Camshaft for 5.9 Magnum

[Idaho]

This is basically a continuation of this thread about choosing a carb and intake, but moving on to the camshaft.
http://www.forabodiesonly.com/mopar/showthread.php?t=178560

My basic recipe started here:

http://www.hotrod.com/techarticles/e...e/viewall.html

This is their setup:

LA timing case and accessories. LA oil pan.
M1 intake w Speed Demon 750
Mopar performance electronic ign.
Edelbrock RPM heads (9:1).
Stock lifters/retainers.
Comp 1.6:1 roller rockers.
Comp Magnum push rods.
Hooker 1 3/4 headers.
Comp custom grind:
Comp's XFI hydraulic roller lobes No. 3016 and No. 3037 on the intake and exhaust, respectively, 230/236 at 0.050 on a 110-degree lobe separation, 0.576/0.571-inch lift

Read more: http://www.hotrod.com/techarticles/...block_mopar_engine/viewall.html#ixzz1oIX3ZzbR


With input from members here, I'll likely make a few substitutions:

RHS X heads
Performer RPM intake
Holley 670 vac secondaries
Summit headers
stock rockers and push rods

I'm in the process of educating myself about cams. I'd like to start by clearing up a point of confusion to me found in this article.

LOBE SEPARATION ANGLE
By choosing a cam with the correct LSA for the engine's intended usage, you can have your cake and eat it too. First of all, the LSA is ground into the cam at the factory and cannot be changed. It represents the number of degrees, in crankshaft rotation, that separate the intake lobe centerline from the exhaust lobe centerline. A wider LSA figure, i.e. 112-116 degrees, moves the lobe centerlines further apart and will smooth your idle due to the decrease in overlap that creates. The lower the figure, i.e. 106-110 degree, moves the centerlines closer and will increase bottom end power, but your idle will suffer along with it. We did a test a few years back running five different LSAs on otherwise identical cams in the same engine. What we found was that the cams with a 108-110 LSA worked best all around. But idle vacuum was higher with the wider LSA cams (112-114) and this would translate to better idle quality. Bottom line here is that most cam companies have put lots of effort into selecting the proper LSA for the cam's intended usage so you'd be wise not to second-guess them.

Read more: http://www.superchevy.com/technical...c_right_cam_choice/viewall.html#ixzz1oIRRmO00

My thinking was that lower LSA should reduce low rpm power by lowering dynamic compression because the overlap is increased. The gain should be at the higher rpm where overlap allows high velocity airflow to pack in more air after TDC.

So I ask (like O'Reilly) where am I going wrong here?

 

[Abodybomber]

A lower lsa tends to make a peakier and shorter power band.Comparing 2 otherwise identical cams.The. narrow lsa will make more low and mid range torque(2 to 5000,roughly).At the expense of smooth idle,and a little top end power.

 

[LXguy]

Well, its never a good idea to get tech info off of a Chevy site. LOL

I can't say with absolute certainty that they're wrong based on their specific test circumstance, but the conventional wisdom definitely indicates you are right, and they are wrong.

It is important to remember that 110 degrees is almost a third of the way around the cam, and that lobes come in all different shapes and sizes.

Increasing overlap lowers low RPM power, yes. Narrowing lobe separation increases overlap (assuming there is any) but not necessarily in a meaningful way, depending on lobe profile, port velocity, gross inlet capability, and on and on. Cams are supposed to be part of a system, and there are a lot of different factors that come into play. This is teh slippery slope where potentially, maybe the Chevy article isn't wrong.

A confounding fact is that whole "comparing otherwise identical cams" thing. As in, that never really happens outside of a magazine article. Typically shelf cams ground with a wider LSA are designed for lower RPM, entry level (or EFI) engines and LSA typically narrows (and duration and lobe profile get more aggressive simultaneously) as you move up into the "great with big carb, headers, gears, ported heads" kind of thing. If you see an entry level cam with any kind of narrow lobe separation, its a fair bet it has very mellow lobes, or is designed for very restricted heads, or some other special circumstance.

It seems like most common performance '268 style' cams are in the 110 range, and no matter what you do for your motor, you will probably either end up at 110 or 112.

I've run a 106* cam before, but that was a custom grind in a restricted cylinder head engine that was designed to shift at 8000 RPM. It needed 3500 RPM to start a climb into an enclosed trailer! BUT it had a ton of duration, overlap and square looking lobes also.

Stock 5.0 Mustang cams are 114* lobe separation and they make a ton of torque (for a little motor), but they're all done at 5000 RPM (intake and heads take some blame here as well).

There are some good tidbits with regards to all this on Lunati's site.

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

There's a cam grinder named Buddy Rawls who has it all figured out. You may be able to find some articles by him if you do a google search. Warning, not entry level.

FWIW My recommendation is still to get a custom cam. Talk to someone who knows all the ins and outs, and let them use their experience to either choose a good shelf cam for you, or grind one to do what you want.

Good Luck!

Steve

 

[805moparkid]

something to add to is the original SS hemi cars ran a 106LSA to raise the power range BECAUSE they didn't have a good tire to hook up with...

so it allowed them to launch and make more power up top...

 

[Abodybomber]

If you want to see real world results and explanations,check out David Vizards How to build low buck small block chevys.Has a entire chapter on this.And better yet,how to apply it correctly the 1st time.Might check it out.

 

[Idaho]

Thanks for the input. I think I have entered into the black art, the very heart of the gearhead

Here's my basic understanding the effects of LSA as it applies to a my typical engine buildup:

Less LSA, say 106-108 increases valve overlap. This enhances high rpm air flow but reduces dynamic compression and vacuum at low rpm. The result is a power gain with band shift to higher rpm and rough idle. Of course all the opposites apply to higher LSA.

My understanding of duration is that it has numerical effects opposite to LSA. More duration has all the above effects caused by less LSA.

My goal is to have a tire burning power band lower in the rpm range but not totally sacrificing power up to say 5500 rpm. The manual tranny will help like a high stall converter helps, avoiding the need for power right down to idle range. The Comp cam program recommendation of 110 LSA with a modest duration around 220 seems sensible.

Some other pearls of the dark art I have obtained:

Roller advantages:
Power gain by allowing more aggressive lobe profiles (high lift without excesssive compression-robbing duration).
Power gain by reduced friction.
Better durability by reduced friction.

The advantages of a roller cam make me happy with the my change in plan from 340 rebuild to 5.9 Magnum. I'm fairly certain the cost to build the 340 with roller would be prohibitive in comparsion.

I found this article particularly helpful.

http://www.enginebuildermag.com/Article/4916/choosing_a_replacement_camshaft.aspx

Lobe profile is a bit of a black box to me that is not so easily accessible.

If you try to compare duration specs between different cams, though, you don’t always get an accurate comparison because duration specs don’t tell you anything about the lobes themselves. Though cams from two different manufacturers may have identical lift and duration specs, the lobes on one cam may be ground differently from those on the other. One cam may have more of a peak shaped lobe while the other has a “fatter” lobe. A “V” shaped lobe will breath differently from a “U” shaped lobe because it doesn’t hold the valve at its maximum opening as long.

One lobe profile may also close the valve more softly than the other, to reduce valve bounce at high speed. Valve float can also be a problem with lobes that change shape abruptly unless valve spring pressure is increased. The profile of the lobes on one cam may also be the same on both the up and down sides of the lobe (which is the norm for most stock and street performance cams) compared to an “asymmetrical” grind (different profiles on each side of the lobe) on the other cam.

The only way to really compare cam grinds, therefore, is to measure and plot lift versus rotation on a graph. This can be done manually with a degree wheel and dial indicator (which is a tedious job), or with an electronic stylus (such as the Cam Doctor) that plots the results on a computer.

I read somewhere that the different cam companies vary in the aggressivemness of their roller cam profiles but I have no information that clarifies this issue.

Just for clarity, in case anyone gets the wrong impression of what I'm doing here, this is from my prior thread:

I don't really expect to learn enough to make a good choice independently but will take advice from members here and whoever I buy from. That said I want to use the process to learn.

At this point I understand that cam choice is hugely important, that it largely determines the "personality" and "functionality" of the engine, and that it is a complicated and evolving art/science. I intend to take some time with the decision.

I greatly appreciate the input from the members here.

 

[Abodybomber]

Idaho,you are correct.If you decide to further yourself,try the book I mentioned,any Isky catalog,and check the circle track magazines.Can't ever know enough.

 

[805moparkid]

Idaho,you are correct.If you decide to further yourself,try the book I mentioned,any Isky catalog,and check the circle track magazines.Can't ever know enough.

yea cams are definitely the dark art to taking any motor to its true potential...

 

[Idaho]

Well my head hurts a bit now after reading a fair bit about camshafts. So here's a few observations.

There's a lot of strong opinion and hot air out there on the subject. Some of it reminds me of the alternative medicine industry - many claims without a lot of hard evidence to back them up.

I do believe that the science has come a long way but you wouldn't know it from reading discussion on the subject. To some degree its the result of competition among those with a stake in the cam grinding industry, maintaining secrecy about how their special grinds have been derived.

Some of the smaller cam grinding companies comment on forums and even get into heated exchanges. The larger companies stay out of the fray.

David Vizard is generally held in high regard but his views are not universally accepted. There are quite a number of other "gurus" out there.

Here's a quote in that regard. This is from one of three long and mostly pointless threads on an LS1 forum. VE refers to valve events. IVC is intake valve closing. The philosophy camps regarding "splits" refers to how much duration is given to intake vs exhaust, standard being shorter exhaust (about 75% of intake). There are of course some pearls to be found.

http://ls1tech.com/forums/generation-iii-internal-engine/101100-camshaft-discussion-part-ii-7.html[/url]

This one is the more general thread they have as a sticky:
http://ls1tech.com/forums/generation-iii-internal-engine/1325476-camshafts-choosing-dummies.html

This is the best paragraph in this whole post

"One of the things that 93Pony brought up and Ed echoed was a different way to look at camshaft design. For instance, folks get hung up on LSA. From Ed's point of view LSA is a byproduct of you VE and your lobe. I.E. You decide how big a lobe you want. You figure out your VE's, and the LSA is just a byproduct of those figures. To me that makes a lot of sense. If you get fixated that a lobe has to be so far apart (via the LSA) then you may totally miss your ideal time to open the valve. At that point you have your LSA, but your camshaft is going to be down on power. Again, whatever camp you are in reverse split, symetrical, or standard split this all works the same."

Right on, I completely agree and couldn't say that better myself.

I was looking thru my book shelf the other day and found Dave Vizzards book on cams. It's a great thing to go back and read once you understand all the concepts in the book. Not because you learn a ton, but because you can critque his writings from 10+ years ago. The guy had alot of practical exprience to share and that in itself is valueable.

He gets into a big LSA disscussion where basically more LSA is better than less is his ultimate conclusion. I'm not from that camp, IVC is the most important with overlap area coming in next in terms of power. The reasoning behind his point is shown in a chart where there are 3 versions of the Isky 270 Megacam, one on a 111LSA, 108LSA and a 105LSA. The 111LSA was down 20-25hp while the 108LSA was the right amount of LSA for the cam with the 105LSA making slightly more power but at the cost of other things not wanted in a street car.

Now just looking at what I wrote, and seeing the graph you say: Yeah the 108LSA is the optimum LSA for cams. Now the problem is, that we don't know the rest of the facts there. The Isky 270 Megacam is a 221/221 .485/.485 108LSA cam. So it has 5 degs of overlap with a 108LSA, 11 with a 105LSA and -1 with a 111LSA @ .050. Now you start to get something usefull from it, the problem being those specs are not listed there. Oviously the overlap area is important, but he never really quantifies it, just says more is always better than less so error on the side of more.

There's enough of Vizard's stuff online I don't feel the need to buy his book, at least at this time. Some of his writing seems to get off on tangents but perhaps thats just my ignorance. This is one I found useful:

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/viewall.html

I have a few pearls I've gathered to add to the post later, really just things that I find interesting.

As far as choosing a cam, at this point I think Comp cams computer program is amazing and may be what influences me the most. I am impressed that its predictions are 95% accurate, or at least that is what's claimed. There are some very nice looking dyno curves for my engine.

It seems however, that if you want to go custom, you have to decide to trust someone and let them apply their particular cam grinding philosophy.

What's funny is it would not surprise me if I would wind up, after torturing my brain adequately, simply copying what someone here has done.

 

[Idaho]

Likely because of their cool dyno program I'm thinking of buying a cam from Comp. I also feel like their hardening process might add to durability.

XR265HR-14 216/224 .506/.506 custom ground to 110 LSA
off shelf LSA is 114

This is the cam recommended by Comp Cams for my application.
I am rather surprised at the power on the Dyno computer:

HP 485 peak, 271 avg.
TQ 482 peak, 307 avg.

Those are with the 114 LSA. Not sure how the change to 110 would affect the numbers. The torque comes on hard at low rpms.

I am planning a big purchase from Summit with a 10% discount code from a kind member here. Not sure if I can do the custom cam that way but there's lots of other stuff including head gaskets.

Anyone got a recommendation for a head gasket? I'm thinking not too thick, not sure beyond that.

Also, any suggestion for header gaskets. I'm planning to use the cheapo Summit headers.

I also plan to degree the cam. I'm thinking I need a cylinder stop tool, one solid lifter and a spare push rod to do it before the head goes on- does this make sense? I have a dial indicator and magnetic base.

 

[Idaho]

Here's one of the interesting tidbits I want to throw in. I was wondering why Comp would shorten the LSA. Here's the answer:

The FI cams are a wider LSA. FI runs leaner A/F ratio's. Wider LSA helps avoid detonation that can be brought on by running these leaner mixtures. Anti knock sensors will dial the timing back if detonation is detected but that also sacrifices power.

 

[Idaho]

OK this will verify my confusion regarding cams. This is from Comp's website. Everything in color is opposite to what I expected. :banghead:

EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA)

Tighten (smaller LSA number)......Widen (larger LSA number)

Moves Torque to Lower RPM............Raise Torque to Higher RPM

Increases Maximum Torque...............Reduces Maximum Torque

Narrow Power band.............................Broadens Power Band

Builds Higher Cylinder Pressure........Reduce Maximum Cylinder Pressure

Increase Chance of Engine Knock....Decrease Chance of Engine Knock

Increase Cranking Compression.......Decrease Cranking Compression

Increase Effective Compression........Decrease Effective Compression

Idle Vacuum is Reduced.....................Idle Vacuum is Increased

Idle Quality Suffers...............................Idle Quality Improves

Open Valve-Overlap Increases.........Open Valve-Overlap Decreases

Closed Valve-Overlap Increases......Closed Valve-Overlap Decreases

Natural EGR Effect Increases...........Natural EGR Effect is Reduced

Decreases Piston-to-Valve space....Increases Piston-to- Valve space

I think the parts in red can be the effects of rpm and air velocity creating dynamic compression gains over what static compression provides. The parts in purple baffle me.

My brain trying to understand: :violent2:


I did find their suggested cam degreeing method does not require a solid lifter:

The Intake Centerline Method still requires accuracy to be correct, but it is somewhat more forgiving. Once you have degreed a camshaft using this method, you will be surprised at its ease. We also recommend positioning the dial indicator on the #1 intake retainer because lift measurements will include any deflection that may occur in the pushrod and rocker arm. This makes the degreeing process as accurate as possible in relation to what actually goes on inside the engine. Before you proceed, you will need a Cam Degree Kit (Part #4796) from COMP Cams®.

 

[bryan340]

I have a 95 dodge dakota short bed no extend cab that I put a mopar crate 360 in here are specs R/t ported heads 202 valve , cam 220 230 507/ 507 114, ported tb, 24 lb injecters , headers , mopar computer, and a 3000 stall convertor with a 355 gear truck would run consistent 12.55 at 106 mph. Now I am putting the motor in a 64 dart gt but with a m-1 and 750 carb with a 904 behind it . Would their be any big gains switching to a different cam? I think the combo was leaving some hp on the table with the computer , it kept going into a limp mode and was giving me some problems. Sorry for the hi jack but this cam stuff is confusing !!!!!!!!

 

[Idaho]

That's impressive 1/4 time! What tranny and tires are you using? What is an R/t head? Do you know the weight of your Dakota?

I agree it can be confusing. Have you played with the comp cams dyno program? It is claimed to be 95% accurate and will show what's the max output with their wide cam selection. They also suggested for my app to slightly cutomize with an lsa adjusted to 110. I've been communicating by email which is not the best, shy on details but will get with them in person at some point. To make it accurate for your engine, you need to ask them what head profile to enter. I'm planning on RHS heads so they recommend "2-valve pentroof, pocket ported stock valves" to match the flow characteristics.

Using the program, adjusting components (like valve size, carb, intake etc) has very predictable results for a particular cam. Very informative in terms of learning where big effects occur. Not exactly where I thought.

However, different cams produce radically different power curves and for the life of me I can't look at the cam specs and see the correlation.

Brian at IMM engines has suggested their thumper cam, but the only one I can see in the dyno program is down in overall power output compared to their suggestion. Its the mild version and they have two more aggressive thumpers I can't see on the dyno. I'll ask them about these.

One thing to contemplate is the lobe type. The best power output is with their XR lobe which of course will be quite aggressive so proper springs will be important, and durability may be an issue. I seems the XE lobe is more popular.

There are many on this site who actually know something on the topic. Perhaps someone will chime in.

 

[bryan340]

Tranny was the factory a518 with a transgo shift kit and a precision industries viper 3000 stall torque convertor, rearend was factory 8 1/4 with 355 gear, truck scaled at slightly over 3500 lbs no driver. The heads were available through mopar from what I hear they don't make them anymore. I purchased mine through KRC performance out of Florida they were ported and polished said to flow 250 cfm some claim more. They called that cam and head set the lightning killer package, supposed to produce 320 rwhp. I sparayed the truck only twice with a 100 shot and ran 11.53 at 114. I'm excited to see what it will do with a carb and no computer in the dart. I'll probably leave the cam in just to see difference!!!! Forgot about tires M/t et street 27 by 11 They hooked good 1.80 60 foot.

 

[crackedback]

Take the numbers from the comp cams software with a grain of salt. I'd be very surprised if that smaller cam made anywhere close to 485hp and that TQ number.

 

[Idaho]

Comp custom grind:
Comp's XFI hydraulic roller lobes No. 3016 and No. 3037 on the intake and exhaust, respectively, 230/236 at 0.050 on a 110-degree lobe separation, 0.576/0.571-inch lift

this parts selection put major firepower in the basic Magnum package, with 448 hp recorded at 5,800 rpm and 435 lb-ft of torque coming to bear at 4,900 rpm

Read more: http://www.hotrod.com/techarticles/...block_mopar_engine/viewall.html#ixzz1qpMGjOxU

Comp's recommended cam:

XR265HR-14 216/224 .506/.506 custom ground to 110 LSA

It has 14 degrees less duration than the one in the article and a lot less lift. Not sure how the lobe profiles compare. I couldn't find it in this article but in at least one other, they claim the cam produced near exact what the program projected.

I get what you're saying, based on the cam specs. Can you give me an idea why the program would give inflated numbers? When I look at different cams on the program I can't see good correlation between duration, lift, and power output so as I said it confuses me.

Perhaps there's marketing BS involved?

 

[Abodybomber]

That isn't a standard set of cam profiles.Those heads peak a .550 to .575 lift.To sell heads,(and cams!) they needed. a big power number to grab your eye.That program is Desktop Dyno 2000.It gives you an rough idea,not dead on the money. This is why good machinists charge more than Jegs or Summitt.Usually , you get more from someone who has done a few of that type build.

 

[YY1]

I ran a bunch of those comp cams simulations, and did print screens, then laid them out next to each other. It was kind of finicky to get them to come out right, and tedious, but with them all in order according to grind, and being able to see two or more at a time, you can easily see the relationship, and where the different profiles add to or detract from the hp/tq curves.

 

[rumblefish360]

WOW! There is so much good chit here, I aint gonna comment. Except;

I've run a 106* cam before, but that was a custom grind in a restricted cylinder head engine that was designed to shift at 8000 RPM. It needed 3500 RPM to start a climb into an enclosed trailer! BUT it had a ton of duration, overlap and square looking lobes also.

Yep. been there done that experienced it as well.

OH WAIT! I like your cam choice with the Edelbrock heads.

 

[Idaho]

WOW! There is so much good chit here, I aint gonna comment.

Dang! Was hoping someone could clear up some of the "chit". I suppose I've rambled on so much it looks to be an impossible task.

OH WAIT! I like your cam choice with the Edelbrock heads.

Are you saying you like the Comp cams choice with Eddy heads?

YY1 I ran a bunch of those comp cams simulations, and did print screens, then laid them out next to each other. It was kind of finicky to get them to come out right, and tedious, but with them all in order according to grind, and being able to see two or more at a time, you can easily see the relationship, and where the different profiles add to or detract from the hp/tq curves.

I actually started doing that and got frustrated with the printing out part. My computer skill are shaky. Glad you could see it.

Abodybomber That isn't a standard set of cam profiles.Those heads peak a .550 to .575 lift.To sell heads,(and cams!) they needed. a big power number to grab your eye.That program is Desktop Dyno 2000.It gives you an rough idea,not dead on the money. This is why good machinists charge more than Jegs or Summitt.Usually , you get more from someone who has done a few of that type build.

So you're suggesting I just trust a good machinist and forget Comp Cams. I may in fact do just that. I haven't decided yet.

I'd kinda like to know how you guys evaluate a cam. Maybe its unrealistic to ask for but I bet there's a set of basic steps that you use to judge the parameters and get a quick read on a camshaft.

 

[rumblefish360]

Yes. I normally run in a 4spd car and cam a little heavy. For a street/strip ride, as much lift as the head will handle before stall is what I like to do. Duration is the RPM band and is so selected to suite the cars parameters and intended purpose and gear ratio/tire size ;)

 

[Idaho]

It would help me a great deal with perspective to have a range from "kinda mild" to "pushing the upper limit" for duration, lift, and LSA.

I'll want to push into the upper limits of what the valve train can handle without asking for trouble. I also don't want to be wishing I'd gone for more.

I just picked up an 8.8 with 4:10 gears and plan to run tires in the 27-28" range. The 4 speed is an overdrive. It will not be a daily driver, just a weekend fun car. A lopey mean idle would be nice but not if it means sacrificing low end torque. Manual brakes so it won't need a lot of vacuum.

It will see occaisonal 1/4 mile runs in Spokane. I have an old set of slotted mags and will put some sticky tires on for that. More important will be just playing. I want to scare my wife and daughters, and anyone else in for a thrill, lighting up a set of not so sticky tires at will. :burnout:

Of course I'll be talking to a cam grinder at some point but any opinions on what's mild and what's wild will make my day.

 

[rumblefish360]

It would help me a great deal with perspective to have a range from "kinda mild" to "pushing the upper limit" for duration, lift, and LSA.

I'll want to push into the upper limits of what the valve train can handle without asking for trouble. I also don't want to be wishing I'd gone for more.

With all the info here, I'd figure you got that one licked. The limit is a blurry line, and depending on who your talking to, the line wavers. IMO, the cam is small but excellent for a daily driver that can produce a good stretch of rubber on the floor. My latest cam in my '73 4spd Cuda with a 11-1 360 @ .030 and a 4spd with 4/10 and a 27-1/2 tire is running a 248* @ .050. I myself do not have a problem with running a cam this size on the street or anywhere I go. Others ***** and whine that it is to much. (That's OK too.)

Running much more duration, IMO, would require more gear as I feel that as it is now, is that it is at the bottom of the gear ratio choice while using that cam.

I just picked up an 8.8 with 4:10 gears and plan to run tires in the 27-28" range. The 4 speed is an overdrive. It will not be a daily driver, just a weekend fun car. A lopey mean idle would be nice but not if it means sacrificing low end torque. Manual brakes so it won't need a lot of vacuum.

To get a lopey idle, it usually requires a low centerline, like the normal 110 should be changed to a 108. I've run the street as low as 106. Not to amused with that one myself. I would not recomend it. Others might, not me.

Of course I'll be talking to a cam grinder at some point but any opinions on what's mild and what's wild will make my day.

Opinions are like socks, there are all sorts of sizes, colors and stinks. LOL!!!
OK :wack: , sorry.

Even cam grinders have there own opinions and will follow there path, which is probably not the same as another grinders path.

 

[crackedback]

That XFI lobe cam the magazine used is a good stick.

Lots of flavors of RHS heads out there... who's model are you planning to use, 1.92, 2.02, etc...

Talk to a GOOD engine builder if you want a recommendation on a cam. I find the major line cam companies tend to look at whatever is in the catalog or on the shelf.