GM "846" cam
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Race Director
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From: Texas
GM "846" cam
Anyone have any experience with the "846" cam in their LT1 or 4?
Here are the specs from the GM Performance Parts website...
). The 846 duration is close to the same as the HOT Cam (2* more intake & exhaust) such that I don't think my idle quality will degrade. Basically I'm buying added lift.
Thoughts?
Here are the specs from the GM Performance Parts website...
12370846 Hydraulic Roller Design
This hydraulic roller design contains eccentric for mechanical fuel pump. It is for off-road use only. The duration at .050" tappet lift (intake/exhaust) is 222/230; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 509/528. Valve lash is zero/zero and lobe centerline is 112 degrees.
I'm tossing around the idea of upgrading from my HOT Cam (which I like but... This hydraulic roller design contains eccentric for mechanical fuel pump. It is for off-road use only. The duration at .050" tappet lift (intake/exhaust) is 222/230; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 509/528. Valve lash is zero/zero and lobe centerline is 112 degrees.
). The 846 duration is close to the same as the HOT Cam (2* more intake & exhaust) such that I don't think my idle quality will degrade. Basically I'm buying added lift.Thoughts?
Melting Slicks
Joined: Jan 2000
Posts: 3,418
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From: NW Chicago Suburbs
What about the CC 305? Same basic spec but a 114 lobe sep angle, should have more low end torque and smoother idle.
http://www.compcams.com/Technical/Cu...ML/198-199.asp
BTW, lots of Impala SS guys love the 846. 305 or 846, I think you'll be happy.
Eric
http://www.compcams.com/Technical/Cu...ML/198-199.asp
BTW, lots of Impala SS guys love the 846. 305 or 846, I think you'll be happy.
Eric
Thread Starter
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From: Texas
Originally Posted by silver & red CE
What about the CC 305? Same basic spec but a 114 lobe sep angle, should have more low end torque and smoother idle.
http://www.compcams.com/Technical/Cu...ML/198-199.asp
BTW, lots of Impala SS guys love the 846. 305 or 846, I think you'll be happy.
Eric
http://www.compcams.com/Technical/Cu...ML/198-199.asp
BTW, lots of Impala SS guys love the 846. 305 or 846, I think you'll be happy.
Eric
With my 4.10 rear gears, I need something that'll peak around 6400 rpm. I'm willing to give up a little in the idle to 3000 range to gain 15 or 20 rwhp above 3000.
Safety Car
Joined: Sep 2000
Posts: 3,524
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From: Hinckley Ohio
Originally Posted by 96GS#007
Thanks for the feedback
With my 4.10 rear gears, I need something that'll peak around 6400 rpm. I'm willing to give up a little in the idle to 3000 range to gain 15 or 20 rwhp above 3000.
With my 4.10 rear gears, I need something that'll peak around 6400 rpm. I'm willing to give up a little in the idle to 3000 range to gain 15 or 20 rwhp above 3000.
http://www.compcams.com/Technical/Se...umber=07-503-8
Last edited by LT4BUD; Sep 27, 2004 at 07:55 PM.
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Drifting
Joined: Feb 2003
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From: San Antonio Texas
The Comp Cam; and most all after-market cams, will have less advertised(total) duration than the factory cams. They should make some more bottom end power, and have a better idle than the factory cams for a given .050 spec.
Melting Slicks
Joined: Apr 2000
Posts: 3,490
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From: Oviedo FL
Hey Jim,
I am going with something similar in my 383 but don't have it running yet... here are the specs:
Comp Cam - 07-000-8 - 224/230 duration with the 3100 series lobes ( 3192/3194) and a 113 LSA. The lift numbers are .605/.622 with 1.6 RR's.
I should have some numbers on this in the next month or so.
Mike
I am going with something similar in my 383 but don't have it running yet... here are the specs:
Comp Cam - 07-000-8 - 224/230 duration with the 3100 series lobes ( 3192/3194) and a 113 LSA. The lift numbers are .605/.622 with 1.6 RR's.
I should have some numbers on this in the next month or so.
Mike
Thread Starter
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From: Texas
Originally Posted by luvmy92
Hey Jim,
I am going with something similar in my 383 but don't have it running yet... here are the specs:
Comp Cam - 07-000-8 - 224/230 duration with the 3100 series lobes ( 3192/3194) and a 113 LSA. The lift numbers are .605/.622 with 1.6 RR's.
I should have some numbers on this in the next month or so.
Mike
I am going with something similar in my 383 but don't have it running yet... here are the specs:
Comp Cam - 07-000-8 - 224/230 duration with the 3100 series lobes ( 3192/3194) and a 113 LSA. The lift numbers are .605/.622 with 1.6 RR's.
I should have some numbers on this in the next month or so.
Mike
That's just sick 
My current head setup won't support those lift numbers. I'm maxed at .600I know a lot of guys like Comp, but I like to use GM parts. Call it a silly quirk I have
I've thought about the 1.7 rockers. In my case valvetrain geometry is a concern because my heads have been surfaced. I'd just as soon avoid the hassle.
I think the 846 cam will give the added kick I want. The only question left is how different is the idle quality of it versus the HOT Cam. With tuning, the idle quality of the HOT Cam can be made such that there's just a hint that something is changed under the hood. I'd like to retain that same quality. I know, having my cake and eating it too. The car does see some street duty on nice days. When I take it to work I spend a lot of time sitting in traffic. With that as a given, cam lope that really rocks the car isn't really acceptable.
Thread Starter
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From: Texas
Originally Posted by 1996man
how much HP are you running 96GS#007 ?
FWIW, I don't drag race the car, only auto-x and open track events/schools on various road courses.
Melting Slicks
Joined: Apr 2000
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From: Oviedo FL
Originally Posted by silver & red CE
WOW, that's a lot of lift. What kind of heads are you running?
Eric
Eric
Mike
Drifting
Joined: Feb 2004
Posts: 1,485
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From: Champaign, IL
St. Jude Donor '05
Originally Posted by 96GS#007
I've thought about the 1.7 rockers. In my case valvetrain geometry is a concern because my heads have been surfaced. I'd just as soon avoid the hassle.
Thread Starter
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From: Texas
Originally Posted by ToyC4
I'm a little new to this - how does surfacing the heads affect the valvetrain geometry? I guess surfacing the heads drops everything lower but is it enough to make a difference? I've had mine surfaced and I'm aware it will minimally bump up compression but I wasn't aware it affecting anything else. I'll be running the GMPP Hot Cam kit with the 1.6 rockers (as soon as the engine is back in the car).
It just keeps adding up.
Drifting
Joined: Feb 2003
Posts: 1,976
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From: San Antonio Texas
GM occationally uses after-market cams, and other parts;Crane roller-rockers, and some hi-performance heads for example. I believe that for a given lift, and duration at .050, a cam with smaller over-all duration numbers will give better idle, and low-end performance. They're faster acting on the lifters.
Safety Car
Joined: Sep 2000
Posts: 3,524
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From: Hinckley Ohio
Originally Posted by 96GS#007
You hit the nail on the head. Surfacing "drops everything lower". Without checking my notes, my heads have had .010 taken off. The 1.7 rocker arm has slightly different geometry than the 1.6 (or the 1.5 for that matter). Eventually you reach a point that you have to change to different pushrods It just keeps adding up.
It just keeps adding up.http://www.powerandperformancenews.c...ory_Code=PSHRD