cam - straight up or degree - Third Generation F-Body Message Boards

graphicideas1 · 06-06-2006, 08:47 PM

i am getting ready to install a cam - is it nessary to degree or can i install straight up?

F-BIRD'88 · 06-06-2006, 09:29 PM

Most mild/moderate performance cams are actually "advanced" a few degrees (4-5) when you intall them in a SBC using the standard cam/crank gear aligning marks.

This advance is built into the camshaft when it is produced. This built in advance generates increased low mid range torque. Usually prefered in a street performance motor. And allows for some timing chain stretch inducing cam retard as the engine wears from use.

Some of the bigger race cams are phased true "straight up" meaning equal intake and exhaust centerlines. You have to "degree in the cam" to determine the timing points and move it yourself (offset bushingsor multi-key way crank gear) to get the "advance" or "retard" you want to run.

eg: a cam ground on 110 lobe separation that shows on the cam card supplied that the intake centerline is 106 and the exhaust centerline is 114 is "advanced" 4 degrees.

If you use a new "matched timing gear set", no further adjustment is *usually* nessessary.

If you try to cheap out and just replace the top cam gear (cause the crank gear usually does not wear) don;t expect the cam timing to be accurate.

What cam are you installing? What does the cam card say for timing points?

84z28350 · 06-06-2006, 09:30 PM

straight up is what you'd want for any sort of stock or mild street app unless the cam was designed to be installed adv/ret.

ede · 06-07-2006, 03:07 AM

i think you might have your terms confused you can degree a cam installed straight up. degreeing a cam has to do with checking the opening and closing points of the cam. straight up has to do with the cam being installed advanced, retarded, or with zero advance/retard, but like was said most cams have some advance ground into them.

graphicideas1 · 06-07-2006, 06:00 AM

i am using a comp cams xr series cam - what i ment is can i just install by matching up the marks on the cam & the timing gear or do i need to use a degree wheel?

sofakingdom · 06-07-2006, 09:21 AM

What timing set are you using?

Does it have adjustment provisions?

Do you know what the cam's intake centerline is designed to be?

Since you can't change the ICL with the timing set you have (in smaller increments than one tooth of the chain anyway), what would you do if you found that the cam wasn't where it was supposed to be? Do you know if that would even be a bad thing?

That's the downside of "degreeing" a cam for most people. Not that it's a bad idea in and of itself; but, if it's off, there's basically not a thing you can do about it except send the cam back or buy an adjustable timing set. All you're really accomplishing, is doing the cam mfr's QC for them, after the fact.

If it's an off-the-shelf cam from a major mfr (Comp, Crower, Isky, Lunati, Crane, etc.), and a good quality timing set from a reputable mfr as well, then your odds of it coming out within a degree or so of its design are probably 99% or better. On the other hand, if you're using a cheeep "roller" timing chain, the $20 kind that we call "bushing roller" or "truck chain", it will stretch about 6° within the first 1000 miles anyway, no matter what you do; so does it really matter how accurate you get it? since it's not going to stay where you put it anyway. "Measure with micrometer, mark with chalk, cut with axe".

So there's no "right" answer to that question, either "yes you must" or "don't bother"; it's all about what YOU feel comfortable with, and how much you want to spend on tools if anything, and what you think you might do if it turns out different from what you think you want.

F-BIRD'88 · 06-08-2006, 03:25 PM

Quote:

Originally Posted by graphicideas1

i am using a comp cams xr series cam - what i ment is can i just install by matching up the marks on the cam & the timing gear or do i need to use a degree wheel?

generally these street roller cams are produced with a little advance built in.
You can tell by looking at the cam card.

You can install this cam as you would a stock cam by lining up the timing marks on the timing gears and go.

If you want to "degree it in", go ahead. You'll need to determine true TDC using a piston stop and get a solid mechanical roller lifter as a hyd's plunger will compress during testing. You need to accuratly measure TDC and position the degree wheel and pointer and align the dial indicator over the lifter body or pushrod to or you'll induce errors in the timing events observed.
If the cam seems to be out of time after repeated accurate degreeing, you can correct the timing using a simple camshaft offset bushing set and locking plate available from all cam co's. and many other supplyers of tuning parts (Mr Gasket) Simply drill out the timing gear bolt holes and locating dowl pin hole and install the offset bushing required to corect the timing. Use the locking plate to hold it all together and a little locktight on the bolts.
Don't know about "cheapie roller timing chains" I don't buy them. But the good "Truck type" heavy duty "link belt" chains work good and last a good amount of time in the street environment. (many years) Quality true roller timing chains (Cloyes) are best and cost the most, but will handle extreme rpm for a longer time. Use matched set timing gears and you should not see any problems installing your cam.

graphicideas1 · 06-08-2006, 03:29 PM

when i install the timing gears to i set it for 0* or 4 advanced or 4 retarded?

sofakingdom · 06-08-2006, 03:36 PM

Generally, 0° (straight up)

spartyon · 07-03-2006, 08:40 AM

sorry to bring this topic back but I have a comp xe 294 that I am putting into my 383. Comp says thatmachine the cam to advance 4*. Does this mean I change the crank gear to 4* advance? I am using the chain that they supplied in the kit. Is there any downside to putting the crank gear in 4* adv as opposed to 0* without degreeing it?

ede · 07-03-2006, 09:15 AM

you can set the crank gear anywhere you like. if it has 4* ground into it straight up is most likely the way the grinder intended it to be installed, but nothing (other than poor preformance) will prevent you from installing the crank gear advanced.

1989GTATransAm · 07-03-2006, 11:15 AM

IMHO it is best to degree the cam if you want the most performance from the cam you bought. There are to many places where manufacturing mistakes can be made such as the keyway on the sprocket. Also build up of tolerances. Like was said above most cams these days come with 4* of advance built in when installed "straight up". Just my two cents.