Big cam on h/c 346
 

I am just curious if anybody has any used a cam in the 240 to 245 duration range and lift between .650 to .680?

:lurk:
Interested in this as well
:lurk:

DAPSUPRSLO is using the new comp lobes of ~.650 in his combo, i believe its a 346.

there has been...i have seen post of them...you could prolly find it with a search if you are lucky...someone will chime in that has one i'm sure...but to answer your question there are people with cams that big...in fact i think futral's car has one that big...i think it may be solid roller though...you did not specify if it needed to be hydraulic

how about hydraulic in the mid 240 duration, .625 lift, and 111 LSA range?

Well that is a huge amount of lift for a 240-250 duration cam.
You would be more of a solid roller setup.


Thunder Racing Custom Camshaft - T-ReX v.2 - 242/248 - .608/.612 - 110 lsa 3500-6700 RPM Power Band. Violent mid-range & high RPM power. Requires computer tuning, 4000+ converter on autos, 4.10's or greater on manual trans cars. Due to the fast ramp rate of this camshaft, the use of 1.8 rockers is not recommended. Due to the extreme nature of this camshaft, piston to valve clearance must be verified when using modified cylinder heads

As you can see in the specs above that a 242/248 only equalls a 608/612 lift.
I haven't see any lift specs (without using a larger rocker) that are in the 650 range while the duration is in the 240-250 range.
You would basicially need to move up over 250 duration to get to 650+ lift, or use a different rocker ratio, or solid roller.

So to answer you question. NO.

However the cam I listed above is very popular.
Do some research on the Trex and you will have 100's of threads to read.

the trex is ran by quite a few...here are specs...i'll look for bigger...242/248 - .608/.612 - 110 lsa

doh someone already beat me to it :bang:

thanks for the info

Wow!

You're saying that not even a custom lobe could get more lift with the same duration?

That's tough... I'd better start shopping for a 250* cam, then.

The lift of a cam is not directly dependent on the duration. You could easily have a cam with .700 or .800 lift that only had 200 degrees of duration. It would just have steeper ramps.

you havent seen these comp lobes have you ;). they've been posted before and are super aggressive. way more so then the TRex lobes.



Lobe#, Dur. @ .006", .050", .200", & Lift w/1.7 rocker
2124 265 215 142 .629"
2125 269 219 145 .632"
2126 273 223 149 .636"
2127 277 227 153 .639"
2128 281 231 156 .643"
2129 285 235 160 .646"
2130 289 239 164 .649"
2131 293 243 168 .653"
2132 297 247 171 .656"
2133 301 251 175 .660"
2134 305 255 179 .663"
2135 309 259 183 .663"
2136 313 263 186 .663"

Slightly off topic, but have you gotten your H/C forged 347 running yet, Jerami? Kinda curious about your thoughts in the EDC cam... :)

nah, im gonna fuck with it some more this weekend. i think my o2's are :turd:

I know what you mean... I didn't have time to finish my tune before the snows so I bumped it up a bit rich (not too bad) so I wouldn't detonate... I've been getting slow-switching codes for about a month, haha.

Sending a PM now for another question...

I saw these listed before, but haven't read of anyone using them.
I wasn't sure if they were available yet or not.
So I stand corrected by the CAM GOD.
I hate being wrong but is someone is gonna catch me, then it's not as bad coming from JRP.
I am sure you have probally seen some results as well using these grinds???
That is some crazy lift numbers. So much for 2cc valve relives, you gonna have to run a turbo piston just to get the cam to fit.
J/K.

I was told that my pistons with a 2cc valve relief would clear .680 with my heads. I am asking because I see alot of people running t-rex and gx3 or 4 with stock heads, but I rarely see max effort out of a 346 with heads and aftermarket bottom end. This cam would be a custom grind not an of the shelf item. JRP I checked out the guy you were talking about and it looks like he has a 408, but thanks for the help. I don't want to go with a solid roller, but I want the most I can get out of the motor. Assuming the valve events don't cause any problems what would the draw backs be to a hydraulic cam that size on a 347?

You missed the J/K part at the end.
I was kidding about the turbo piston part.

The next post will be long, so hit refresh in 10 minutes.

I see you have 5.3 heads which is good for compression so thats a start.

Here is where your gonna run into a problem.
You shortblock is gonna hate you. Just because you have a bigger cam dosen't mean your gonna run faster. With the lift being that high your going to need to shift high. This is gonna put a lot of added stree on your motor. Lets say to get rid of that problem you built a nice forged shortblock. Now you can shift at higher RPM's but will it be worth spinning the motor that high?
With 5.3 heads I am gonna say no. For max effort I would suggest a better set of heads. You will also need to add a 90mm TB and Intake. You have to get a ton of air into your motor and have a set of heads that will flow past 650 without dying off too much. Maybe a stage 2.5 LS6 head, or AFR head.
Without having heads that keep flowing real well way way up top spinning the motor that high isn't going to net you the results you are looking for. (Not saying it wont make power, just not much more power)
Now you turn to driveability. I know Norris is a good tuner, but tell him I said good luck when he goes to tune it. Your ramp rates are so aggressive and high it is gonna be a pain in the ass to daily drive. (If you are gonna drive it daily)
Springs might be a problem. Make sure you buy the best spring you can, b/c there are only a few that will stay together with 650+ lift and reving to 7500 RPM's.
Anyways these are some problems I can see taking place. PtoV clearance might be a issue is you go to a larger valve even with 2 cc valve relives, but probally not.


I am in no way saying what your after isn't possible, just not the easiest goal to have.

BTW with Nitrous 4.10 gears and this much power your gonna have to shift 5th in the 1/4 unless you shift well past 7000 RPM's, which is a problem you gonna have, and or already do have.
Also once you add the 12 bolt and slicks make sure your driveshaft is straight or that baby is gonna go by by as well.