Valve specs: tight for both intake and exhaust?

[rjnakata]

'01 GT Wagon 5MT 225Kmi

I'll ask here among the wise:

When adjusting valves does one use the minimum spec for intake AND exhaust...or other?

 

[awfulwaffle]

Set them to nominal or a hair looser, particularly on the exhaust side. Those tighten up over time.

[silverton]

.008"(.20mm) for the intakes, .010"(.25mm) for the exhausts. You need to use both of the .010's in your feeler set for exhaust adjustment since they share one rocker arm.

 

Though to be honest I have found this spec to be a little on the loose side, at least by ear.

[xt2005bonbon]

The exhaust valve clearance does tend to tighten over time. In our case (B25 heads), target for exhaust is 0.35mm +/-5mm. I usually target 0.37mm. For intake, I target what the FSM says for our heads (i.e 0.20mm). I have not seen them shrink or loose clearance over time, not like the exhaust valves.

[rjnakata]

.008"(.20mm) for the intakes, .010"(.25mm) for the exhausts. You need to use both of the .010's in your feeler set for exhaust adjustment since they share one rocker arm.

 

Though to be honest I have found this spec to be a little on the loose side, at least by ear.

 

Given the intake loosens and the exhaust tightens over time how about going +0.05mm toward the middle of each range:

0.15mm intake / 0.25mm exhaust

 

Sound good?

[silverton]

Eh, not really. I think it's wild the underhood sticker has that large of a range. the service manual calls for a spec of 20 on the intake, and 25 on the exhaust, with a range of .02mm in either direction. A valve clearance check, and adjustment if necessary, is done every 105k with the timing belt, so you should set them to spec and not worry about it "loosening or tightening over time"

 

Basically make it tight enough that the feeler gauge doesn't fall out, but loose enough that you don't have to really force it, if that makes sense. a set of stepped gauges is ideal

[boxkita]

nearly every USA machine shop uses inches for measurements. so they will use .008 & .010 for setting the valves. .001" is more than the spread allowed by the specs.

 

final setting can only be determined when timing belt is installed and tensioner enabled. Having your camshaft be within spec will help more than finagling the last .001mm out of the lash.

 

alit agony has been spent on setting valve lash correctly. Ppl have 300k engines on here that have never been opened. Some myths are false. ymmv.

[rjnakata]

.008"(.20mm) for the intakes, .010"(.25mm) for the exhausts. You need to use both of the .010's in your feeler set for exhaust adjustment since they share one rocker arm.

 

Though to be honest I have found this spec to be a little on the loose side, at least by ear.

 

Ok, I'll (re)set them to 0.20mm/0.25mm.

I might error on the tighter side if anything. I did hear some lifter noise when set on the looser side of the range.

[xrayspecs]

So I learned the lesson in highschool with a hot cammed VW engine (it bent a pushrod), if you do have work done at a shop, be sure to check the work. while YMMV best practice is to check the lash after getting parts back from maching.

 

More information on the valve setting from the FSM.

[rjnakata]

All super helpful. Ok I'm done asking on "that" social media site for technical info.

[silverton]

tumblr? yeah that place has gone downhill since they banned porn.

[rjnakata]

Follow up:

I set the intake/exhaust at 0.18mm/0.23mm and not 0.20/0.25 (+/- 0.02mm) as recommended by the service manual.

Why?...umm why not as an experiment with the low end of the recommended clearances and to keep valve noise down... I can always widen it I suppose.

Bad Idea jeans?

 

I do notice when I floor-it there is a new low register "growl" sound from the motor that I've never heard before and it seems to have a miniscule amount of extra acceleration. (Not that it ever had any breathtaking pickup ever).

 

New "growl" = good? OR "growl" = bad?

 

 

 

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Edited June 4, 2022 by rjnakata