I have a 1982 Toyota Pickup RWD, 22R w/Weber 32/36 carburetor, W50 5-speed, emission control system removed, custom 2" exhaust w/MagnaFlow muffler.
I just got the truck back on the road after two years of extensive restoration work that included a complete engine rebuild. In fact, I completed the 500 mile break-in on my drive in to work today.

I haven't loaded the truck yet, but so far the engine starts quickly, runs well, pulls hills, etc. That said I've observed a few issues:
- I have the ignition timing set at 12° BTC because I can't get it any closer to the specified 8° BTC than that. The distributor is hard up against the adjustment stop. I tried pulling the distributor and turning it one tooth, but apparently there is no overlap in the adjustment and I couldn't even get it close that way.
- I have the idle set at about 1050 rpm - the lowest I can get a smooth idle. (Fuel mixture is set at best lean.)
- I have a little backfire from the exhaust when decelerating in gear. (Backfire stops when the truck is out of gear and the engine isn't being reverse torqued.) I had some exhaust leaks before hot torquing all my fasteners, but I think I've got it all buttoned up now and I'm still getting some popping.
- I don't get the torque I was expecting. As I said, I haven't loaded it yet (I have a load of scrap metal I plan to haul to the recycler tomorrow - I'll know better how she performs under load then), but she just doesn't feel like she's got the pick-up she should have when accelerating. I know it's a 40-year-old truck with a 22R and I can't expect it to burn rubber, But I don't think I'm getting the torque I once got out of her.
- I'm only getting about 20 mpg. The last time I checked the fuel economy was about 5 years ago, and I was getting about 24 mpg then. I was expecting to get at least that much after the engine rebuild.

I adjusted the valves when I put the engine together, but I have not checked them since. I have not checked the compression, either, but based on how easily it starts and how tight it is when I crank it over by hand, I'm guessing the compression is fine.

So, here's my question: Is it possible that I have the cam shaft advanced one tooth on the timing chain?
I was careful when I installed the timing set and cam shaft and used several resources to get the right alignment, but this was my first time rebuilding a 22R and I could have gotten it a little off.
I plan to change the oil and filter and check the valve adjustment this weekend. I'm thinking about turning the cam shaft back one tooth on the timing chain, but I'd like some knowledgeable input first.

Thanks
Raymond Fast
Dallas, GA

 

I'm not familiar with the 22R specifically, but yes, 1 tooth on the cam sprocket will throw off your timing significantly. If' your target is 8 and you can only get 12 at max adjustment, then you're probably closer to 16 out if you were on the correct tooth. 4 cyl engines will run at over 30 deg, although very poorly at that point.

 

Here is a good clear picture. One tooth off is about 10°

You should verify TDC by pulling #1 sparkplug and using a touch test to verify (straw, dowel or *crinch* screw driver in the hole) that the piston comes to a stop at the top.

It's very much worth noting if you overshoot by any significant amount you can't just turn the crank backwards you have to go all the way around because the chain has so much slack on the tensioner side. Somewhere/when I've posted the video of this showing the cam won't move for about 15° (from memory) of crankshaft rotation.

 

This is very much dependant on the cam. From what I recall the ECU advance is capped somewhere in the 25-30° range.

 

moto809 and Co_94_PU, thanks for the input! That's very helpful. I'm going to turn the cam shaft back by one tooth this weekend while I have the valve cover off to check/adjust the valves. I'll see what that does for me. (One of those adjustable cam sprockets would be really nice in this situation. Too bad I can't justify the expense being that I'd probably never adjust it again.)

In the mean time, any other comments would be appreciated.

 

The adjustable cam sprocket was just to illustrate the ten degrees between the peaks of the teeth, however..

How much material was taken off your head and block, this effects the cam to crank timing by retarding the valves. It might actually be advantageous to install the adjustable sprocket. While it is possible to tinker with the valve timing I don't expect many people are doing a lot of tweaking it and feel it's safe to say most are "set it and forget it" only doing it once.


You should check the TDC and verify the indicator points at 0° when it should and there isn't an issue with your casting mark or the pulley hasn't slipped on its rubber ring.

You should verify the location of the cam dowel when the piston is at TDC. (It should in the 12 o'clock position) If this is ten degrees off you can move the cam, but if it's five out your only choices are live with it or install the adjustable to get the power band back to design specs.