SR20DE Adjustible CAM Pullys
SR20DET engines often need to have the cam timing either advanced or retarded to get the best torque/power curve. Vernier adjustable cam pulleys are an expensive option. But some times they are needed to correct for head surfacing or head gasket thickness changes.
We have decided to make the stock CAM pulleys adjustable in increment of 2.5 degrees measured at the crank shaft.
The adjustment are Advanced 1=2.5, 2=5, 3=7.5, 4=10, 5=12.5 degrees.
Retarded -1=-2.5, -2=-5, -3=-7.5 degrees.
The pulleys can be used on all SR engines all models. 180sx red top & black top & S14 & S15 & RNN14 GTiR. If your SR has a VVT sprocket and you want to keep it, we can sell you only one for the exhaust.
To do this we needed to use our scanning machine and reverse engineer the std pulley so we could re-machine it as needed.
By using a square ended 3 mm parallel stylus we were able to capture all facets in one operation.
The Stylus was calibrated as normal on the 50mm reference sphere. This allows the machine to guarantee accuracy ever time a stylus is changed.
All 2D facets needed were scanned.
The DATA was then transfer for the scanning machine to the CAD workstation as a DXF file.
The scanned CAD data was used to make a drawing of what would be the finished part after machining.
The tool-paths were sent to the Deckel Maho DMU 50 T machine and a fixture was made to allow for multiple parts to me made with high accuracy.
The fixture or nest for the part allowing for very quick loading of the part without the need for re-setup.
The STD pulley is test fitted in the fixture.
The STD pully post machining.
A STD modified pulley and a STD original pulley side by side.