How much lift and dur. can you go before having to go to a smaller base cam or clearance the rods? need to know if 266/274 @.050 .660 lift on a 108 will have any problems?? (would like to know before ordering)
Is it worth going to a solid roller over the hydr. roller or do they run out of rpm?
I'm looking at building it for bracket racing and I'm looking at something fairly aggressive and am wondering what some of you are running or think?? THANKS

 

not really an advanced question if you ask me, but for a daily driver, stick with a hydraulic roller

 

SR 396 here...big cam, 7200rpm, 200hp n20 later on. It is not daily driven, but could be if I *really* wanted to...and I'd have to really want to do it, lol. You can make a 396 pretty agressive with hydraulic cam. If you are going to braket & enjoy it, stick with hyd. Additionally if you stick with ported LT1/LT4 casting heads, they pretty much run out of steam at the upper end of where you want to be lift-wise with a hydraulic cam. Pick up 15~25hp max going with solid staying in the same general lift/dur range. Solid just allows you to run more aggressive lobes.

But in short, to answer your q's: 1, prolly up in the .7~.8"+ lift range and 2, for what information you've given, no.


P

 

P
So hows does your car run then HP/ track time??
You didn't have to have the rods clearanced at all??
THANKS

 

Didn't need additional clearance with I-beams. Some H-beams will need it. Don't know the official HP #'s, had it on a dyno twice and had issues both times. Actually going to try to get it to the track tomorrow, we'll see how it does. Just hoping I can make a full pass with nothing breaking. Last time I was at the track, I was over conservative on the launch and the clutch was slipping really bad (11.7 @ 122). Would like to see a 10 sec slip n/a before I spray it. I don't run bracket racing.


P

 

Do a search for the HR v. SR issue for a range of opinions. Mine is that an SR is not a good choice for a street car and that the gain is small in the rpm/lift range usable on the street. Clearance has as much to do with the design of the rod big end as the cam. It's hard to say w/o mocking it up unless someone else has tried an identical combo..

Rich

 

First of all what heads are you using, what are the flow numbers? this will tell you how much cam to use, another is if you plan/need to spin the motor to the stratosphere, then you will need a solid as hydraulics are pretty good up to 6500 rpm..

 

I'm running the Comp XFI-292 HR w/ 1.6 RRs, 918 beehives and AFR-195 LT-4 heads in my 396 and turning it just over 6500. I'm also upgrading my springs to PAC-1518s w/ titanium retainers. I believe the 918s are currently a minor issue at the upper RPM range.

I'm very happy with the XFI-292, it has a broad power band in the 396 and performs well in my N/A only bracket car. On yes, it was custom ground on a small base circle just to be on the safe side.

WD

 

Thanks
sorry guy's I should have give more info. on the parts I'm using, crank and rods are eagle rods are H-beam with 8740 bolts. I've talked with comp about a cam and the one they came up with is 266/274 dur. .660 lift and 108CL. I'm wondering if someone is running something close to this what had to be done??? (small base, clearancing rods, ect...) THANKS

 

With that much duration & lift it better be a solid roller. If not those hydraulic lifters will last less than 1k miles before they puke on themselves. With a good set of heads and with that amount of duration I'm thinking you will be in the mid to upper 7k RPM band for peak power. If you are going to spin a big cube LT1 up that high, don't skimp out on cheap parts. It will be a mean machine, no doubt. I don't know where exactly my peak power is, but I still feel like it has more left in it when I'm tagging the rev limiter at 7200. Cam specs are: 260/266 .672/.672 110lsa (lobe sep & center line are not the same). I'm running a normal sized billet core cam with Oliver I-beam rods, Callies 3.875" stroke crank and needed no clearance for the cam. With H-beams, like I said before, they may need clearancing. Check with your engine builder or others who have a similar set up.


P

 

Your specs (260/266) are duration at 0.050"? I am guessing that the 266/274 are advertised duration? Anyway, I agree that the Eagle H-beams are not the best for cam clearance and usually need some work to clear the cam. I would go with a small base circle to avoid the problem and not have to grind on the rod, if it were I.

Rich

 

Thanks guy's
and dur. is at .050
Thanks again

 

That is a HUGE cam for a SB 396. I run a 270/280 @ 50 cam in my 469 BB bracket motor and it peaks at 6,900, pulls strong to 7,500. This thing ought to make peak hp around 7,500 unless something else chokes it off, which I am suspicious that it will. Is this a race car? What are the full cam specs? I am now agreeing that it will take a SR setup to work right - I doubt you can put enough pressure to control the lobes on a HR lifter. How did you arrive at this choice of components? And yes, I suspect you will need to have the valve reliefs cut in order to have clearance, though there is not any way to know for sure w/o mocking it up. The narrow LSA will help with P-V though, you do have that going for you.

Rich

 

I figure I will put in my info. I am running a lunati crank and eagle h-beams. I didnt clearance the rods but I did run into clearance issues with my little 242/248 .588 lift cam. So I had to go down to a 1.05 small base circle keeping the same specs. So I am sure you would need to clearance yours.

 

I got the cam specs from comp, I my self thing thats alot of dur. for an LT motor. I run some thing close to that in my old car with a sbc 358ci and spun to 8200 but that was alot more serious.

One more question for you guy's, is anyone running a single-plain intake converted to an LT1/LT4 or are you running an LT1/LT4 intake??? Is it worth changing too?? THANKS