What shaft for ductile iron rockers?

[Jonas Nordstrom]

Ive got a set of mopar Ductile Iron adjustable rockers for my 440 build.
Now, I read something about special shafts for these with "banana" shaped holes etc?

Ive not digged into rocker arm shafts before so please educate me.

 

[Lefty71]

All systems benefit from the banana groove shafts from what I've heard. Really just gets oil more thoroughly scattered up top, which is good for cooling and longevity of all the components in the upper valve gear. Hughes Engines, and others can supply them for you.

ROCKER SHAFTS W/GROOVE BB (PR) :: HUG-1620

 

[lewtot184]

use induction hardened shafts; don't use chrome or stock. i believe the hughes shafts are induction hardened.

 

[gkent]

"from what I've heard" yikes !!!

Call Rocker Arms Unlimited and get the right advice. Back in the day those rockers worked ok on stock shafts - just look at what max wedges and both gen I and gen II hemis came with! The only problem with them on the B motors is they'd go oval if the bolts were overtightened and then the rockers would bind and gall. The best fix "back then" was a set of over-the-counter TRW shafts that were thicker and had a ground finish. Banana grooves, sure, but not having them isn't a show stopper.

 

[RJRENTON]

Ive got a set of mopar Ductile Iron adjustable rockers for my 440 build.
Now, I read something about special shafts for these with "banana" shaped holes etc?

Ive not digged into rocker arm shafts before so please educate me.

IMO.....my vote is for shafting made from SAE/ASME 1045 cold rolled material, centerless ground and machined to dimensions to replicate the origional shaft. 4140 cold rolled steel, machined similar to the first choice, would be an excellent alternative.
BOB RENTON

 

[gkent]

IMO.....my vote is for shafting made from SAE/ASME 1045 cold rolled material, centerless ground and machined to dimensions to replicate the origional shaft. 4140 cold rolled steel, machined similar to the first choice, would be an excellent alternative.
BOB RENTON

And who makes those Bob ?!?

 

[lewtot184]

of all the ductile iron rockers and stock shafts i've used thru the decades they always go to crap at the fulcrum points; no exceptions. chrome plating will wear off and hasn't faired as well as i'd hoped with iron rockers. the best results i've had is with induction hardened shafts and the truth is they probably will still go to crap at the fulcrum points; just not as soon. i've kept a couple of sets of cranes laying around for small cam stuff, but truth is i know that ductile iron is just a 1950's obsolete end to a means. i don't understand the love affair for them when a roller tip rocker is far superior; especially when setting rocker geometry up.

 

[padam]

of all the ductile iron rockers and stock shafts i've used thru the decades they always go to crap at the fulcrum points; no exceptions. chrome plating will wear off and hasn't faired as well as i'd hoped with iron rockers. the best results i've had is with induction hardened shafts and the truth is they probably will still go to crap at the fulcrum points; just not as soon. i've kept a couple of sets of cranes laying around for small cam stuff, but truth is i know that ductile iron is just a 1950's obsolete end to a means. i don't understand the love affair for them when a roller tip rocker is far superior; especially when setting rocker geometry up.

I was under the impression that it is easier to get the geometry right with a non- roller tip rocker.

 

[Cranky]

I've pulled lots of engines apart that had hardened shafts.....from the factory. These engines were from the 70's and had no evidence of anyone modifying them so, what was up with that? Was 'mom' experimenting with what worked the best for extended warranties? Lots of shafts were soft soft and some were harder and some were even harder! I've run ductile non roller rockers at the track and had good results with that but yeah, some rockers transfered metal on one shaft while the other side didn't. The one that had metal transfer was softer than the other on the same engine...and yes, do the banana groove. As for roller tips....never used them.

 

[lewtot184]

I was under the impression that it is easier to get the geometry right with a non- roller tip rocker.

nope. the non-roller can have a big scrub pattern, rollers don't and that makes the roller easier to correct. the more valve lift the longer the scrub pattern gets on iron rockers. keep in mind that this problem wasn't much of a "problem" in the late '50's and 60's because there weren't high lift/fast rate lobes, and big spring pressures. those old max wedge double yellow springs were only about 280lbs open. the 300 letter series engines had even less spring pressures and very gentle lobes.

 

[lewtot184]

I've pulled lots of engines apart that had hardened shafts.....from the factory. These engines were from the 70's and had no evidence of anyone modifying them so, what was up with that? Was 'mom' experimenting with what worked the best for extended warranties? Lots of shafts were soft soft and some were harder and some were even harder! I've run ductile non roller rockers at the track and had good results with that but yeah, some rockers transfered metal on one shaft while the other side didn't. The one that had metal transfer was softer than the other on the same engine...and yes, do the banana groove. As for roller tips....never used them.

never heard of or seen a factory "hard" shaft. i believe induction hardening was in its infancy for detroit cars and i sure don't remember seeing thick shafts; or at least i never had any. the smog engines that i've taken apart had those low pressure green springs on them. a magnum spring was only 230-240lbs open with a very gentle cam lobe.

 

[BSB67]

I use standard shafts with ductile iron rockers once. My machinist told me not to do it. They galled the shafts badly. Had a hard time getting them off.

 

[Jonas Nordstrom]

Good info here, thanks.
The hughes shaft seems to be a good choice.
Now lets see if I have some luck and my rockers fit a .875 shaft.

(I have a set of used Crane ductiles that use the .872 shaft)

And roller tips are prolly awesome, never used them but they are almost the only rockers you find in stores today.
Though in my build I want as little moving parts as possible. A street 440 with a cam close to stock.

 

[Geoff 2]

Standard shafts ARE hard. Hard steel & perfectly suitable for ductile rockers. No need for grooves either; you are just removing surface area where the load is at it's greatest.
Chrome shafts were made for alum rockers that ran direct on the shaft, were bushed or had roller brgs. Hard chrome, not decorative chrome.

 

[Lefty71]

"from what I've heard" yikes !!!

I'll throw in that probably way more important that running banana grooves (or not), that the OP should go to the trouble to set the rocker geometry up properly and shim the entire rocker assembly to .015" on each side. The importance of a well set-up upper valve gear, even on a street engine shouldn't be overlooked, because it will go miles towards reducing stress and ensure oil control where it's needed for the rockers.

 

[lewtot184]

stock shafts are not hard. they are far from being hardened.

the main reason i chase rocker geometry is to keep from tearing the valve guides up. the large scrub pattern of the ductile iron definitely can affect guide wear. there are some tutorials out on the web about setting geometry with a non-roller tip. the more lift the longer the scrub can be and geometry can become more critical. i think it's easier to check/set geometry with the heads on the bench than with the engine on a stand and virtually impossible with the engine in the car. i put checking springs on the heads, mount the rockers and shafts and then manually work the rockers with some typewriter carbon paper under the valve tip to show where the contact pattern is. if you try to set geometry with engine in the car about the only thing you can do is apply some layout dye on the valve tips, run the engine, then take the rockers off and look at the pattern. a lot less messy to just do it on the bench. there's a big difference in wear pattern on a non-roller vs roller tip. when that is solved then mount the heads on the short block and go after the push rod geometry.

 

[Jonas Nordstrom]

I'll throw in that probably way more important that running banana grooves (or not), that the OP should go to the trouble to set the rocker geometry up properly and shim the entire rocker assembly to .015" on each side. The importance of a well set-up upper valve gear, even on a street engine shouldn't be overlooked, because it will go miles towards reducing stress and ensure oil control where it's needed for the rockers.

Shim .015 on each side?

 

[lewtot184]

Shim .015 on each side?

don't shim anything until you've checked the scrub pattern on the valve tip.

 

[Jonas Nordstrom]

don't shim anything until you've checked the scrub pattern on the valve tip.

What would be the best way to do that?
Put on a paste and turn the engine by hand?

 

[Lefty71]

Shim .015 on each side?

I meant each bank (each side) of the whole engine.... The shimming I'm referring to is side to side for each rocker.... The .015" clearance measurement will be found as a total in each pair between the rocker shaft hold-downs. This reduced clearance will allow for better stability and oil control. Some people call rocker geometry "shimming" because there is a way to use shims to lift the shafts up off the cast-in pedestals. I suspect this is what Lewtot184 is referring to in post #18, but he'll chime in I'm sure.
Try reading here for some info on geometry correction;

B3 Racing Engines LLC - Mopar Rocker Arm Geometry Tech

HTH, Lefty71