Camshaft help
Posted: Sat Jul 30, 2022 11:06 am
I am stripping down the engine from my Sprint. There engine has clearly been tuned, and it has been suggested the engine was fitted with L1 cams. I am a believer in trying to figure out what I am dealing with before I strip it down, so with the help of Youtube, I have taught myself about cam timing. Its a PITA.
I checked the clearances first and got.
Exhaust
1 - 0.004"
2 - 0.014"
3 - 0.013"
4 - 0.008"
Inlet
1 - no clearance
2 - 0.001"
3 - no clearance
4 - 0.003"
I measured the cams - they have a base circle diameter of 24.25mm and lift of 10.58mm (0.42"). The cams are marked VJ5 - which a bit of digging indicates they are Vegantune camshafts.
I messed around for ages measuring the timing. As best as I can figure, the Exhaust MOP is 105 degrees BTDC, the inlet MOP is 118 degrees ATDC. Measured duration is a very approximate 280 degrees.
The only info I could find on the cam on the web indicates that the cams should be timed to have an Exhaust MOP 110 degrees BTDC, inlet 105 degrees ATDC. Rohan's very helpful post on cams suggests that cams with 280 to 290 duration and lifts in the 0.40 to 0.44 range should have MOPs of 108 to 106 degrees, so the data I found on the web for the cam looks about right. The engine as set up currently is however a complete dog's breakfast.
I intend to rebuild the engine completely. Are my VJ5 cams a jewel worth persevering with? or should I mount them on the garage wall and buy modern known quantity camshafts?
Thanks as always for any feedback.
I checked the clearances first and got.
Exhaust
1 - 0.004"
2 - 0.014"
3 - 0.013"
4 - 0.008"
Inlet
1 - no clearance
2 - 0.001"
3 - no clearance
4 - 0.003"
I measured the cams - they have a base circle diameter of 24.25mm and lift of 10.58mm (0.42"). The cams are marked VJ5 - which a bit of digging indicates they are Vegantune camshafts.
I messed around for ages measuring the timing. As best as I can figure, the Exhaust MOP is 105 degrees BTDC, the inlet MOP is 118 degrees ATDC. Measured duration is a very approximate 280 degrees.
The only info I could find on the cam on the web indicates that the cams should be timed to have an Exhaust MOP 110 degrees BTDC, inlet 105 degrees ATDC. Rohan's very helpful post on cams suggests that cams with 280 to 290 duration and lifts in the 0.40 to 0.44 range should have MOPs of 108 to 106 degrees, so the data I found on the web for the cam looks about right. The engine as set up currently is however a complete dog's breakfast.
I intend to rebuild the engine completely. Are my VJ5 cams a jewel worth persevering with? or should I mount them on the garage wall and buy modern known quantity camshafts?
Thanks as always for any feedback.