My turn to adjust valve clearances :)

[JmP6889928]

Measurements are in (see below)

 

A few questions:

1. I am shooting for 0.37mm clearance for exhaust side instead of 0.35mm. Good choice?

2. Shooting for 0.21mm clearance for intake side instead of 0.2mm. Or should I even go to 0.22mm since the max clearance is 0.24mm?

3. Two of my intake valves have actually extra clearance (see 'cyl 2 intake F' and 'cyl 4 intake R'). Do you think it'd be OK to leave them as is, or will it really lead to extra wear on valves, valve seats and cam lobes?

 

Really tempted to do heiche method here....

 

 

http://legacygt.com/forums/attachment.php?attachmentid=211620&d=1435376078

 

If I recall, I had my measurements in .001" (Haynes Manual) rather than metric and I believe that the intake was .007" to .009" (I set mine at .010") and the exhaust was .013" to .015" (I set mine at .016") and it's slightly noisy at first cold startup but then it sounds like any other Subaru DOHC engine after about a minute and I know the valves are closing.

 

NOTE: If you are using the Haynes/Chilton/etc (non FSM) manual for your valve clearances, there is an error on the exhaust side inch value. It should be .014 inches for exhaust which is .356mm, not the .010 listed in the book.

[xt2005bonbon]

So it sounds like you have set your clearance slightly higher than the upper bound of the clearance range for both intake and exhaust valves then. Interesting.

[boxkita]

If measure in inches, the tolerance is much less. As Sgt.Gator found, Subaru changed the tolerance to much smaller numbers. basically spot on.

 

That said, the values in the fsm are for a head that is fully torqued down with a timing belt on. Which is OP's case.

 

Adding more clearance (more valve lash) actually makes the valve open for less time. And defeats purpose of avcs. If you can set them to exact values then do so.

 

This is my opinion based on lots of reading and talking to machine shops. I don't have the math, physics, etc to back up anything I said. Which leaves me contemplating which route to take as well. I'm opting for as close to stock as possible. especially on intake side which has avcs and is based on exhaust position.

[boxkita]

If I recall, I had my measurements in .001" (Haynes Manual) rather than metric and I believe that the intake was .007" to .009" (I set mine at .010") and the exhaust was .013" to .015" (I set mine at .016") and it's slightly noisy at first cold startup but then it sounds like any other Subaru DOHC engine after about a minute and I know the valves are closing.

 

NOTE: If you are using the Haynes/Chilton/etc (non FSM) manual for your valve clearances, there is an error on the exhaust side inch value. It should be .014 inches for exhaust which is .356mm, not the .010 listed in the book.

 

As updated on JMP's post, you should be checking your valve lash with the metric part of your feeler gauge not inches. The conversion back & forth will put your valves out of spec very fast.

 

You will have to stack gauges to get the closest measurement.

[xt2005bonbon]

If I recall, I had my measurements in .001" (Haynes Manual) rather than metric and I believe that the intake was .007" to .009" (I set mine at .010") and the exhaust was .013" to .015" (I set mine at .016") and it's slightly noisy at first cold startup but then it sounds like any other Subaru DOHC engine after about a minute and I know the valves are closing.

 

NOTE: If you are using the Haynes/Chilton/etc (non FSM) manual for your valve clearances, there is an error on the exhaust side inch value. It should be .014 inches for exhaust which is .356mm, not the .010 listed in the book.

 

I am using the FSM. Target for intake according to FSM is 0.20 mm, and 0.35mm for exhaust side. So you did not shoot for 0.016" exhaust side then cause that would be like 0.406 mm . Instead, it sounds like you did adjust your clearance to FSM target for the exhaust side (0.35mm).

 

That said, the values in the fsm are for a head that is fully torqued down with a timing belt on. Which is OP's case.

 

This is a very good point. I will post later on the clearance measurements I made AFTER I took the timing belt off. Essentially, the clearance from cylinder 2 on the exhaust side got noticeably larger (e.g. one clearance went from 0.04 mm to 0.13mm). However, the intake/exhaust clearances on cylinder 4 did not change before/after taking the timing belt off.

 

As updated on JMP's post, you should be checking your valve lash with the metric part of your feeler gauge not inches. The conversion back & forth will put your valves out of spec very fast.

 

You will have to stack gauges to get the closest measurement.

 

I am doing everything in metric (grew up that way anyway ). No conversion here.

[boxkita]

This is a very good point. I will post later on the clearance measurements I made AFTER I took the timing belt off. Essentially, the clearance from cylinder 2 on the exhaust side got noticeably larger (e.g. one clearance went from 0.04 mm to 0.13mm). However, the intake/exhaust clearances on cylinder 4 did not change before/after taking the timing belt off.

 

This was the original argument from the machine shop. Until I said they did their math backward. Starting with tight clearances and having them get tighter when bolted down wasn't going to help much.

 

And this is where math comes in, as we all set the lash with the heads unbolted, then put them back on fully torqued down. I did check mine after putting on heads and cams. Which is why I pulled them off and took them back. They are still at the bottom end of the spec, so not installed at the moment.

 

And, last one, this is where JmP's adding a .001" to his values kind of makes sense. The OCD part of me, says if you don't check once its back together, you're still guessing.

 

Best of luck. I'm interviewing more machine shops today.

[xt2005bonbon]

Best of luck. I'm interviewing more machine shops today.

 

Let us know what they say.

[xt2005bonbon]

Here are the clearance measurements with the timing belt on vs. off. I only posted measurements for cylinder 2 since it was the only that had different clearances.

So from what I understand, once I install the new buckets, the clearance should be larger than expected for cylinder 2 with the timing belt off. But once I put it on, the clearance should be fine. We shall see.

 

http://legacygt.com/forums/attachment.php?attachmentid=211748&d=1435630541

[boxkita]

Here are the clearance measurements with the timing belt on vs. off. I only posted measurements for cylinder 2 since it was the only that had different clearances.

So from what I understand, once I install the new buckets, the clearance should be larger than expected for cylinder 2 with the timing belt off. But once I put it on, the clearance should be fine. We shall see.

 

http://legacygt.com/forums/attachment.php?attachmentid=211748&d=1435630541

 

well isn't that interesting. The shop I visited today (east valley auto) talked about setting the valve lash .001 above the upper tolerance on everything for high perf engines. That's the same thing JmP said/did.

 

I thinking of doing the same thing, then checking once the TB is in place. Then buying buckets to bring it back to spec?

 

The shop also confirmed everyone cuts the tip off the valves rather than swapping buckets. So if I was going to do it right, I'd buy all new same thickness buckets, have the valves tipped to the same length, then mount the heads and add the TB. Then replace the buckets again to bring it back to spec. Sounds expensive.

[StkmltS]

Sounds like racecar stuff

[boxkita]

Sounds like ocd stuff

[heiche]

fyi - not sure if it matters or not, but when i did "my" method, with the TB off and engine on a stand, i would simply press the camshaft down (towards the center of the engine) in the area of the valve being measured with the heel of my hand while taking measurements. It definitely made a difference in the measurements - perhaps the same difference observed with TB on vs off.

[boxkita]

I suck as a thread jacker. Sorry, op.

 

However anyone know how to do the math to figure out theload the tb puts on the cams? I know its pretty hefty given the pressure required to press the tensioner back together.

[StkmltS]

Here's my (almost) no-math proposal:

 

If I'm looking at the FSM correctly, each cam is held by the head and two caps; the large front cap that holds both cams, and an individual rear cap for each intake / exhaust cam.

 

How much clearance is there between the cam shaft diameter and the head/cap diameter? (the diameter the cam rotates inside of minus the camshaft's diameter)

 

The TB can't pull the camshaft any further than the head will allow. It can apply as much force as it wants, but the camshaft is limited by where it sits in the head. Make sense?

 

So, I imagine that if you put an appropriately sized shim (as thick as the difference between the two diameters) between the camshaft and the cap you would effectively be forcing the camshaft to be located in the same position as if the TB were installed and 'pulling' on it. Ya Follow?

[xt2005bonbon]

I suck as a thread jacker. Sorry, op.

 

However anyone know how to do the math to figure out theload the tb puts on the cams? I know its pretty hefty given the pressure required to press the tensioner back together.

 

No biggie .

 

To answer your question, from my measurements posted on post #83, the TB load made

1. a +0.07 mm difference in clearance on cylinder #2 exhaust valve closest to the exhaust camshaft sprocket.

2. a +0.04 mm difference in clearance on cylinder #2 exhaust valve furthest to the exhaust camshaft sprocket.

3. a +0.03 mm difference in clearance on cylinder #2 intake valve closest to the intake camshaft sprocket

4. a +0.01 mm difference in clearance on cylinder #2 intake valve furthest to the intake camshaft sprocket

5. no effect on cylinder #4 clearance

 

My conclusions:

-->the closer the valves are to the driver side camshaft sprockets, the more effect the TB load has on their respective clearance (especially on exhaust side)

-->this effect should not matter if you measure your clearance with the TB ON, prior to removing the buckets. Just don't freak out when you install your new buckets and check clearance with TB OFF, as I would expect it to be off.

[boxkita]

So it turns out, based on 5 minutes of google searching thus making me an expert, that you can use a "beam deflection" calculation to figure this out. Article reference here - http://www.engineersedge.com/beam_bending/beam_bending9.htm

 

As to what those values are to plug into the calculation, got no idea (5 minutes did not make me a master)

[boxkita]

Here's my (almost) no-math proposal:

 

If I'm looking at the FSM correctly, each cam is held by the head and two caps; the large front cap that holds both cams, and an individual rear cap for each intake / exhaust cam.

 

How much clearance is there between the cam shaft diameter and the head/cap diameter? (the diameter the cam rotates inside of minus the camshaft's diameter)

 

The TB can't pull the camshaft any further than the head will allow. It can apply as much force as it wants, but the camshaft is limited by where it sits in the head. Make sense?

 

So, I imagine that if you put an appropriately sized shim (as thick as the difference between the two diameters) between the camshaft and the cap you would effectively be forcing the camshaft to be located in the same position as if the TB were installed and 'pulling' on it. Ya Follow?

 

What I was guessing would happen is the valve lash closest to the TB would get tighter and those farther away would get looser. This assumes the camshaft "bearing surface" is line bored, parallel and has a matching distance from the bottom of the head. The deflection after load is applied should be minimal (<0.001 inches), however, there is a plasti-gauge test to verify.

 

I know I'm overthinking it, however, I'm getting tired of guessing as more metal is removed from the head.

[xt2005bonbon]

Just in case,

 

those are the buckets size I need:

1x4.43

1x4.72

1x4.78

1x4.86

1x4.89

1x4.91

 

I doubt people have these (smaller) sizes. I'll just bite the bullet and buy them.

[rmoore5]

All I have is the 491, pm me the qty and your address if you want me to send it.

[1-3-2-4]

It's been so long since I did valve adjustments..I'm checking to see which next thinnest size fits then subtract to get the bucket size? I think that sounds about right

[xt2005bonbon]

It's been so long since I did valve adjustments..I'm checking to see which next thinnest size fits then subtract to get the bucket size? I think that sounds about right

 

Formulas, according to FSM, are:

NBS = (CBS+MCLE)-.20mm for intake side

NBS = (CBS+MCLE)-.35mm for exhaust side

 

NBS stands for 'NEW BUCKET SIZE'

CBS stands for 'CURRENT BUCKET SIZE'

MCLE stands for 'MEASURED CLEARANCE'

 

I modified the name of the variables

 

NOTE: all above variables are assumed to be in mm, not inches.

[outahere]

I have to wonder what procedure is used at the factory to set valve lash when the engine is built. They will want to do it as quickly as possible, because time is money. Anyone taken a factory tour and seen this done??

[rmoore5]

I have to wonder what procedure is used at the factory to set valve lash when the engine is built. They will want to do it as quickly as possible, because time is money. Anyone taken a factory tour and seen this done??

 

I work at SIA, in the body shop. I went over to the engine shop a few months ago when I was doing the 2009 OBXT.

 

The new motors don't use buckets anymore. They have roller rockers but, the lash is set with small caps that cover the end of the valve stem. They are of various sizes like the bucket method.

 

It was explained to me that the valve lash is calculated and set by an assembly machine.

 

Then checked by a human readjusted if needed and then further down the line it is checked again by a machine (after the head is on the motor).

 

They weren't running at the time. It would be hard to get over there while they are running as I am expected to be near my line diligently waiting for a break down:rolleyes:

[rmoore5]

Something else I found interesting:

 

The new motors have the big end of the connecting rods split at 45 degrees to the length of the rod.

 

This allows the piston and rod to be installed as a assembly rather than the way the previous engines had to put together. As the rod bolts can be accessed after the crank and case halves are assembled.

 

Also, the connecting rod big end is literally split (fractured) at the mating surface rather than having 2 ground surfaces. The mating irregular shapes apparently cause the halves to align, if you can envision the surface of 2 pieces of broken cast iron.

[StkmltS]

^^^ Good info!