Cam Lobe Pictures, Need Analysis Help

[madmaxx]

Can you feel a lip at the end of where the roller rides? If you can you got a bad cam which will lead to spalling. The depth of the hardening is too shallow. No doubt in my mind!!!

[wrogers55]

First Rick, thanks for the effort and info via PM. I really do appreciate it.

This might be my chance to tweak the cam specs a bit for my use. All street, no track or strip.

This is where I am:

Rear tire is a bit over 25" and the current rear gear is 3.10, with a 5th overdrive of 0.82. I'm changing the rear gear to 3.46 or 3.55, still making up my mind. I use the car mostly for local cursing and a bit of highway driving and of course a 2nd or 3rd run up once in a while. Of note, the 3.10 rear gear/25" tire was a dream with the TKO600 1st gear being really useful and the 0.82 5th still had great pulling ability with the power this motor made. Lowering the rear gear might make it come to life a bit more, but I also worry about screwing up a pretty good combination for the way I use the car.

I really liked this cam for power and the drivability was OK for my use. But it came on strong everywhere and especially from 3,000 or 3,500 up. I have it limited at 6,250 for now. So, on this grind it was really pulling hard right through the limiter. The motor would clear up from a rough idle at about 1,500 and freeway driving was at about 1,800 to 2,000 and smooth. Seems like maybe for where I have it limited, the power band could be driven down a bit and be more useful (fun). I suppose that's why it was originally set up at 2+ advance on the cam. This isn't my specialty, so my understanding may be off here.

The rest of the motor story is: Heads are AFR 205s, FI is MassFlo, 1000 cfm, 42 lb injectors, compression is 10:1 or so the piston specs say, not sure how that works out with my bore/stroke combination. I'm not sure of the crank/rod setup, but the rods are H beam and the crank looks to be steel. The motor was supposed to be build with all top shelf parts, but I acquired it at about 2,500 miles so I'm discovering as I go.

Your thoughts and advice will be greatly appreciated. I want to do this one time only and hopeful I can get it right. If I go back with the same grind, I'll probably be as happy as I was before, but if it can be made better, I'm all in.

I'm going to repost this on the public forum and hopefully it can help with the educational/operational process for others as well. An amazing wealth of knowledge and opinions flows out here. We should all be grateful for the time others take to help!

[DAVID GAGNARD]

Rear tire is a bit over 25" and the current rear gear is 3.10, with a 5th overdrive of 0.82. I'm changing the rear gear to 3.46 or 3.55, still making up my mind. I use the car mostly for local cursing and a bit of highway driving and of course a 2nd or 3rd run up once in a while. Of note, the 3.10 rear gear/25" tire was a dream with the TKO600 1st gear being really useful and the 0.82 5th still had great pulling ability with the power this motor made. Lowering the rear gear might make it come to life a bit more, but I also worry about screwing up a pretty good combination for the way I use the car.

Sounds like you have a really nice set-up and enjoy the car for what you do with it. I'm not making any suggestions to changes, but would suggest you think about what you do with it and how satisfied you are with the set-up "as is", then decide how it would be better for YOUR intended usage and make changes accordingly......

David

[blykins]

Wayne,

I would go back with a hydraulic roller and cut the duration down a little. I always applaud guys for building the engine for the intended purpose, not for sound, not for peak horsepower, etc.

My advice would be to do a custom cam, use the XFI lobes, 242/242, .621/.612" lift, on a 112 LSA. I would run it on a 106 ICL.

[Keithc8]

For what it is worth on that size en gine with that style fuel injection I would look at something in the 236/242 range with mid .500 on lift on a 12 lobe speration on the conservative side to 242/248 with mid to high .500 lift on a 112. The fuel injection will like this and the bigger exhaust will let it breath a little better up high. Most 418s have a 4.100 stroke so you should have good torque. The 112 lobe seperation will work well with the EFI and I would install 4 degrees advanced. I also like to use a smoother lobe than the ones you listed. Most cams are design with a SBC or LS1 enigne in mind and most are to aggressive for the SBF valvetrain and cause floating issues. Good luck,

Keith Craft