WHEN DID CAMSHAFTS GEARS CHANGE in 18RG?

[RT104GT]

Does anyone know when Toyota Dropped the single dowelled non adjustable timing gears and cams in favour of the dowelled mechanically adjustable units?
My 1973 GT Corona had 210 head and camshaft gears like from the 8RB.
Then the 230 series heads had dowelled camshafts to enable precise timing of valves and slack takeup between the cams.

Pictured are the early cam gears as bought recently in an NOS timing gear kit.



These gears are held in by three 12mm steel bolts and a single dowell.

Yamaha head dowelled gears have a single large 17mm bolt and a dowell and washer.

Dates anyone/

Anyone got an old pair of 210 cams?


ADDED

TOP GEARS FROM 2TG and 18RG are identical

13523-88220.

10 1972 to 07 1977 2TG

and 10/1975 to 7/177 18RG.


This is the dowelled variety.

[71TA22]

If its any help my JDM parts manual gives part number 13523-33010 for 18RG cam gears from 7304 to 7510, then 13523-88220 from 7510 to 7707 (the last part number same as for 7012 to 7509 for the 2TG). Toyota did not put 2TG's of any form into JDM Celicas between 7510 and 7707.

[RT104GT]

That ties it down to when thanks. The 3010 is same gear set as 8RC 8RB 18R, the second is the dowelled set commn to both 2TG and 18RG just need to find some.

Steve