Mopar Cam- how many more degrees @.006 to equal at .200?

-
W

Wyrmrider

Well-Known Member
Joined
Sep 5, 2016
Messages
3,611
Reaction score
1,785
Location
los angeles
The comp XE 250 Closes the intake at IC 51 ABDC @.006 110 LCA 106 ICL
comp provides similarl cams with 108 and 111 ICL you can calculate the IC
.006 .020 .050 .200 lobe valve lift
VOODOO.701..250.........213...................454 108LCA IC about 49ABDC
Comp XE 250 250 .........206 ................ .432 110lca 106 ICL IC 51 ABDC
Comp Magnum 252 .......206.................. .425 110LCA
Comp Special 252..........206........//..........425 108lca
Comp Special 252 .........206.................. .405 111
Hughes.........???.......... 206........ 0.315 ........ 113lca
Howard .......252 229...206..126 0.316 .472 standard acceleration .904 HM2063164A
Lunati .........253 ..........204................. .427 10200260 UDHarold .842
Lunati......... 253..........208................. .454 VOODOO 10200700 .904
Howard .......252 229...205..118 0.293 .......3HF205293 High Acceleration .842
Howard .......253 226...199..101 0.260.........1hf199260 Standard Acceleration .842
3HF207297..254 231.. 207 ..120. 0.297
Comp 4X4.... 254 .........209.. 126 .311 .467 lobe 2901
HM2083190A 255 232 208 128 0.319 .479 711381-10 110LCA 106 ICL
MP 248......... . 256.......... 202 113............................410 112IDL?
1hf201273....... 255. 228... 201... 109 .......0.273
3HF209300...... 256 233.... 209... 122....... 0.300
Comp XE......... 256 ............ 212 ....................... .447 110lca 106 icl IC 54 ABDC
10200701...... 256........... 213 ....................... .454 Voodoo note 1
Jones ..............256 .......... 202 ...120 ..... .307 .461 note 2

HM2103219A 257 234 210 130 0.322
1hf203277 257 230 203 111 0.27
10200701 258 213 .454
Comp 4x4 256 213 130 .476 lobe 5902
20200714 258 207 .485 Voodoo HR
Howard 259 ......205................420 Street Farce 1
Howard 259 236 212 134 .329 .494
Comp 4x4 259 210 131 .474 lobe 3324
Comp 260 HE 260 212 .440 110 lca 106icl IC 56 ABDC
Comp Spec 260 212 .444 108 LCA
10200205 260 210 .441 Lunati High Efficiency
3HF213307 260 237 213 127.. 0.307 Aggressive .842
Howard ......261 238 214 134.. 0.329 .494 (used in AMC)
bhr209300... 262 236 209 124..... 0.300 Standard HR
bhr209310 262 236 209 127.... 0.310 Standard HR
Note we have to go to a 260 cam in either Aggressive .842 HFT or HR to equal 126 degrees @.200 lift of MOPAR the LOBE(s) above

SO HOW MANY DEGREES FOR A standard performance ,842 lobes

several have asked about 340 cam so here it is with a few of similar duration at .006
340 cam 279 210................... .429 2899206 intake @.006
Thumper 279 227................... .486 107 LCA IC 63 ABDC
Rattler... 281 227.................... .480
Howards 279 256 232 .......152 .357 .535





so how many degrees do we have to add to reach the 126 @200 of the Howard or Hughes
High Acceleration lobes and standard lobe
you'll notice that a high acceleration .842 lobe can't compare with a standard .904
Where do you want the Intake Close for your compression or build
Do you think the Voodoo is a high acceleration lobe?

note 1

VooDoos are true Chrysler profiles, designed for the .904" tappets.
That 213/.454" profile is about 5 or 6 degrees fatter at .200 than the Chevrolet one.
UDHarold



note 2 50% fatter @.275 than DC 260






 
Last edited:
How much of a difference will you see in TQ and HP between 199 and 208?
 
9* is ~1.3 cam sizes.
Check out the associated lifts.
Having a cam 1.2 sizes bigger @.050 with the same or similar .006 numbers, means you don't have to suffer the associated pressure loss with that 1.2 sizes bigger advertised cam.
At 250* advertised this may not be a big deal on most engines, but the chart illustrates the difference that doing your homework before buying, can make.

If you are shopping for a 268/276, 340type cam for instance; changing the Ica just 3.5* puts you up into the next bigger cam.So if you have the option of 228* .050, or 224*@.050, with the same 268@.006, that could mean 15*hp at the peak....... without the loss in cylinder pressure that would normally be associated with that next bigger cam.
So if you already have a pressure-challenged engine, then, choosing a fast rate-of-lift cam could get you where you wanna be, and still have enough cylinder pressure left over, that you don't need the next higher stall TC.

For streeters; the normal range of cams IMO is from 230*@.050 down to 209@.050..... which is about 4 sizes; each size being 7*.

Typically, the ramps will add from 38* to 48* , to get to the advertised.... which itself is rather ambiguous on account of that advertised could be at .008 tappet rise, or .006, or .001 or anything in between; they don't always tell you. Furthermore, from advertised to on the seat and not leaking could be many more degrees. That may not make any difference at WOT and jamming gears;but how much time does your streeter spend in that mode.
No, for a streeter, that advertised has several ramifications; including but not limited to; hiway fuel-economy, city consumption, take off-characteristics, busting the tires loose, Part Throttle torque, choice of stall and rear gears, and tuning the bugger. Did I mention;all this is on about 4 cam sizes.
Generally; if you have a small displacement, lo-compression engine, you need to stick to the small end of the scale, to keep your pressure up, so you don't have to run a big TC and race gears, so you can bust the tires loose. But if it is possible to get a fast-rate cam, maybe you can go to the next bigger cam. Or, with a bit of a compromise, maybe two sizes is possible. And that , I'm pretty sure, would make a lot of smoggerteen owners happy. If it is possible to combine this fast-rate, with a hi-lift, then you have winner.
So while a difference of 9* doesn't seem like much; we can't lose sight of what is happening at the other ends of the scales. 9* at .050 is a lot. About 1.2 cam sizes.
Each cam size moves the operating rpm up about 200rpm. By the formula for finding hp, 200 is the big player. Have a look;
TQ x rpm/5250=HP is the formula
Say your engine picked up,
20 ftlbs at 5250 rpm; ... then 20 x 5250/5250= 20hp
Or say 20ftlbs at 5050, then; 20 x 5050/5250= 19.2
Or say 20 at 4850, then; ..... 20 x 4850/5250= 18.5
...............at 4650, then; .............................. 17.7
.............. at 4450, then; ...............................16.9
This 206 cam,in Wyrmriders post, in a 318 to 360,might have a power peak around 4450. I can't say how much power/torque your combo will pick up; every engine is different. I pulled 20 ftlbs out of thin air for illustrative purposes.
For example; from 4450 to 5250 is 800rpm, which according to the example above might lead you to think that the power increase might be ~70/80hp, but that is patently absurd. A 273 will not make the same increase as a 440.
Nevertheless; if your 273 picked up 20 ftlbs at peak with whatever changes you make; be it cam, heads, or exhaust/induction, whatever; the formula predicts correctly according to the chart. The formula doesn't care how you got the 20 ftlbs; it only wants to know at what rpm this occurred; then it spits out a made-up number we call horsepower.
Now, having said that; if the plus 20 ftlbs that occurred at 4450, cost you 20 ftlbs at 2000 stall, then you just lost;
20 x 2000/5250=7.6hp right there. Losing 7.6hp at 2000 with a lo-compression 318 is like the 4bbl quit. But not just that, in normal operation, you have to drive that much deeper into the carb, to maintain what you had before the cam swap, and if you thought your city fuel mileage sucked before the swap, get ready for an eye-opener.
However; if the new fast rate cam, has the same ICA as the one you just took out....... then no horsepower will be lost at stall..... because the cylinder pressure has remained the same.
That is the point, I think, Wyrmrider is making. At least that is what jumped off the page for me.
And a great big thank you to him for making this info available to us.
 
Last edited:
The best way to tell is to degree each cam and compare...


Also, the faster the ramp on the cam, the faster the valve will close... The faster it closes, the harder it hits the seat which will increase the wear on the seat and limit durability...
 
hysteric
don"t focus on the .050 look at the difference in .200

no fast rate cams here except the howard 3HF series
 
krazykuda said:
The best way to tell is to degree each cam and compare...


Also, the faster the ramp on the cam, the faster the valve will close... The faster it closes, the harder it hits the seat which will increase the wear on the seat and limit durability...
Click to expand...


That’s an old wives tale and it’s wrong. You can shut the valve quickly and not have it slam on the seat. In all my years I’ve NEVER seen seats beat out from a valve “slamming” into the seat. When the springs are worn out or incorrect for the application you see the seats getting beat up, but that’s not the cams fault.
 
yellow rose said:
That’s an old wives tale and it’s wrong. You can shut the valve quickly and not have it slam on the seat. In all my years I’ve NEVER seen seats beat out from a valve “slamming” into the seat. When the springs are worn out or incorrect for the application you see the seats getting beat up, but that’s not the cams fault.
Click to expand...

No, it's simple physics...
 
Wyrmrider said:
hysteric
don"t focus on the .050 look at the difference in .200

no fast rate cams here except the howard 3HF series
Click to expand...

Sorry Wyrmrider I was looking at the wrong column. What I should have posted was what would be the difference between in TQ and HP of the 101 and 126 @ .200?

It would be great if we could compare the lobes through out the entire lift range. Does Mike Jones have a lobe you could put up for comparison?
 
krazykuda said:
The best way to tell is to degree each cam and compare...


Also, the faster the ramp on the cam, the faster the valve will close... The faster it closes, the harder it hits the seat which will increase the wear on the seat and limit durability...
Click to expand...

Not if its an asymmetrical lobe.
 
I cleaned up post one and took it down to 256@.006

Rumble- what do you want to know about the Hughes? the current ones look a lot like Howards lobes, earlier ones were Engle, maybe others
Some say Hughes pushes the envelope too far IDK but it's nice to have the .200 data without having to dig for it
Hysteruc- great question that 200 duration is around the LCA which is in the area of just after maximum piston velocity and where the intake charge is still accelerating
Perhaps someone will post up some sim programs to answer your question because head flows and piston demand get involved- But in my experience it does make a big differnece
Krazy UDharold said that he used fewer polydines on the comp XT line than on the later Uldradyne and Lunati lines and that the additional computation allowed him to gentle out (my word) the close right before the close- one reason the comp is noiseer than the others- there is a duarability factor and early roller rockers like the Crane "quick lift"
are the same problem, What quick lifts up must quick come down
One thing I do is check the spring requirements- one way to sort out high rate cams
 
Last edited:
Wyrmrider, Hughes has a lot of missing data on there web site and (as most every) cam card. I can go to the master cam catalog and look up any lobe rate from most places. This I have done decades ago. I’d like to see there love profiles like I can from a master cam lobe catalog. I can only have half a picture with what is written.
Hysteric said:
Sorry Wyrmrider I was looking at the wrong column. What I should have posted was what would be the difference between in TQ and HP of the 101 and 126 @ .200?
That is a unanswerable question due to so many variables of the engine. If you did a test on a 360, swapped cams around you will find an answer to that question but only for that engine. Increase or decrease the size of the engine, new answer. Single plane? New answer. Tunnel ram? New answer. Etc....
Click to expand...
 
krazykuda said:
No, it's simple physics...
Click to expand...


Really? The physics says the damage comes from the valve bouncing, not from bouncing because the closing rate is too quick, but because the springs don’t have enough load to let th3 valve hit the seat once and not bounce.

It also beats the crap out of the locks, the groove in the valve and the retainers.

It has ZERO to do with the closing side of the lobe. It’s a control issue.

This lie has been around forever, and it was started by cam companies that were behind in their R&D, and when their junk was getting outrun, they claim the other cam grinders cam was a part breaker.

BTDT. I was there, doing this **** when Edelbrock released the first valve spring that was 300 pounds at 2.000 installed height. And all the ignorant fools who though that spring loads were killing parts were proven ignorant. The smart guys bought them and didn’t say a word. The idiots and posers kept using 200, maybe 220 on the seat and kept beating the hell out of their valve train and valve jobs because...well...because they had to be right. They weren’t.

So the fact is, the closing side of the lobe can’t be “too fast” and cause valve bounce. I can take a stock lobe, use the wrong spring and duplicate the results.
 
rumblefish360 said:
Wyrmrider, Hughes has a lot of missing data on there web site and (as most every) cam card. I can go to the master cam catalog and look up any lobe rate from most places. This I have done decades ago. I’d like to see there love profiles like I can from a master cam lobe catalog. I can only have half a picture with what is written.
Click to expand...

Comp still has the best master lobe catalog out there. They list everything. Too bad more don’t do it. I know the cost is staggering to print the stuff, but I hate using the web to find data like that. To me, a catalog is much quicker and easier, though much more costly to the cam grinder.
 
Oh heck yea man! X2!

Just 2 days ago I had to call up Lunati and ***** about the seriously huge lack of information on there web site.
Comp cams web site is just as pitiful & truly pitiful they are. They should be ashamed of themselves for going to that toilet or a web site design!

I have to state and give it up to there quick email response from Will Vance who answered every question quickly. His effort is exactly how it should be and his bosses at Lunati should be happy to have him.
 
yellow rose said:
Really? The physics says the damage comes from the valve bouncing, not from bouncing because the closing rate is too quick, but because the springs don’t have enough load to let th3 valve hit the seat once and not bounce.

It also beats the crap out of the locks, the groove in the valve and the retainers.

It has ZERO to do with the closing side of the lobe. It’s a control issue.

This lie has been around forever, and it was started by cam companies that were behind in their R&D, and when their junk was getting outrun, they claim the other cam grinders cam was a part breaker.

BTDT. I was there, doing this **** when Edelbrock released the first valve spring that was 300 pounds at 2.000 installed height. And all the ignorant fools who though that spring loads were killing parts were proven ignorant. The smart guys bought them and didn’t say a word. The idiots and posers kept using 200, maybe 220 on the seat and kept beating the hell out of their valve train and valve jobs because...well...because they had to be right. They weren’t.

So the fact is, the closing side of the lobe can’t be “too fast” and cause valve bounce. I can take a stock lobe, use the wrong spring and duplicate the results.
Click to expand...


The faster it moves, the more force involved...

Newton's second law of motion:

F = M*A
 
Now what happens when we add a 1.6 or higher rocker......
 
krazykuda said:
The faster it moves, the more force involved...

Newton's second law of motion:

F = M*A
Click to expand...

Accurate to a degree because the cam lobe controls the valve and its rate of opening and closing and where does it on the lobe. The lobe can slow the valve down. And that’s what it does. Earlier fast rate cams had the problem you think they have. It is all in the valve spring to control most of the action. Since valve spring tech wasn’t what it is today during the advancement in aggressive cam lobe profiles 30-40 years ago, the cam got the blame. It is partially true due to the cliff the lifter fell off of & lack of spring to keep it closed. Modern profiles slow down the losing rate at the last little bit.
Remember it is the springs job to keep the lifter on the cam lobe. The job of closing the valve is second banana. The valve train can be made super light to make the job easier. And it is done when the need comes into play. And when ignored, the springs wear out. This is evident in drag racing. The higher the performance, the more often the valve spring is changed out.
 
rumblefish360 said:
Accurate to a degree because the cam lobe controls the valve and its rate of opening and closing and where does it on the lobe. The lobe can slow the valve down. And that’s what it does. Earlier fast rate cams had the problem you think they have. It is all in the valve spring to control most of the action. Since valve spring tech wasn’t what it is today during the advancement in aggressive cam lobe profiles 30-40 years ago, the cam got the blame. It is partially true due to the cliff the lifter fell off of & lack of spring to keep it closed. Modern profiles slow down the losing rate at the last little bit.
Remember it is the springs job to keep the lifter on the cam lobe. The job of closing the valve is second banana. The valve train can be made super light to make the job easier. And it is done when the need comes into play. And when ignored, the springs wear out. This is evident in drag racing. The higher the performance, the more often the valve spring is changed out.
Click to expand...


true, the valves are opened and closed slower at the beginning and end of the lobes... some manufacturers have faster lobes than others....

I have over two dozen cams that I degreed so I can compare them apples to apples and have seen the difference in valve lift and close rate... some cams have had dfferent .001" - .050" ramp speed than others...
 
You must log in or register to reply here.
-

Back
Top