LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

the gm 847 cam

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Old 02-26-2004, 10:37 AM
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Originally posted by badblackta
the 847 cam is not sold in a kit like the hotcam is it? Another thing, if I put just the cam in and did not rev it past 5500 with the stock rockers and all that, would it be ok for just driving around town and stuff till I get the money to beef up the valvetrain, or would I like bend the pushrods and break the rocker arms and stuff. Kind of on a limited budget But I just wanted to see if I can get it in there and do the rest when I got more money.
No, when you put the cam in, put better hardened pushrods with guideplates, significantly stiffer springs to handle the lift and the increased ramp, and rocker arms, preferably pro-mag 1.52's. Since this cam is pretty big and needs a stiff spring to keep the valves in check, you'll also need some strong lifters in there too. The stockers aren't gonna tolerate things very well in there. When you go with a big cam, things start adding up fast.

So basically, save more $ for upgraded valvetrain parts.

Jason
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Old 02-26-2004, 11:36 AM
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Originally posted by mebanditws6
No, when you put the cam in, put better hardened pushrods with guideplates, significantly stiffer springs to handle the lift and the increased ramp, and rocker arms, preferably pro-mag 1.52's. Since this cam is pretty big and needs a stiff spring to keep the valves in check, you'll also need some strong lifters in there too. The stockers aren't gonna tolerate things very well in there. When you go with a big cam, things start adding up fast.

So basically, save more $ for upgraded valvetrain parts.

Jason
Seriously man... I just went through this. My cam specs are listed in the sig. The gross lift with 1.6rr's is 560/577, a good amount. I ended up getting 612 valve springs from combo motorsports, cc875 (comp r) lifters, and pretty much everything else new except the actual valves to handle that cam. But holy **** does my car fly now...

As for driveability, it all depends on tuning. I still have a little bit of surging at low RPM but I will get rid of it soon. Another thing I will say is that with a big cam, your low end will disappear like the great houdini. GET GEARS! Low ones at that... my car is supercharged and I decided on a Ford 8.8 with 3.90's, I think that should be a good ratio. I think Atljar is running 4.56's!!!! That is insane, I can't imagine what first gear feels like on slicks, the car probably leaps forward haha.
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Old 02-26-2004, 11:45 AM
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atljar has 4.30's...
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Old 02-26-2004, 12:06 PM
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Sorry, my post was in response to "badblackta" on the 2nd page. Forgot to hit the quote button.

Jason
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Old 02-26-2004, 01:50 PM
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Originally posted by marshall93z
atljar has 4.30's...
Yup, but they're COOL
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Old 02-26-2004, 02:05 PM
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How would the EX 612 springs (good to .600") work with the 847? Anyone using them? I'd be retaining my 1.6 rockers...so the lift would be very close to .600"...
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Old 02-26-2004, 02:55 PM
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Two questions- 1) how much is this cam and where? 2) would the 1.6 rockers from the HOTcam kit be ok with this cam?
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Old 02-26-2004, 03:00 PM
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you should be able to get it from Dal or Jason for about $220 SDPC also sells it

when i was gonna use that cam and cancelled my order about 2 months ago it was on back order (must be popular now)

yeah the GMPP rockers would be fine with it, just not the springs that come in that kit
i would think the CM612 springs would work with it also
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Old 02-26-2004, 03:04 PM
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Nice, thank you!
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Old 02-26-2004, 03:04 PM
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Originally posted by LPE Z convt
Here, http://www.madz28.com/chris847.mpg is a idle sound clip of the 847 in my car with open plate borla....The car on a mustang dyno was still making power at 6800rpm the power never fell off... I made 363rwhp with Ion (madz28.com) doing the tuning.....
is that a stock head car?
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Old 02-26-2004, 04:52 PM
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Originally posted by simple
is that a stock head car?
No that is with LPE heads ... The mustang dyno gives #s about 12-15% lower than the dynojet... I would love to go to a dynojet but the closest one is like 1.5 hours away that has wideband the mustang was in my town.... 363 times 12%= 43.56 plus 363=406.56rwhp.....
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Old 02-26-2004, 04:57 PM
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If you want to hear a stock headed car with the 847, ive got a clip on my webpage. Its in the video/pictures section called "idle and rev video" or something like that
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Old 02-26-2004, 05:05 PM
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Originally posted by LPE Z convt
No that is with LPE heads ... The mustang dyno gives #s about 12-15% lower than the dynojet... I would love to go to a dynojet but the closest one is like 1.5 hours away that has wideband the mustang was in my town.... 363 times 12%= 43.56 plus 363=406.56rwhp.....
i didnt know if that was your car or not!
we've got one of each here a Mustang dyno and Dyno jet
screw equations strap it on a dynojet and get the real #'s

atljar, i've heard your car a few times but am more impressed with the times you've layed down
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Old 02-26-2004, 05:11 PM
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Originally posted by FacelessZ
How would the EX 612 springs (good to .600") work with the 847? Anyone using them? I'd be retaining my 1.6 rockers...so the lift would be very close to .600"...
According to your sig, you have GMPP 1.6 rockers. They are only good up to .575 lift (that's what GM says). I would go with better rockers for GM847.
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Old 02-26-2004, 07:18 PM
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Originally posted by simple
i didnt know if that was your car or not!
we've got one of each here a Mustang dyno and Dyno jet
screw equations strap it on a dynojet and get the real #'s

atljar, i've heard your car a few times but am more impressed with the times you've layed down
And who are you? Screw equations my car made 363rwhp on a mustang dyno ... Screw dynojet#s, I don't even run that cam anymore so no 847 #s on a dynojet for me... I will have new Mustang dyno #s in the spring.....
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