Checking Timing Chain Stretch

[Diseazd]

Steve....where did you find your Nismo? I was told they were all gone.

[SBK86]

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

Sure, if you'd be willing to sell your old one I'd be interested. I was also looking at this one on eBay: Datsun 69 83 510 240Z 280z 280ZX Camshaft Gear 13024 U8000 | eBay

[madkaw]

Sure, if you'd be willing to sell your old one I'd be interested. I was also looking at this one on eBay: Datsun 69 83 510 240Z 280z 280ZX Camshaft Gear 13024 U8000 | eBay

I'll be out of town till Tuesday and I will PM you then. Don't be afraid to remind me though.

I thought I got it through Courtesy Nissan.

[madkaw]

Steve....where did you find your Nismo? I was told they were all gone.

Courtesy Nissan I think.

[djwarner]

My chain has 179K miles on it and the head has been reworked so the chain is already set on position #3. While changing the head gasket I snapped this photo as a guide for re-installation.

[Diseazd]

DJ. You need to get the bright mark on the chain lined up with number 3 and cam locating mark (as shown) for reinstallation of your chain. Don't want to miss by a tooth.

Edited December 16, 2013 by Diseazd

[djwarner]

Thanks Diseazd, as you know, at TDC, several different links will line up with the sprocket mark. Since I didn't dis-assemble the front case, I used a wedge to jam the chain. To ensure I engaged the right link, I degreased the link and sprocket and marked both with a magic marker. Worked fine.

[madkaw]

Thanks Diseazd, as you know, at TDC, several different links will line up with the sprocket mark. Since I didn't dis-assemble the front case, I used a wedge to jam the chain. To ensure I engaged the right link, I degreased the link and sprocket and marked both with a magic marker. Worked fine.

Right. You don't need to have the bright link lined up to change your sprocket adjustment. It's dumb luck if the bright link lines up when you do this. Think about it-where's the other bright link? Could be behind or ahead of that link, not necessarily on the crank. More important to be TDC compression stroke on #1.

As said above, clean the link that lines up with the mark on the sprocket and use a marker to mark that link, then just spin the sprocket around to the next setting lining up with that mark.

[Zed Head]

You should be able to just put the new sprocket back on using the same dowel hole - 1, 2 or 3. Assuming that the flaw with the old sprocket is just the fact that they didn't cut the notch in it. Once it's on, you can determine if cam timing is retarded or not.

And, if the old sprocket isn't worn out, the only reason to install the new sprocket is to check cam timing. So, you could also get a used one and stick it up next the old one, aligning teeth and 1-2-3 holes, and check notch alignment. Or, if you're good with measuring tools you could even transfer the notch location to the old sprocket and just leave it on.

Just offering a new view. Nissan stopped referring to chain stretch in the later ZX FSM's. I wonder if it really has that much effect, considering all of the other things that wear. The funny thing about it is that it moves the power peak to higher RPM (as I understand things). Which is what people who modify usually want to do. My thought has been that one cheap way to make a higher revving engine is to put a used chain on.

[Diseazd]

Thanks Diseazd, as you know, at TDC, several different links will line up with the sprocket mark. Since I didn't dis-assemble the front case, I used a wedge to jam the chain. To ensure I engaged the right link, I degreased the link and sprocket and marked both with a magic marker. Worked fine.

Right DJ....Doesn't matter where the sproket is, as long as the new one goes back on the same way as the old one came off. Paint works fine as long as it doesn't getted rubbed off.

Edited December 16, 2013 by Diseazd

[SBK86]

I got a replacement cam gear from madkaw and everything looks much better!

I made a hardwood tool using the instructions from my manual, here's a pic in case anyone on here ever needs that info:

I had trouble getting the sprocket back on there and I was really worried I didn't jam that tensioner well enough. I had to really pry the gear up with a screwdriver while pushing it onto the peg.

The '-' mark is on top of the V a bit. I may just move it to hole 2 later but I'll keep it as is for now. Next project is rebuilding the carbs with the kit I got from ztherapy. Thanks everyone for the help