I am thinking of changing the cam in my Z28. I currently have the HOT CAM. I am thinking of adding 1.7 RR's to it.

But the last few days I have started thinking about changing my cam to either the CC306 or the GM847.

My question is: Keepin the stock LT4 heads (upgrading valve springs of course), which of these would get the best results for my car. Keeping HOT CAM and adding 1.7's, CC306, or GM847?

How much of an increase 1/4 mile wise should I expect from each of these?

 

Id say 1.6s instead of 1 7s. Thats what most people are using. But I would go with the CC306 but it will need a tune to get it right. Yah its a big cam but with very big potential. As for ET Im not to sure there. Keep us posted with whatever you do.


Good Luck,
JOhn

 

both the 306 and the gm847 are going to make peak HP really high in the rpm range , just make sure thats what you are wanting to go with.

i wanted to go with the 847 in my car, but im not going to due to the fact i dont wanna take my stock bottom end that high

for power, i would probably go with the gm847 IMO

 

I'd go with the 847 on the automatic, but remember, that thing has almost close to .600 lift with 1.6 rockers, so you won't be able to use the 1.7s, or it wouldn't make sense anyway.

You will need some good springs with it too.

 

You have to rev CC306 higher to see the HP. To a stock bottom end that have never seen rpm's above 5k this will basically mean kaput (70% case,read somewhere). If you could get a nicely balanced short block, then CC306 would be perfect. I would go with XE grind if I were you.

 

I am only going to add the 1.7's if I keep the HOT CAM. If I go with a larger cam like one of these I know I won't need the 1.7's.

madwolf, I was thinking of the 612 springs from Combination Motorsports. What is your reasoning for thinking the 847 would be better than the CC306. Also, how do you like your new cam, the 233/239 I think it is. Any track times or dyno #'s yet? I have also considered that cam, what are your thoughts on it?

 

Plenty of guys revving up to 7k on stock bottom ends. They're a lot stronger than you think.

 

I agree I have seen quite a few revving stock bottom ends very high. I am just at the point were I want to go faster, I don't really want to change the cam but I think it might be the best way to get the car where I want it.

I change my mind about it constantly, need to make my mind up in the next week so I can start gathering parts (get a few parts for Christmas).

 

I picked the 306 before I knew about the 847, if I had known about it, i would have done it. But I am happy with how my 306 sounds, it is a beast at idle and up through the duals.

 

I would go with a custom grind. You could have it close to either of the cams you listed. But being designed around your heads it is going to peak at a lower rpm. The cams you choose make peak power at 6800rpm. I would definately go bigger than the hotcam. Call up combination motorsports or ls1speed they know cams.

 

I don't know about the 306, but there is no way the 847 makes peak power at 6800 rpm. I've got the Crane 109841 it's the exact same specs. as the 847. Actually, it's the exact same cam, since Crane makes the cams for GM Performance Parts. The cam card says the recommended rpm range with matching components is 3000 to 6500 rpm with valve float at 6800 rpm. My 383 with this cam and TEA ported LT1 heads made peak power around 6200 rpm.

 

I agree the cams might pull up to 6800 but I don't think they will make peak power at 6800.

 

I also spoke with Lloyd Elliott earlier and he thought I would be better off switching to a CC306 without mentioning any type of cam that I was considering.

He said with new valve springs and the CC306 I should pick up around 25hp. Around 3 tenths 1/4 mile and 3 mph. That he said was with it shifting at around 6600. I think that sounds like a pretty good gain for the money.

He also said that the 230/236 would give a similar gain.

 

I had the 847 cam and on the mustang dynoit made power up to where we cut it off i believe it was 6700 (the power never peaked it was still climbing) The 847 will make power to 6800rpm... You just need good springs to prevent valve float... Ion was their (madz28.com because he was doing the tuning.

 

LPE, did you change from the 847? If so why. I have been considering it alot of people really like it. I am surprised that there hasn't been a lot more people in here saying definitely 847.