Hello,
Was in the process of degreeing in my cam, a Comp Cam Extreme Energy Hyd.268 and new Comp Cams magnum timing set with 3 keyways cut in the crank gear.
I am using the 0 degree keyway, and after degreeing the cam a few different times, I keep getting 104 degrees.
Comp Cams calls for 106 degrees and I know 1 degree wont hurt but what about the 104 I get? Is this worth fussing over?
My car is a street driven'70 GTX with a 440, TRW Six-pack pistons, stock heads, stock torque convertor and 4.10 gears.
Any comments and suggestions are appreciated.
Thanks, Jeff

If there is no spring pressure on the cam now it will retard a degree or two when you do add it. Id roll with it at 104.

Are you using a hydraulic lifter to degree it in.

the keyway in the crank could be off a couple of degrees. don't think it will run on pump gas. that short cam will make a bunch of cylinder pressure with those pistons.

Thanks for the replys



Yes, I am positioning the indicator tip on the top edge of the lifter body

You are 2 deg advanced from their recommendation which I would assume is advanced a certain # of degree from the LCA (tho I'm a bit rusty on cam tech). Agreed, run it & see how it acts & work from there & retard it as needed. I'm assuming you've checked P/V clearance etc & as said you want NO pinging (not even slight) no matter what. & I cant hear mild pinging but my buddy can.

I would, and do on every cam I degree, try checking the intake lobe center at three different lifts, .200,.100 and at .050 before and after max lift to see if it changes from 104 to 105 to 106 ILC. Once you see what results are from that take the time to check exhaust lobes at the same three different lifts, if it mimics, duplicates, the ILC results your going to have to decide if you want to run it or change it
If it changes to 105.5 or 106 on the ILC I would run it, if I checks the same on all three locations then go from there

I'll start with the assumption that this is 99.9% street car, and your goal is for it to run as well as it can. Understand that run as well as it can might actually mean different things to different people.

First understand that there is nothing magical about 106°. It is nothing more than a safe recommendation from Comp Cams. It will generally work well in most cases. The reality is that no body knows with certainty what will be the best in you car.

It will run well at 104°. It will be very crisp with light throttle at lower speed. Street guys generally like this better. There is absolutely nothing wrong with 104°.

However, if it were mine, I would do it different, and vastly different than conventional wisdom on this forum. With a cam that size, your compression, and a 4.10, I would put it in at 108° or even 110°. The throttle will not be as crisp, but the car will probably be faster, IMO.

Like someone said, a new chain will stretch and it will back the cam up at least 1°.

Now you'll just need to figure out where you want to put it.

An advanced centerline will give you more lower end torque and throttle response. A retarded center line will give you more top end charge. As far as detonation, that can be worked out with thermostat temperature, spark plug heat index, octane ratings, timing curves. But in all reality, 2 degrees on a street car will not have an overwhelming change in engine characteristics. If it bothers you that much, though, that you want it at 106, you could buy an offset bushing kit, drill out the gear and put a 2 degree bushing in it. I stake the gear to keep the bushing from coming back out when I am done.

I would have been targeting 108-109 in that combo......... And it's still likely to rattle on hot days.

would that be cuz the midrange/high end would gain it back? (& then some).

I dont know what your true compression is.. I dont
see where it was stated with these heads.. but I
always try to advance the cam on a street car so
it has better grunt on the low end.. do you know
your compression.. did you measure it

I did some heads and supplied the cam for a similar build a few months ago.
I used a cam that was 279/287, 227/235@.050, .480/.490, 113lsa, installed at 109.
Stock type 906's set up for proper quench using KB quench done pistons, along with the bowls and short turns reworked(flow 256/182@.500).

This combo was getting run with ex manifolds, which was a big driver in the cam choice.

Noticed that you normally recommend Thumpr profiles for street hydraulics.

The Crower 271 on a 112° with its easier lobe profiles and larger lsa seem like a decent fit albeit a little smaller.

I like that Crower 271 cam, ran one myself in a mild 440 years ago.
Good power and good manners......... But I have heard from a few customers who used one that had some detonation issues with it.
I feel a 440 can tolerate a bit more seat timing than 271, and I like the fact that the Thumper lobes aren't particularly fast(or noisey).

That particular grind I use has made 460hp(on ARC's SF-902 dyno)from a quench dome pump gas 446-6 with ex manifolds with 906 heads that were slightly better(more rework) than the ones that went on this last build.

That being said, I don't feel there's anything magic in that cam, and I'd expect similar results from just about any similarly sized cam.

from my experience with those short intake lobe cams in 440's I wouldn't use that cam. I wouldn't use 110lsa either and damn sure wouldn't use old trw 10.5:1 flat top clones with open chamber heads; pump gas or not.

Sure. But other than cam choice, I think that is now water under the bridge for the OP. In the big picture I think that he did okay, and possibly could have done lot worse. We certainly see that enough.

Thanks for all the comments.
I don't know the actual compression, but the pistons are about .020 below the deck, I'm using the Fel-Pro blue gaskets about .038 thick and the '906 heads are stock.
This car will never go to the drag strip again, but I might do a small burn out here and there when no one is looking.
I rechecked the degree of the cam and it's close to 104.5
I think I'll run it like it is and be careful about pinging. Have no problem mixing a little race fuel in with the gas.
Thanks again, Jeff

Mine was 104.5 when assembled, had it apart a few thousand miles later and checked it and it was 106.

Whatever you do, be careful with the +/- 4 key ways, mine was really +/- 8 from 106, so in reality your straight up is +4, your +4 is +12, and your -4 is -4. If yours is the same you will need another timing set for any other setting, and those chains have slots instead of holes for the cam dowels so you can't use a bushing.

I would recommend checking your +/- 4 key ways while you have the engine out so you'll know what you're up against if you want to change it later.