ATTN: Cam Guru's
Thread Starter
Joined: Aug 2007
Posts: 372
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From: Chocolate , city
ATTN: Cam Guru's I have what I feel is a problem with a custom-ground cam. Stock ls1 w/ ported heads, 2.055int 67cc chambers and 10:1 cr. The cam was spec'd out to be max-effort n2o w/ stock pistons/no reliefs. The cam was installed and degreed by one of the best, and his readings were double-checked at the same time by someone even more ****.
The problem is the motor flatlines on the dyno at 5000rpm and goes in the toilet by 5800rpm. This cam was supposed to pull to 7k+. The springs were checked and found to be 125#seat and 400+ open. Below are the specs:
comp cams 3016r/3038r HR116+5
230/242 @ .050 .613/.613
116LS
valve events:
int. open@ 4 BTDC close 46ABDC
exh. open@ 62 BBDC close 0 ATDC
Can someone please tell me what it is about this cam? It made 370rwhp @5200 and went away from there making no power or climbing above 5800rpm
The problem is the motor flatlines on the dyno at 5000rpm and goes in the toilet by 5800rpm. This cam was supposed to pull to 7k+. The springs were checked and found to be 125#seat and 400+ open. Below are the specs:
comp cams 3016r/3038r HR116+5
230/242 @ .050 .613/.613
116LS
valve events:
int. open@ 4 BTDC close 46ABDC
exh. open@ 62 BBDC close 0 ATDC
Can someone please tell me what it is about this cam? It made 370rwhp @5200 and went away from there making no power or climbing above 5800rpm
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What intake mani also? ls1s don't pull much past those types of rpms....A ported FAST, or even just a ls6, will pull out harder. If you are wanting to spin that high, maybe look into the Edelbrock Performer intake or something.
TECH Apprentice
Joined: Dec 2008
Posts: 333
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From: Westbank of N.O.
He has the ls6 intake, motor spun to 6100 no problem b4, stock cam and heads. His current set-up should be good to 7k+ rpm, heavily ported big-valve heads that spun 7250rpm on previous motor w/ 232/237 cam. This cam was spec'd for him by someone to use these heads and n2o w/ stock pistons/no reliefs. He is convinced it is the cam, someone else said it may be the generous exhaust duration coupled w/ the 116+5. All I know is the motor peaks at 5200rpm, don't go saying it's the intake LOL. We wish
New cam should be here today, so it's gonna be fine. He does, however, want to know what it is about this cam. We have a cam card, but no cam doctor sheet. I degreed forward and backward, checking .006 and .050, as well as LS and got the intake opening @.050 dead nutts at 4* BTDC.
New cam should be here today, so it's gonna be fine. He does, however, want to know what it is about this cam. We have a cam card, but no cam doctor sheet. I degreed forward and backward, checking .006 and .050, as well as LS and got the intake opening @.050 dead nutts at 4* BTDC. Yea, not the intake. It wasn't stated at first....was hoping it would some a simpled fix like that. I can't comment on the cam though...116+5 for N/A would be way to weak on the LSA (from my knowledge....I am still trying to learn about cams), but for a nitrous grind.....I honestly haven't a clue.
Last edited by AznMuscle; Feb 13, 2009 at 01:16 PM.
a 116 lsa would push the peak farther up in the band. got a dyno graph to post? it makes no sense that proper fuel, timing, and valvetrain setup would peak at 5k and nose over at 5800. ported heads and that cam would most likely peak closer to 6700 with use of a crossover style intake. something is definately wrong, but i don't think it's the cam. what valve springs are you using? what pushrods? lifters?
TECH Fanatic
Joined: Jun 2002
Posts: 1,979
Likes: 3
From: Upstate NY
a 116 lsa would push the peak farther up in the band. got a dyno graph to post? it makes no sense that proper fuel, timing, and valvetrain setup would peak at 5k and nose over at 5800. ported heads and that cam would most likely peak closer to 6700 with use of a crossover style intake. something is definately wrong, but i don't think it's the cam. what valve springs are you using? what pushrods? lifters?
Initially it sounds like a valvetrain control issue with the XFI lobes, but unless you went to aftermarket roller rockers and dual springs with normal weight steel retainers with low seat loads and wimpy pushrods, 5200 sounds WAY low.
Last edited by Old SStroker; Feb 14, 2009 at 09:20 AM.
Thread Starter
Joined: Aug 2007
Posts: 372
Likes: 0
From: Chocolate , city
a 116 lsa would push the peak farther up in the band. got a dyno graph to post? it makes no sense that proper fuel, timing, and valvetrain setup would peak at 5k and nose over at 5800. ported heads and that cam would most likely peak closer to 6700 with use of a crossover style intake. something is definately wrong, but i don't think it's the cam. what valve springs are you using? what pushrods? lifters?
Also heads have titanium retainers.
TECH Apprentice
Joined: Dec 2008
Posts: 333
Likes: 0
From: Westbank of N.O.
They are heads I used to own, they have 1.550 dia. springs and ti retainers, the new cam going in tommorow or monday, but he thought that someone here might have some insight as to what is going on w/ this cam. The heads are not going turbulent, and the lifter pre-load is fine.
I would find out what spring you have, spring loads alone do not tell the story.
The cam also may be advanced too far, making it peak way low. Ive seen that happen a few times. Did you degree the cam?
The cam also may be advanced too far, making it peak way low. Ive seen that happen a few times. Did you degree the cam?
TECH Fanatic
Joined: Jun 2002
Posts: 1,979
Likes: 3
From: Upstate NY
They are heads I used to own, they have 1.550 dia. springs and ti retainers, the new cam going in tommorow or monday, but he thought that someone here might have some insight as to what is going on w/ this cam. The heads are not going turbulent, and the lifter pre-load is fine.
I'm not a cam guy, but I listen to a couple of good ones.