Cam Swap Advice

[Greenville68]

Hey All,
After having my new motor running for a short time, it doesn't really have that thump or power I was hoping for...its not really a slouch, just not what I know it can be. I had planned on inquiring with Lunati and maybe Crane too, but was wanting some honest opinions from forum members too since some may have a similar setup or experience. I feel like the current cam has too much duration and not near enough Lift for what I'm looking for. To help, I don't really plan on taking my car to the track...I just like driving aggressively on the street and having some fun here and there. So, I'm not looking to get every 1/10th second on the track or anything, just high HP and TQ numbers, and preferably under 7200RPM. I was hoping to get something reaching its peak at 6500-7000 to keep it fun on the street...and maybe even get that front tire in the air a little one day (just running Hoosier Drag Radials). I forgot to mention I'm running the FAST EZ-EFI 2.0 Multi-Port Fuel Injection system (1000HP accommodations) and it states that it needs about 8 inches of vacuum to operate correctly. If this becomes burdensome, I will go to the FAST XFI when money allows, but was kind of why I went with a modest cam at first.

I would love to hear opinions...my setup is in my sig, but please let me know if any pertinent information is missing. Not sure it really matters, but I do run Dart Stud Girdles too.

Thanks in advance!

[rp930]

Call Chris Straub

[swampbuggy]

Did Comp Cams recommend that cam? and what rocker arm ratios are you using? Mark

[MadBill]

Definitely get some expert cam advice!
My shoot from the lip suggestion would be 10-20° more duration* depending on drivetrain, 4-5° less LCA , 0.100" more exhaust lift and at least 0.150" more intake lift. I don't know the limitations of your present EFI, but you might have to compromise cam specs to the tune of 100+ HP to keep it happy.
(*It's highly unlikely you can hook this engine up on the street regardless, so as long as you maintain a trace of driveability, a big loss of low end torque won't much matter.)

[Greenville68]

Yes, Comp Tech Support recommend that cam...I was really worried about keeping 8 inches of vacuum at the time and didn't know any better back then on what combination of cam characteristics would keep the vacuum happy. I'm using the standard 1.7 ratio for the Rocker Arms---the Comp Ultra Pro Mags.

Thanks

[Greenville68]

Thanks for all the feedback...so far, I have Mike Jones and Chris Straub on my list to contact. I have already submitted an inquiry to Lunati too...surely we can get more out of that motor and keep 8 or so inches of vacuum for the EFI, or the tail will quit wagging the dog and I'll just get the FAST XFI to replace the EZ-EFI and get someone to tune it...probably should have done that to start. Priorities and goals change unfortunately

[MadBill]

It will be really interesting to see how the cam recommendations compare; hope you will share. My bet is that they will be very similar.

[prairiehotrodder]

My somewhat educated guess would be 265 / 270 @ .050 around .700 lift and 109 LSA.

That cam you have now looks more like a 454 cam not a 572 cam.

I'm not a pro and am also interested to see what suggestions you will get. You may also want to look at a Coscam from David Vizard.

Brian

[Greenville68]

Thanks All, I will certainly share the recommendations I receive...if the current list of 3 end up being very similar, I will likely go with one of the 3 versus continuation of pursuit and probably be a pretty big difference compared to the current.

[F-BIRD'88]

Before you change cams re-set the valve lash on the current cam
at .010" set COLD. The lash opens up once warm and will be just right.
The real effective valve duration and overlap will be increased and the idle will be more "lumpy" It will also probabily be more powerfull too.
I have advised others on this specific cam and valve lash and performance
more than once.. Try it. Its a lot easier and user friendly to set the lash COLD instead of HOT. And it will be where it should be when fully warmed up.

use the IC EO method.

There are many more and bigger cam lobes within this same XR street roller cam lobe family you can choose from if you still want to step up the game.
Comp Cams will be glad to custom grind one for you. This is a good lobe family to choose from for what you are doing. They have XR series lobes that are a Lot more serious duration and lift all while still being a "street roller".
Avoid race roller cam stuff for what you are doing.

Try the lash re-set first.

[Greenville68]

Thanks, but I'm already running .006 on the intake and .008 on the exhaust...so it's already taking about as much advantage as possible (as far as I'd go down for lash) of the possible Duration and Lift. I called Comp back when I didn't see lash settings on my cam card a year later (i had multiple back surgeries) and it turned out to be a Hydraulic Roller cam instead of Solid Roller cam. They would not send me a new solid cam as I originally specified, so Comp has lost my business. This cam just isn't what I had in mind and I thought the large duration would compensate for the lack of lift, but it's just not cutting it.

[prairiehotrodder]

In your opening post you stated that you don't go to the track and this car is just for aggressive street driving. Looking at your signature I see this is a tall deck 572. That's a big motor with a big cylinder head. How can it not be enough for aggressive street driving and you aren't in jail yet ? If its not making 750 hp there is a problem. I'm sure if it had the right cam and an 1150 dominator it would make well over 800 hp. Have you had it on a dyno ? Have you tried it with a carb ? You also say that its got to much duration and not enough lift. My guess says any pro cam designer would want it to have more of both. Again that's a big motor. Have you got any recommendations yet ?
Brian

[Greenville68]

No, I haven’t dyno’d or anything like that. Just seat of the pants, rev and response characteristics,WOT characteristics and just overall driving and listening to everything. Since I’d like to have the power brought in a little earlier for the street, I figured the duration was a bit much and the lift just isn’t enough to give the horsepower to back up all that torque. The cam doesn’t really have a predominant lope to it either, which I understand doesn’t mean performance, but it should lope harder than this for my taste. The FAST throttle body is a dominator style and I believe a 1350 CFM unit...it’s pretty darn big. I have some pretty unique requirements to my build and I think it’s about there, just a couple of weak links to work out.

I haven’t received any recommendation back yet from the inquiries I sent out, but have received a few recommendations from other posts and research. Seems to be a concensus of around a 270 to 280 duration with a .715 to .740 lift on a 109 to 110 LSA. I fear the LSA may need to be reconsidered if possible, as I’d like to keep that 8 inches of vacuum needed for the fuel injection system, but if it gets in the way too much I’ll replace with the XFI unit. Not sure how much LSA plays into the role of vacuum, but probably a combination of all the cam attributes determine that...was just in my head that LSA played a big role in it.

[Greenville68]

Maybe it would help by explaining my "unique" requirements. Before this, I had a 98 T/A that I built a LSX 383 Stroker when I blew up the original LS1. The last dyno pull was a little over 500 RWHP at LG Motorsports, and the tech said the valves were floating at 4200, which was when the power was really brought in. I did buy some Comp 921 springs to rectify that issue, but never installed them and sold the car.....as it just wasn't enough power anymore and I was having a tough time getting it inspected at most places. So, I decided I wanted an old muscle car like I've always loved, and build a setup that wouldn't have so much issue keeping legal on the street..and I chose a 68 Camaro because I've always liked them and got a good deal, versus the 66-67 GTO I really wanted to build. I have it registered as an Antique, so no Inspection required and I can drive it without getting hassled since I only take it out on Saturdays, or maybe to Work on a Friday (1/2 mile away).

I wanted to build something with more power than my last car, but keep it somewhat reliable and sturdy. Meaning, I didn't want something that I had to run on the ragged edge just to make 700HP. I figured I could build a large cubic inch stroker motor, with moderately aggressive performance components, and make quite a bit of power while staying reliable and consistent. With the right multi-port injection system, I could 'arguably' make just as much power if not more than a carb, but again keep it very reliable and consistent (cold weather or not), and give it quite a bit of tuning possibilities. So, I thought with the large cubic inch motor, stroked, but with everything balanced within an inch of its life and not too aggressive, I could get quite a few miles out of this setup and just enjoy. Keeping in mind, one day I will want more and I wanted a platform that could scale up with no issues if that day comes. I could probably throw a lot larger cam in than what has been recommended and get more peak HP, but I think it will be night and day just by upgrading to the lower end of the recommended ranges I've received so far and will still be quite sturdy. I still have P&P work that could be done and probably give it even more, and wouldn't sacrifice any reliability.

Hope I'm making sense...hard for me to convey the whole picture sometimes.

[Greenville68]

BTW, when I say balanced, I mean it was Hines Balanced too...all steel forged internals. What I consider to be a bullet-proof bottom end.