I called up CMS and I ordered a custom cam based on my LE heads and made for my 382. I gave them my flow numbers and anything. I was told the lift was .56X/5.57X lift and was a 233/242 based on the GM 847, on a 112LSa+4 adv. I got a cam that looks to be the same as an off the shelf CMS cam, except the site doesn't say anything about the 4 degrees advance. Anybody ever have this problem? I'm kinda pissed off right now...and I'm gonna call on monday and ask WTF the deal is.

I was kinda worried the 233/242 would be too small for a 3.8" stoke 10.5:1 382 LT1 to make 415 RWHP. Now I'm worried that my cam isn't even a custom or is just bogus now!

I'm not so worried about the small difference in cam...I just feel like I've been treated like a stupid customer that doesn't know any better I paid for a custom, I want a custom!

 

comp cams already have 4* advance put into them out the box,the rwhp can be attained with that cam 415 you stated.i think you may make more but that all depends on your tune and matching parts,i understand your concern but i am sure dave has you taken care of,have you tried to contact him@702-798-8504...

 

I'm calling them first thing when they open monday morning. I just got it in so I didn't know until a few minutes ago. Damn I'm pissed...

 

how can you tell it's not customized, just curious

 

Is there a price difference between a "custom" CMS cam and a off the shelf cam? If so then that's shady IMHO...... I have "shelf cams" that I tweak for motors so I have a good starting point, this is a standard practice with cam guys. OTOH i don't change the price on a design I have already done vs. a new design. If it's the best setup for the job, it's the best setup. Starting off with a known cam and then tweaking it to match the combintion it's going into is a good idea.

I don't know if they were taking advantage of you, I don't know if I would go that far. Does custom mean that it's specs that nobody else uses or the right cam for the job?

Big thing I see on that cam is the LSA is a bit high for the motor, and as I have said before the 233 lobe is not the best in the word.

BTW Comp only grinds cams at a +4 if you ask for that. the 233/242 is not a "off the shelf" Comp cam but as in any Roller cam from Comp they all cost the same no matter the duration, just the material (cast or billet) and the firing order change the specs.

Bret

 

Bret said it well, but just to state the same thing somewhat differently. Cam guys have a general idea of what will work based on past experience, often combined with some sort of engine simulation software. If they analyze your combo and decide what is best, that is a "custom" cam even if it comes out the same as one of their prior designs, or if it is the same as a catalog ("off the shelf") grind. You are paying to get a cam matched to your combo and intneded use, not necessarily a unique design, unless it is needed.

Bret designed my current cam, which works great. It does happen to be quite different from any off the shelf LT1 grind. But that because my combo is pretty unusual. If, in the end, we decided that the bast cam for the job was a pre-existing design I would have been just as happy to pay him for his expertise. If I take out your appendix, should I charge you less because the operation was pretty much like the last appendectomy?

Rich

 

not to make an argument about a cam manufactuer,i have been using comp for 16 + years and every cam has had+ 4 from the little cams that are used to the cams run in door cars:268-290 @.050 with lifts from 680-820 on 108,110,112 lobe sep.now if you specify to comp they will change that for you.....on another note,i have also seen where people will try to make their own cam specs for a cam grinder to follow but if they have a grind that is almost dead on you will end up getting that cam.
i dont beleive that their is any shady doing here,if you dealt with dave he took care of your request to the best of his ability.

 

What makews me wonder is that I was told the cam was going to be a 233/242 and that it would be a custom from comp...and it ended up being an off the shelf grind they list on their site. If they carry those grinds as 'custom' grinds that are selected based on someone's particular combo, then I see what you're talking about. I'm not really too sore about it but when someone tells me I'm getting a custom cam, I guess I dont expect to see it sitting on a website with a part number. Sounds like the term 'custom' is kind of misleading to me. That's where I'm kinda pissed.

My original intent was to get a cam for my 383 based on the GM847, using lift numbers that compliment my heads.

As far as I know, that cam would idle pretty tame in my new motor, kinda like a hotcam. I wanted something a little bigger than that, especially since it has 4 deg. advance ground in. I doubt the 3 degrees on the exhaust would make much difference, I'm just sure there's an explanation and I really want to hear from them what it is.

Bret, I was going to get one of your cams, but I ended up falling on store credit from CMS that made it so the cam cost me like $25. I'll eventually get something that flows more like some LT4 TEA heads, and when I do I'll get a custom ground on those. When I do, I'll give you a crack at it. Probably be later in the year after my 12 bolt.

 

An example of one that I was working on today....

406 SBC for a drag car, big stall, 7500rpm shift.

Everyone has a cam for this setup on the shelf (Comp, Crane, Isky, Lunati)

Isky 201673
Comp 12-970-9
Lunati 50140

Basically 275-280 @ .050 intake 284-288 @ .050 exhaust on a 104-107LSA

It's a big cam compared to what you guys are used to seeing! Well in general it's big.

All of them are ground +4 and that makes a ton of TQ for the motor at this stall. None of them really make the HP kick in at the top end though because they are geared for the launch and more duration starts killing the TQ at launch.

I worked on this one for a while and came up with something in this same duration and LSA area, makes around the same TQ at stall and more average HP. With this setup the converter is not really made for this much TQ so it will probably stall 200rpm higher where this setup would be at TQ peak and then pull even harder. I didn't throw in a +4 on my design and worked more on the E/I % based on valve curtain area and lobe area calculations. Basically started with a guidline and worked from there. Thankfully there is a place to start on something like this, Rich's setup was a odd ball setup that didn't have a baseline.

The cam is really close to the off the shelf cams, but I found a good 1.5%-2.5% more average power (in simulation of course) because the cost of the cam is the same reguardless if Comp (my choice in cam grinders) has it on the shelf or I custom make it.

Now this is in Solid Roller land where you can get a lobe in any duration from 230-328 in at least 2 deg incriments and sometimes 1 deg incriments. Granted these lobes differ from super aggressive to very mild high RPM lobes, but for the most part you will have lobes that are 2 degs apart for +/- 10 degs from the optimum lobe for the application.

Hyd rollers aren't the same here. You are very limited in your lobe choices (for SBC & LT1, not so for LS1's) and +/- 6 degs is doing well from lobe to lobe. For example Comp has the 224, 230, 236, 242, 248 lobes in a number of different lobe profiles. So you get into the right range with the duration and tweak the LSA and advance to get the valve events in the right spots. Considering that most peoples cams are way off here you find some good gains to start with. Then it's mostly a choice of which lobe and combination of parts you are going to run. Custom hydraulic cams are harder to see by the obvious numbers (duration, LSA) there is a lot in the lobe shape and where the valve events happen.

BTW Cam design and Surgery have things in common, making each one go as well as the last is a big comonality!

Bret

 

It just kills me that people get on here and rant and rave about something a vendor [supposedly] did, even before talking to them. Like someone on here can tell you if you were treated wrongly. It just doesn't make any sense. Sorry, but all I end up hearing is a whining noise.

 

hey Rob, let me buy you a beer buddy

 

If I remember correctly CMS has their own lobes these days. When they first opened business they basically ordered cams that were popular like the XE grinds guys are running. More recently however I have seen them start to make their own lobes based on the XE design so you can get just about any combination of duration you could dream up. So a cam that may "seem" off the shelf is just exactly what you need. Also the differences are not always obvious looking at the cam card. I have a somewhat custom cam because I wanted it ground on a 110 LSA for a higher DCR but it didnt cost me any more $$ and if you dont look closely at the cam card you might think its the regular XE224/230 everybody talks about(224/230 112LSA). On top of that if you go to Comps webpage and look up the Extreme Energy lobes you will find 3 cams that you could call the XE224/230 but of which all have considerably different profiles because of the lift ranges.

 

BTW they are not their own profiles.

226 .560 lift at 1.6 = Comp 2113 S Lobe
227 .560 lift at 1.6 = Comp 3441 S Lobe
233 .567 lift at 1.6 = Comp 3442 S Lobe
239 .578 lift at 1.6 = Comp 3443 S Lobe

Those are all old Comp lobes.

I could make you any cam with those lobes but I choose not to for my own reasons based on what I know. Again this is not a knock against them but if you wanted a 233/239 cam on whatever that's not that hard to do if you know the lobe numbers.

Any other setup is going to be a estabilshed lobe ground based on a different journal size to make the duration change. Guys did it all the time on LS1 cams before they made all the LS1 lobes.

Sometimes this is as easy as matching up a lobe and a lift and saying ah ha! When you get into it, knowing what lobe is the most aggressive and least aggressive and what works with what spring is another story that very few people know and understand.

I could go on and on about this stuff. If you know the story of what's going on it's really not that hard to come up with these "custom" lobes.

Bret

 

It was my understanding they were based off the XE designs... but I always kinda wondered in the back of my mind if they actually did what you are claiming. Thats too bad.

 

Give me an example of you cam.

Duration 224/230

lift with what rockers

LSA and ICL or advanvce.

Bret