Hello,

I'm rebuilding my 4AGE 20V BT and i've arrived at the head. I've already grinded the valves, cleaned everything, mounted the valves (ofcourse ), leak tested the head, etc etc. But now i have a question about the valve clearance.

The exhaust side is all perfect within spec. For the intake side all, except the middle notches of the intake camshaft, are on the end or just about 0.01-0.02mm (0.000393-0.000787inch) above of spec.

We've also measured the 0.30 mm plate of the thickness gauge we used for this to be absolute sure of the measurement. It's a bit below what it says, about 0.28-29mm. So were we've painted between 0.28-0.30 it can be either 0.28, 0.29 or 0.30 mm because of the not completely perfect gauge. So all are very very very near to the spec The specs for the intake valve are between 0.19 (0,007 inch) and 0.29mm (0.011 inch). So 0.30 will be just above this.

To explain what i'm saying i've made pictures with the measured valve clearances in top. (NOTE these are in mm, not inches. To save you some calculation time: 0.24 = 0.009448 inch, 0.26 = 0.010236 inch, 0.28 = 0.011023 inch and 0.30 = 0.011811 inch).

I think it'll be absolutely no problem that they are just 0.01-0.02 out of spec (at max), cause most probably the clearance will normally gets lower. I think that maybe the grinding and remounting will also caused it to be just a bit out of spec. It'll be a different story imo when it's below the spec.

But to be sure i'm asking you, the guys that now the 4AGE engines all the way!

By .01 above specs is that .01 mm or inches too tight of clearance? If it's too tight it tends to wear the lobes too quickly and doesn't allow the required film (amount of molecules) of oil between the lobe and the bucket. If there's too much clearance than as the lobe comes around it slaps the bucket causing the ticking noise. This can over time cause damage to the camshaft as well. I would reshim that valve so it's clearanced properly rather than let it "work itself out." It will save you lot's of work and possible big bucks in the end.

kennyb01 wrote:By .01 above specs is that .01 mm or inches too tight of clearance? If it's too tight it tends to wear the lobes too quickly and doesn't allow the required film (amount of molecules) of oil between the lobe and the bucket. If there's too much clearance than as the lobe comes around it slaps the bucket causing the ticking noise. This can over time cause damage to the camshaft as well. I would reshim that valve so it's clearanced properly rather than let it "work itself out." It will save you lot's of work and possible big bucks in the end.

Hello,

Too tight means too much clearance. I think the grinding had also effect on it.
I think i'll drive it for approx 5000-10000km and then check them again. I mean 0.01 above spec, then we're talking about a hair thickness. Can't imagine that would be bad. Especially when taking in cosidering that the clearance will be less over time. When it was too tight i think that would be worse because of the valves that are going to float a bit.

Use the feeler gauges as go-no go gauges for the lowest & above whatever the factory spec range is, the lower limit size should easily fit and the next larger size above the factory limit should not fit, that'll tell you that your clearance is within range. Easy, no worries & no maths to F up.
Check them again at your first oil change & re-torque the head.

Thanks! The feelers weren;t going in that easily. We had to put them in with a little bit of force. So they must be right.

I'll be checking them in 10.000 km again. My first oil change will be at 2500 km and that's a bit early to check them i think.

After the rebuild and finishing the swap i can tell you that the valves are ticking .

So you guys are right, that 0.01-0.02mm is enough for the ticking. Just drove only 80 miles or so yet, but i doesn't disappear yet. For the rest...the engine feels STRONG! Really as new.

Honestly I wouldnt worry about the ticking. For some reason valve lash always gets tight on subaru's with buckets or shims and the general rule for us at the dealer is too tight will misfire, too loose will make noise. Better on the loose side, but as close to spec as possible. Also unless you have some bad ass expensive feeler gauges, feeler gauge readings will also not be 100% accurate.

onnaj wrote:Hello,

Too tight means too much clearance. I think the grinding had also effect on it.
bit.

Sorry I have to disagree with this statement. Valve lash being too tight means there is NOT enough clearance.

ElChinoxNJ wrote:Honestly I wouldnt worry about the ticking. For some reason valve lash always gets tight on subaru's with buckets or shims and the general rule for us at the dealer is too tight will misfire, too loose will make noise. Better on the loose side, but as close to spec as possible. Also unless you have some bad ass expensive feeler gauges, feeler gauge readings will also not be 100% accurate.

onnaj wrote:Hello,

Too tight means too much clearance. I think the grinding had also effect on it.
bit.

Sorry I have to disagree with this statement. Valve lash being too tight means there is NOT enough clearance.

You're right, i mean too loose --> too much clearance. Thanks!