AJ'S 88NA said:
Get head studs. Forget head bolts.
The factory cam wheel is a vernier wheel.:icon_bigg
The cam is varied either by 3 or 4.5 cam degrees by moving the sprocket dowel pin by one position. It works on exactly the same principle as an old fashioned vernier scale and these wheels are often called vernier cam wheels.
This method is as old as the hills. If you have a different number of equally spaced cam wheel positions to the number of teeth on the gear then each cam wheel position will have a slight misalignment. In this case the cam wheel has 3 holes but they are spaced as though there are 5 equally spaced holes. The gear has 48 teeth. If you divide 48 by 5 you get 9.6. So when you move the cam wheel by 1 postion you change it by 9.6 teeth. To then make the belt fit you have to either advance the wheel by 0.4 teeth and go to 10 or retard by 0.6 and go back to 9.
0.4/48 times 360 degrees = 3 degrees.
0.6/48 times 360 degrees = 4.5 degrees.
If you just move the cam on the belt by one tooth, one tooth equals 7.5 cam degrees or 15 crank degrees.
Obviuosly if you change the drive pin hole then the original timing mark is no longer valid and you will have to make new marks on the cam wheel. Fortunately this is dead easy. If you use the spoke as a coarse marker there will be two positions that are close to having the spoke vertical. The one with the spoke pointing leaning 1 o'clock corresponds to cam advance.
If the spoke is leaning towards 11 o'clock corresponds to cam retard.
Good luck
Below is a direct copy and paste from the cressida forum. Since you won't be able to see it unless you sign up I just copied and pasted from there.
Original author was spooled 7mgte.
7M's has 9 different setup of cam timing that can be achieved by playing with cam holes, and camgear holes.
Cam, as the camgear, has 3 different holes, for 3 different timing setup.
But in reality, I do think you can only have 5 setups, since -3 with +3 will give a 0 (stock configuration)
-3 cam with stock gear will give -3 timing. -3 cam with -3 gear will give -6 timing. You still following me?
Heres some pictures of the 9 different setups that dans be done (9 setups, not 9 timings!)
Here, we can see 3 different cam holes, the middle, as for the camgear, is the stock 7M setup
This is the stock setup, notice the timing marks wich we will use to see the differences that will be provided with following setups. We will call this setup : 0
This is the stock cam hole with timing gear reversed of 3 degrees wich by the timing mark should provide a -3 timing setup.
we can call this setup : -3
Here we can see a nice difference between the -3 and +3 positions, telling you that I'm not takin a bunch of pictures for nothing!
We can call this setup : +3
This is camhole position -3 I made grove on cover and holes to try to make them perfect match, not 100% perfect but enough so we can see differences in following pictures.
Since this is a -3 camhole with a 0 cam gear, it should give the same as the stock camhole with -3 camgear, so we can also call this setup : -3
Camhole-3 with camgear -3, we should notice a big difference now between stock setup with the timing marks. We can call this setup : -6 since we've got "-3" + "-3"
here we have -3 camhole with +3 cam gear, so it should also gives a setup called : 0
Camhole at position +3
+3 with 0 will give a setup called : +3
+3 with -3 will give a setup called : 0
and finally, both holes on +3 wich are gonna give a +6 setup.
This is pretty basic and "home made" so pictures may not give a clear view of REAL result. If I am wrong in any part of this guide or my writings are not clear or full of ponctuation errors, please notice me so I can edit.
This is only for consultation and results stated in this guide are not confirmed by toyota or TRSM. for the moment.
Enjoy!
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