I was going to set valve lash on my new to me 240Z and decided to check cam chain timing. From everything I have been able to find in terms of service manuals it seems like the chain is off a tooth? Can someone confirm or deny my suspicion? Shouldn't the #1 mark coincide with the center of an "outer" chain link? Also, the horizontal mark is to the right of the sprocket groove, wouldn't this be indicative of being one tooth advanced? Any help is greatly appreciated. 

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Also, the silver chain link is way off of where it should be, per the manual the silver chain link should line up with the #1 mark on the cam sprocket. It is like 100-some-odd degrees off which leads me to believe someone has been in here. I am finding that I have to use up almost all of the distributors adjust-ability to reach the appropriate timing advance, maybe these are related?

Edited September 17, 20177 yr by Strat067

Its amazing how dirty everything looks in my pictures - kind of depressing. I sware it doesn't look that dirty in person. 

That shiny link only lines up with #1 every so many times. It moves around I found out the hard way.

If the line is out of the grove you can pull the cam sprocket and put the shiny link on #2 or #3. That is for chain stretch over the years. Not too bad a job if you have a timing chain wedge tool. That will keep the chain and tensioner in place while you remove the sprocket. If the chain falls into what they call "the hole of doom" you have to take the front of the motor off to get the tensioner back in place. Major PITA. Try googling 240z cam sprocket position. Maybe you'll see something. There's an illustration in the factory service manual you will hopefully find, google images.

Here it is

 

Does your's have the electronic ignition distributor off a ZX? I do and my distributor is just about maxed out on the adjust plate. FYI

How's it run? I can get 6,500rpms with my stock 2.4 and SU carbs, fairly new rebuild.

30 minutes ago, siteunseen said:

Does your's have the electronic ignition distributor off a ZX? I do and my distributor is just about maxed out on the adjust plate. FYI

How's it run? I can get 6,500rpms with my stock 2.4 and SU carbs, fairly new rebuild.

Yeah I have the 280zx distributor. Runs pretty good, sometimes it breaks up under Accel. Do you have the vaccum advance hooked up? Mine runs like $^!# with it hooked up. I'm running only mechanical advance, 15 Deg at idle, and I only get like 23 degrees max, trying to get up to like 34 max but not sure how 

My advance hose comes off the front carb. I rebuilt them when I did the motor so I can't speak of the effects the fresh carbs had. Seems like in the DVD from Ztherapy there was a hole in the throat that the brass plate couldn't be in front of, I think that cut the vacuum pull???

I bought a nice digital timing light with full advance feature. I set it 34 degrees and run the motor to 2,000rpm then move the distributor until the digital display say "0". That is the number stamped on one of two weights in the distributor,  17 then double that for full advance for the number 34 I entered in the timing light. I think 16, 16.5 and 17 are the different weight numbers. There's an Excel spreadsheet member @Walter Moore put together for us to know the specs on each dizzy. I'll post the link in the a.m when I'm on my laptop. The distributor number is stamped on the body, write that down and use Mr Moores spreadsheet and see where your's should be.

Here you go, maybe it'll help.

Distributor advance curves S30-S130.xls

The cam sprocket notch position, in your picture, relative to the groove, looks like the chain has some wear but not enough to adjust the sprocket.  It looks okay.

The cam timing has nothing to do with distributor shaft position.  They are two totally separate timing operations.  The drive quill, connected to the oil pump shaft, is what determines where the distributor's range of adjustment is.  You have to relocate the oil pump drive shaft to change that.

If you're only getting 8 degrees of advance mechanism movement there's something jammed up inside your distributor.  The advance mechanism doesn't care where the starting point is.  A typical distributor in good condition will move about 16 to 22 degrees from the starting point, just on centrifugal motion.  So if you start at 15 you should easily see 30 degrees at above 3000 RPM.  The upper limit varies, usually around 2500 - 3000 RPM.

The vacuum advance is separate from the centrifugal advance.  Seems like you might just have a bunch of small things to work on.  

Edited September 18, 20177 yr by Zed Head

57 minutes ago, Zed Head said:

The cam sprocket notch position, in your picture, relative to the groove, looks like the chain has some wear but not enough to adjust the sprocket.  It looks okay.

The cam timing has nothing to do with distributor shaft position.  They are two totally separate timing operations.  The drive quill, connected to the oil pump shaft, is what determines where the distributor's range of adjustment is.  You have to relocate the oil pump drive shaft to change that.

If you're only getting 8 degrees of advance mechanism movement there's something jammed up inside your distributor.  The advance mechanism doesn't care where the starting point is.  A typical distributor in good condition will move about 16 to 22 degrees from the starting point, just on centrifugal motion.  So if you start at 15 you should easily see 30 degrees at above 3000 RPM.  The upper limit varies, usually around 2500 - 3000 RPM.

The vacuum advance is separate from the centrifugal advance.  Seems like you might just have a bunch of small things to work on.  

Yeah something is not right with my setting then - if I look at the excel spreadsheet siteunseen link above (thank you siteunseen) then the s130 distributor should be giving me 17 degrees of advance with the mechanical advance alone. so at 15 I should be at 32. This definitely helps me focus my problem solving. 

 

I am still wondering why the chain looks like it is one tooth off, maybe I am missing something. If I look at all manuals and pictures on the web, the outer chain link is centered on the timing marks on the sprocket, not the inner. Mine is centered on the inner. Does it matter? I would have to take my timing cover off to confirm, but if the crank is centered on the outer and the cam sprocket is centered on the inner, it would put cam timing off 9 degrees no?

 

From the web:

Notice timing marks are centered on the "outer" chain link.

 

Mine:

Edited September 18, 20177 yr by Strat067

18 hours ago, siteunseen said:

That shiny link only lines up with #1 every so many times. It moves around I found out the hard way.

Like site said, the links only line up occasionally.  They are there for installation only.  First time.  Once the chain moves they're not useful anymore.

It's very common for the old ZX distributors to have broken parts inside.  Also very common for people to use the wrong pedestal/base when they swap to a ZX distributor.

Take the distributor apart and you might find that it needs work.  If it doesn't now it probably will later.  They're not very durable.  

Agree with Zed H. My old ZX dizzy's ball bearings from the vacuum advance weights slung out and were stuck to the magnets on the stator. Pull your cap off and look around, you probably will see some ball bearings.

I bought a nice reman one from amazon.com for $100 a couple of years ago. No cap or rotor button included with it though. I put in a '79 ZX manual transmission in the "make sure it fits" boxes on amazon and they sent me the best one according to that excel spreadsheet. I wanna say D 06 was part of the number???