem has to be smooth!

It is very important that the valves and ID of the guides are clean and properly lubed with engine assembly lubricant when assembled.

I never use teflon valve seals and I do leave off the spring clips on the viton valve stem seals to allow more lubricant to get into the valve stem/guide area.

Visceral

iTrader: (1)

But then dont you notice oil leaking into the chamber through the valve guides?
Theres such a fine line between lubricating them properly and keeping oil out of the chamber... only its not as clear cut as a set of rings :-/

Nick (ARE) is going to look at them and see what is up. Its different valves each time.

chris

Steve Underwood

I would check to play on the valve to guide clearances. As long as they are within tolerance, the oil blow by should be very minimal. Also, Knurling the guilds has it benfits as well. It leaves grooves in the guide that hold oil. Better lubrication always helps...

McRat

I would be suspicious of non-lubrication factors. Modern bronze-silicon guides have natural lubricity with steel. I've seen 1,000's of cylinder heads abeit not LS1's, come in for rebuilding. Stuck valves are often caused by:

Bent valves.
Guide not "true".
Insufficient guide clearance.
Severe over-heating/burned valve.

The valve issue can be checked in a V-Block and a dial indicator.

Before seat grinding, check guides with a go-no/go plug gauge. The "go" must fall through, not pushed through.

LS1derfull

Valve guide finish and clearances are critical. Loose clearances make valve run hot, and they also allow action on valve(side thrust) to beat giude out of shape sooner.Finish dictates valves ability to transfer heat to cyl. head. Which is why guide honing instead of reaming is needed with more radical cams. Guide concentricity and taper spec. must be tightly held to expect good performance.

jmX

I'm thinking ARE knows how to setup valve guides...they've done them on these particular heads twice and I doubt they screwed it both times (same crap happened both times).

On these heads, the valve has been moved a bit from its stock location, and maybe that was just enough to screw up the geometry, causing sideload stresses/wear on the valve stem?

ChrisB

[quote]On these heads, the valve has been moved a bit from its stock location, and maybe that was just enough to screw up the geometry, causing sideload stresses/wear on the valve stem? <hr></blockquote>

That was going to be my guess, though I didn't realize that the valves had even been relocated. Is there anyone else running with this same setup? I would be very suspicious of the valetrain geometry.

Chris

McRat

Installing new guides in Aluminum Heads is an art. I've dealt with bronze silicon and iron guides in German heads and have replaced guides in thousands of heads.

Guides come in different OD's. After you push out the stock guide, you push in an oversized guide. If you use a guide that is too big, it will deform the guide tunnel in the head (especially in heads that have been ported removing the intake runner guide boss), making it slightly banana-shaped. All the reaming in the world won't make the guide straight. This is why you verify with plug gauges. If any resistance on the go gauge is felt, you've got a problem that's not easy to fix. With VW heads, we just chucked them. It was easier than fixing them, and they were cheap.

This may not be the case with your head, but I would certainly verify that guide is straight in any case.

Visceral

iTrader: (1)

[quote]Originally posted by ChrisB:
<strong>[/b]

That was going to be my guess, though I didn't realize that the valves had even been relocated. Is there anyone else running with this same setup? I would be very suspicious of the valetrain geometry.

Chris</strong><hr></blockquote>

The valves were moved to the inside, perpendicular to the rocker, .030.
According to both MTI and ARE, this has no effect on the geometry, which also makes sense to me too. Its within the side-side slop in the rocker.
Jon (jmX) has the same thing (Im pretty sure), and has had no issues. I also believe that ARE has done this on several other heads and has seen no ill effects.

Big possibility for THIS time (not the previous). THe heads had to have the roof on the intake ports TIG welded when the spring seats broke through (secretly a very common ported LS6 casting problem). The heat from that might have slightly warped the guide.

Nick is totally replacing the guides and the valves. I have every bit of confidence that he will do it right and measure everything twice.... as long as something else isnt creating the problem. MTI says the heads are oiling OK.

Im baffled. #5 the first time, #3 this time.

Chris

Visceral

iTrader: (1)

That was the first time.

Now while at MTI, it happened a second time.

MTI folks say the oil is getting to the top of the head...

This is getting old.

In the below picture, I had 4 sets of head bolts. My car now has created 2 more sets in the last month, and its getting REALLY OLD.
Im actually having to stud the block because the block head bolt threads are getting tired.

chris