Mopar RB ?

[blwilliams]

Looking for facts and opinions on what the limits are on factory stamped rocker arms and shafts on 440 RB engines.
This is for a street/strip engine. Hydraulic cam.
How much lift can they handle?
Any RPM limits or will lifters be the determining factor of how much RPM?

[Frankshaft]

My rule was always low .500 lift. Like a .509 cam, would be it. Use new heavy duty mopar stamped rockers if you can still get them. Old ones will be brittle and push thru in the push rod socket. 6500. 130-350 springs as a limit.

[mag2555]

If your not gonna build the motor with big big Cam as in use for a NHRA super stock build , then 6500 rpm is already way above tapping out the flow of a stock head!
Send your rockers and shaft out to be Cryo treated and then you can apply more lift and spring pressure if you want a bigger safty factor or just plain can resist taking the motor above 6500!

[wyrmrider]

Agree with Frankshaft
HD rockers have not been available for years- if you find a source please let us know
Rocker Arm Rebuilders
http://www.rockerarms.com/index.html
can fix you up wit Industrial tipple plated hard chrome shafts and either stock or bushed iron rockers
you still have to adjust the stand height for high lift if you want to live- you can machine off the cast Iron stands and Rocker Arm folks can fix you up with the early aluminum stands that are easier to adjust
or you can use longer valves - about half the increase in lift over stock- even lash caps- just do not ignore the issue
vales are heavy- go light if you can mag has it right about rpm especially with heavy valvetrain what lifters
converting to beehive springs and light retainers helps
viton seals- the center two valves get real hot
30 degree seats work well in the .500 lift range-
I have a stack of RB heads if you need any- see the for sale page LA Area
what's your application

[Geoff2]

Mopar Performance had HD rockers in their catalog for years, P/N 4529743. They were extra thick in the p'rod cup area.

[blwilliams]

Thank you for all of your replies.
Here is the combo.
440 +040 stock stroke. Stock rods rebuilt with ARP bolts
Ross flat forged pistons. .000 deck
Edelbrock performer heads cut to 79.7 CC
Comp cams CRB XE258HL 10 241/.545 247/.545 110 LC set at 106.5
Edelbrock Torker intake with Holley 850 carb.
Engine made 509 HP 530 TQ on 91 pump gas.
As always money seems to be the bottom line, and roller rockers is just out of the budget at this time.
As I asked, just wondering how the stock rockers are going to hold up.
Doubt that this will see any thing over 5500 RPM.

[Geoff2]

I have had a lot of BB Mopars, drag racing included, always used factory arms & never had a problem. BUUUT, I have heard of p'rods punching a hole in the rocker, but pretty rare. If you have a few sets to choose from, maybe measure them all & pick the ones that are thickest in the p'rod cup. They are very strong rockers & no problem with the cam you have chosen. I once did a deflection test on the factory rockers to see how much they flexed & I was unable to detect any deflection.

[mag2555]

Untill you can fund better valve train parts take the time to tweak your spring pressure to allow no more than 6K rpm, something like 120 on the seat and 280 to 300 open sounds about right to me if you want some breathing room and to sleep better at night!

[blwilliams]

Untill you can fund better valve train parts take the time to tweak your spring pressure to allow no more than 6K rpm, something like 120 on the seat and 280 to 300 open sounds about right to me if you want some breathing room and to sleep better at night!

Yes I set the springs at 120 on the seat. just over 300 over the top.
My rationale is that other motor company's stock stamped steel rocker arms are capable of handling springs like mentioned above and lift in the .600 range (as long as the slot is long enough) and 6500 RPM range as well. Looks like the Mopar shaft has as much area around the haft as would be under a rocker ball if not more. As far as the pushrods going through the rocker that is probably the weak spot.

[wyrmrider]

Congrats you are the first I've seen to use a Comp cam with a master designed for MOPAR .904 Lifter
Note most other comp Hyd series use chevy .842 masters
that's the good news
the bad news is is your cam may have more acceleration than most installers are used to with a comp cam
so bvvc with that spring pressure

lots of times chrysler rockers go out because used pushrods are used or pushrods are swapped around
keep your pushrods and rockers in order if you take it apart
you do have new parts or kept them in order- right?

cheers
you can use LA/AMC lifters and oil the rockers through the pushrods (in addition to stock oiling- solves lots of problems

[blwilliams]

Congrats you are the first I've seen to use a Comp cam with a master designed for MOPAR .904 Lifter

you can use LA/AMC lifters and oil the rockers through the pushrods (in addition to stock oiling- solves lots of problems

That is a great idea.

Thanks

[wyrmrider]

done it for years- new lifters and hollow pushrods works on Hemis and especially LA and Early Hemi with the wide lifter angle, Tray it on a FE FORD
hate smoked balls, (or cups)