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SteveUK
Dodge Dakota
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3/04/2007
05:24:56

Subject: good cam for 5.9 magnum
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this is part of an engine swap for a muscle car, but you fellas seem to have as much experience with the magnums as anyone so I thought I'd ask you.

for uprating the cam in a late 360 magnum - any ideas on a suitable cam/springs etc. ? the spec. is:

stock 360 block/heads etc.
M1 dual plane with 4bbl Holley
early magnum iron headers
2000-2200 stall
3.23 rear end (bear in mind my wheels/tyres are smaller than yours)

something for "lively" street, occasional strip

by the way - I tried the search facility on here and it won't work for some reason

thanks

Steve



brad
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3/04/2007
16:09:20

RE: good cam for 5.9 magnum
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I have a grat cam for a 97 magnum 5.9 just upgraded it for a 408 i'm building would like to get rid of it, the valve lift is .480 on the exhaust and intake, it was a great cam for my truck, i bought it from KRC Performance its the 210B cam if interested just let me know, FSTdodgeky@yahoo.com



SteveUK
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3/04/2007
16:40:15

RE: good cam for 5.9 magnum
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Thanks,

the specs you give do not match the specs given on the KRC site for that cam.

Nevertheless, it sounds interesting - I have emailed you.



Dustin
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3/18/2007
11:51:07

RE: good cam for 5.9 magnum
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I Just Bought a Comp Cam out of their cataloge for my injected 408 stroker.

It is the middle choise (of 3) with
262 intake 264 exh duration
206/ 210 @.050
112 degree seperation
.408/ .512 lift

I havent installed it yt but it was recomended to me it says may require computer mods thoe



capone
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4/14/2007
21:27:37

RE: good cam for 5.9 magnum
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A cam needs to be matched to the intake and heads for best
performance. I'm kinda concerned that you are using iron
exhause manifolds rather than headers. The magnum exhause
ports don't flow great in the first place and without full exhaust
you can lose power by putting in to big a cam because you cant
get the air out as fast as it comes in. I think your best bet is to
call comp or crane cams and tell them your situation. They will
be able to custom grind a cam for you application. You'd want
more duration on the exhause valve so you can scavenge the air
out. All the cams you'll find at performance sites pretty much
assume you have higher flowing exhaust, or even ported heads.
The custom grind isn't that expensive, just 150-200. Give that a
shot, I hope it works out for you.



gen1dak
Dodge Dakota
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4/16/2007
14:23:22

RE: good cam for 5.9 magnum
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Note that he specified "early magnum iron headers" which are only barely eclipsed by the latest aftermarket offerings, unlike later Magnum exhaust manifolds. Also, the exhaust ports actually flow very well, especially compared to earlier LA heads (over 40% peak flow improvement). The exhaust port of the Magnum was patterned after the W2's exhaust...not an exact copy, and not as good as the W2, but pretty good. Also, simply looking at one port or the other doesn't fully explain it. The Magnum has a very good flow balance between intake and exhaust, thus making for a better, more efficient engine. The better the flow balance, the smaller the differential between the cam lobes that dictate lift and duration. A stock Magnum head has better flow balance than the 340 "X" head with 2.02 intake 1.60 exhaust valves, despite the Magnum having smaller intake valves and the same size ports. As for cylinder filling, You have it backwards. Air never enters as fast as it exits. This can be improved with superchargers/turbos, but you're still dealing with, typically under 14psi on the intake side, while the exhaust side has the mechanical force of the piston forcing the gases out. This is why the intake side is always larger than the exhaust side. The intake side must be able to move a greater volume in a given time because the force behind it is atmospheric pressure or a blower application, the exhaust side can flow less at a given measure because it has a much greater mechanical force behind it in the form of a piston, which literally forces the issue. The resulting exhaust velocity is greater because you have roughly the same volume exiting a smaller opening.



SteveUK
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4/16/2007
16:18:35

RE: good cam for 5.9 magnum
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Hi again and thanks for the input.

I agree with Gen1dak except that it is not just the piston which is forcing the exhaust gas out - the exhaust gas is also still under a lot of pressure from the combustion itself - most of it therefore forces itself out when the valve opens, and would do even if the piston stayed at the bottom. You can see this effect most noticeably on a two-stroke engine.

Apparently the early Magnum headers are at least as good for flow as the late '60s 340 Hi-po cast headers, although obviously neither have the tuned length advantages of true tube headers.

Anyway - I have acquired a cam - it is 215in 220ex @ 0.050 on a 112 centreline.

It's not a Magnum cam - it has the LA style long snout but that's OK as I am using the LA timing cover.

If anyone is interested, I think you could convert a cam like this to work with a Magnum timing cover just by cutting the snout down (the threads go a long way in).

I'll let you know how I get on.

By the way - I am in need of an early 360 Magnum harmonic balancer (the one with holes to bolt the pulley on) if anyone has a used one to sell.



SteveUK
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4/16/2007
16:24:16

RE: good cam for 5.9 magnum
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sorry - I meant 112 lobe seperation, not centerline



capone
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4/16/2007
22:29:48

RE: good cam for 5.9 magnum
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I understand the flow mechanics in a motor and I don't know
where you got the idea that I didn't. I didn't suggest that the
ports should be the same, all I'm saying is that the magnum
heads don't have the best flow on the exhaust ports. Yes, much
better than LA heads, but not compared to most other
aftermarket heads. And while the early magnum exhaust
manifolds flow better than the recent ones, they still aren't as
good as headers. If you've read any books written by mopar
engineers they will confirm this. The longer duration for
exhaust was actually a quote from one. Also, like I said, most
aftermarket cams are designed with the assumption of headers.
Small differences can mean a lot when you get into higher
performance applications. If I was unclear in what I meant and
that's why you misunderstood, then I'm sorry. I was just trying
to help him find a cam that would work best for him. Custom
grinding is never a bad idea since the technicians working at
comp or crane certainly know more than all of us. In any case
I'm glad you found a cam for your motor and I hope it works out
well for you. Best wishes to all.

- capone



gen1dak
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4/17/2007
23:56:52

RE: good cam for 5.9 magnum
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SeveUK, agreed on the explosive evacuation, which only makes the point that much more. I wasn't even going to complicate things any more than I had to.

capone- If I have read any books written by Mopar engineers? If only you knew how laughable that statement is. Speaking of reading, perhaps if you re-read the first sentence you will see that I said the early manifolds weren't as good as headers, (but they are better than later units). In fact, the early units were better than any header available at the time they were in production. And what's this? Stock OEM heads aren't as good as aftermarket heads (exhaust flow)? Get outta here! Well golly gee damn, I thought that's why there WAS an aftermarket. The stock heads will support 400HP. Not everyone wants to pop a couple grand for heads they may not need. I got the impression you don't have quite have the grasp you think you do because you are hung up on exhaust port flow only, and made no comment on flow balance. It's the difference between 2-dimensional and 3-dimensional thinking. If the intake side flows great, but the exhaust side can't evacuate the cylinder, power will fall short because of excessive exhaust remaining in the cylinder, thus restricting the next intake charge. If exhaust flows great, but intake is restricted, power is down for the same basic reason, in that the intake charge is weaker than optimal. When both sides work well, i.e. are balanced, there is high cylinder filling coupled with efficient evacuation and scavenging on the exhaust side. Naturally, the Hemi's straight-through design is an even better example of this. Both sides work optimally within a given setup for max power. That, very briefly, is the concept of flow balance.



SmarterThanU
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4/18/2007
17:23:59

RE: good cam for 5.9 magnum
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gen1dak: I don't see how ANY of that lengthy post of yours makes capone's statements less accurate. Headers > stock manifolds. Aftermarket heads > stock heads. Custom cam > all your ideas and fancy babbling.

Your post is filled with nifty information, and thanks for that, but it came across with an heir of sarcasm and unhelpfulness. You agreed with capone, and then argued about something random. Doesn't matter how much you know, only how much it helps. A custom ground cam will always be better and more precise (intake and exhaust) on ANY given application, whether combining stock or aftermarket components. The end. Period. There is no debating that. I win!



gen1dak
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4/18/2007
22:02:05

RE: good cam for 5.9 magnum
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Stay on the porch, pup.



StillSmarter
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4/18/2007
22:59:54

RE: good cam for 5.9 magnum
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Stay on the porch, pup? Another useful post from gen1dak. You had no reasonable responses, so you decided to take up more forum space with another pointless one? Fair enough, chief. A simple "yes, you're right, I'm sorry" would've sufficed, son.

"A cam needs to be matched to the intake and heads for best performance." That's the very first thing he said, and you've been supporting it with every statement you've made, boy. He's right about the magnum heads exhaust port flow. Just because some of us compare heads over the full range of stock and aftermarket, doesn't make him wrong just because you misunderstood what he said, child. More attitude seems to be your only reply. Did you run out of technical responses, youngster, or did you just realize you've been supporting him the entire time and decided not to argue further?

The funny thing to me, is that the entire point of this thread is to help find a good cam, and after all your ranting, you haven't made a single suggestion. What's your opinion on camchoice, pro?



capone
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4/19/2007
00:43:24

RE: good cam for 5.9 magnum
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Guys, all I wanted to do was make a suggestion that might help
him. He obviously has an interesting configuration. He has a
very high performance intake with no modifications to the
exhaust. The iron manifolds will be very constrictive on the
motor. Like you said gen1dak "If the intake side flows great, but
the exhaust side can't evacuate the cylinder, power will fall short
because of excessive exhaust remaining in the cylinder, thus
restricting the next intake charge." Thats exactly the point I was
trying to make the whole time, misunderstandings aside. The
only way to counter that in this motor is to have a cam that is
appropriate, which I think all would agree. Custom grinding was
my suggestion, since most pre-ground cams assume that both
the intake and exhaust aren't constricted. I'm not worried so
much about the exhaust ports on the heads, since the manifolds
will be the bottleneck anyways, I just mentioned it. You can
disagree with how the port flows if you want, but it doesn't
change anything that he's actually got on his engine.

I don't disagree with what you've said gen1dak, infact its exactly
what I was trying to say. The flow needs to be balanced. Is it
your opinion that an M1 intake with iron exhaust manifolds is a
balanced configuration? My suggestion was to have a cam made
that would balance it the best, and a custom grind is the best
way to ensure that. I'm a bit offended that all your posts
centered on bashing mine, rather then helping the man. But I
am curious what your suggestion would be for his application,
since you never made one.

- capone



gen1dak
Dodge Dakota
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4/19/2007
05:29:29

RE: good cam for 5.9 magnum
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Seems like something has been overlooked here.
"M1 dual plane with 4bbl Holley"
This is not the 2400-6000+ rpm single-plane MPI intake. It is the off idle-5500rpm M1 intended for use with carbs. So, yeah, when coupled with the early iron Magnum exhaust, it's a good match.
Cam choice. Oh gee... Ya really got me sweatin' now. Ummmm. Ummm. Just a guess, but......
I would shoot for something in the range of 220/230 @ .050, with gross lift at around .508" with a 110 lobe separation. Any bigger and it'll be slow off the line without numerically higher gears or more converter.
As for bashing, that goes both ways.



gen1dak
Dodge Dakota
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4/19/2007
05:50:45

RE: good cam for 5.9 magnum
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On using a long snout cam under a Magnum timing cover. We're talking about 3/16 of an inch. It'll fit without cutting. Sure, there's the oddball cam maker out there that'll have it a bit longer, maybe it'd touch, but that's on their end, exceeding tolerances. That "no fit" rumor falls under the same propaganda from Mopar Performance as the one about Magnum heads not fitting on LA blocks. Says so right there on page 150 of MP's own "Small Block A Engines" book, but they also sell everything to make that conversion. Not that I've read anything written by Mopar engineers or anything....

SteveUK:
I agree with Gen1dak except that it is not just the piston which is forcing the exhaust gas out - the exhaust gas is also still under a lot of pressure from the combustion itself - most of it therefore forces itself out when the valve opens, and would do even if the piston stayed at the bottom. You can see this effect most noticeably on a two-stroke engine.

Yeah, and 2-cycles suck in the efficiency dept. We're talking 4-cycle engines, and the 4th cycle is exhaust. This is primarily accomplished by movement of the piston upwards in the cylinder, opening of the exhaust valve, and removal of said exhaust. Again, the ongoing combustion helps, and can be manipulated with overlap and duration of the valves via the cam, but the primary exhaust mechanism is the piston pushing the exhaust out. Residual combustion evacuating the cylinder is a very distant second place.

Hey SmarterThan....I'm sorry.....


......................for talking over your head.



SmarterThanU
Dodge Dakota
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4/19/2007
15:38:26

RE: good cam for 5.9 magnum
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Oooooh good comeback. *Shiver* I'm pleased to see your first bit of relavent information in your post. *applause*



jj
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4/20/2007
09:24:44

RE: good cam for 5.9 magnum
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"something for "lively" street, occasional strip"

What do you define as "lively" and what times are you looking for in the strip?

Are you going to run the full magnum electronics or just an ecu?



gen1dak
Dodge Dakota
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4/21/2007
00:12:04

RE: good cam for 5.9 magnum
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Capone. Tell your girlfriend to stop humpin' my leg.



gen1dak
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4/21/2007
00:15:54

RE: good cam for 5.9 magnum
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Sorry Capone. Shouldn't automatically say girlfriend, but whatever "it" is, they seem to feel the need to defend you.



gen1dak
Dodge Dakota
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4/21/2007
00:19:36

RE: good cam for 5.9 magnum
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oh, hey, NOTSMARTER, haven't seen anything relevent on the subject from you. So, ante up sport.



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