Help!!! GM 847 Cam Question.
Thread Starter
Heel & Toe
Joined: Oct 2004
Posts: 21
Likes: 0
Help!!! GM 847 Cam Question.
What lifters, valve springs, pushrods if any should I get for the GM 12370847 cam. Mainly I am wondering about which Valvesprings would hold up. But I also have to replace one of my lifters so I might as well just get a set. P.S. All those new billet aluminum rocker arms out there for around a 150 dollars. Are they just as good as the Crane gold race self aligning or not? Please Help.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by Paul96lt4
What lifters, valve springs, pushrods if any should I get for the GM 12370847 cam. Mainly I am wondering about which Valvesprings would hold up. But I also have to replace one of my lifters so I might as well just get a set. P.S. All those new billet aluminum rocker arms out there for around a 150 dollars. Are they just as good as the Crane gold race self aligning or not? Please Help.
Melting Slicks
Joined: Jan 2000
Posts: 3,418
Likes: 1
From: NW Chicago Suburbs
I doubt your stock rockers will work with the 847 cam. The stock LT4 rockers are zero lash, they only work when the push rods, cam base's diameter and the rockers are perfectly matched. If they are to work, the base circle diameter of the 847 must be the same as the LT4 cam.
The $150 rockers are not self aligning, if you want to use them you'll need new hardened pushrods, guide plates and studs.
You can't upgrade to 7/16" studs with the stock LT4 rockers, they are 10mm.
I dumped my stock LT4 rockers and I'm going with Comp Cams Pro Magnums.
The $150 rockers are not self aligning, if you want to use them you'll need new hardened pushrods, guide plates and studs.
You can't upgrade to 7/16" studs with the stock LT4 rockers, they are 10mm.
I dumped my stock LT4 rockers and I'm going with Comp Cams Pro Magnums.
Melting Slicks
Joined: Jul 1999
Posts: 2,875
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From: Olive Branch (Memphis suburb) MS
Cruise-In II Veteran
Paul, just curious why you decided on that cam. You're going to need some custom tuning and you're still going to have a very choppy idle. By the way, that's the cam I'm running in my 396 w/ported stock LT1 castings and larger valves. Here's the Crane spec page http://www.cranecams.com/?show=brows...41&lvl=2&prt=5 
Thread Starter
Heel & Toe
Joined: Oct 2004
Posts: 21
Likes: 0
I have all bolt ons and ported heads. Also 355. I have read that this cam will give my setup around 360 rear wheal horspower. I just want to get everything I can out the cam I choose. But I also want brakes. Which means I am probly over zelouse with the 847 but I still want everything I can get.
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Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by Paul96lt4
p.s. thank you for the web page
Its got a nice healthy lope to it. There will be some cam surge at lower speeds but it really cranks it one when the engine gets on the "cam".....really gets your attention as it just pulls and pulls. In my opinion a lot harder pulling cam than the venerable Comp 306 cam.
Burning Brakes
Joined: Apr 2002
Posts: 934
Likes: 0
From: MO
Originally Posted by Paul96lt4
I have all bolt ons and ported heads. Also 355. I have read that this cam will give my setup around 360 rear wheal horspower. I just want to get everything I can out the cam I choose. But I also want brakes. Which means I am probly over zelouse with the 847 but I still want everything I can get.
I also went with the Crane golds. Also I agree with everything TJwong stated above! I haev 4.11's so soon as you get going I just keep her above 3000 and the surge is gone. Its not horrible but its there down low. Goodluck!
Last edited by James94LT1; Nov 28, 2004 at 06:56 PM.
