I've built several SB non stroker motors using the standard 590 Mopar lift cam with great HP results. Do I use the same cam specs if I use a roller cam?

I've done that before. They have to change the lobe profile itself but they can give you the same specs.

...but if you do that, are you really taking advantage of what the roller lobe design gives?

Or are you saying: grind me a lobe with this much duration at 0.050" (to simplify) AND of course grab as much extra duration & lift at all the other places in comparison to what the non-roller lobe had?

I assume what they did was make a roller cam with that lift and duration.

I'm looking to see if the roller , because of its faster ramp, needs a different spec? I guess I'm looking to find out if the roller will make more power with a similar cam profile.

I very much doubt you'll find a solid roller camshaft that will have the same seat timing and lobe lift. I'd expect the solid roller to have more lobe lift.

What specs are you referring too? Adv duration, 0.050 duration, 0.200 duration and max lift?

If all those Specs are the same between the two cams, the lobes will not be faster, and the power will be the same.

Well, here is something I actually went through to try to answer this very question in a QUANTITATIVE way:

1) CAM1 - hydraulic flat tappet - HughesEngines HE3844AL, 286/290, 238/244, 0.536/0.540 on 108 LSA
INTAKE: open 12 BTC, close 48 ABC
EXHAUST: open 53 BBC, close 11 ATC

2) CAM2 - hydraulic roller - CompCams custom (but basically their XR292HR with a few adjustments), 290/300, 240/248, 0.547/0.544 on 112 LSA
INTAKE: open 13 BTC, close 44 ABC
EXHAUST: open 60 BBC, close 8 ATC

The big difference in specs is a much earlier INTAKE closing event and much earlier EXHAUST opening event on the roller.

Mapping these out in terms of actual lobe lift gets me the following comparison, see attachement. What I see here is a consistent 10 deg (crankshaft) earlier delivery of the same lobe lift on the opening ramp, while the closing ramp stays pretty consistent.

The reason the profile are shifted is because of the LSA and ICL, not the lobes themselves.

Being a roller cam doesn’t automatically make the ramps faster.

Some high endurance type lobes would be slower than the MP590:cam.

The way I see it, if I’m spending the $$$ to upgrade to a roller, I’m going to try and get some more power for my money.

oh?

...but the LSA impacts only the overlap between the closing and opening points of the lobes (with the wider LSA leading to less overlap and therefore normally more docile idle, etc) all other parameter matching, and if this was a true shift I would have expected the full lobe profile to shift over, but here I'm only seeing the extra 'area under the curve' on the opening ramp.

I would like to understand this better because I'm just not visualizing this.

Take the INTAKE lobe as an example: roller has all of 2 deg @0.050" extra, and only 4 deg extra at seat. Split that into half and that means the opening ramp has only 1 deg more duration...but the graph certainly tells a different story, no?

The graph doesn't make sense to me if the @ .050 is only 2 degrees larger, why does it look like ~10 on the chart?

The roller should have the same seat to seat but have a more severe ramp from and back to the seat (or .050) , is that not right? Some Flat tappets can actually be quicker initially but by (at least .200) the roller pulls away.

I would think a .590 with Lightweight Valves (not the chunky 3/8" mopar valves) and good heads might be pretty formidable for a lot of rollers to beat, especially on a dollar for dollar basis. There's only so much power and RPM to get of most Mopar Wedge heads anyway.

It's always how much VE you can hang on to after peak torque RPM that determines PEAK HP....and most of that happens when the valves are closed.

Wringing the last availble HP (RPM) out of a wedge is more than just the cam. Even the Vaunted LS heads can't carry RPM past the torque peak as well as the Ford/BBC motors do

Part of the equation on how much more the roller could make will be, how much power is the .590 leaving on the table?

If the engine is a high CR big cube stroker with really good heads/induction/headers……..it’s probably a fair amount.

If it’s a 10:1 360 with bowl blended 1.88 valve factory heads, and you’re looking at roller cams that are fairly easy on parts…….there won’t be a big difference.

It is your graph so I cannot speak to them directly. The ICL will make a difference on how stuff lines up, and your 0.050" duration numbers do not match the open and closing events that you posted so something does not seem right there too.

The graph is scaled wrong.
Timing events are supposed to be listed in crankshaft degrees.
For crankshaft degrees of both lobes it should be 360-0(TDC)-360

The 290/300-112 cam depicted has a total duration event(@.006) of 519*(290+300-71).

Both of these can’t be correct:

240/248, 0.547/0.544 on 112 LSA
INTAKE: open 13BTC, close 44 ABC
EXHAUST: open 60 BBC, close 8 ATC

The open/close points show 237/248@.050, with C/L’s of 105.5 in/116 ex, which works out to a lsa of 110.75.
Of course those are just mathematical midpoints of the open/close points, which doesn’t take into account any lobe offset from the asymmetry of the lobe design.

Exactly. Same numbers I got. The 286/290 cam intake lobe specs conflict with themselves too. It almost like the intake timing eventnumbers got switched between the two cams.

OH CRAP!!!

Yeah, you guys I'm so sorry...I swapped the intake lobe valve events when I was doing the COPY & PASTE into the post here!!!

So here are the correct values:

1) CAM1 - hydraulic flat tappet - HughesEngines HE3844AL, 286/290, 238/244, 0.536/0.540 on 108 LSA
INTAKE: open 13 BTC, close 44 ABC
EXHAUST: open 53 BBC, close 11 ATC

2) CAM2 - hydraulic roller - CompCams custom (but basically their XR292HR with a few adjustments), 290/300, 240/248, 0.547/0.544 on 112 LSA
INTAKE: open 12 BTC, close 48 ABC
EXHAUST: open 60 BBC, close 8 ATC

And I've attached the resulting graph, this time correctly showing the CRANK degrees over the full 4 stroke cycle.

What the graph is depicting is how the two cams compare wrt total timing events.
This is how the engine will see it, but it doesn’t directly compare the lobes.

If you want to show how the lobes themselves compare to each other, irrespective of their positioning in the cycle, you’d overlay them(intake and exhaust separately), with the two lobes centerlines lined up with each other.

The lobe profiles still don’t look right. The HFT is faster from zero to 0.050 than the hyd. roller for these give lobes, but the graphed profiles look the opposite.

How exactly are the graphs generated. The only right way is actual lobe measured lift-duration data.