m20 valve to eccentric contact area

[e30davie]

Hi All,

Doing the valve adjustment on my m20b23 on the weekend. Just maintenance. All of them were pretty good, had to adjust 3 or 4 of them slightly.

The one that gave me the most drama was cylinder 1 exhaust. Felt like i couldn't get enough out of it. At its current setting it was only just acceptable at 0.25mm. I probably would have liked to make it a bit tighter.

As can be seen from the photo the eccentric sort of sits on the edge of the valve. is this typical? I must admit it was getting late and i didn't take much notice of the others. Thinking back i probably should have.

I did remove the eccentric adjuster and it didn't appear to have much wear on it, hardly a mark on it to be honest. certainly no flat spot. I have another spare engine and i pulled one out of that too and that one was worn.

I put it all back together and drove to work this morning, sounds great and goes great. No issues to report and i have no intention of opening it again for another 5000 km or so. But figured the m20 boffins might be able to comment. My only thought was if Is this an indication of wear on the camshaft end of the rocker arm?

[digger]

Going by my memory it looks off. Rotate engine and check the sweep.

[zaq123]

m20 valve to eccentric contact area

it's definitely off.

My pic:
HD rockers, new cam (not regrind), standard size new OEM eccentrics with 0.25 set valve clearance and OEM new hardware. Kind of hard to see with all that assembly lube but they are centered on the valve stem. This head had valve seats recut and new valve installed so that would in theory put eccentric closer to the edge (like in your case) but as you can see, it's negligible

[e30davie]

I had a look at my spare head and yea something up with mine in the photo. Is it possible to put the eccentrics on backwards? I suppose it is given they eccentric. Maybe I need.to flip mine around.

[zaq123]

I had a look at my spare head and yea something up with mine in the photo. Is it possible to put the eccentrics on backwards? I suppose it is given they eccentric. Maybe I need.to flip mine around.

No, they have no left/right side so that wouldn't do it. pop the cover and look at the rest of them. What can do you have, regrind? If everything is stock, most likely very worn cam (easy to see) or very worn rocker (not so easy to see unless disassembled) or something very very worn valve seat/valve (unlikely). What did you set your clearance to?

[e30davie]

Everything is stocko but no idea of age/mileage. I had the head overhauled 30,000km ago. They didn't mention worn cam or rockers, but I didn't ask.

See how your eccentric sticks out side the rocker arm? But mine doesnt. I'll go have a play with my spare head.

[zaq123]

Everything is stocko but no idea of age/mileage. I had the head overhauled 30,000km ago. They didn't mention worn cam or rockers, but I didn't ask.

See how your eccentric sticks out side the rocker arm? But mine doesnt. I'll go have a play with my spare head.

the amount it sticks out will be dictated by the valve clearance on the valve side or the rocker/cam clearance on the cam side), both things are relevant to each other. If they overhauled the head and used a reground cam and/or reground OEM rocker and OEM size eccentric - that's your problem. Remove the cover, look at the rest of them, check for proper clearance, check cam/rocker for any wear. If all the above checks out - buy OME oversized eccentric to see what it will do. Buy the rest of oversized eccentrics as needed if everything else is good. You still didn't say what is you valve clearance is set to

[e30davie]

I had a bit of a play on the spare head i have. I think iv'e actually over rotated the eccentric. I reckon if i take it back a half a turn ill get the same adjustment but the thing will be in the middle of the valve.

I'll pull the cover off tomorrow after work (its late Monday night here)

The only thing they they did to the head was new exhaust valve seals, rest was untouched. They just said the rest was in good/great condition. The engine purs along, so quiet now, i think we are all good, i just stuffed up this first valve.

[zaq123]

I had a bit of a play on the spare head i have. I think iv'e actually over rotated the eccentric.

well that possible...but doesn't make any sense why would you do that. Over rotated eccentric will change your valve clearance. They only reason to have them loose is to set the clearance. If your clearance is set to spec'd 0.25 and your eccentric is on the edge like that, something is off.
What did you set the clearance to?

[e30davie]

well that possible...but doesn't make any sense why would you do that. Over rotated eccentric will change your valve clearance. They only reason to have them loose is to set the clearance. If your clearance is set to spec'd 0.25 and your eccentric is on the edge like that, something is off.
What did you set the clearance to?

It was getting late. I got the feeler gauge between the edge and the eccentric and did my best to set it to 0.25mm. Felt weird sure but it ran good. I'll have another go tomorrow:)

[e30strokr]

It was getting late. I got the feeler gauge between the edge and the eccentric and did my best to set it to 0.25mm. Felt weird sure but it ran good. I'll have another go tomorrow:)

I just did my eccentrics and the hole is offset..... that would explain the "over rotated"

[kronus]

I just did my eccentrics and the hole is offset.....

.. that's why they're called eccentrics

[e30strokr]

.. that's why they're called eccentrics

OK.. he just need to flip it and it will be normal, also the hole has one side concave

[e30davie]

Realised last night that the hole for the Allen key adjustment tool is only on one side though so they only go in one way.

[nando]

I was going to say it's in backwards, which is why it looks wrong.