Valve Adjustment cam sprocket #2 mark

[athoose]

I decided to adjust my valves 06/73 L-16.

I watched Hainz video and read several posts including Mklotz. This is what fell out.

 

Timing 8 degrees BTDC (sticker on hood) FSM calls for 5 BTDC but I think that

[Phlebmaster]

Isn't that fun? :D

 

Sounds like you did it right.

[datzenmike]

I'm almost positive that the L16/L18 is set on the #1 and all L20B Z20/22/24 are on #2, at least to start with. Having the V to the right is the governing factor.

[athoose]

No scanner so a few picks will have to do, sorry.

 

Manual shows that #2 is factory setting and if chain stretches and the notch moves to the left of the oblong groove ( as represented in the before adjustment image) you can move the sprocket to number #3 and the notch will be to the right (advanced) of the oblong groove. Pretty cool, you can save yourself a chain replacement.

 

 

 

Thinking about it a bit more, you can still set an advanced cam at 10 and 2, if you can judge it or what 8 degrees BTDC looks like on the crank pulley. Keep in mind if your lash is out (loose) the cam lobe could still be lifting and when you adjust your actually adjusting with a bit of lift involved. I actually found it less confusing to set all exhaust then all intake valves. It took a bit more crank turning but less to think about while doing it. As long as the lobe you

[datzenmike]

Good enough for me. I was using the 510 L16s. Maybe cars have different emission standards.

 

Make sure the crank is at TDC and not 8 degrees... that's just for ignition advance. As long as the rocker is not on the cam lobe it's good for adjusting. I looked and it isn't that critical. You would have to be +52 or -54 degrees out from TDC to be even close to the next valve opening on cylinder 2 and 3.

 

Yes the cam can be advanced to keep the proper valve timing but the chain is still stretched. The job of the tensioner is to push outward on the chain and keep it tight. In order to do this it has to move further out of it's bore. If I had one on the last adjustment I would order a new chain set.

[HRH]

The crank sprocket holes are:

 

#4 12 degrees advance cam timing

#3 9 degrees advance cam timing

#2 6 degrees advance cam timing

#1 3 degrees advance cam timing

 

Number 4 you have to make from a copy of the old Nismo comp gear, or know how to calculate that crap. Number 4 works well for the L7 rally cam grind.

[banzai510(hainz)]

Update

that brite link looks off( but dont worry about that yet, it still could be correct)

 

But remember you put the crank to ZERO keepin the chain tight dialing it up). I repaeat Zero!!!!!!!!!!!! then look up at the cam sproket to see where the notch is.

 

That 8 degress is eleltrical(this is a separated issue). And that is adjustable anytime you want it. ot 10 12 or whatever make it run best for your head carb set up. Unless you put the oil pump spindal off a tooth

 

 

far as my book is concerned

a stock sprocket

1 = Zero degree

2= 4degree

3= 8 degree

 

if your truck is running fine dont fuck with it.

 

 

dial it to Zero on crank and if V notch is line up call it good!!!!!!!

[banzai510(hainz)]

the bright link moves around. I guess you just line it up on assembly.

 

 

exactly but looks off. Dont matter as long as your on TDC zero degree on crank the the cam timming is in line with the V notuc its ok.

 

photos look closely

PS L20s come from factory on #2 all else #1 but I set thi motor on #2 to bring power on sooner.

notice the brite link is right on the dimple!

[athoose]

Okay so I didn't get to check it warm today ... will do tomorrow.

 

What I observed per my feeler gauge is if I set No1 cylinder to TDC, lobes at 10/2 (though 10/2 is advanced due to #2 mark) a .008 feeler gauge would go ... .009 would not go (this is for exhaust) ... If I turned the lobe straight up the .009 would go. This says to me the cam lobe is effecting the lash. I suspect because of #2 mark advancing the cam. I'll check this again tomorrow and see if it happens again. My valves don't seem to be as noisy now.

 

The remark about timing it at 8 degrees BTDC was to avoid the lobe effecting lash. I don't plan to do this. I'll just adjust individual lobes straight up. Just thought I would mention it on here so if someone else had a cam on #2 mark. Again I am not positive, I'll check again tomorrow, but it seemed like the lobe is lifting when crank is TDC on a cam #2 position.

[datzenmike]

As long as the rocker is not on the cam lobe it's good for adjusting. I looked and it isn't that critical. You would have to be +52 or -54 degrees out from TDC to be even close to the next valve opening on cylinder 2 and 3.

 

According to my stock cam profile you could be as far as 52 degrees before or after TDC and the rockers are just starting to touch the cam lobe. So for lash adjustment close is good enough. For checking stretch it's critical that you get it spot on the mark while turning clockwise on crank.... if you overshoot, bring the marker back well before TDC and try again. This will remove all chain slack on the tension side for a good reading.

[athoose]

Alright I checked them hot again and they were pretty close. I adjusted them a bit more while hot and got them closer but a little loose here and there. Done.

 

 

 

So I checked the lash at TDC with lobes at 10/2

[banzai510(hainz)]

athoose your making this harder than it is.

Does the car run fine? If yes then set the timming to 8 degress w/ timming light. If runs OK still your done.

 

 

Whne adjusting the valve lash. I usaully say just point it straight up as some do it at 10 and 2 but this makes it confussing to some poeple so point lobe up adjust. Your done.

 

as for the timming plate on the dizzy its ajust a basic timming marks.

Go by the timming plate at the crank when setting the timming using a light.

 

 

But a earlier remark you made:

somebody has worked on this motor before. The Brite link on the top of the cam sprocket is off 1 tooth. Look closely.

So only way to ck this is take it back up to TDC zero deg and see where the mark is at. If the same as in the photo the truck will run . But your off. Not a big deal if you just drive marginally just you wont have your full top end power(i think).

 

another way is to take the front cover off and see if the brite link on the lower crank sprocket is on the dimple. If yes then your cahin is off alink up top.

 

But if your not that mech inclined I woundnt worry about it if this is just a around town rig.

Edited February 1, 2009 by banzai510(hainz)

[athoose]

The first pick is #1 TDC.

 

That link changes places, it could be there on TDC or if I rotate again to TDC its somewhere else, not seen, rotate again to TDC its like on left side of cam sprocket. Of course this could be the lower link I don't know ... could mark it. It does come back to that spot but it takes around 5 +/- revolutions.

 

Yeah I can definitely do the mechanical to put this back right. Is it definitely off? Does your link move around like this? I may not due it tomorrow, I've driven it like this for a year. But would definitely like to put it back right at some point, especially if it's causing a loss in performance.

 

The truck runs, runs alright, shakes pretty good ... I don't really know what to expect from a 35 year old 70 HP Auto. To be honest, I am astonished it moves. :D

[datzenmike]

As I understand it the later L20B were set on #2 at factory as a pollution reducing measure. This is a California spec motor so.... maybe they started early.

 

As for the 8 degrees advance.. this is another trick to reduce pollution at idle.

[athoose]

Cool. Didn't even put one and one together as I didn't see air pump.

I might swap this to #1 mark/5 degrees BTDC timing down the road then. Thanks