GM 847 Cam question
GM 847 Cam question
Would this cam work well and compliment a set of Stage 2 TEA LT1 heads w/1.6rr's? Max lift on the cam would be .575/.595 with 1.6rr's. Its in those lift areas that the TEA heads have the best flowrates. I believe 270cfm intake and close to 240cfm exhaust. Thanx for any adivice. Cam info is below.
Info on Cam:
"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 234/242; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 539/558. Valve lash is zero/zero and lobe centerline is 112 degrees. "
-taken off gmpartsdirect.
Info on Cam:
"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 234/242; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 539/558. Valve lash is zero/zero and lobe centerline is 112 degrees. "
-taken off gmpartsdirect.
Re: GM 847 Cam question
Yes it will work great. The problem your going to have though is finding one. They are all on back order. I ordered one today from Jason Cromer and even he's out of stock. Nobody's sure when they're comin but they'll get there sometime.
Re: GM 847 Cam question
I believe the GM cam's are made by Crane maybe it would be quicker to call Crane and see if you can get one ground for you. I think that cam would work well with you heads. I would probably just run it with 1.5 RR's. That would take a lot of spring to hold that much lift.
Re: GM 847 Cam question
Originally Posted by Z95m6
I believe the GM cam's are made by Crane maybe it would be quicker to call Crane and see if you can get one ground for you. I think that cam would work well with you heads. I would probably just run it with 1.5 RR's. That would take a lot of spring to hold that much lift.
also if his STG 2 came with double springs hes good to go up to .650 lift
Re: GM 847 Cam question
Originally Posted by The Cartel
Yes Crane makes them. I'm runnin the Comp987 springs w/1.6 rocker 7/16s stud. You'll also want some rear gear to spin it up nicely. Is your car an A4 or M6?

Its been a long time since i looked but i'm pretty damn sure the comp 987's are only good to .600 its been over 2 yrs since i put mine on. That is just asking for trouble.
Re: GM 847 Cam question
I thought i always heard you want at least .030 less lift than what your springs can take. I also think if you push the springs to their limits they have a very short life span. Not a good idea.
Re: GM 847 Cam question
Ok just posting what i see on TEA website. The head get returned to you with:
Disassemble Head
Bead Blast Head
Competition Multi-Angle Valve Job
Cut Spring Pockets for Larger Diameter Springs
Back Cut Valves
Fully CNC Port LT1 Heads to Stage 2
C.C. Combustion Chamber
Mill Heads To Customer Specs
Clean Heads, Set Spring Heights, Assemble, Check Seat Pressure, Installed Height, and Coil Bind
Flow Intake and Exhaust Ports
2.000 Severe Duty Intake Valve
1.560 Severe Duty Exhaust Valve
1.440 Dual Springs 150 lbs@ 1.800” and 380 lbs@ 1.200”
1.440” Chromoly Retainer
11/32” 7 Degree Machined Locks
1.550 Inner Diameter Spring Locator
.341x.563 Viton Seals
Im not to sure what those spring numbers will translate to for maximum lift? Can anyone explain?
Disassemble Head
Bead Blast Head
Competition Multi-Angle Valve Job
Cut Spring Pockets for Larger Diameter Springs
Back Cut Valves
Fully CNC Port LT1 Heads to Stage 2
C.C. Combustion Chamber
Mill Heads To Customer Specs
Clean Heads, Set Spring Heights, Assemble, Check Seat Pressure, Installed Height, and Coil Bind
Flow Intake and Exhaust Ports
2.000 Severe Duty Intake Valve
1.560 Severe Duty Exhaust Valve
1.440 Dual Springs 150 lbs@ 1.800” and 380 lbs@ 1.200”
1.440” Chromoly Retainer
11/32” 7 Degree Machined Locks
1.550 Inner Diameter Spring Locator
.341x.563 Viton Seals
Im not to sure what those spring numbers will translate to for maximum lift? Can anyone explain?
Re: GM 847 Cam question
You might look at the K Motion K-800 springs. They are good to .700" lift and don't require any machining. I ran the K-800s on my '97, stock heads, with the GM 847 and the car ran great.


