Someone please explain adjustable cam gears!

[srdub-t]

One thing i never really learned about and dont really get is adjustable cam gears. When would you need them? Whats overlap? Why would i want them?

[blinker_fluid]

Self explanitory there are cam gears, and you can adjust them. Basically you can do a couple of things with cams. When you change the camshaft itself the cam profile determines the amount of lift(how much the valve opens), and the duration(how long the valve stays open). ACG's allow you to control when the timing events take place (valve opening, closing, etc.), in relation to TDC and BDC. The concept is simple however the more you get into it the math can get a little complicated. I'm probly gonna get burned by someone for this but there is no overlap in a our engines. Over lap is when the intake and exhaust valves are open at the same time. The only time this is possible is between the exhaust and intake stroke on a non-interference engine.

[srdub-t]

ok so im getting 270 270 cams with 12.5 lift. why would i want cam gears? i get the basics but im still confused. Help educate me guys any input will be apreciated.

[blinker_fluid]

Cams are the most complicated part of an engine. I get a headache thinking about them, let alone explaining to someone. Alot of consideration has to go into cam timing, air flow velocity, amount of cusion, how long after (or before on turbos) TDC to open the intake, valve clearance, vaccum, pressure, etc.. Your best bet is to take a good look at the base timing events of the cams that your getting and try to invision what would happen if you moved it a few degrees in one direction. You have to be able to imagine the inside of the engine while its running and whats physically happening to the air/fuel inside. Try going to howstuffworks and watch the animation of the combustion cycle(stupid I know) but it will help you to get a clear picture of whats going on.

Or you can take the lazy way and see who's had them and ask what setting worked best.

[srdub-t]

yea i know exactly how a motor works and what goes on inside, i just cant make sence to why you would want to tweak things? Like whats the benifit i would assume you just kinda like move your power band around? i dont think you would neccisarry gain power?

[tEknoS13]

may not help a lot but, the reason for ACG's is so you can advance or retard timing. (OBVIOUSLY) now, think about getting a turbo upgraded to your engine. if you get a bigger turbo you are going to need more fuel and air rushing in or your car will run like crap. im sure you are thinking "but thats why there are aftermarket cams with longer duration etc." sure cams do make a big difference in all this but its not all that precise. ( is that spelled right?) with the gears you can make more accurate adjustments to your timing especially if you take your car to get tuned somewhere. timing sure does add a lot of power to you car if you chose the right combination of parts. hope this helps

[srdub-t]

it actually did help. Anything that anybody has to say is a great help. So im guessing the adjustments are somthing thats done on a dyno? Also when do we know when the added power from the cam gear tuning starts to compramise reliability?

[tEknoS13]

glad i could help. unless u have some experience with tuning, yes u sould leave the adjustments to a dyno tune. to ur new question im not really sure but it is wise to plan ahead of time what type of power you want for ur car. set your goal, then start buying parts and start making upgrades. this happens to a lot of people out there. EX: they start buying huge cams on n/a or stock turbo engines and when they plan to upgrade or go turbo, they discover those cams are now useless because they dont suit their new setup.

[srdub-t]

yea i already have everything for my 500 hp setup. Im just buying the cams now and doing solid lifters. A few more things and im done. I just wanna know more about acg's and if i should use them or not

[tEknoS13]

thats kool. im going with TOMEI solid lifters also, cams, you name it. im probably gonna upgrade to a gt28rs, and if i do i'll probably end up getting 264 cams. if not i was thinking of a t3/t4 turbo and go for the 272 cams.

[srdub-t]

thats kool they have ball bearing t3-t4s that would be an awsome setup with 272 cams. Im running gt3071r with all the supporting goodies and now i built the block so im going a different setup on the head.

[T-rev]

I used to have a prelude and it was like the 2nd thing every honda guy had to have (after a fart can) was cam gears. And then of course you had to trim your valve cover to adjust them without removing the valve cover every time.

I always thought they were kind of a gimmick, some trick to eek out 1 or 2 more horses on a 1.6L, why do I need that when I have a turbo? Also they're kind of hidden under the SR's valve cover.

[srdub-t]

anyone else?
Modified by srdub-t at 1:59 PM 3/30/2008

[srdub-t]

ttt