Solid lift cam to roller Q's

I have run a Mopar Performance .590 solid lift purple cam for years. Want to switch to a solid roller, but stick to something "comparable"., or basically the same cam, except for it being a roller. Do I leave the duration the same and change the lift or do both need changing to keep it the "same"?
Bowtie guys tell me that a solid roller needs about .100" more lift than a sft cam to maintain, but with mopar lifters being so much larger, do they "act" like a roller already?

Thanks, Brian

Have to take into consideration the lash for the MP cam and the rollers lash per Tim Goolsby at Bullet Cams.

Changing the cam, lifters, push rods, and valve springs with plans to keep the same level of performance. Kinda curious as to why.

Combo is well sorted out. Tired of trying to find a .590 & lifter kit and tried of dealing with junk cam & lifters.

Brian

I seem to read as many complaints on forums about roller cams and lifters as I do flat tappets. So much crap out there today. Personally, I don't know which way I would go today if I were doing a project.

Good luck!

You need to keep in mind that the roller cam lobes are design to open the valves quicker and the effective duration from .050 lobe lift opening back to .050 closing is a lot longer than a flat tappet cam will be if you go of the .050 duration numbers.
As far as the timing and jetting I would leave both alone and go see how it performs before touching it
Try it, you may REALLY like it

I posted this years ago, but it sounds like a good thread to bring it back up. It's the solid ft cam that Dwayne Porter spec'd for my old Stage VI combination compared to the solid roller he got me for my Victor heads. Both cams were profiled in the 452's block and the roller was checked using .800"-wheel IMM lifters. I'm sure due to the bigger roller wheel than the standard .750", the roller cam came out a tad bigger than the supplied spec card:

The solid came came from COMP's XX .875"-lifter family and is an older NASCAR-type lobe. It isn't as aggressive as the later .904"-type lobes, but has still proven to make good power and RPM.

COMP XX
@ .020" - 297.5 (adv 298)
@ .050" - 266
@ .100" - 232
@ .200" - 178.5 (adv 180)
@ .300" - 121.5
@ .400" - N/A

Lobe lift .3975 (adv .400)
Gross lift .596 (1.5); .636 (1.6)
LSA 108
Lash range .016" - .024"

The COMP RX roller series is a moderately aggressive endurance lobe which Dwayne has said has been very successful for his customers looking for decent valve train life when running a solid roller.

COMP RX
@ .020" - 300 (adv 298)
@ .050" - 266 (adv 265)
@ .100" - 233
@ .200" - 184 (adv 183)
@ .300" - 134
@ .400" - 68

Lobe lift .434
Gross lift .651 (1.5); .694 (1.6)
LSA 108
Lash range .018" - .026"

A larger tappet wheel does enlarge the "area under the curve", but also distorts the tappet motion slightly by changing speed on both sides of the lobe.
.050" difference probably has minimal effect; a much larger roller may need more spring tension.

Harley-Davidson has used .855" rollers 1929-83 on all engines, and minimized the side thrust vector by offsetting the tappet center line advanced (earlier) w/r/t the base circle CL. This places the roller over the rising lobe (rather than along side it).
It has been suggested that the optimum amount of offset is ½ the lobe height. H-D 4-cam motors (1929-* 750, 900, 1000, 1200 & 1300cc) with lobes between .220” and .440” all used ⅛” offset, single-cam big twins (1936-83 1000, 1200 & 1340cc) are 3∕32”.

You can't use cheap roller lifters. There are chinese lifter sets on ebay for les than $300. Not everyone needs a set of $1300 Isky lifters, but you have to use decent stuff.
Not to mention, used roller lifters are about the same as used aluminum rods...they're all advertised as having dyno time only, lol.

For a bracket race type application, the only argument I can see for not using a roller is it one simply can’t afford it.
Or, it’s an engine platform where roller cam parts are difficult to come by.

BBM? It’s a no brainer for me.