robm

Ha ha, you and me both! Ive had my head off 3 times now and I don't even know how many times my intakes been removed.

robm

Yes I did, but honestly I wasn't sure what that noise was, but I knew it wasn't normal.

robm

It's the pro-top line head with o/s stainless valves.

Runner4Luke

This head has stainless valves, not over sized though.
The head in my '87 has stainless and over sized valves though (but it's 2 years old w/20k on it).
Seeing as they're both on number one, I wonder if it was the casting.. I'm not sure what all Ted does to his heads to be honest.

robm

It'll be interesting to find out.

DHWRIGHT

very interested to know the cause of your valve problem so I can look for it in the future because I cut and lap my own valves.

Runner4Luke

Spoke to Tod today, he said its quite common to bend the valves during initial head install, if the tappets aren't relaxed or if they're riding on the side of the valve stem when the head bolts are torqued down.
He says they normally bend bad, not mildly, like it would be in my case.
I did relax the tappets a bit, but who knows... I'll pull the head and drive it up.

@robm,

You said you pulled the head and valves multiple times?
If your valve was bent, it would be apparent when the valve was removed.

robm

Yeah, heads been off twice now. I didn't see any signs of them being bent. I even rotated the crank with head on, intake manifold and exhaust manifold off, and they opened and closed. I also loosened up my rockers and installed with the inside down as per his instructions.

robm

If it's bent why would it only affect it at idle, doesn't make a lot of sense to me. Seems it would affect all rpm ranges.

Runner4Luke

If they're only slightly bent, then they're only slightly binding, and at idle the springs aren't getting much in the way of assistance from air pressure. You open up the throttle and increase compression w/ more air, you get additional forces pushing that valve shut.
Yea this sucks, I was careful when I put that valve assembly together..
Nothing looked awry, he said if they're bent the valve stem seals would be broken and riding up and down with the valve. They weren't though, I'm going to take a closer look tomorrow.

bswarm

It could be too tight clearance between valve stems and the valve guides. But I'd suggest following up with a vacuum gauge before you pull the head again.

Runner4Luke

I 95% sure that the valve is sticking, and Tod concurs. I sent him the video.
I hear ya with the Vacuum gauge, but the AFM slapping shut is telling me what the vacuum gauge would already, big vacuum fluctuations.
Only disassembly will verify what the cause is of the valve binding is.
And If its slightly bent, it wouldn't have been when he slid it in during assembly, which means it either happened when the valves were lapped, or springs where put on or when I torqued the head/rocker arm assembly down.
Unfortunately it's impossible to know definitively. He did say that torquing the head down with the rocker arms slightly off kilter would bend the valves, bad, as he's seen many times. But not normally just slightly.
The important thing is that I, nor anybody else, actually knows.

robm

When you pull the head off I'm interested in hearing what you find. I was examining my valves last night and none appear to be bent.

Runner4Luke

Pulled the head off today, I can't say I see anything that looks off.
Guides looked fine, I guess its common that they crack and stick to the valve when the valve bends.
I can't really inspect the valve without removing it, and I i'm not going to do that. I'll leave the real inspection to Tod.
I should have the full story by the end of next week, I'll let you know the verdict.

Shady Cadence

That's what my money says.

But I predict he also finds a couple new, uninstalled valves with the same issue.

Runner4Luke

Well I'm stumped, Tod pulled the valve right when I arrived, and it moved competely freely. Not bent, everything appeared fine mechanically. A little blueing around the valve he said from higher temps, (running lean, when it does run?)
So he threw in a new valve and gasket kit, no charge.
I'll put it back together and see what happens I guess.
Man, what a mystery.

bswarm

Yikes. Should've bought that $16 vacuum gauge! It's a good tool to have around.

bswarm

So, you have compression, spark, fuel, and air. Any vacuum controls/lines on #1 intake runner?

Shady Cadence

You proved that. On video. We just don't yet have an explanation as to why.
Of course it didn't stick on the bench, by hand. Remember, it didn't stick during cranking rpm either, did it? Only at idle, driven by the tappet riding the camshaft.

So new valve, make sure you back the tappets off when you torque the head like Tod said, and we'll see what happens. I hope it's gone, but I'm apprehensive. If your miss is still there, the only things left are either the guide itself has an issue, or it has a geometry issue in relation to the tappet.

I'm pulling for you. Good luck.

robm

You get the head back on? Any updates?