So when I install the two row chain (originally single row) I heard this rumour that you will need a shorter distributor drive gear as well. I have checked Toyota part numbers for each set-up and there doesn't appear to be two different ones. I also heard some local yahoo salesman guy say I'll need a different timing cover as well which from what I've read here isn't true. Not that I care if I'll need them, its just if I do I'll get them so the re-assembly isn't stalled until they arrive. Yup, I've got the shorter oil pump drive in the 'parts to go on box'.


Build date on the truck is Nov 82.

 

Distributor drive gear is the same - only thing you will need is the short oil pump drive gear which you have so you should be good to go.

 

So all my goodies arrived and I started to install the new chain. Set up every thing as per FSM, crank and cam TDC, rockers loose on #1 cyl, 2 bright links on cam sprocket bracketing the dot, bright link on crank sprocket on the dot. (I even put dots of white paint in the right spots so my retired eyes don't trick me!) Put it all together, torque bolts, and drown it with Royal Purple assembly lube. Then I go and turn it over by hand before proceeding any further with re-assembly to make sure nothing hits, binds (breaks!) etc. Turn it 2 full turns to get it back to TDC #1 and the bright links no long line up with the pre-set position. I think I did something wrong and re-do the install 3 more times with the same results. The bright links move away from the pre-set point each time. Crank and cam do return to TDC (Keyway on crank at 12 o'clock, pin on cam at 12 O'clock) Take it apart again! So I count the teeth and chain links on the new and they're same as the old (36 on the cam, 18 on the crank and 49 links in the chain) Being a meticulous guy, a retired industrial mechanic with 38 years experience who re-checks stuff 3 or 4 times before moving on, I cant believe how stupid and incompetent I am, so I leave it and start thinking about this. Now after 6 sheets of paper I think I've answered my own question and a simple thing like this hasn't tripped me up and I've done it right 4 times.


(Again the crank and cam both return to TDC every 2 turns of the crank but the bright links do not re-align with the original set up.)


So...because the number of links on the chain is not evenly divisible by the number of teeth on both sprockets the chain will do exactly what I observed. Because the ratio of teeth to links is 1.2564, and if I done my math correctly it will take hundreds of turns for the links to align with the sprocket index marks again. This is to spread the wear over more teeth much like the reason for rear end gear ratios being 4.10:1/4.11:1 rather then 4:1(it will take 41 or 411 turns of the pinion to hit the same contact on the ring gear rather then 4)


Theory/reasoning correct?


Sorry for the rant length...I'm used to industrial engines with timing gears not chains, some of which displace 3 or 4 times more per cylinder than the 22R has total.


Addendum...I set up a quick fixture to hold the old chain to experiment with this. It takes 49 turns of the cam sprocket or 98 turns of the crank sprocket to return those links to the set up position...hey winter returned here on April 3rd and 4th, and I wasn't freezing my fingers off in -6C weather complete with 6" of snow.

 

You are correct. Sorry to say but you had it right the first time and stressed yourself out over nothing.

I know this because I had the same panic moment the first time I did a 22R chain

Never hurts to check/be cautious, right?