Cam Tech Talk on Custom Grinds
 

Engine guys,

I need some guidance on putting together some custom ground cams. Bear with me... I'm venturing off into new territory. My goal is something that produces a low and wide tq band, without sacrificing valvetrain durability. I'm also aware that the cam alone won't accomplish this.

First, I've been looking at the Comp Cams Master Lobe Library, both to understand what I have now, ( I currently have Comp custom grinds) as well as make some changes. Is this the "bible"? Do other cam manufacturers have a similar and comprehensive library? Please point me there.

Next, on cam specs: There's differences in the @ .006 duration numbers vs. the @ .050 numbers. Some lobe profiles have narrower @ .006 duration spec with a given @ .050 number, others have wider durations. I assume a narrower base ( @ .006 ) equates to a more aggressive ramp profile, so what's this accomplish? In a marine application, does more aggressive equate to higher torque? Does it move the tq band up or down? And what affect does this agressiveness have on the durability of valvetrain components?

Comp Cams generally has 4 lobe profiles that appear geared toward marine hydraulic applications; High Energy, Magnum, Dual Energy, and Xtreme Energy. Comparisons of @ .006 specs vs. @ .050 specs show the aggressiveness of these profiles from low to high, relative to the above list. Can someone characterize how these profiles relate to marine use? Tq vs hp? Wider or narrower tq curve?

Also, does anyone have any experience with the Comp Xtreme Energy profile lobes? These have an inverted radius ramp design. What's this for, and what's your experience relative to valvetrain durability? They supposedly make pretty decent torque.

I realize these are very vague questions, but I have to start somewhere. I have a LOT more questions, so again, bear with me. I've heard good and bad here on Comp Cams... who else does custom grinds?

Thanks in advance,
Brian

Re: Cam Tech Talk on Custom Grinds
 

Call Comp and ask for Gordon Hollowell. Gordon can answer all of your questions about their products and help steer you in the right direction. Gordon works with many of the Nascar teams as well as the drag racing circuit. There are numerous cam specialists on this board and I'm sure this will be hot thread. Good luck!!

Re: Cam Tech Talk on Custom Grinds
 

Don't forget to look at the Extreme Energy XFI HR grinds as well. (they're not just for EFI setups) These have even slightly more agressive ramps as well. These more aggressive ramps also appear to reuce overlap a bit compared to a gentler ramp which should help with reversion when comparing similar @ .050 numbers.

After some lengthy conversations with Comp I just ordered and received in 5 days a 238 Extreme Marine High lift grind int / 248 XFI grind exh and had it put on 114 LSA for a 565ci motor with GM heads.
(Adv 294/300) 238/248 114 .612/.615

You should get a lot of good input here.
Oh yea...It was $249 for any grind you want from Summit :evilb:

Dave

Re: Cam Tech Talk on Custom Grinds
 

Without knowing what the cam has to work with (airflow) all you can do is guess at a profile.

Along with airflow the combination and the rpm range is then considered. Lobe selection looking at duration on the seat, .050", .100", .200, .300 and so on can be catered to the engines requirements.

If this is a competition OEM headed BBC then you may want to look at grinding cams with 2 intake lobes, 1 for the good runner and 1 for the bad runner. This is old Pro Stock stuff but works very well on class limited engines. These cams are expensive but will squeeze more power out of the engine.

Re: Cam Tech Talk on Custom Grinds
 

I was assuming he knows that data and is trying to find a grind to fit his particular needs. There are many, many grinds available thru Bullet, Cammotion, Comp, Crane etc... that would more than likely fit his flow profile at a decent price.

Might as well swap 4 and 7 lobes while your at it :eureka: Comp does this for a minimal charge.
Unfortunately I found this out after I ordered :(

Re: Cam Tech Talk on Custom Grinds
 

Dave,
I wasn't knocking your advice, just giving mine to Brian. Comp is a great company but your correct there are a ton of great cam companies out there:

Demos
Reed
Cam Techniques
Cam Motion
Schnieder
Elgin
Cam Craft
Bullet
Lazer
Airrington
Hyder
LSM
Jones
Cornett
Huggins

Sometimes the smaller guys can spend more time with you.

Re: Cam Tech Talk on Custom Grinds
 

I would also try to get ahold of RMbuilder (Bob). He's an excellent source to speak with when it comes to custom ground cams for marine applcations. N.Y. (585) 654-8583

Re: Cam Tech Talk on Custom Grinds
 

Hi Brian,
Consider talking to Dave Generous at Cam Techniques. Dave throughly understands the marine needs...all of them. Last winter, we Spinton tested my valve train to 7000 RPM. The valve train stability was absolutely excellent, very smooth. The only change we made while on the Spintron was to increase the exhaust push rod wall from .125 to .160 (increased weight and stiffness).
These engines, including Dave's cam design, exceed all expectations on the Spintron, the dyno and in the boat.
As you know, I run my boat hard and I spend significant time above 6000 RPM. This package is excellent at top end, acceleration and idle.
I never checked my valve lash last year. As the engines sit on the shop floor, neither the intake or exhaust lash changed .001 in 2005.

Re: Cam Tech Talk on Custom Grinds
 

Contact Bob Madera at Marine Kinetics. He set me up!!

RMBuilder on the board.

Re: Cam Tech Talk on Custom Grinds
 

Jason Saris at performance marine in lake George has experience with custom grids and also request specific billets that the cams are forged from. I got mine from him. The cam was made by Iskidarian (sp?) The motor builds lots of tork.

Re: Cam Tech Talk on Custom Grinds
 

Just getting back into this, what a weekend. Between St Pats day and the OPA Kart 2 Kart bash, I just woke up from a nap. :D

Thanks for the input guys. Here's the problem I'm trying to solve; my current cam setup makes great power, tq comes on strong with 550+ at 3000 rpm. It also stays fairly flat with a peak of 625 at 4700, peak hp at 5400. This torque band was my stated goal with my the 04/05 winter upgrades, and I was and still am satisfied with the results. After all, I run P-class, and I am right at peak performance for my class. Just for clarification, hydraulic roller, spinning at 54-5600 rpm.

Ok, so that's not a problem... the real issue here is I had a problem last fall where a lifter tie bar rivet popped off, lifters rotated in the bore, lobes knocked off the rollers, lifters dug into cam, cam dust through motor, and All Bad from there. In trying to analyze the failure, there was a contingent from the various manufacturers and engine folks involved (let's leave names and brands out of this) looking at my numbers, and the concensus was I needed to make changes due to the "agressiveness" of the Xtreme Energy lobe profile (inverted ramp). There was no real evidence of valve float or lifter toss, so the solution was a theoretical one. The gist of those changes were to change springs to a pacalloy(sp?) based design, lighten up sprung weight with titanium retainer hardware, and increase spring pressures to 175 on seat and 415 over the nose. They were originally set to 150 on seat and 390 open. Of course, both motors had these changes applied.

Now that I'm putting things back together for the season, I'm revisiting my cam selection. Things to consider are moving away from the inverted radius ramp profile to ease valve train abuse, but my main question is what changes would need to be made in duration and lift to "make up" for less aggressive lobe profile. Avoiding another valve train meltdown is now my primary goal, preferrably without sacrificing my torque band.

And there's another option: be happy with how it runs now, and write off the previous incident as a fluke, which has since been adjusted and corrected. Pucker factor has set in, however.

I've got about 2 weeks before dyno sessions begin, so I'll be making a decision what to do this week. The cobwebs should be cleared out by the morning, :rolleyes: so I'll call a few of your suggestions tomorrow.

Thanks again for the help,
Brian

Re: Cam Tech Talk on Custom Grinds
 

XFI profiles are going the opposite direction in agressiveness from what I'm trying to accomplish. Was anything special done to your top end? Do you know your spring pressures? What rocker setup and spring hardware are you using? How many hours on it so far?

And thanks for the Summit tip. Good to know.

Brian

Re: Cam Tech Talk on Custom Grinds
 

I'm using Pro Topline 320 runner aluminum heads, Jesel Sportsman rocker hardware. Some port work has been done and I can get you flow numbers if necessary. Also running a Dart rect port single plane intake manifold, port matched to the intake runners of the heads.

Please explain what you mean about 2 different intake lobes for "good runner and bad runner".

Thanks,
Brian

Re: Cam Tech Talk on Custom Grinds
 

Dave will be one of my calls. Having someone with specific marine knowledge is a big benefit. Often times when you call the tech hotlines of some of the bigger cam companies, you get folks that know how to make power in a straight line or a 1/2 mile track, but don't understand why I don't want to run a 106 LSA.

I've chased your boat while you were spending "significant time above 6000 rpm" :cool: If your valve train is staying together, that speaks volumes. But keep in mind I'm running hydraulic, not solid. Nor am I dry sumped, nor vacuum scavenged, etc, etc. :D

Thanks for the tip,
Brian

Re: Cam Tech Talk on Custom Grinds
 

I've talked with Bob on a number of occasions, and he will be another call tomorrow,

Thanks,
Brian

Re: Cam Tech Talk on Custom Grinds
 

My engine builder has recommended Bullet as well. Does anyone have any experience with these guys? Website?

Thanks,
Brian

Re: Cam Tech Talk on Custom Grinds
 

Ok one last question, then I'm done post-whoring for the evening...

What does swapping 4 and 7 do for you?

Thanks,
Brian

Re: Cam Tech Talk on Custom Grinds
 

Bob/rmbuilder of Marine Kinetics engineered the valve train set-up for my engines, and did a nice job of working closely with the person who assembled my engines (Dave of WESCO). I am very pleased with the results. Plus he gives wise, straight forward instruction. I hope all goes well for you this year.

Re: Cam Tech Talk on Custom Grinds
 

Now I remember this project. Brian as much as RMbuilder helped you last year with your issues with the one engine I would highly suggest working with him.

BBC have 2 intake runners. These runners are different from each other. Grinding a specific lobe for each style runner can optimize the combination.