F-Body Europe

Has anyone experience with the GM 847 cam ? would it be too much cam for a street driven car with stock heads ? Will the idle be very rough ?

Oh you are gonna be lumpin hard w/ that cam. That's a big cam for a untouched LT1 head. Get the necessary valvetrain for it and it won't be a problem. But it's gonna idle and sound like a muscle of the past. You'll need a program for it too.

Thanks John, I was thinking about doing the CC305 or the Hotcam but then again if I'm going through all that work I might as well go ahead and put something real big like the 847 in. How would they work with ported LT4 heads ?
The only thing I wanted to avoid is a very rough idle, I don't want it to be too obvious that there is a big cam inside.

Specs for the 847 are 234/242 .575/.595 112 LSA
There is no hiding this cam . Arough idle is what you are gonna get . No bottom or mid range in this thing to speak of . This is all top end . I hope you can rev that high to really enjoy that peaky band. Gonna need some steep gears to keep the revs also.

Who're you afraid of? I thought you don't use the LT1 as your daily driver...

If you want to hide a cam go with one with around .540 lift, 218-224 duration at .50 and a 114 LSA. Stock LT1 Heads max out at around .550 lift. Also, it is easier on the valvetrain. With lift numbers of the cam you described, you will be changing valve springs often. What the hell do I know though. I gave up on my LT1 and bought an LS1.

@ Roy
yea I think there really is no wayl to even try to hide that cam.. its going to be very obvious. I would like more power in the upper range though, my LT1 is everything but strong on the top end.
As far as I know neither the Hotcam or the CC305 will raise the power band beyond 5800

@candy
Nothing to be afraid of, but you know in which country we live in

@NX28
Do you think valvespring wear will still be bad even when using titanium springs ?
Even if I'm doing the Hotcam or the CC305, I guess I would have to change the valvetrain either way ?


Anyone know how much big of a gain the CC305 would be ? I know its a little better than the Hotcam

@Alex,

you know how I think. I'd go for the heads too if I change the cam. Country sux, but hey, the yellow plates will still help us!

A good set of double springs would be the ticket. Also, Comp Cams makes the 918 beehive spring but they only last about 20,000 miles or less. The bigger the cam the less streetable it will be. With the CC305 cam, that is a big upper rpm cam. You will need to have the motor gone through with some good pistons and rods to survive that cam. Small block chevy rods tend to stretch the big end of the rod once you get in the 6500 rpm range. This is due to the weight of the factory pistons. I have learned this the hard way.

I spun my hotcam to 6400 rpm on my old LT4 heads daily. That was a nice cam in it's day. Beehive springs are the way to go but I've never heard of a 20K run life. 847 and some LT4 will do the job easy esp since you want the upper rpm to run down on the bahn. You low and mid range will suffer but not as much as you think if you get that program right. PCM4Less does a helluva job.

But like they all said forget about idling all unoticeable. UNLESS you get that cam ground on a 114 LSA then you could get away with it.

I guess a good PCM tune is the key with every cam change, I read a few posts on CZ28 that showed that small wonders can be achieved through pcm tuning after a cam/head combo
John, did you use the "stock" LT4 valve train to rev it up to 6400 ?? I imagine you were able to rev that high due to the LT4 heads ?
I guess I'm now leaning towards the CC305 though since it should be much easier to hide and also reliability should be better. I really don't have the money to do a complete rebuild if I screw up with the 847. How much smaller would the cc305 be compared to the 847 ?
I read that the cc305 should work great with stock lt1 heads, is that true ? How high would that lift my powerband ?

Actualy the CC305 of the XE version are not the high rpm performers. Ley are designed with TQ in mind. I had the EX verson and loved it. Of course it was in my heavy SS with the Procharger and Stage 1x ported heads. Idle would be barely noticable. Lowend was a tad stronger than my stock TQ cam, midrange was NICE, and the topend was less than a hotcam would be. The CC305 was designed to rev under 6000rpm, and had my shift point set at 5800(loose tranny). The hotcam is a nice cam for the F-body, but due to the idle you will know it's there. PCM tunning is the key too. Also the idle lope can be tamed down with a higher RPM idle setting. As for stock heads, these two cams would be maxing them out. You can get a set of new springs fairly cheap. Go with some CC 10308(I believe for the Aluminum heads) of get with Cmotorsports for one of there spring packages.

Mav

Hello, new to forum and I'm looking to buy a long block with the 847 cam. Anyone have any dyno info, would like to see what the torque curve looks like.

thanks
robert

GS340 that's pretty vague. Don't know what else you want on the setup but on average 380 to the wheel or so depending on the heads and exhaust work.

Good luck finding a Longblk here. People tend to keep their parts since it's hard to to not get raped in shipping.

I'm going to order the long block in the states. Shipping should be around 300 bucks to 450 to ship over the long block via BAX or similar Air courior.

spdc 10.4 compression 383 short block
spdc Stage III heads.
with the GM 847 cam
BBK 52MM throttle body
Long tubes w/ cats
tuning? hypertech custom program or fastchip, or PCM4less.. not sure yet.

stage III head flow numbers
LIFT---------------INTAKE------EXHAUST
.200---------------138-------------117
.300---------------198-------------161
.400---------------240-------------188
.500---------------267-------------205
.550---------------273-------------209
.600---------------273-------------213


http://www.spdc2000.com

Now you are talking. Skip the 52mm tb and go 58. 847 needs more air than w/ that 383. PCMforless and no other period. I was a loyal fan of Fastchip until I received my PCM4less and is far superior in every way not to mention hella cheaper.

Where are you buying the Longblock from? What kind of heads? Looking at the flow sheet those gotta be AFR's. You'll never see exhaust numbers like that w/ LT1 castings.

buying the long block from sdpc2000.com...

They sell CNC LT4 heads and those are the flow numbers for the heads. AFR 195 heads have similar flow numbers.

What I want to know is what the power curve will look like? Can desktop dyno produce a graph and/or the power numbers?

I'm going order the long block in 2 weeks... i hope... have it shipped over and starting ripping into her sometime in sept. Takes about 6 days to get the motor to Frankfrut airport for pickup.

I still need injectors. 24# enough? 30#???



robert

30# injectors. Dyno graph? You may have better luck on the main board and asking and looking around. http://www.cz28.com if you don't know the site.
It's gonna be about 6400rpm peak but that cam can spin close to 6800 depending on the LSA.

Good to know another stroker will be in our midst.

maybe I'll have the motor installed and running for bitburg on 2 and 3rd of OCT ..