TR2/3/3A Timing Chain Installation Procedures [TR3 engine TS 36161E]

[DornTRoriginal]

This is a procedure that I have never completed so any advise is appreciated!

I am trying to figure out the best way to properly install the timing chain on the camshaft sprocket and crankshaft sprocket. There is a mark on the camshaft sprocket but can not find one on the crank shaft sprocket. It seems that I can install the camshaft sprocket two ways (180 degree) so that the mark is on either side of the camshaft. How do I go about determining which side is the correct alingnment or does it matter? I watched the videos from Moss Tech that are very informative but I will need to study it in greater detail to completly understand it. I have read the shop manual and I am feeling a bit anxious about this, Yikes! I think this has to be correct or more trouble later to deal with and I would like to avid that if I can.

Do I need to get a degree wheel or is there another way? Do I "open" the chain and install it or slip it onto the camshaft sprocket and bolt it on? I should have marked it when I took it off but I am not certain it was ever installed correctly in the first place... Help is appreciated, Thanks!

 

[martx-5]

The manual talks about scribe lines to line up the crank gear with the cam gear, but when I did my engine, there weren't any, so I wound up using a degree wheel. Besides, I had the cam regound and wanted to make sure it was as close as possible, Anyway, if you have the scribe lines it will be a lot easier. The keyway on the crank gear should point straight down, which would put pistons 1 & 4 at TDC. There are four possible combinations with putting on the cam gear, but there should be a punch mark on the gear and one on the cam. If you haven't changed the cam or had it reground, you should be able to use the original punch marks. Place the cam gear on the shaft with the punch mark out and rotate to line up with the punch mark on the camshaft. That's the way the cam gear goes on the cam. Put in (hand tight) a couple of screws and line up the scribe marks, by turning the cam wheel. Remove the cam gear without moving the cam and then you can put it back on with the chain. Drape the chain over the cam gear and hook it around the crank gear. Then offer it up to the cam. You'll probably have to play around with it a bit to get everything to line up with the chain in place.

 

[TR3driver]

Summit racing has two different degree wheels for under $20; or you can even make your own:
https://www.tavia.com/free_degree_wheel.html

As Art mentioned, with the stock cam sprocket there are 4 possible ways to install and each provides roughly 1/4 tooth (about 4 degrees IIRC) of timing adjustment. However some replacement sprockets are cut wrong and the timing comes out the same no matter how you turn them. Even 4 degrees is enough to make a noticeable difference in how the engine runs, so I would definitely want the adjustment.

With the stock cam (and most aftermarket grinds), both valves on #4 should be open by the same amount when #1 is at TDC on compression (ready to fire). You can find this point by turning the cam until both valves on #1 are open (which ensures both #4 valves are on the base circle) and setting the lash on the #4 valves to some large (but equal) value. ISTR that .050" works well. Then turn the cam 180 degrees and use your feeler gauges to get the gap equal on the #4 valves. Turn the crank to TDC, loop the chain over the sprockets and hold up the cam sprocket to the face of the cam. Try the different orientations until you find the best fit, or with the holes in the sprocket just slightly clockwise from the holes in the cam.

Unless I made the marks myself, I don't trust them. Even then it's probably worth a double-check. Bad cam timing can cause all sorts of strange problems: loss of power, overheating, fouled plugs, high fuel consumption, etc. Generally an engine will still run well enough to drive with the cam off by a tooth, but it won't be right.

 

[DornTRoriginal]

Thanks so ummmm The head is off the engine, pistons are installed and I am starting to put it all back together. I am thinking my next step is the timing chain so how do I determine if the valves are fully open if the head is off or do I put in the tappets, pushrods yada, yada and THEN do the timing chain. O my I am such a novice..... what have I got myself into????

 

[martx-5]

OK, it can be quite intimidating at first, but can be done by an average Joe. Below is a link to Macy's Garage who specializes in TRs and they have a tutorial on degreeing in the cam on the TRactor engines.

https://www.macysgarage.com/myweb6/cam_degree.htm

That should get you going, but you will need a degree wheel.

 

[Jerry]

To know that you are close, put the new sprocket on top of the old sprocket. Line up the keyway and look for the DOT or scribe mark from the original sprocket. My old one had the dot, the new one often does not. It will get you very close. PS: if you don't have the pan on yet, just shine a light up into the cam area. When you can see the point part of the lobes on cylinder #1 pointing down, you should have the valves set up to be closed. IE: compression stroke. For the future: when I take off the old sprockets and chain, I always zip tie them together to use for reference. I know you said you were not sure it was set right, but the rest of the instructions above in the previous posts should help. Jerry