adjusting valves hot.

[DÌEGØ]

it doesn't give you worse results. you are adjusting the exact spec that the engine will see while it is running. when it's cold you are basically hoping that the rate of thermal expansion is precise enough for your .010" clearance to grow to .012" hot. once I tried it and realized how much better it works, I would never go back to doing it cold. it also isn't that hard, it only takes about a half hour anyway which is fast enough to do it before it cools.

good point. my results probably relied on the fact that it was my first time, I was outside and it was ~38F :neutral:

[nando]

it doesn't give you worse results. you are adjusting the exact spec that the engine will see while it is running. when it's cold you are basically hoping that the rate of thermal expansion is precise enough for your .010" clearance to grow to .012" hot. once I tried it and realized how much better it works, I would never go back to doing it cold. it also isn't that hard, it only takes about a half hour anyway which is fast enough to do it before it cools.

[dranttna]

the specs bently use comes striaght out of bmws abl's. so the hot spec would be for a tech that has to adjust them and doesnt have a few hours to let the engine cool off. there is no reason to do it hot if you can let it cool off. it will probly give you worse results

[CHIF8008]

gonna have to be butthole fast man. stone cold adjustment is easyier, you can take your time, and you wont get burned haha hot adjustment against cold is not any better. your not gonna run better because you did it hot, but W/e its your E30. do what you want.

[lolcantturn]

really? then why is there a hot adjustment spec? :roll:

adjust them to .012" hot. the valve clearance actually gets bigger as the engine heats up. And hey, you actually get a better adjustment since you are changing the operating clearance and not the cold one.

Thanks!

[lolcantturn]

when I went to do my adjustment [hot] by the time I was on the 3rd cylinder I noticed my head had cooled down quite a bit [it was like 40F tho] so I just waited a bit for it to cool down some more and started over doing the cold adj

Guess I'm going to have to be quick

[DÌEGØ]

when I went to do my adjustment [hot] by the time I was on the 3rd cylinder I noticed my head had cooled down quite a bit [it was like 40F tho] so I just waited a bit for it to cool down some more and started over doing the cold adj

[nando]

You shouldn't adjust the valves when the engine is hot.. ever. Who gave you that idea?

really? then why is there a hot adjustment spec? :roll:

adjust them to .012" hot. the valve clearance actually gets bigger as the engine heats up. And hey, you actually get a better adjustment since you are changing the operating clearance and not the cold one.

[lolcantturn]

ah alright. I guess I'm going to fill her up with 20W-50 and hope for it to smoothen out

[otto325e]

Valve chatter is actually much quieter than piston slap, which is what the diesel sound is. You can't really hear valve chatter unless the hood is open anyways. Completely normal for e30s

[lolcantturn]

The problem with adjusting the valves hot lies in defining what "hot' is. The only condition that would yield repeatable results would be to run the engine to get it to operating temperature, shut it down, and immediately adjust the valves. If you can complete the job quickly and the ambient temperature is at least warm, the head won't cool down much.

Well shucks. I see no point in doing it then if I'm not going to get any "Real" results.

My engine is very rough sounding, like a diesel engine litterally. When I pull up at gas stations they ask "Diesel?" But the idle is as smooth as butter and so is everything else. The engine noise bothers the heck out of me though. I reduced it with my previous valve adjustment, but it's still pretty damn rough sounding, even though M20's are supposed to sound like "sewing" machines and arent the quietest of engines, this is not like it.

[NigelStu]

I've heard of cutting down trees with a herring, but never adjusting valves! Kudo's to you sir!

[jlevie]

Yep that's what the bentley recommends.. I'd just figure it would be better to adjust it hotter? Or it wouldn't make any difference?

The problem with adjusting the valves hot lies in defining what "hot' is. The only condition that would yield repeatable results would be to run the engine to get it to operating temperature, shut it down, and immediately adjust the valves. If you can complete the job quickly and the ambient temperature is at least warm, the head won't cool down much.

[u3b3rg33k]

I'd suggest you adjust them cold, with a herring can lid.

Very simple to do:
1: Misplace your feeler gauges
2: get angry
3: find micrometer
4: measure stuff until you find a .010" object
5: cut the herring can tab into a rectangle
6: adjust valves

[call me jack]

Yep that's what the bentley recommends.. I'd just figure it would be better to adjust it hotter? Or it wouldn't make any difference?

since the hot and cold specs differ from one another, i would assume they are accounting for different metal expansion rates, and it wouldn't make a difference if you did it hot or cold... frankly though, when i finally adjusted my valves, i couldn't accurately get a feeler gauge under my rockers, so i just did it by feel. worked fine