What is the preferred system for an adjustable camshaft timing gear? I have seen some adjustable helical gears for sale on European sites, they seem to use offset bushings. I have also been looking at modifying a stock setup.
I made a prototype. I put a gear on a rotary head in a mill and extended the holes (with a 1/4" dia. mill) up to 6°. The front (away from the cam) of the pulley was surfaced in a lathe, just enough to remove the rough cast finish. I then installed m6-1.0 "Screw-Lock" "Helicoils" in the cam shaft. Then I screwed the whole thing together with 12.9 flanged socket head cap screws (to a yet to be determined torque) and hardened washers. I marked the cam flange, and scratched some small marks into the gear every 2°.
Note: The existing rivets are 6.2xmm dia..
It seems that there are many aftermarket gears available for more modern engines that use a similar approach with a similar bolt size and count, but often on a larger radius. However our drive torque must be considerably less.
Has anyone run a pulley like this? Will this hold up or will it fail.
Adjustable camshaft timing gears
Re: Adjustable camshaft timing gears
Your approach sound ok to me. I've seen everything from sloppy holes to concentric washers. Most of the adjustable gears for VW are straight cuts that aren't legal for our use. I get the cam in the ballpark with an offset key then fine tune with the bolts and slightly larger holes in the gear. I drill and tap the cam for a 5/16 24 bolt and recess the gear so the bolts and washers will clear the oil pump.
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