Valve Clearances - How much is a "slight drag"? (1 Viewer)

[Dork]

When checking/adjusting Valve Clearances on the 1hdft, the FSM says to put in a 0.2mm feeler for intake, 0.5mm exhaust, and adjust until there is a very slight drag. What exactly constitutes a slight drag?

Current example:
I can fit a maximum 0.3mm feeler under intake rocker 1, but 0.2 does have a bit of noticeable drag on it. Intake 2 I can fit 0.28, but still feel resistance down to 0.15 if I'm really looking for it.

Is it better to err on the side of tight, or loose in this scenario?

 

[mudgudgeon]

Slight drag to me would mean you can hold the feeler feeler gauge by the handle, and only just, gently slip it through the gap without it bending

Clearances will get wider with wear. I'd err on the side of slightly tight

 

[Dork]

Ok, that's a decent bit tighter than I was originally considering. I get what you're saying about it going looser over time too.

 

[Malleus]

That's one of those "calibrated elbow" procedures. You'll have to find someone who has one.

Similar to the 1-15 lb•in torque values you don't have a wrench for.

 

[BILT4ME]

Or find someone that used to work on a car with a points style ignition. They'll know what it feels like.

Think how much pressure or force it takes to pull a sheet of paper out of a stack of paper when there are 25 sheets of paper above it. ( I'm thinking of a ream of printer/copier paper)

 

[nukegoat]

Clearances will get wider with wear. I'd err on the side of slightly tight

Is this true? I thought with valves that the valve and seat wearing would close up the lash. The tappets and cam wear faster?

 

[Dork]

Or find someone that used to work on a car with a points style ignition. They'll know what it feels like.

Think how much pressure or force it takes to pull a sheet of paper out of a stack of paper when there are 25 sheets of paper above it. ( I'm thinking of a ream of printer/copier paper)

The paper stack is a great reference that is absolutely doable. Thanks

 

[Malleus]

Is this true? I thought with valves that the valve and seat wearing would close up the lash. The tappets and cam wear faster?

x2
I thought the valves were the wear items...

 

[Tools R Us]

Is this true? I thought with valves that the valve and seat wearing would close up the lash. The tappets and cam wear faster?

Depends on design, and intake can differ from exhaust. Some close up, some get clackity. If your adjusting them and most/all are loose, they are likely to keep getting clackity, if most are tight....

Slight drag means just what it says, should feel drag on the gauge, should be able to pull it out and reinsert. With a full set of gauges, the the one .001" thinner should have no drag, .001" thicker should not be able to be forced in. Play with that a few times to get the "feel". That said, it's not that critical, +/- a couple isn't likely to be a big deal. On known motors where they get clackity, I often set them slightly tight, on ones where they go tight, a little more slop.

 

[nukegoat]

Depends on design, and intake can differ from exhaust. Some close up, some get clackity. If your adjusting them and most/all are loose, they are likely to keep getting clackity, if most are tight....

Slight drag means just what it says, should feel drag on the gauge, should be able to pull it out and reinsert. With a full set of gauges, the the one .001" thinner should have no drag, .001" thicker should not be able to be forced in. Play with that a few times to get the "feel". That said, it's not that critical, +/- a couple isn't likely to be a big deal. On known motors where they get clackity, I often set them slightly tight, on ones where they go tight, a little more slop.

The 1FZ is goldilocksy, right? Sort of stays the same?

 

[Tools R Us]

The 1FZ is goldilocksy, right? Sort of stays the same?

Pretty much, the cam on bucket is a great design.

 

[Proven]

My calibrated elbow from working on Japanese outboards with shim over bucket is the same as stated in this thread.

Pushing it in should require minimal force for "Slight drag" and the measuring device should not deflect when inserted.

Going down a size should result in no force at all and going up would likely cause the device to deflect/bend slightly.

I always aimed at keeping the measuring device flush with the top of the bucket and pushing it straight in. If I have to walk it, wiggle it or otherwise - that maybe too tight. It was taught to me that it needed to be a little resistance and required no leverage to push it in.

That was a different motor, but I feel like the lesson I learned is the same.

 

[Dork]

Ok, all good stuff here. I guess when I hear VERY slight, I'm even noticing the feel of the oil sticking to the feeler.

This engine is an adjustable type with no shims needed, but I assume the feeling and tolerances should be quite similar. The little rounded plunger doohicky that surrounds the adjusting screw and makes contact with the valve bridge is a little tricky to get the feeler into, but after checking them all I got a bit of a method figured out.

Based on all that, I figure they're still a bit loose and could probably use to be tightened up by about 0.05mm or so.

I got another week or so before i button everything up and run it, but would that small amount of play contribute to any significant klacking sound, or loss of power out of the engine?

 

[mudgudgeon]

Is this true? I thought with valves that the valve and seat wearing would close up the lash. The tappets and cam wear faster?

you might be right

I know with my HZ and HD-T (cam over bucket too) when I first did valve clearances on "new to me" vehicles, the clearances on some valves were tighter than spec (both engines with in excess of 200k km, and no service history)

@Dork, my understanding is the hd-ft can get a little clattery if clearances aren't adjusted, but I dont have 1st hand experience with this motor. Sorry if I muddied the water.

Maybe worth putting this question in the diesel tech section

 

[nukegoat]

Ok, all good stuff here. I guess when I hear VERY slight, I'm even noticing the feel of the oil sticking to the feeler.

This engine is an adjustable type with no shims needed, but I assume the feeling and tolerances should be quite similar. The little rounded plunger doohicky that surrounds the adjusting screw and makes contact with the valve bridge is a little tricky to get the feeler into, but after checking them all I got a bit of a method figured out.

Based on all that, I figure they're still a bit loose and could probably use to be tightened up by about 0.05mm or so.

I got another week or so before i button everything up and run it, but would that small amount of play contribute to any significant klacking sound, or loss of power

i doubt it will hurt anything. .05mm is 2 thousandths. Not a big deal

 

[shibubba]

Most important thing with a valve set IMHO is that they are all the same. I have a pre set 6inlb torque wrench I use when setting valves. That way it consistent across all valves .

I have adjusted thousands of valves ( was a field service tech for Cummins for years ) I have seen super tight and super lose sets...albeit the design of a H series engine is different the principal is the same .

I notice you're in Alberta. If you're in Calgary I can come by and lend a hand...if you want .

 

[Dave 2000]

Clearances will get wider with wear. I'd err on the side of slightly tight

I have experienced the other way on this motor as in closing up of clearances, also be careful, this motor will throw the valve collets the first chance it gets if the adjustment is wrong, and damage follows very closely afterwards.

Regards

Dave

 

[Dork]

Most important thing with a valve set IMHO is that they are all the same. I have a pre set 6inlb torque wrench I use when setting valves. That way it consistent across all valves .

I have adjusted thousands of valves ( was a field service tech for Cummins for years ) I have seen super tight and super lose sets...albeit the design of a H series engine is different the principal is the same .

I notice you're in Alberta. If you're in Calgary I can come by and lend a hand...if you want .

The offer is much appreciated, and I'd probably take you up on it if I wasn't up the road in Edmonton. Thanks anyway.

 

[Rivman1243]

I err on the loose side to account for the valve getting bigger the hotter it gets. If you're really worried about what the clearance is use a dial indicator. TakeT all of the guessing out of the equation bit takes a lot longer to do. What you want is to be consistent.

 

[Dork]

Alright, so that job's done.

I went with a bit of everything method I guess. I played around a bit at first until settling something that feels right. 0.20mm is intake valve spec, and that feeler goes easy, but with some noticeable difference. 0.23 can fit with effort and bending if held by handle, 0.25 won't go in at all. Same thing with the exhaust at 0.50/0.53/0.55. All made to feel about the same. Figure that should be plenty safe.

I am in no way qualified to comment on the tendency of valves loosening/tightening over time, but based on my initial measurements, it seems that on this particular truck, they loosened up slightly.

Thanks for the help all.