speed_demon24

iTrader: (6)

So just because he knows the cam is ground correctly means he knows the timing chain set was machined perfectly, and that the keyway in the crankshaft was machined perfect? I hate to be the one to break this to you but tolerances add up. If he's so worried about the cam being off 2 degrees then he better degree it because chances are it will be a few degrees off once he installs it. I love it how the people who have no idea what the hell they are talking about bash the people who actually know what they are talking about.

ArrestMeRed99Z28

iTrader: (1)

so I want a custom cam to be ground for me. Should I spend the $250 to degree in the stock cam with all the other upgrades (hardened PRs, LS2 TC, LS4 Oil Pump, TSP Platnium Valve Springs, etc) to figure out what I should compensate the cam design for? That would be a waste of time and money IMHO. I know there is going to be some error, but I'm not going to pull my heads to measure if the carbon build up on my pistons is .001 inch or .002 inch on my 85K motor to figure my CR . We all know this is the real world and nothing and no one is perfect. +2 degrees is beyond the acceptable real world limits and I am glad that he posted these results because now more people will pay for the fancy cam doctoring service.

PREDATOR-Z

Guys, let me clear some smoke here.
For straters if you want to be **** about grinds and like to do it perfect, you get a cam ground with zero advance and you dial it on dyno with adjustable timing chain trying runs with 2* increaments (advance or retard) and test what gives the best results on you combo.
Even if the cam is ground 100%, which it will never be on mass grindings, sticking it dot-to-dot cannot garantee that it is actualy at said ICL.

The only thing I agree about this whole argument is if you order something a certain way, you should get it that way and no other.
What I would have told Comp is since they messed up, instead of gettingf another cam to send me an adjustable chain FOC so I can dial in my advance. I had a sponsor do exactly that for me a couple of years ago.

csmc711

iTrader: (4)

True dat, the guy just didnt get what he ordered and like I said before, degreeing it once he gets it is his problem. Yes, like I said, one should degree no matter what, just to see whats up, but, you should get what you pay for so you know if you stab it in the car, at least THAT part of the equation is something you DONT have to think about (just the cam itself).

N4cer

iTrader: (11)

Since I know nothing, explain how you know that the adjustable timing set will be perfectly machined.

brad8266

iTrader: (23)

I understand that tolerances will allow for a bit of error, but each lob was off by 2 degrees, I dont think it has anything to do with tolerance, it has to do with the person who ground it may have though 4 degrees for whatever reason, he probably just misread something, hell even the order taker could have wrote a 4 and the grinder did what the order said.

csmc711

iTrader: (4)

Oh, jeesus, god help us!! ---->

1989GTA

I agree this is just to much. Hahahaha. This is turning into a commedy.

On a serious note I have to agree with Predator Z and Speed Demon24 on the subject at hand.

speed_demon24

iTrader: (6)

Re-read my post, just because the cam was ground perfect doesn't mean everything else was. Thats why you degree a cam.

Greg Good

A camshaft ought to be degreed in. Degreeing a cam is easy and something that anyone wanting to tear into an engine should be able to do. Putting a cam in dot to dot is for the guys at the dealership working on stockers. All of these aftermarket parts are built by humans, and guess what, people make a mistake now and then. It up to the assembler to check everything to make sure it's right.

I personally wouldn't put the front cover on an engine without degreeing a cylinder on each side of the engine to make sure both banks of lifters bores are in the right place. Another thing that will get you is if the axles in the lifters aren't perfectly centered. that will change lobe centerline and valve timing events. I've seen that one drive some top tier engine builders crazy trying to find that 40 hp gremlin.

hammertime

iTrader: (1)

I'm glad someone mentioned this. Too many people put too much emphasis on the VE's being exact and that means its OK to just install dot-to-dot. Your adcole could say everything was with 0.5*, but if the mass produced LS2 timing set used has a 1* error on the crank gear, a 1/2* in the chain and 1* in the cam gear, you have the potential for 3* or error in tolerance stacking if you are not checking. Intake centerline angle is relative to the crankshaft, and no cam card can tell you what that will be in your engine, only the degree wheel can.

1989GTA

Exactly and that is why I refered to Speed Demon's post.

thehammer69

iTrader: (2)

i finally found time to actually post the results of the new Adcole report from the regrind. To save some re-reading for some, basically Comp ground me a cam that had a hair over 4 degrees of advance when I ordered only two degrees of advance. Because i had them do an Adcole report on the original cam, I was able to see this discrepancy even though the Cam Card said it was a 114+2.

So Comp admitted that the cam should not have been let out the door and had me send it back to be reground. They also said it would be done by their race department to ensure better grind accuracy. After they were done, my Custmer Service rep called me and said they actually ground a new blank because the cam was too far out to get correct. The accuracy of all the specs are noticably better in that deviation is very little compared to the deviation of the first cam. Now the advance isn't spot on 2.0 advance this time either...it is now basically a 2.5 advance. But that falls in my acceptable range and actually works out for the better once the new cam chain stretches a hair.

Comp also gave me a $50 discount on any of their cam and dyno software, so I took advantage and picked up DynoSim Advanced with Protools.

So anyway, here is the old report so you don't have to page back to see it:

Adcole report:

=====================================
=====================================

Cyl.....LSA......Advance

1 --- 114.02 --- 3.86
2 --- 114.16 --- 4.31
3 --- 114.07 --- 3.97
4 --- 113.96 --- 3.90
5 --- 114.28 --- 4.09
6 --- 114.23 --- 3.98
7 --- 113.77 --- 4.59
8 --- 113.77 --- 4.46

===================================

Intake Lobes:

cyl ------ .020 --- .050 --- .200 ---- lift

Design-- 249.3 -- 222.8 -- 148.9 -- .3750

1 ------- 250.5 -- 223.8 -- 149.4 -- .3752
2 ------- 250.6 -- 223.9 -- 149.4 -- .3745
3 ------- 250.5 -- 223.7 -- 149.2 -- .3742
4 ------- 251.4 -- 224.4 -- 149.6 -- .3751
5 ------- 251.5 -- 224.4 -- 149.4 -- .3747
6 ------- 251.5 -- 224.4 -- 149.4 -- .3746
7 ------- 251.0 -- 224.1 -- 149.5 -- .3747
8 ------- 251.0 -- 224.1 -- 149.5 -- .3750

=======================================

Exhaust Lobes:

cyl ------ .020 --- .050 --- .200 ---- lift

Design-- 253.3 -- 226.8 -- 152.6 -- .3770

1 ------- 254.2 -- 227.6 -- 152.9 -- .3758
2 ------- 254.0 -- 227.5 -- 152.9 -- .3759
3 ------- 254.6 -- 227.7 -- 152.8 -- .3757
4 ------- 254.7 -- 227.8 -- 152.9 -- .3760
5 ------- 254.3 -- 227.7 -- 152.9 -- .3758
6 ------- 254.1 -- 227.5 -- 152.8 -- .3755
7 ------- 254.4 -- 227.7 -- 152.9 -- .3761
8 ------- 254.3 -- 227.5 -- 152.6 -- .3758

==========================================
==========================================



Here is the new report:


Adcole report:

=====================================
=====================================

Cyl.....LSA......Advance

1 --- 114.00 --- 2.45
2 --- 114.01 --- 2.46
3 --- 113.99 --- 2.48
4 --- 113.99 --- 2.49
5 --- 114.00 --- 2.47
6 --- 113.98 --- 2.48
7 --- 114.01 --- 2.50
8 --- 114.01 --- 2.51.

===================================

Intake Lobes:

cyl ------ .020 --- .050 --- .200 ---- lift

Design-- 249.3 -- 222.8 -- 148.9 -- .3750

1 ------- 250.7 -- 224.3 -- 150.3 -- .3751
2 ------- 250.6 -- 224.1 -- 150.2 -- .3749
3 ------- 250.7 -- 224.2 -- 150.2 -- .3749
4 ------- 250.7 -- 224.2 -- 150.2 -- .3749
5 ------- 250.6 -- 224.2 -- 150.1 -- .3749
6 ------- 250.3 -- 224.0 -- 150.0 -- .3740
7 ------- 250.2 -- 223.9 -- 150.0 -- .3749
8 ------- 249.9 -- 223.7 -- 150.0 -- .3748

=======================================

Exhaust Lobes:

cyl ------ .020 --- .050 --- .200 ---- lift

Design-- 253.3 -- 226.8 -- 152.6 -- .3770

1 ------- 254.5 -- 228.1 -- 153.8 -- .3769
2 ------- 254.5 -- 228.2 -- 153.9 -- .3769
3 ------- 254.7 -- 228.2 -- 153.8 -- .3769
4 ------- 254.6 -- 228.2 -- 153.8 -- .3769
5 ------- 254.4 -- 228.1 -- 153.8 -- .3769
6 ------- 254.6 -- 228.2 -- 153.8 -- .3769
7 ------- 254.1 -- 227.9 -- 153.7 -- .3770
8 ------- 254.1 -- 227.9 -- 153.7 -- .3769

==========================================
==========================================


Any comments?

Hammer

GrannySShifting

iTrader: (10)

Have you seen an Adcole? It has a 5000 lb block of granite or some chit in the base to maintain stability, and checks the cams vertically because it can measure the lobe sagging if mounted in v blocks like most Cam Doctors and such


This is the problem when you give a kid a machinists ruler to measure or a blind man a microscope. Some people are shown the way to over analyze (No offense to the original poster)

This has nothing to do with lunching #7. A 1% variance in numbers isnt goingg to make or break a ringland. Lean and mean is what does it.

GrannySShifting

iTrader: (10)

No one here knows the exact DCR limit accurately enough for any given fuel it will likely be run on for any of that .5% cam innacuracy to honestly matter anyway. 5000 miles down the road and 1 mm3 of carbon buildup and it might detonate into oblivion!

Dont build your motors so close to the edge that you have no margin if your seriously worried about it. There is little to nothing to be gained as far as hp differences between 8.5:1 DCR and 8.8:1 DCR that the average chassis can make use of so why bother? If your going to be that exacting, then you should have an adjustable timing chain and degree your cam in ANYWAY, you think GM gave two ***** about your DCR measurement and your stock sprocket is dead nuts on with its stretch stock chain?

Put an adjustable set on it degree it and be happy. If you got a cam to spec 110% and put it on with your stock chain itll still be off a degree or two

Glad to see Comp got one back to you as accurate as your happy with. Id like to do some back to back testing with a cam like yours first and one as close as possible. Id think 1% power is the most you could find

hammertime

iTrader: (1)

bearness

Here's my Adcole report

254/268 .659 .659 114+0

I 254 @ .50

255.2
254.8
254.9
254.9
254.9
254.7
254.9
255.1

E 268 @ .50

267.7
267.6
267.9
267.9
267.7
268.4
267.8
268

Advance 114+0

113.83
113.89
113.89
113.81
113.82
113.76
113.81
113.81

Mine is well within Comps 2' margin for error.

02sierraz71_5.3

iTrader: (2)

Good thread; puts alot into perspective

Im in a similar boat recently ordered a grind on a 108/107(lca/ICL) and got a 109/105; the lobes/duration are about perfect its just the ICL has gotten worrysome.
From now on Ive learned to provide some leeway and save me from myself.

PREDATOR-Z

I think it has to do how you order it as well, If you just go for expl: 232/234 112+4 such and such lobe it will come out with a higher off margin than if you actualy give them the VEs.
The LSA/ ICL is a by-product of VEs
At least this has been my experience. Perhaps I just get lucky?? I have no idea how they actualy input the grind parameters and specs in the grinder.