Why is it...

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indirect_connection

indirect_connection

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When Mopar guys are talking about camshafts, they seem to refer to lift. For example, "I have a .590 cam in my....".

In my past experience with Brand X, camshafts are referred to by their duration, either advertised or at .050. It seems duration is more relevant when discussing cams because it tells you how streetable the cam is, and if it'll require stall/headers/gear.

So were the old Purple cams advertised by their lift? I'm just curious as to where this started.
 
Some guys measure their manlyness buy the size of their lobes.

"My lobe is bigger than your lobe!"

Others measure manlyness by how long that can last.

"My duration is longer than your duration"

I say get a room!

:rofl:
 
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IMO, both are equally relevant to the lobe profile. Neither is more or less important, it's the combination of the two.
How do your Brand X friends refer to split duration cams?
 
Instead of putting my Man Card in my wallet I carry my Cam Card.
 
Professor Fate said:
IMO, both are equally relevant to the lobe profile. Neither is more or less important, it's the combination of the two.
How do your Brand X friends refer to split duration cams?
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To be honest, I don't remeber specifics. About 10 years ago I started my Stingray project and would spend hours a day on the Corvette Forums. If asked about the cam in my Chevy I would say it's a 218/230 @.050. I think duration at .050 is the best indication of the powerband and drivability.

Wouldn't two cams with equal duration and LSA share the same rpm range even if their lift was different?
 
I noticed that too, but if you know your Mopar cam providers, the lift will often be like a signature.
For example; who all makes a .509 cam? and how many different durations go with that?
If you tell me you have a .509 cam in your engine, I'm going straight to the Mopar catalog to find that it is a 292/292.. This may be a poor example, cuz everybody recognizes the 292/.509 signature. But you get the idea.

indirect_connection said:
Wouldn't two cams with equal duration and LSA share the same rpm range even if their lift was different?
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If equal duration at .050 and same basic type ( like FTH) then possibly/probably yes. But you cannot directly compare different types of cams, because the lobe-shapes are different.
Furthermore, two different manufacturers might have identical durations at .050; but by .200 lift, one of them could be out in front, maybe up to a cam-size bigger. This will change the rpm range.

Advertised numbers are a crapshoot, because the manufacture of any cam can pick and choose the starting and end-points to arrive at whatever numbers he wants; there is no standardized lift specification. One manufacture might choose .006 tappet-rise; while another might choose .008, and another , .001. Those cams could all be the exact same cam, but will have three different advertised numbers. Furthermore; what happens between advertised and .050, from the specs, nobody knows. The ramps could be long, short, or in between; which will not affect the power or rpm range, but it could affect the idle..... a lot; like a Whiplash or a Thumpr.
 
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Correct! Lift is more a function of matching the cylinder head flow peak point to the camshaft (or what most cylinder heads and valve springs are set up for). But with flat tappets, lift will limit how much .050 duration can be implemented with a given amount of duration at .006 lift (or lift at lash clearance if it's a mechanical flat tappet) most cam grinders are willing to put onto a profile to keep the ramp rates on a prescribed (usually conservatively paced) schedule.
 
Dodge never published duration at .050 numbers. U can calculate it if u wanted but not many ppl did. Just easier to go by the lift numbers. Other than the first step up that was referred as the Street Hemi Grind. Even though it was made for the big and small wedges. It is the same profile as the 426 Hemi Cam. Kim
 
MP states to get the duration @050, multiply the advertised duration by .850. It was just easier for us MoPar guys to say I’m running the .590 cam. Right there, if you were an engine guy or racer, that this was a big solid cam designed to take advantage of ported heads and high compression. Just stating the cam size should tell you most of what the engine should be built up like.
(Or at least if you were a serious fella.)

FWIW info for the new guys to camshafts:

Two different cam grinders can have the same advertised duration on there cams but wildly different numbers @050.
Also, via comparing any cam @050 should be done. When two cams are compared @050 and have the same numbers, there cruise and power bands are similar but not the same because there’s more to a cam than the advertised and 050 numbers.

Two cams could have the same advertised and duration @050 numbers but have different lifts at different points on the lobe. It is possible to find this. But that’s looking through hundreds of cams from all grinders. Good luck!
LMAO!

But! What you’ll find is cam A is a streetable cam and cam B is a street strip cam and then cam C is a drag cam. There numbers are very similar. You can see this in some Ford racing camshafts.

A Hyd cam is designed for longevity and quite operation in a general performance arena.
The solid cam more rpm and overall performance. S/S type of grind.
The solid roller more strip.
Let’s just say…. The numbers can be seen something like this;

Hyd. ———-- 280/230 - .480 - Gen performance/cruiser
Solid ———-- 280/238 - .500 - More serious hot rod
Solid roller —- 280/244 - .550 - race grind

This is why the industry went to the 050 for comparisons. It helps level the playing field.

What these numbers are telling you is how aggressive the ramp rate is on each cam. But you can also look at lift rates anywhere you like. Commonly done in .100 Increments.

What a lot of people don’t know is a aggressive solid flat tappet cam can have a quicker off the seat rise of the valve than a solid roller. I don’t know if it is possible with the Chevy lifter being so small, but getting into a larger Ford lifter helps. Even better is our .904 lifter size. This is only beat by a 1.00 lifter. At the moment, IIRC, and I’m not betting on that one right now, but I think it was GM’s Caddy or Oldsmobile.

(Someone correct me here if I’m right, wrong or other.)

The only way you can actually get to a roller cam performance (or just a hair shy off) is with a mushroom lifter.

The rollers main advantage is the ability to open the valves up quicker and higher as well as hang the valve open longer since the roller wheel is “rolling” around the lobe which can get very aggressive except on initial lift. To what exact degree or length of time in lift is another totally dependent cam lobe grind design.

To top this off, there are more numbers to look at that can change the way the cam acts and performs. It can be a heck of a time looking at all the numbers and getting a grip on what’s going on with them. Even though the numbers can look the same they can be very very different in performance.
 
That all came about when the MP line of cams was introduced. It's a Mopar thing. They're even listed in the MP book by lift, just like the example you gave.
 
AJ/FormS said:
If you tell me you have a .509 cam in your engine, I'm going straight to the Mopar catalog to find that it is a 292/292.. This may be a poor example, cuz everybody recognizes the 292/.509 signature. But you get the idea.
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Actually this may be a perfect example. As a youngin reading my Dad's Car Craft magazine, every feature with a Mopar invariably had a Purple Shaft cam. If Mopar Performance cams were commonly identified by lift, then I could see how it could get ingrained in the community as much as "four bolt main and camel hump heads" is to the Bowtie crowd.

TE]
 
never really questioned it but ever since i can remember mopar cams were always refered to as a purple 509cam (292/509). a purple 484 cam (284/484) they did like stated above have that one that was always refered to as the hemi grind 280/474 if i remember correctly.
 
abodyjoe said:
never really questioned it but ever since i can remember mopar cams were always refered to as a purple 509cam (292/509). a purple 484 cam (284/484) they did like stated above have that one that was always refered to as the hemi grind 280/474 if i remember correctly.
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Even before the purple cams, they were Direct Connection cams when Racer Brown ground them all, they were still referred to by lift. I have a Direct Connection book around here "somewhere".
 
oldkimmer said:
Dodge never published duration at .050 numbers. U can calculate it if u wanted but not many ppl did. Just easier to go by the lift numbers. Other than the first step up that was referred as the Street Hemi Grind. Even though it was made for the big and small wedges. It is the same profile as the 426 Hemi Cam. Kim
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Yep, had the .474 Street Hemi grind in my 383 Coronet 4 spd car, over 30 years ago. Man, what a Blast!
 
mopar head said:
Here`s one that has me confused. Chevy cams are listed from 0-6000 rpm power band and Mopars always seem to start from 1800 to 5800 ???
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Well, cause the 350 is the best engine ever! My neighbor put roller rockers on one,and it had an instant 700 HP! He'd always threatened to jump over my Dodge truck w/ a mash of the pedal! Never did, when called out... lol
 
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