I Need Help making Wood block for adjusting timing chain stretch!

[Larry 73Z]

Hey, does anyone have a good detailed picture and description of how to make one of the wood blocks that you make when you have to adjust for timing chain stretch?

Thanks---Larry

[240ZX]

Larry, I believe the wood block you are talking about is intended to keep the timing chain secured (by wedging it in place) and properly indexed to the crank drive sprocket during partial disassembly. There is an automatic chain tensioner that addresses timing chain stretch, located on the non drive side of the timing chain, in the front aluminum casting. Some of the after market repair manuals provide details on its fabrication. Is this help at all?

[MikeW]

Larry, I believe the wood block you are talking about is intended to keep the timing chain secured (by wedging it in place) and properly indexed to the crank drive sprocket during partial disassembly. There is an automatic chain tensioner that addresses timing chain stretch, located on the non drive side of the timing chain, in the front aluminum casting. Some of the after market repair manuals provide details on its fabrication. Is this help at all?

It's true that the tensioner addresses timing chain stretch but when it has stretched too much you have to move the timing chain sprocket to the next of the three possible positions. The main reason that the block is needed is to keep the tensioner from coming out. Keeping the chain properly indexed on the crank sprocket is also accomplished with the block.

For the original poster: if you're planning on doing this job yourself you presumably what either a factory service manual or one of the aftermarket manuals to step you through the process. These manuals should cover this very issue and even give instructions on how to make the block. I don't recall but the FSM may only direct you to acquiring the "special tool" from Nissan.

[LanceM]

The shape is simular to that of a door stop, attach a cable to it so you have something to grab when you want to remove it. I have used a section of wooden broom handle and it worked well for me. I have also seen the datsun tool on ebay quite often for around $7.00.

[240ZX]

Mike, thanks for the additional specifics!

[Larry 73Z]

Thanks guys, but I was hoping someone would have the actual picture so as not to have to buy one if possible. I have a picture of one but it is not clear as to if both bottom sides are tapered or not. I think I saw somewhere that the wedge is suppose to be 1 inch wide by 7 inches long and 1/2 inch thick and tapered at the end where your drive it in against the timing chain tensioner? I am not sure if that is correct and hope some can clairfy it for me.

Thanks again!---Larry

[ZSaint]

We always used a 16" length of 1" hose to stuff between the chains. I found a plastic-handled screw driver in an engine I purchased. It had run so long that the handle had warped from the heat but the driver part did not hit anything. I guess they were just lucky and I was lucky to find it.

[RIP260Z]

Larry 73Z,

I too have looked for an diagram of the dimensions for the wedge. The best I have found is http://www.datsunworld.com/ (in the tech tips page) but I can't quite figure all the numbers, so its exact. But I am sure its a starting point.

Ian

[v_balge]

Not Complete but good enough to make piece.

Vince

[Bambikiller240]

Sorry if the dimensions are hard to read, I had to shrink the image to get the website to accept it.

If you copy the image to your computer, you can then enlarge the pic in MS Paint or another program to see them better

This diagram is from the bible. "How to Modify Datsun Engines and Chassis" book published by H.P. Books in 1973

EDIT: I see someone else posted while I was creating this. Oh, well.

[owenk]

http://www.californiaparts.net/JigsToolsEtc/JigsToolWire.htm

[MikeW]

It's funny how the so called tools are all so different. The fact is you just need something that will wedge in tight enough to keep the tensioner from popping out. I'm a little skeptical of the hose idea but I've even seen a big screwdriver used - on the ZTherapy video. I really don't think the dimensions and/or angles are critical; just jam it in good.