Thread: Techinspector1's cam recommend was right on! More questions on cams

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To remind everyone, I was looking for a mild, streetable cam with a low to midrange power for my aluminum headed 355 to go into my undergeared Jeep with 35" tires. Techinspector1 was exactly correct on what Crane would recommend. Here are the 3 recommends I got. I have questions at the bottom:


Crane PN 113492
215/228 duration at .050"
5 degrees advance ground in
112 lobe sep angle
.454"/.480" gross lift

Lunati PN 60102 (voodoo cam)
219/227 duration at .050"
4 degrees advance ground in
112 lobe sep angle
.468"/.489" gross lift

Comp Cams PN 12-310-4
212/218 duration at .050"
0 degrees advance ground in
108 lobe sep angle
.444"/.444" gross lift


So from all 3 of these options, I would like some additional input. Remember, my goal is lower rpm power and street driveability when using a quadrajet carb. Smooth running and idle are not as important, but still a factor.

I am leaning toward the Voodoo shaft because it has the lowest rpm range, has 4 degrees built in (I would not add 4 degrees more BTW), and the has a shallow valve closing ramp to smooth out the drivetrain, and make it last longer. I'm open to discussion.

I will buy the hyd lifters with the cam (kit). I will use Shell Rotella during the 30 minute, 2500rpm+ break in. All 3 companies stressed how important breaking in of the cam was. I have not decided if I will degree the cam yet (check that all parts are mfg correct and lining up correct).

Im a huge fan of the Lunati Voodoo series. I think you would be really happy with any of them, but I would go for that one. And I would install it with an additional 2* of advance. (Intake CL 106*) I know that the guy who designed the Voodoo series always recommended 6 degrees on all his cams, they run best that way. Did you talk with Steve at Lunati? And for what it's worth, yes, degree the cam. It's always a good idea so you know where you're at. Plus, it's a good learning experience. Make sure you have the right springs too! John

"has a shallow valve closing ramp to smooth out the drivetrain, and make it last longer."

pnut, I'm not sure what you are thinking here, but I'll give you my take on short ramps.

As I've explained before, a fellow can determine the length of the clearance ramps on a lobe by subtracting the 0.050" tappet lift duration figure from the advertised duration figure. Well, you can't figure the whole ramp this way, but you can get close enough for comparison purposes and that is what we're interested in here. In other words, if a cam has 0.050" lift duration of 230 degrees and an advertised duration of 280 degrees, the difference is 50 degrees, or 25 degrees on the opening side of the lobe and 25 degrees on the closing side of the lobe. Now, some lobes are ground with these clearance ramps being symmetrical and some are ground non-symmetrical. Again, for comparison purposes here, we'll assume a symmetrical lobe.

Now, if you picture the lobe coming around to make the lifter begin climbing in its bore, it is understandable that if you have less clearance ramp, the lifter will rise more quickly and there will also be quite a lot more pressure on the lobe/lifter interface than if you pushed the lifter up more gradually with a longer ramp.

Back when I was a kid, it was common to see a cam ground with 70 to 80 degrees difference (35 to 40 degrees on each ramp). But competition does strange things to a product. In order to bring something new and exciting to the market, some manufacturers began to snap the valve open and closed for more "area under curve". Comp uses the term "extreme energy" to label their products that use this design. While it is true that you can have the valve open longer for the same duration design with a "snappy action" cam, it also puts a tremendous amount of stress on the lifter/lobe interface and tends to "wipe" the lobe of lubricant more easily, leading to failure.

Another contributing factor to this cam failure epidemic that I've been seeing lately is the lack of extreme pressure lubricants in motor oils. I can't remember the others, but I know zinc is one of the minerals being left out of oils lately due to the negative impact it has on calalytic converters and the increased pressure from car makers to produce a car that will live to 100,000 miles. I very strongly recommend that any of you high performance enthusiasts out there who want additional protection use some of the specially formulated racing oils that still have these additives in them and also to always keep a bottle of GM Engine Oil Supplement in the oil. It is formulated with molybdenum disulphide, a very good extreme pressure lubricant which will help protect the cam lobes/lifter faces.

Originally Posted by techinspector1

"has a shallow valve closing ramp to smooth out the drivetrain, and make it last longer."

pnut, I'm not sure what you are thinking here, ....... Now, some lobes are ground with these clearance ramps being symmetrical and some are ground non-symmetrical. Again, for comparison purposes here, we'll assume a symmetrical lobe.

You hit on a point here. The lobes on the voodoo series actually IS assymetrical. The opening is quite quick to give "more area under the curve" to quote Lunati's description. But it goes on to say that they close more slowly to reduce the extra stress which would be caused by fast closing.

So now I have to decide if the fast opening and the associated risks are worthwhile. I think my answer will be yes. From the research I have done online, the voodoo cams have been spoken of favorably.

I did ask the Lunati tech if the springs which came with my Holley heads (assembled) were appropriate for this cam, and he said yes. The are single springs, I have to look at the spring rate and compare those to the springs recommended on my own to be sure.

I did decide to go one cam tamer however. I will be installing the 60101 instead (looking at Lunati's site on the cam details and description). The 60101 gives and even lower rpm torque curve.

Thanks for all the advice, and I will degree the cam (an extra 2 degrees).

[QUOTE=techinspector1always keep a bottle of GM Engine Oil Supplement in the oil. It is formulated with molybdenum disulphide, a very good extreme pressure lubricant which will help protect the cam lobes/lifter faces.[/QUOTE]

Is this a GM part only? Maybe there is a parts store substitute that could be used? I am interested in more specifics so I know exactly what to buy (either from the dealer or at parts store).

Thanks techinspector1

JohnnyO brought up a good point about using the right springs with the cam. Always ALWAYS use the springs that the grinder recommends with his cam.

To take this a step farther, always use stock, STOCK, S-T-O-C-K springs for the break-in. I'm talking about just the outside single coil without any flat-wound damper or anything else. I used to keep an old set of worn-out stock springs on the shelf just for this purpose. Once the motor is broken in, replace the stock springs with the ones recommended by the grinder. Use shop air to hold the valve on their seats and use a Moroso valve spring compressor to change out the springs. It's not that hard to do it right.

Richard I always read your post with great interest. One thing i was really interested in was your post on snappy action cam like the extreme energy which I have in my engine. Now you have me concern about the oil and since you mentioned using a good quality oil such as a formulated racing oil, would it be appropiate using it in a street engine that will see just a few drag races. My 315(bored 305) puts out 303HP and 313 lbs. of torque and I usually put about 2500 miles on each summer. I also need to ask why use your old vavle springs on a new cam break in. Was I wrong using my new springs when I broke in my cam?

"would it be appropiate using it in a street engine that will see just a few drag races?"

Absolutely.

"I also need to ask why use your old vavle springs on a new cam break in."

I always recommend this because you never know what valve springs came with the cam if the writer doesn't say in his post. If it is a mild cam and uses pretty much stock strength springs, I would say it might be ok, but you never know when a guy is going to use a set of springs that he got from a buddy that were meant for a 8,500 rpm motor (outer, damper and inner springs) that will wipe all the lube off the lobes during break-in and result in having to tear down and replace everything. If your cam is relatively mild, then the springs are probably pretty mild also, and you skated by.

I cant speak for Richard, but what I believe he meant about the springs is that you want only enough spring pressure to get you thru the break-in...it seems very common that one of the primary causes of cam/lifter failure is spring pressure, on the tip of the cam..or tip of the lobe I should say. If your cam uses double springs, just use the outers, without the dampers. If it uses a single spring, I would just use that, which you apparently did. Richard uses an old set of springs, which is a great idea also. The main thing, at least to me, is to do what the cam mfgr. recommends. That way, if you still have a failure, you can at least say you did what they instructed you to do. Im talking mainly of using the correct (or lighter) spring, and the right lubricants for break-in. Also, on the oil issue, I have been running Rotella (shell) deisel oil. It still has lots of the additives that have been taken out of most motor oils. I run 15w-40 all the time. The EOS is a great idea also. Especially for the cam break-in. John

Oops...beat me to it Richard!! Im trying to make supper at the same time!

Thanks from both you Richard and Johnny for your input. My cam(not really very aggressive) 218/224 dur. .050 lift .462-.469 110 degree lobe, I used what comp said as far as valve springs. I was going to use my stock since I had only 2,000 miles on them with a stock cam that was in my 305. I broke it in with the correct lubricant and haven't had any problem with it with about 2,000 miles on it. For a fairly mild cam it really has a noticable idle to it. I have been using 10w-30w oil and at 70 I have a good oil pressure of 45lbs. but I've noticed that using that light of oil when it's ideling and warmed up my pressure is only around 8 so I'll start using a heavier oil.

Buy Engine Oil Supplement at the parts counter of any General Motors dealer, Chevy, Cadillac, Pontiac, GMC.
DO NOT SUBSTITUTE !!!!!!!!!!

Man-o-man pnut, when you show up and give your buds an earful about how to put a combination together, their jaws are gonna drop to the ground. I'd love to be there to see it and hear it.