Valve adjusting problem on U20

[jasmith1975]

Sounds like you're doing it all right. I'm guessing that what you're hearing is the few seconds before oil pressure comes up and stops the chain slop and rocker arm rattle. Run the engine for 20 seconds or so and it should quickly quiet down in the first few moments. (BTW, check into shimming the chain tensioner and inspecting the "evil L"...).

Do one set (one intake, one exhaust) at a time (they will be on different cylinders). The lobes won't be exactly straight up, but close. Your description of the "feel" was correct. Too much "lash" or having them set too loose is not as serious as going too tight... the valve must seat down or it can't transfer heat to the head and can become damaged, and no space or lash doesn't allow that. Stock settings as I recall are 8in and 12ex hot. Many of us go 6in 8ex COLD because they actually loosen with heat and will end up at 8 and 10 respectively (the 10ex being a little tighter than stock to reduce noise) once the engine warms up. Understand, so long as there's some space between the rocker and the cam you will be OK. The specification from the factory is as it is to allow for varying conditions such that the valve will ALWAYS be able to seat and transfer heat under all engine conditions, so there is no HUGE difference between 6 and 8 other than to potentially reduce valve noise by reducing "slop" if you will. If you were to go waaaay loose (like 16 and 18 hot) you might throw a lash pad at high rpm and they'll be very loud.
Hope this helps, feel free to continue to ask questions!

Thank you, this is super helpful! Ok, so a few additional questions before making a 3rd attempt:

1. Before I did the valve adjustments I didn't notice any ticking noise on a cold start. Post adjustment it's really loud (granted the hood is open)...again cold start. Would valve adjustments cause delays in building oil pressure? In other words, why wouldn't I hear the same noise pre-adjustment?

2. My plan for a 3rd attempt is to follow your "one intake, one exhaust" approach and triple check each gap again. OCD much?!

3. Re: the "feel"...on my second attempt I adjusted the "medium" drag to more of a "tight" drag (per an earlier suggestion) . Does that mean I set the lash slightly more loose?

4. The service manual has stock settings at .008/.012 hot for intake/exhaust. I went with .006/.010 cold. Should I adjust exhaust to .008? Could that be part of the problem?

5. As for checking chain tensioner shimming and "evil L", I'll have to follow-up on that after sorting through the valve adjustment. I didn't notice any death rattle before, but will do some research and look into it.

[redroadster]

You need the go - no go feeler guage maybe , I use mine all the time . Or just try them .001 thicker
Did you check after snugging the nuts ?

[jasmith1975]

You need the go - no go feeler guage maybe , I use mine all the time . Did you check after snugging the nuts ?

I heard about the go-no go feeler gauge. Might be a good tool to own. After snugging down the locking nuts, I rechecked the gaps before moving on. All were good. I haven't started attempt #3 yet, but I may repeat the same lobe up process and just recheck adjustments to see if somethings off. Can the locking nuts loosen up? I didn't crank on them, but snugged them pretty tight.

[Gregs672000]

Valve lash and oil pressure or delivery are unrelated, so no, your adjustments make no difference there. Were they significantly different from the first time you checked prior to making your first adjustment? I would not expect a lot of change from your original settings to now. However, if I think about how the valves/seats wear, I'm imagining that they actually get tighter/less lash as the valve moves up higher into the port and against the rocker (?). I honestly don't know, but others like JT may...

Regrardless, the tighter the feel, the less lash you have, so if a 6 goes in with some wiggle work, a 5 should slip in without a lot of effort, but a 7 will not go.
You could adjust exhaust a bit tighter to the 8 cold or 10 hot if it's still making noise (they all do!). Exhaust is the more critical of the two as exhaust valves get a lot hotter than intake, so they must seat to transfer heat. Less than 8 cold or 10 hot is a risk IMHO.
No need to reef down on the locking nuts. However, the lash can change when you tighten them, so recheck the final setting... can be frustrating but you'll get it with practice.

[jasmith1975]

Valve lash and oil pressure or delivery are unrelated, so no, your adjustments make no difference there. Were they significantly different from the first time you checked prior to making your first adjustment? I would not expect a lot of change from your original settings to now. However, if I think about how the valves/seats wear, I'm imagining that they actually get tighter/less lash as the valve moves up higher into the port and against the rocker (?). I honestly don't know, but others like JT may...

Regrardless, the tighter the feel, the less lash you have, so if a 6 goes in with some wiggle work, a 5 should slip in without a lot of effort, but a 7 will not go.
You could adjust exhaust a bit tighter to the 8 cold or 10 hot if it's still making noise (they all do!). Exhaust is the more critical of the two as exhaust valves get a lot hotter than intake, so they must seat to transfer heat. Less than 8 cold or 10 hot is a risk IMHO.
No need to reef down on the locking nuts. However, the lash can change when you tighten them, so recheck the final setting... can be frustrating but you'll get it with practice.

I recall during attempt 1 some of the valves needed some good adjusting. Seemed weird but I should have taken down specs before fiddling. I'm going to give it another go this morning. I'll first recheck each valve with cam lobes up to see if anything moved from attempt 2. Then I'll go back through and adjust a bit as it sounds like I made the gap too tight on the feeler gauge. I'll report back with an update. Appreciate all the help!

[jasmith1975]

So 3rd time really is the charm! She's alive and purring beautifully. I backed off the "tightness" of the feeler gauge from attempt #2. Basically I loosened each valve until the next size up went in, then tightened a little until it wouldn't go. As a triple check, I rotated the engine through each cylinder. First with intake fully closed and exhaust fully open but just starting to close. Then flip flopped exhaust and intake with the same method. Lash was still good. I'll take her for a ride and check hot settings to confirm.

A big thank you to all for the help and patience! I'm still learning and this group has a ton of knowledge and experience. Now let's hope the weather improves to get out for a ride this weekend!!

[Gregs672000]

We are always happy to help... we want everyone in the family to be having fun with their cars in what ever way they desire. BTW all of us start with no knowledge or experience, just at different times in our lives! I remember being 16, having been ripped off by a non-Roadster-at-heart person with my first car, and exploring my 2nd car ('73 Datsun 620 PU), where I took the valve cover off and started the engine cause I wanted to see how it worked... this led to my first purchase for this car in the form of Engine Bright degreeser as it sprayed oil EVERYWHERE. DOH!

[Gregs672000]

We are always happy to help... we want everyone in the family to be having fun with their cars in what ever way they desire. BTW all of us start with no knowledge or experience, just at different times in our lives! I remember being 16, having been ripped off by a non-Roadster-at-heart person with my first car/truck, and exploring my 2nd car ('73 Datsun 620 PU), where I took the valve cover off and started the engine cause I wanted to see how it worked... this led to my first purchase for this car in the form of Engine Bright degreaser as it sprayed oil EVERYWHERE. DOH! Fast forward to today any my third car (the Roadster) is modified with a crank fired ignition, fuel injection and many internal mods... all from engine degreaser...

[jasmith1975]

We are always happy to help... we want everyone in the family to be having fun with their cars in what ever way they desire. BTW all of us start with no knowledge or experience, just at different times in our lives! I remember being 16, having been ripped off by a non-Roadster-at-heart person with my first car/truck, and exploring my 2nd car ('73 Datsun 620 PU), where I took the valve cover off and started the engine cause I wanted to see how it worked... this led to my first purchase for this car in the form of Engine Bright degreaser as it sprayed oil EVERYWHERE. DOH! Fast forward to today and my third car (the Roadster) is modified with a crank fired ignition, fuel injection and many internal mods... all from engine degreaser...

Hahaha...best way to learn is trial by fire. Sometimes it's costly. Sometimes it's ugly. But most times it's worthy. Chances are you never started the car with the valve cover off again.

[Gregs672000]

All this valve adjustment talk reminded me that I needed to retorque my head and check lash as the engine has had several heat cycles since the repair, and Dean suggests a retorque after a few when using the thicker head gasket. Sure enough it took a lot more before it clicked off again at 65lbs (ARP studs with their lube). I had checked the lash prior to torquing the head and found an intake that was way too tight where I could not force in a .005, the smallest feeler I have! Not sure how that happened. Everyone else was fine or very close. I rechecked after the retorque and lash had not changed, so I adjusted the offender, tweaked another one or two and we were good to go! A cold compression test found 200-205lbs in all 4, and I didn't hear any leaking past the valves when I put air to each cylinder, so that's cleared up.

I'm reminded that helping others ends up helping yourself too! I love this family...

[redroadster]

I did ? so many L28 L 20 valve adjusts ?7-8 a week
1st doing them I would get them very tight to the specs ....in the hot summer , older techs said a thousand off loose even 1.5 is good too
Because in the winter here it came back now 20-30 degrees and running/ idling. bit rough valves a smidge tight worse cold start
The 03- on mitsu mivec motors went back to solid lifter same conditions sloppy loose in 100 degrees , adjust then too tight in freezing cold

[redroadster]

We are always happy to help... we want everyone in the family to be having fun with their cars in what ever way they desire. BTW all of us start with no knowledge or experience, just at different times in our lives! I remember being 16, having been ripped off by a non-Roadster-at-heart person with my first car/truck, and exploring my 2nd car ('73 Datsun 620 PU), where I took the valve cover off and started the engine cause I wanted to see how it worked... this led to my first purchase for this car in the form of Engine Bright degreaser as it sprayed oil EVERYWHERE. DOH! Fast forward to today and my third car (the Roadster) is modified with a crank fired ignition, fuel injection and many internal mods... all from engine degreaser...

Hahaha...best way to learn is trial by fire. Sometimes it's costly. Sometimes it's ugly. But most times it's worthy. Chances are you never started the car with the valve cover off again.

Canada requires a 4 yr Auto tech degree to buy parts or work on a vehicle ...think they still do,