BUDGET valve clearance job

Just sharing a project done over the winter. Valve clearances were getting too tight. I'm sure this has been done, but thought I'd share...

Rather than buying new buckets to get the desired clearances, I modified the existing ones using a drill press and a small stone that is intended for a dremel. The drill press keeps the flat stone surface parallel to the "nub" that needs to be ground down inside the valve bucket. Most of mine were too tight, so this was an option. Some were fine, so I left them as-is. Note that if any valve clearances were too large, this wouldn't have been an option since you can't easily add to the height of the bucket (reduce clearance).

So first measure all of your clearances with feeler gauges and figure out what the desired clearance should be (for example, middle of high/low specs), and record the difference on paper/spreadsheet/whatever.

Now, one at a time, remove each bucket, measure its thickness using a micrometer from the nub to the opposite smooth side where the cam rides. Subtract from that the "difference" you got in the previous paragraph, and that will be your desired bucket height.

Now place that bucket in your crazy custom bucket grinder, hold it with one hand, click it on, and with your other hand pull the drill press lever to start grinding. Just a little pressure is necessary. Slide the bucket around frequently and try not to nick the sides, but come as close as you can. Frequently mic the bucket to see if you are approaching the "desired bucket height" above (wipe the nub off first so you get an accurate result).

When you start to get close, you can wash that bucket in soapy water with a toothbrush and temporarily install it in the head. Put the cam in place with that lobe facing up - no need to bolt it down or even install the cam caps, simply press the cam down above the bucket with the heel of your hand, and use your other hand to measure clearance with a feeler gauge. If you haven't reached your desired valve clearance, go back and grind down the bucket nub more, and try again. When you get the valve clearance correct, move on to the next one, etc...

When you're done, clean everything up, oil it, and torque down the cam caps per spec. Then do one last check of all the valve clearances to make sure everything is ok.

It's all a bit labor intensive, but oh my it's inexpensive.

http://legacygt.com/forums/attachment.php?attachmentid=179140&stc=1&d=1396893345

Nice but you do realize those buckets are designed to spin as the lobes run across them?

I'm afraid if you didn't put the proper finish on them they might bind on the valve stem and not turn, or possibly grind the valve stems down. Just a theory, don't go jumping off a bridge!

hah - i hope not - but thanks for the caution.

so far it's running great... no more rough idle... but then i've only put 300 miles on it since this was done

Yeah let us know how it goes. If it works great on the long run, then I'll remember this method (had to buy 8 new buckets last year ).

Yes, those buckets are not cheap!

Hats off to the OP for thinking outside the box ( or bucket lol ).

Yes, that's my understanding. After a lot of discussions here, I believe that when the valves (especially exhaust) get too hot, the valve head starts to deform, like a flower closing slightly. This effectively increases valve length and decreases valve clearance, which causes a rough idle and a some loss of compression, especially when the engine warms up and the cylinder head expands slightly, taking up what precious little valve clearance that is left (that is why when valve clearances are too tight, a cold compression test might come out fine, but a hot compression test could show problems).

If the valves aren't too badly deformed, they are most likely otherwise fine, and adjusting the clearances can usually remedy resultant rough idle/compression loss.

All of this being said, the actual cause of valve clearances becoming too tight is probably due to knocking and/or an overly lean mixture ("bad tune"). The stock tune is guilty of this, when you floor it, it is very slow to transition from 14.7:1 to the required richer mixture. So you can have a second or 2 of high-boost with dangerously lean a/f ratios. But it's not limited to the stock tune... there are lots of situations that can cause an overly lean mixture or too much timing advance. Best to pull LV's often and be aware of how your tune is performing, to prevent valve clearance issues (and dozens of other fun issues like broken ring lands, etc, etc).

Good times.

Just sharing a project done over the winter. Valve clearances were getting too tight. …………..

How many miles on your engine?

Over time and mileage it is normal for valves to recede into the seats on any engine. This is why clearance should be checked on a schedule as much of a pain in the ass it is.

Probably a good time to check valve lash is just before a scheduled timing belt change. Decades ago, when I owned some air cooled VWs, I had to check valve lash every 3000 miles. But it was a very easy job on the old VWs. On the Subaru it looks like a major undertaking. Might just be easier to pull the engine.

how many miles on your engine?

130k

Good to hear.

Did you do it with the engine left in the car? I may have to tackle this on the driver side for my 06...

Also, if you have bad valve clearance in a given cylinder, would you think it is more pronounced at idle when the engine is still cold? But as it warms up, the misfire may go away?

I've been monitoring (thanks to your wonderful app ) roughness in each cylinder for the past three months now whenever I drive the car. And lately, I've been getting high counts in cylinder 2 while idling during colder weather and while the engine is still cold (threw a CEL twice now). As it warms up, the count usually stays at zero in that cylinder during idle. This engine does not consume oil btw, and the idle is not rough.

hey...

I had pulled the engine to do this job (and fix 5th gear in the 5MT). Not sure how feasible it would be to do it with the engine in the car.

Thanks for the app comment

Regarding whether it would misfire cold or hot, mine was actually the opposite! Cold it seemed fairly normal. Then when the engine heated up, it would get a occasional misfires, and the AFR correction would start to go up in the first (idle) cell. I think when the engine heats up, the clearance tighten up, exaggerating any too-tight tolerances. Might be why they've said that compression tests won't reveal tight valves on a cold engine, and to try to perform the test on a hot engine (ouch).

I know you've done a lot of work on your engine, so this has probably already been addressed, but have you ever replaced your tgv-to-intake-manifold o-ring gaskets (the orange ones)? Those are notorious for causing issues only when cold.

Thanks for your input heiche. So it should be the opposite then huh?

It's funny cause I thought about these o-ring gaskets as well. I have not actually done a lot of work on the 06. I bought that car last March and put 9k so far on it. It is a stage 2.5 ish car. The only thing I have done to it so far is change all the plugs, put a new timing belt+new pulleys, and change the tb hose with an avo one+retune. that's about it really. Although I would note that I changed the timing belt because the 'old' one skipped about 3 teeths due to improper clearance of the tb guides (they were rubbing on the tb..). So I hope it is not related..

But yeah, I have not done the oring gaskets and I am not sure if the previous owner did those. I am actually hoping that's the case. But I've usually heard people having issues on multiple cylinders, not just one...

well tgv/intake o-rings might not be a bad move, even as preventative maint. maybe it'll help the cold misfire issue too? i do hear you about how it would make more sense if all cylinders were affected, not just one. So I suppose that is a little scary.

But - thinking positively - maybe one o-ring is especially bad, which might influence that cylinder the most, even though it is a common plenum? If the cyl #2 tgv o-ring was in bad shape, it would make the "vac leak" only about 3 inches away from the cylinder.

Hey heiche, bumping your old thread .

First, how's the car running?

Second, which valves were really out of clearance? Exhaust ones?

Third, how far off were they from the clearance range tolerance (as a reminder, exhaust range: .35+/- .05 mm ---- intake range: .20 (+.04) (-.06) mm)? Just curious..

Hey heiche, bumping your old thread .

 

First, how's the car running?

 

Second, which valves were really out of clearance? Exhaust ones?

 

Third, how far off were they from the clearance range tolerance (as a reminder, exhaust range: .35+/- .05 mm ---- intake range: .20 (+.04) (-.06) mm)? Just curious..

Hey there! Going back to my initial measurements made for this thread...

Oddly, all of my exhaust valves were measured at around 0.254mm - so they were all tight!

But not wanting to miss out on the fun, about half of my intake valves were tight (as low as 0.127mm), and some were absolutely fine.

So I used the method in this thread to carefully open up the clearances until they were just a little towards the wider end of spec.

Car is still running great. Still running the same heads, but #igansb last summer. Just converted it to E85 last month.

EDIT: forgot to mention... when I had the engine apart last summer for my shortblock project, I re-checked the valve clearances. surprisingly, a couple of them had drifted a little towards the tighter side of spec. Still within spec, but enough that I ground those down just a little to get them back to where I wanted them.

Thanks for the info man. so the lower end of the 'tolerance' range for the exhaust valve is .30mm, and yours were ~.05mm off of that. How bad was it misfiring? Were you just getting high counts in specific cylinders, or actual CEL?

I have an extra 8 buckets. So hopefully, I won't have to grind any down...

Also, what was your target clearance for the exhaust valves? .35mm or did you try to get closer to .40mm?

When you rechecked the valve clearance and you noticed it already drifted, how many miles did you do at that point?

Thanks for the info man. so the lower end of the 'tolerance' range for the exhaust valve is .30mm, and yours were ~.05mm off of that. How bad was it misfiring? Were you just getting high counts in specific cylinders, or actual CEL?

When it was cold, it seemed fine. But after a good drive, the idle would get pretty rough. Didn't have BtSsm fully operational at that point, so I didn't have some of the specifics like misfire counts.

I have an extra 8 buckets. So hopefully, I won't have to grind any down...

 

Also, what was your target clearance for the exhaust valves? .35mm or did you try to get closer to .40mm?

For intake, I was shooting for 0.008" (.2mm). For exhaust I was shooting for 0.014" (.36mm)

When you rechecked the valve clearance and you noticed it already drifted, how many miles did you do at that point?

About 2K. I don't put a lot of miles on it. But please note they were actually still in spec, but I wanted to bring them closer to the target clearances above.