being that im asking about the lo3, i figured i would post here instead of tech/general engine. has anyone experimented with advancing/retarding camshaft timing maybe a tooth on your lo3. to my understanding advancing is more for torque, while retarding is more for horspower. would it cause our motors to run ****y?

 

One tooth will be about 15 some odd degrees I think. Too much. Advancing the cam will shift the torque curve over toward lower rpms, IOW, itll peak sooner. Retarding it will move the curve out to higher rpms. If you have crummy flowing heads like the present ones the heads will put a cap on the peak power output so retarding the cam probably will just kill the low end response. Id leave the cam timing where it is with a stock motor.

 

im not doing anything with it, i was just wondering. 15 degrees, wow, i was told one tooth was about 5 degrees

 

so in other words, retarding it would make it run like crap in the lower rpms and smooths in the uppers? and vice versa for advance?

 

Well, it can cause poor performance at low speeds if its retarded. Really it just moves the torque curve around. If your dialing in a race motor changes to the cam timing can help. Obviously there are limits, like a few degrees either way. Most cam manufacturers usually add in a couple of degrees of advance to help improve the low end feel of the motor.

Couple of years ago when I put an edelcrap cam in I used the stock timing set. Couple of months later I heard that the stock timing sets can have a certain ammount of retard built in. At that time, the engine wasnt really tuned and the motor was only pulling 13 inHg of vacuum at idle. Even now it only pulls around 16 or so at 750 rpm. Has 20+ at 1000 rpms, but the vacuum rapidly falls off after that. Basically my suspitions for the past year or so is that the cam timing is retarded. The car also hates to idle below 1000 rpms. With careful tuning Ive gotten it to have a decent idle, but it was a pain. Moral of the story, follow the cam manufacturers suggestion to not only use a quality timing set, but degree the cam if you can.

 

It all depends on the exacts of the timing set you're using, but basically it comes down to ~8* on the Cam gear and 16* on the crank gear.

For instance, I have one of those cheap Summit-type cams with 214*/224* @ .050", 112 LSA, and the cam car said it was ground with 100* ICA.

I degreed the cam using a Milodon timing set and set the cam 4* retarded using the keyway in the crank gear.

Sure as heck the ICL was at 104.5* ATDC. (.5* is nothing to fret over.) Still not what I wanted to see.

What I did was counted the teeth on the cam gear (44) then divided 360* by 44. That works out to just a "c" hair over 8*. Of course the crank gear has 22 teeth. So 360 divided by 22 would be slightly more than 16*.

By putting the crank gear back on with the keyway at "0" and retarding the cam one tooth on the cam gear, I was able to get 108.5* ICL. I confirmed that with a degree wheel.

BTW, I think RB gave a good rule-of-thumb.... 250 RPM per 4* is about how much of a shift you'll see either way, whether you advance or retard the cam.

That's not exactly a lot to worry about. :shrug: