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

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AndyF’s big block showed this IIRC.
Dulcich (sp?) also faced this in an article once as well. He had zero gain IIRC.
Like PRH said, when the engine is already well sorted out....
 
rumblefish360 said:
AndyF’s big block showed this IIRC.
Dulcich (sp?) also faced this in an article once as well. He had zero gain IIRC.
Like PRH said, when the engine is already well sorted out....
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IIRC, AndyF did more than one test with rocker ratio. Maybe he can chime in here and review his findings.
 
Andy tested 4 ratios on one combo as I recall.
1.5, 1.6, 1.65, 1.7.
Essentially repeated the same power with all the rockers.

I can’t recall if it was that exact motor combo or not, but he also did a cam swap from one pretty fast cam to an even faster cam.
They were rollers.
The two cams were very close in duration, had very similar split, and the same lsa.
The faster cam made slightly less power.
(My understanding is that the faster cam was supposed to be an “upgrade” over the previous cam. But you never really know how that stuff is gonna pan out until you test it).

I could easily orchestrate a pair of tests where the results would contradict each other.
One test would show how much more power the high ratio rockers make, and another to show they lose power.

When “painting with broad stokes”....... claiming this or that is what’s “better”....... the answer is usually......”it depends”.

One of my buddies that races a 535” Pontiac with aftermarket heads had a cam that made pretty good power, but was a little rough on valve springs/rockers/lifters.
I told him...... just change the cam to something smoother and all those problems will just go away.
It might lose 15-20hp. It’s a bracket car...... do you need that last 15-20hp?
So, he finally got tired of changing parts and had me get him a different cam.
I basically duplicated the events and lift of the previous cam, only used lobes from some families that I knew from experience were easier on parts.
Dynoed motor with new cam....... only down maybe 5hp(on an 800hp motor).
Car runs the same....... parts last way longer.

The fast cam was worth next to nothing in his combo........ but it was def harder on parts.
 
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Funny you mention that PRH. Between now and my last post, I was searching t for that Mopar Muscle issue where Steve did that test. For some reason, in the back of my head, I thought he may have even lost power. The point of diminishing returns into chaos where he lost power by adding more rocker ratio to an already fast ramp cam.

The article is old, long time ago. I have a hard time searching that parent publications on line site. I can’t find jack.

From what I remember (IIRC) it seemed like he was, over exciting the combo with a to quick valve lifting. Perhaps it may also have been a Hyd. cam and the lifters couldn’t keep up?

The lessons learned over the years is the quicker you open up the valves, the more power you can make, to a degree or point. So yes, there is such a thing of “To much of a good thing isn’t a good thing.”
 
rumblefish360 said:
Funny you mention that PRH. Between now and my last post, I was searching t for that Mopar Muscle issue where Steve did that test. For some reason, in the back of my head, I thought he may have even lost power. The point of diminishing returns into chaos where he lost power by adding more rocker ratio to an already fast ramp cam.

The article is old, long time ago. I have a hard time searching that parent publications on line site. I can’t find jack.

From what I remember (IIRC) it seemed like he was, over exciting the combo with a to quick valve lifting. Perhaps it may also have been a Hyd. cam and the lifters couldn’t keep up?

The lessons learned over the years is the quicker you open up the valves, the more power you can make, to a degree or point. So yes, there is such a thing of “To much of a good thing isn’t a good thing.”
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Don’t feel bad. I can’t find jack on the digital magazine web sites either. That’s a reason I keep the hard copies. Drives the wife nuts. That’s just an added bonus.
 
Me too! Lots of paper. Just not at my finger tips.
 
rumblefish360 said:
Ummmm, AJ, could you explain this?
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AJ don't take no vaccines. There is no way I trust anybody to tell me the truth as to what ALL is in that needle. And even if I knew, I wouldn't willingly let anyone stick me. I'd sooner die.
You know that once a food is GMO'd, it can never be undone. If my DNA gets modified, to be different from what was created "good", what will my DNA be? There is no changing it back. Will my Spirit return to He who gave it?
 
OK, let’s skip the religious crap first.
Second, are you claiming that eating GMO food will alter your DNA?
Third, you can do research on what is in a certain vaccine to know all that is in there. So what’s the issue there?
 
open the intake and too early and you not only get reversion you stall the flow
you need just enough lift get the velocity up during exhaust pull till piston demnd takes over
 
exactly
that's why Ilike to see .050 flow
the .006 to .050 can be around 46 degres with both mopar solid and hr cams
The larger mopar lifter allows more valve acceleration .050 to .200 than a.842 can do
so you n open later and still follow the piston down
cheers
 
Well I answered the question with an Aggressive .842 lobe Howards and a HR - see additions to post one
Now how about some guesses for standard performance accelerations
I also posted some data on the 340 cam at .006 since some asked
 
aj your box is still full
drop me a pm or

https://www.forabodiesonly.com/mopar/conversations/howards-cam.202305/
is a conservation linking to another thread
Stockish 340 upgrades, cam needed
is main thread takes 7 pages to get all the info but a few posts back is a link back to the calcs
by cudafever I think

another thread
Need help choosing a cam 1969 340

on both get the car specs clear
one is a 4 speed with 3:23 gears and a lot of help throwing big cams at it
I think all want to get their builds running as good as possible not just putting in a big cam and then having to go to lower gears etc
and they want to dial in their compression to not leave any low end on the table I would think especially with a stick which you have experience with that could be very helpful

all the best
Jim
 
we left off with a race only agressive .842 cam of 260 degrees to get the same .200 duration as the 252 Howard
lets see what duration a standard .842 cam will take
we do not have .200 durations for a lot of cams (wonder why) but this list is a "best fit"
3HF213307 260 237 213 127 0.307 Agressive .842
XFI 260 216 129 0.312 .468
Crower 31240 260/267 214/215 .455/.474 112LCA

Howard 261 238 214 13 4 0.329 .494 (used in AMC)
XFI 262 218 131 .315 .473
bhr209300 262 236 209 124 0.300 Standard HR

bhr209310 262 236 209 127 0.31 Standard HR you can get there with a HR- what a chevy would have to do without boring their lifters out to Mopar size

Crane 693511 261/275 213/220 .459/.480 112LCA

comp XE262 262 218 .462 110LCA 106 ICL IC 57 ABDC
compXFI 262 262 218 131 .315 .473 fast lobe
lUNATI 702 262/268 220/226 .475/494 112LCA

29299710 262 211 .507 Voodoo HR retro fit
Nostalga Plus 265 218 124 .280 .420
10200702 265 220 .475 VOODOO
Howard ------265 242 218 138 .502 HRS 711651 110 265/273 502/525

10200312 266 220 .485 Lunati Street Master 9:1 3.55 gears

Crower 31241 267/271 218/222 .474/485 112lca 267HDP

Howard 267 213 ,450 Street Farce 2 .842

Howard 267 213 ,502 .904

Howard 267 220 .506 HS 711451-08

10200206 268 218 .457 Lunati High Efficiency

Comp HE 268 218 .454 110lca

Comp Spec 268 222 .464 108 lca
Here is the first standard chevy lobe that gets to 127 at .200
Comp XE 268 224 .130 .477 on 110 lca 106 ICL IC 60ABDC
Comp XFI 268 224 138 .325 ..488
10200703 268 /276 226/234 .494/513 Voodoo 110LCA
....................006..020..050..200 lobe.....valve
1hf215303 269 242 215 127 0.303 .454 Standard .842
17 degrees longer than the 252 Howard and the same duration as the DC 260 @.006

DC 260 269 221 430

Howard 269 215 .455 RS-710931-12

Voodoo 271 226 494

The 340 cam is 279 @.006 but only 210 @ .050
 
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FWIW.... how curve plots and some basic processing can help to understand the cam better.

Here is a plot of a cam for a 4 banger cam that I took recently: it's an older Isky grind for a hydraulic lifter. The bottom graph is the lobe lift; the upper graph is the velocity. The slope (steepness) of the velocity curve is the acceleration; the steeper the velocity curve, the higher the acceleration. (And it would not be hard add a graph of the lobe acceleration.)

The .050' lobe lift point is at 5 degrees ATDC, so the hardest acceleration is almost all before the .050" point. That is not so obvious from just the lift curve.

BTW, the actual valvetrain lift gets modified from the direct lobe lift vale as the lobe on lifter contact point moves out from the center as you move up the ramp. This data was measured off of the lifter, so it actually reflects the lift/velocity/acceleration on the valvetrain.

So that begs a minor question of whether the cam mfr's measure lift directly off the lobe or with the appropriate sized lifter. Maybe wyrm can answer this....??
OR-4H Lift-velocity.png
 
Why no comp Nostalgia Plus??
All of Comp's Nostalgia Plus are universal grinds- one size fits all and comp does not give the Intensities for these cams
The Purple Plus series is the exact same program as the Nostalgia Plus but uses the ,904 Mopar lifter- but the smallest PP is 280
you can read both descriptions in comps lobe catalog
Why no Dual Energy-- no info in the lobe catalog and extremely long exhaust lobes
Another question was why not the Comp XFI lobes- well ok if you have light valves and retainers etc take a look at an expensive custom cam, but why?
The smallest XFI 252 lobe compared with the Lunati 250or 253 and the Howard and Hughes 252
.....................,006...050 .200 lift
Lunati 700.... 250 208 .454 some say 253 for this Voodoo (marketing games ?)
comp XFI .... 252 208 121 .447
Howard 164A 252 206 126 .472 and Hughes is close
3HF205293 .., 252 205 118 <.450 Howard fast chevy cam
anyone not think that either the Lunati or Howard are going to be easier on your valvetrain than the "pushing the envelope" chevy grinds while providing more area as indicated by the .200 durations?

I added some XFI and Nostalga Plus lobes to post 64 but do not recommend either when there are so many other better lobes for MOPAR
Interesting that Comp makes special 4X4 lobes for Jeeps but nothing for Mopar smaller than the HE275HL
 
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Wyrmrider said:
The smallest XFI 252 lobe compared with the Lunati 250or 253 and the Howard and Hughes 252
.....................,006...050 .200 lift
Lunati 700.... 250 208 .454 some say 253 for this Voodoo (marketing games ?)
comp XFI .... 252 208 121 .447
Howard 164A 252 206 126 .472 and Hughes is close
3HF205293 .., 252 205 118 <.450 Howard fast chevy cam
anyone not think that either the Lunati or Howard are going to be easier on your valvetrain than the "pushing the envelope" chevy grinds while providing more area as indicated by the .200 durations?
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Help me understand something here.... I think that last sentence says that that aggressive Chevy grinds are going to be harder on the valvetrain. Have I read that right? But the .200 duration is smaller for the aggressive Chevy grind. So is the problem up between the .200" lift point and the peak lift?
 
problem is the nose when you chase that last little bit of lift
When you read the write up on XFI cams it reads like a race lobe
light valves, beehive springs, light retainers etc check out the intensities in comp's lobe catalog
I do not see any reason for them in a Mopar when MOPAR lobes are available you can get the same "intensity" with a big lobe
one reason is the XFI is designed for the smaller SBC cam core instead of a BBC/Mopar cam base circle actually putting an XFI on the larger Mopar core helps
lots of luck putting that lobe series on a stroker chevy of Buick size base circle
lots of chevies get bored for Mopar lifters
I did it all the time as much less expensive than bronze sleeves
unless rules require stock bores- Like RAMM's ongoing build
 
I've never cam doc'd a xfi but can see what they are doing
and then they add marketing hype
 
I don't have a lot to offer on the tech stuff, mostly just absorbing. But on the sharing end...
nm9stheham said:
get a library started on this site
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probably the way to do it is the same way the head flow info is being shared.
That's a third party shared spreadsheet. right?
MOPAROFFICIAL said:
They call it an asymmetrical lobe, one half is not the same as its other half
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And Chrysler did this even on the factory cams. Right? This was, maybe still is, the problem with the cam lobe data and calculation portion of Dynomation sim. Maybe its been improved. We could try discussing with Larry. He's answered my e-mails before. I think he genuinely appreciates suggestions to improve his sim programs. I don't know if the relationship with CompCams complicated things but it seems to have limited the datsa the could include in the cam library.
Wyrmrider said:
Wish I could find better .200 data
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We could pull some data from the dgital cam library. I just don't know how accurate the .2 durations will be. I think there are some cam doctor files, but most are 10 point. And we've already proven the Chrysler 340 ones are wrong.
Wyrmrider said:
open the intake and too early and you not only get reversion you stall the flow
you need just enough lift get the velocity up during exhaust pull till piston demnd takes over
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Isn't that (reversion and stall) dependent on rpm, and to lesser extent on intake and exhaust tracts?
 
reversion lots of things, the ones you mention
backcut on the valves, reverse flow, header suck, rod length/ ratio, overlap
my pet peve is that most cams are designed for the short rod sbc where the piston timing at TDC is short
vs the MOPARs where it is relatively longer
sbc starts to pull the piston down quicker so you have to get started on the intake opening earlier
doing the same Thing with a MOPAR allows more time for reversion
same on the ex close
on the other end SBC is rreal slow around BDC so it is not nearly so important whenyou open the ex or close the intake
The post 67 MOPAR cams are VERY aymetrical but for different reasons than modern performance cams-- warranty and wear and smog
 
Mattax said:
Yes. This one.
Small Block Head Flow Chart

Iit would make it easier to view tables too as there doesn't seem to be any way to keep things in columns in the posts.
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OK, tnx very much. Here is one obstacle: I take data in 2 crank degree increments in order to get fine detail for computation of lifter velocity, etc. With a symmetrical lobe, and same lobe for IN and EX, that is still something in the range of 60 to 80 data points, not 5-7 points like for head flow. With assymetric lobes and different IN and EX, now we are talking 250-300+ data points. It might work OK with fewer data points.

It almost has to be entered into an Excel spreadsheet or something that can be presented as a table. But it would be even better to have access to the file data in some common format (like .csv) so people could import the data. But that requires an accessible file system. Hmmmmm.....
 
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