This is a mod that is totally unknown in the world of domestic cars. I was just wondering what they do, affect the timing? Duration? Other?

 

adjustable cam gears allow you to alter the cam timing. you can fine tune them to shift your powerband around. The newer cars with VVTL-i or i-VTEC constantly adjust the cam timing while you're driving. i think it's just for the intake cam though.

 

The same functionality exists in the 'domestic world' where when u install a cam, u can advance or retard the upper/smaller gear on the timing chain (the cam gear).. Based on the advance or retard, u are effectively raising and lowering your powerband position (basic principle on a single cam setup).. On an overhead-cam motor, the cam gears are run by the crank in the same way a timing chain/gear drive is.. Rather than the chain or gears, there's a timing belt with teeth.. Hope that helps..

Glad to see some domestic guys trying to learn, makes me feel all warm and fuzzy inside, realizing I'm not the only one.. mail me up if u need anything else..


[Modified by HKxBlur, 11:53 AM 10/27/2001]

 

Aha, I am familiar with indexing a cam on a pushrod engine, didn't realize it was the same thing (or at least similar) as that.

So why are new gears necessary, why can't the cam just be indexed with the stock ones?

 

You can probably index them with stock. It was my inderstanding that using an adjustable gear made it eaier for on the fly adjustments to the cam. If you want to move the power band down the RPM band, then you adjust the cams accordingly. If you get a better flowing, or custom header/exhaust, the peak power may be made at different cam settings, due to the resonance and flow chacteristics of the exhaust. Having adjusable cam gears makes this an easy change...
Without them you would have to pull the timing belt each time and advance or retard the crank. Even then, that is moving both cams the same amount, not exactly tuning them, since your exhaust cam may like more advnace or retard than your intake...

Jason

 

Stock cam gears are not adjustable.. You can move one of them a whole timing belt tooth over, but that's like 5-10 degrees..

The crank movement is possible, but as u said, not a good idea..