slimbobaggins

Disclaimer: I've sent a message to the vendor that spec'd the cam, asking what he'd do. Haven't heard back yet. So what he says will weigh the most.

Cam is new, straight from Comp:

Spec'd cam is: 222/230, 115+2 LSA, so ICL is 113.

Degreed the cam, this is what I got:

220/229, 114.75 LSA, ICL is 114.5.

So instead of having 2 degrees advance, I've got 0.5 degrees. I lost all the advance mainly because the intake opening is retarded a couple degrees from what it should be.

The cam was spec'd for a turbo. LS2 with L92 heads.

So... since I haven't heard from the vendor yet, I'll play the "What would you do?" game. I kept the stock timing set and bought an IWIS chain, since the advance was supposed to be ground in the cam.

Not knowing how much of a difference the lack of advance will make for me, my options as I see it are:

1) Install as-is, and run it. Without hearing from the vendor, I dunno how this will affect performance.

2) Buy an adjustable timing set, and advance it 1.5 degrees to make up for the timing advance I lost. Sucks because I already bought the chain. I haven't seen anyone that just sells an adjustable top gear, anyone know of one?

Alternatively, I could drill out the dowel hole and use a bushing like old-skool, but I'm a little leary to do that.

3) If this cam is beyond acceptable machining tolerances, I could try to get Comp to regrind it... would likely take it to a local cam doctor for documentation if that's the case, which is going to run me $50-$100.

Had a buddy (Schmendog on here), help me with this to make sure I wasn't screwing up the measurements, and I'm pretty confident within a half degree.

outkast6991

iTrader: (34)

My last comp cam was off 4*. I had an adjustable set so I just moved it. I'd go with whatever your cam guy says

slimbobaggins

Havent heard back from him yet, but Im thinking about getting a bushing and drilling the dowel hole on the timing gear.

itsslow98

iTrader: (18)

Adjustable timing set or run it as is. Id likely just run it the way it is though.

JS01

iTrader: (10)

You cant really pin the advance being wrong on just the cam. thats not how it works.

JS01

iTrader: (10)

Just to be crystal clear for those who dont realize, The crank keyway can be off a half a degree, the upper and lower cam gear can be off half a degree each, and the cam dowel could be off a half a degree. Just an example, could be a combination of more or less on each part. There's your two degrees. Tolerance stackup.

Gray86hatch

iTrader: (83)

did you degree it by the open and closing specs at .050

what lifters this can change things also

Tim

slimbobaggins

Yes, degreed on opening and closing specs at .050. Lifters used are stockers coverted to solid

Per what i measured:
Ivo: retarded 2.5 deg from spec
Ivc: retarded 0.5 deg from spec
Evo: advanced 2.5 deg from spec
Evc: retarded 1.5 deg from spec

Going to redo measurements today for consistency, and check #2,#7,#8 as well.

I can only fit a 9 inch degree wheel in there, so I'd consider my measurements to be no better than +/- 0.5 degrees.

If it was tolerance stackup in the crank, gears, etc, I'd expect all events to be consistently off, which isn't the case. Ie all would be retarded 2.5 degrees, since Ivo is retarded 2.5 degrees, if it was due strictly to tolerance stackup.

sreve

iTrader: (3)

Comp Cams has an active company sponsored forum manned by
Comp employees. Might be interesting to hear their response.

http://www.cpgnation.com/forum/comp-...t-support.html

WRXINTX

iTrader: (3)

I would say tolerance stacking and a small degree wheel both could be causing You to read on one side of the degree hash mark or the other....


I say run it as is and have fun....


or, buy an adjustable timing set and advance it 2 degrees


either way, You are splitting hairs.....

99Bluz28

iTrader: (35)

Add to that list possible wear on the stock timing gear. I hate to say it but that cam most likely is within spec for a Comp Cam. I'd conceder just getting a adjustable timing gear set, degree the cam again and call it good.

slimbobaggins

I'm not trying to split hairs, I don't know enough about cams to know whether I'm splitting hairs or not. That's why I started this post... so that people that know more about cams than I could tell me if I was splitting hairs.

Unfortunately no local shop had an adjustable timing set, so I'll get one on order.

Thanks everyone for the responses.

WRXINTX

iTrader: (3)

Sorry, I hope the "splitting hairs" comment didn't come off as being rude....

it wasn't intended that way....

I agree with the above member in saying that Comp gets them close, but not always exactly on the number.....

I was merely just trying to say that the minor discrepancy would likely not matter whatsoever, as a +/- 2 degrees advance is such a miniscule amount, that it won't even barely show on a dyno....

When a cam being degreed shows a discrepancy of 6+ degrees either way, I get concerned and will take actions to correct it....


If You aren't in a hurry or tight on money, get the adjustable timing set and advance it a few degrees, but, if You need to get it put together asap, just use the chain and gears that You have.....

with boost, it will be unnoticeable....

slimbobaggins

No offense taken. It's difficult to judge demeanor over the internet.

Just ordered a timing set from a local shop, it'll be here tomorrow. Of course I'm going to recheck it with the new timing set, it'll be interesting to see if the new gears alone change my measurements.

I was going to measure #2,#7, and #8 yesterday as well, but got a late start last night due to Labor Day family stuff. Checked the Exhaust on #2 and it was nearly dead on with what I measured on #1; tried to check the intake up gave up because I was having difficulty getting the geometry correct with the dial indicator, and it was getting late.

Will update this thread with results once I get the new timing set on, just so it's available for someone else for future reference.

RonSSNova

iTrader: (3)

Hard to say if it's just the cam. I suppose it could be checked in a Cam Doctor to be sure.

There are advance bushing kits that can be used for this, it's old school, but works.

You could also get a set with the multiple key ways on the crank gear.
Remember too that the chain will stretch a bit after time.....which retards tha cam a bit.

Personally, I'd want it set dead nuts.

Ron

99Bluz28

iTrader: (35)

I went through the same thing a few years ago with a custom CompCam that I decided to have put on a Cam Doctor before it was shipped to me. I was pissed-off when I read the specs and it was off 1.5-2* on the int. an exh. lobes, and after some calls I confirmed it was within spec.
IMO, it's very disappointing when you go through the time to order a cam expecting a cam to be within .5* or less of the stated specs only to find out that the stated specs are roughly the target specs. Myself I find it a little hard to believe that Comp can offer multiple lines of different lobes that are all 2* apart in duration at .05", but can't keep the tolerance to under 1* . IMO, as long as you choose you Comp Cam only expecting it to only be within the ballpark of the advertised specs you won't to disappointed with the actual specs. I still do use CompCam since I like some of the lobes they offer, I just wish the tolerances were tighter.
BTW, I hear the Cam Motion cam grinds have a lot tighter tolerances than the CompCams grinds.

slimbobaggins

I don't know jack about one camshaft company over another, so I just went with whomever my vendor chose. I was going to call him today, but since I ordered an adjustable timing set, I'm going to install that and re-degree it and call him with the updated specs.

Seems like this is common place, based on the feedback from this forum and ls1gto... but how are you supposed to do R&D and really fine tune your engine if you're paying $400 a pop for a cam, and can't change the grind by a degree?