Pardon my ignorance. ( adjustable cam gear )

[e30 gangsta]

Hey guys pardon my ignorance, but can you guys explain to me what the benefits of installing a adjustable cam gear is? I am currently about to drop my turbo prepped motor into my e30, and I am thinking of purchasing one. I would like to get more information on how it works and the pros and cons of it. Please educate me. And thank you for your time.

[Fidhle007]

It allows you to adjust your cam.

[e30 gangsta]

^ great thanks. I understand that much. I wanted to know how to adjust it, and benefits of advancing or retarding cam timing.

[Fidhle007]

Personally I'd stay away from it if you're not at the track but in short it would give you some control over your torque curve and such. I'd get a good cam first but that's just me.

After all, what do I know. My cams adjust automatically.

[e30 gangsta]

It is a track car. And I plan on installing a turbo cam also.

[Fidhle007]

It may benefit you then, it's nice to have options when tuning.

Here's the way I look at it though: I'm one of those people that WILL adjust something if it can be adjusted so for my daily cars I want to have NOTHING I can fiddle with. The track toy is another story but even then I like the "set it and forget it" idea. There's no harm in installing it and leaving it in the stock location and never touching it but if you think that's what you'll do, you could spend that money elsewhere.

[nando]

this isn't something you screw with on a track, or ever.

it's something you play with on a dyno - adjust for the "most area under the curve", set and forget. definitely not a bad idea, cam timing is often overlooked on M20s. it's unlikely the "stock" position will give you the best curve.

[e30 gangsta]

^ perfect I planned on tuning it on the dyno, so I could see the differences in the graph. As for installing it and setting it up to the stock location, is there a cam lock tool?

Or do you just set the motor to TDC take off the old one, and reinstall the new one?

[nando]

you don't need one

set it to the middle, get a baseline, retard ~1-2 degrees, see what it does to your torque curve, then try advancing it 1-2 degrees, and decide which works best for you. more than ~3 degrees or so is probably too far, but it depends if your head/block have been skimmed or not. you could also go off the cam card and a degree wheel, but dyno evidence works just fine. :)

also beware of advancing too far if you have a cam with an agressive intake valve openting at TDC. Might be worth measuring the clearance to make sure you don't go too far advanced - min piston/valve clearance is 1.5mm.

[george graves]

Why do honda and VW guys always seem to run them? Just more go-fast parts to have?

[nando]

I meant he doesnt need a cam lock tool. I gained like 15ft/lbs over a broad area by adjusting mine 2 degrees, so there is definitely a benefit on an m20.

[e30 gangsta]

you don't need one

set it to the middle, get a baseline, retard ~1-2 degrees, see what it does to your torque curve, then try advancing it 1-2 degrees, and decide which works best for you. more than ~3 degrees or so is probably too far, but it depends if your head/block have been skimmed or not. you could also go off the cam card and a degree wheel, but dyno evidence works just fine. :)

also beware of advancing too far if you have a cam with an agressive intake valve openting at TDC. Might be worth measuring the clearance to make sure you don't go too far advanced - min piston/valve clearance is 1.5mm.

Perfect thank you. I assume measuring the clearence would be done with a feeler gauge like when adjusting valves?

Also if the head is decked, and or skimmed, does that give me more range of adjustment or less on the cam gear?

[digger]

Why do honda and VW guys always seem to run them? Just more go-fast parts to have?

on a engine with seperate inlet and exhaust cams it allows more flexibility since the inlet and exhaust can be adjusted independantly