your-real-dad

I got a rebuilt 3VZ off of Fleabay, and thought they would adjust the valves as part of the rebuilt. Apparently not. Every gap measurement on every valve is out of spec on the low side. Both intake and exhaust. Is it normal to have to adjust the valves with a newly purchased rebuilt engine? And is it normal for all the gaps to be too small? The only thing I could think of is the "3 angle grind" that they supposedly do on the valves might allow them to sit deeper in the heads, which would raise shims.

MudHippy

Grinding, and/or lapping, the seats or valves...yes. It's not always going to be the case that you need thinner shims for a rebuild. But it's more likely you will. Good thing is you don't need to buy shims. You can just grind down the ones you already have. So it's a partial win really. It'd be worse if they were too loose.

your-real-dad

You mean like just a flat surface, some emory paper, and take a couple of mils off? I never thought of that; thanks! I was going to pull the shims from my old engine, and hope to mix and match, but this should work fine.

Does anyone have any thoughts on whether to shoot for the nominal specs (.009 and .011) or should I go a little tighter so that as they wear, they drift toward nominal?

MudHippy

It's more of a chore than that. They're quite hard, and it takes more time/effort than you'd think to remove a significant amount of material from them. I have a thread on it.

And you're better off shooting for the loose end, if you're aiming at nominal. Since as they wear they'll actually get tighter, not looser.

your-real-dad

Checked with the rebuild shop. They said they do set the shims, and they set them on the tight side because "they will open up with running." Most people say they get tighter with wear, not looser. Any idea why they get tighter? Is the wear at the top side of the valve greater than the wear on the cam lobe / shim interface?

MudHippy

The valve face where it contacts the seat, as well as the seat itself, is where all the significant wear occurs. And really only to the exhaust valves/seats...of any significance. As those surfaces wear, the valve clearance shrinks. The intake valves, however, will almost never require readjustment, unless they were as tight as allowed to begin with. They just don't wear very much in use. Being air cooled and all.

Wear to the valve stem tips, bucket tappets, and shims is so minor and insignificant it can be regarded as negligible(if it even presents itself at all). Same goes for the cam lobes. Since this is essentially a roller cam setup.

millball

Not hardly. I know a flat tappet when I see one.

MudHippy

Very much so in fact. If you understand the mechanics involved.

Cam lobe contacts shim. The shim and/or bucket tappet spins/rotates/turns by action of the cam lobe. Not only does the shim within the bucket tappet act as a roller bearing, in case it doesn't the bucket tappet itself will spin/rotate/turn acting as a roller bearing. This is EXACTLY how it works. That much is not contestable.

My point...camshaft lobes contact what is essentially a roller bearing. It's essentially a roller cam setup. Period. End of story.

Thanks for playing!

BTW...I know how jealous that makes you 22RE lovers with its nightmare prone to catastrophic failure cam setup.

millball

Whutta crocka poo!

It is surely a rotating flat tappet, but it just as surely ain't no roller tappet, its flat.

Totally different cam profiles are required for roller tappets than for flat tappets.

Sometimes you're right and sometimes you're not.

This time not.

I full well know the mechanics involved, better than you I guess.

"Thanks for playing"

millball

Back to the original query, the clearances do generally close up in service, for the reason MudHippy gave, ie- recession of the valve into the seat.

I personally think that the exhaust clearances should be set preferentially on the wide side for safe long service.

I have a friend who has a precision surface grinder with a magnetic table and he just slapped my shims onto the grinder table and ground off whatever I had calculated that needed removed from each one. I had him grind the backside of the shims so as not to disrupt the existing cam to shim wear pattern.

MudHippy

Seriously? Wow. I was starting to think you kinda knew WTF you were talking about. I guess not.

BTW...if there's even the slightest chance I'm EVER wrong about ANYTHING...I let you know ahead of time. If I haven't stated I might be wrong...there's no chance in hell I am. Sorry to burst your bubble.

millball

I really am the kind of genius that you think you are, and
I'm occasionally wrong.

Not this time though.

your-real-dad

Uhh, well at least it sounds like there's consensus that the gaps will get smaller with wear? Mine are all at minimum or under, and I think the rebuild shop was just lazy; did a three angle grind on the valves, and stuck them back without touching the shims. That removes material from the seat side of the valve and makes the tappet buckets and shims ride higher, which means a smaller gap. This same shop left me with two stripped exhaust manifold studs that I had to pull and heli-coil, and the crankshaft was flared by .003 to .005" at the front end, so the sprocket and pulley wouldn't fit. Had to sand and file it down.