Checking Timing Chain Stretch

[SBK86]

Over the winter I'm working on giving the car a thorough tune up. Today's project was checking the timing chain to see if it has stretched at all.

I got the car to TDC by using a ziptie in the #1 cylinder to feel when the piston came up then checked that against the mark on the crankshaft pulley. I then tried looking through the camshaft sprocket to look for those V and _ marks the haynes manual mentions. If I look behind the camshaft sprocket and down at the camshaft locate plate I can see the _ groove but I don't see a V indentation anywhere.

I noticed my sprocket has three holes which differed from the 4 holes the one in the manual had.. so I checked ebay and found that my sprocket is actually a Cloyes part and not the original sprocket. Surprise to me.. is it possible that my sprocket doesn't have the V indentation to check for chain stretch? Is there something I'm missing?

I attached a pic of my sprocket.

Thanks again for the help

[Zed Head]

Is that picture from when you had everything set to zero? No sprocket bolt, and the holes in the sprocket aren't at the top where the groove is. You might be on the exhaust stroke for piston position. The timing mark actually passes zero twice for each chain sprocket revolution. Check that the cam lobes are both up, not contacting the rocker arms.

The sprocket has the 1, 2 and 3 adjustment holes so it should have the notch also, to show the need for adjustment. The first is not much good without the second.

[SBK86]

Sorry forgot to mention I removed the sprocket bolt, I haven't done this before so I thought that might help me figure out what I'm missing. First two cam lobes are up, not straight up but they make a v shape when looked at from the front. Pretty sure its at tdc.. I'll probably just redo everything tomorrow and see if lines hp right.

[Zed Head]

Something seems weird then. One of those three holes should be up near the top so that you can look through it. I think that each one has a notch. And one of those three holes that was under the bolt washer should have the can shaft dowel in it, you can check that. Maybe someone in the past broke the dowel and eyeballed the camshaft sprocket in to place, locking it down with clamping pressure.

One of the guys on here who's done more engine work should have an idea. Doesn't look right (to me) for the settings you described.

[SBK86]

Thanks, yeah I agree. From all the pics I've seen online and all the manuals I've read, mine looks a bit off :/

[240260280z]

It may have an indent on the inside top edge rather than a triangle on the flat

[Zed Head]

Found a link on ratsun that suggests some sprockets don't have the mark. Still wouldn't makes sense to have the 1, 2 and 3 numbers, but no mark.

Post #12 -

does this cam timing look correct? - Engine - Ratsun Forums

[EuroDat]

I have heard of some people removing the dowel to adjust the valve timing. One guy in our club here in The Netherlands did that, but he had access to a dyno and spent a lot of time fiddling with the engine.

Its not my speciallity, but it doesnt look right to me. Maybe the PO did something along this line to correct chain stretch and play with the timing?

Chas

[Diseazd]

Simple........Wedge the chain and install a new sprocket.....doesn't appear to have the "v". Maybe it was manufactured on a Monday or the marker was texting. :stupid: IMO

Edited December 14, 2013 by Diseazd

[SBK86]

I looked at the car again today to see if I could figure it out. I am curious what the 1, 2 and 3 marks on the outer edge are on the image in my original post. They don't line up with the 1, 2, 3 holes on the inner part of the sprocket. I couldn't find any other marks on the sprocket that might help me out.

I did verify I'm at TDC. I'll post some images below to show the dizzy lining up at 1 spark plug, pointer is at the correct timing mark and the cam lobes are at about 10 and 2 pointing up just in case maybe someone sees something wrong that I did.

So next I'm going to order a new sprocket, wedge the chain and install it like Diseazd suggested. Anything else I should be aware of when installing the new one? If everything is correct and it's at TDC it should look better once I install the new one... I'll update once the new gear comes in.

[Diseazd]

Everything looks right.....crazy about that sprocket. Make sure you're wedged good and tight.....don't want to have to drop that pan and pull the front cover looking for a dropped chain. Also...make sure your number 1 mark is where it is in the first picture (lined up with the bright link on the chain) so you go back the same way with the new sprocket.

Edited December 15, 2013 by Diseazd

[madkaw]

I have Newer Nissan sprocket off my motor , less then 10k miles that I'm not using . I went with a Nismo adjustable.