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adjustable rockers

Started by GoMangoBoys, April 13, 2020, 10:18:10 AM

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GoMangoBoys

As you all may know, we are new to Mopar.  We are planning our engine build.  We are planning to stroke the 383.  We have not made a final decision to go 432 or 489.  We are going to run the 906 heads with the 2.14 valves.  I picked up a very nice set that a guy was using on a drag car when he upgraded to a set of trick flows.  I am trying to build a good engine with a performance upgrade, but want to control cost.  To be honest, I am a bit shocked at the price of the Mopar stuff compared to the Chevy small block stuff.  I have a guy that has a crane roller rocker assembly with the shafts and everything for $200.  They are 1.5 ratio and adjustable.
What is the purpose of the adjustable rockers when using a hydraulic lifter?  I am not used to the concept of the rockers on a common shaft.  The Chevy has each rocker on its own stud.  The nut adjusts the lash.  Don't get me wrong, I am not an expert on Chevy by any means either, but I have done it a couple times.

I have a quote from an engine builder that I saw at the Indy swap.  He was quoting me a stoker kit along with the cam and the rocker assembly.  The rocker price was close to $900.  The $200 used but nice option seems like a better choice for me.  Also, the ratio is different, 1.5 vs 1.6.

My questions are,
1.  What is the purpose of the adjustable rockers vs the stamped ones that came from the factory?
2.  Can I get away with using a set of stamped factory rockers?
3.  I assume that 1.5 vs 1.6 can be dealt with by the amount of lift in the selected cam?
Thanks

JS29

 :thinking: Are you talking roller of non roller?

GoMangoBoys

The rockers that I have the chance to buy are adjustable roller rockers I believe.


RUNCHARGER

It depends on what camshaft you may want to run. The stock rockers will work adequately on a hydraulic, flat tappet camshaft with a lift in the .500 range. After that you will need a set of adjustable rockers. Crane makes good stuff, I would be tempted to pick those rockers up if they are in good condition.
Sheldon

JonH

1. Adjustable is just that. You have the opportunity to fine tune lifter preload for each lifter. This assumes a hydraulic cam. With solid lifters you need the rockers to be adjustable.
2. Depends on what cam and valve springs you run. High lift cams and high spring pressures may not be compatible with stock rockers and shafts. Cam profile and spring pressure will determine this.
3. Pretty much. I would not stress over this on a street motor.

Bottom line your engine combination (cam profile, spring pressures, intended use) should dictate what you need. Personally I would buy the Crane stuff you are looking at if you want to upgrade. Others will give you some alternatives.

usraptor

#5
Quote from: RUNCHARGER on April 13, 2020, 10:38:04 AM
It depends on what camshaft you may want to run. The stock rockers will work adequately on a hydraulic, flat tappet camshaft with a lift in the .500 range. After that you will need a set of adjustable rockers. Crane makes good stuff, I would be tempted to pick those rockers up if they are in good condition.
I agree with Runcharger.  For the price I would go with the crane rockers.  Make sure you check the rocker roller tips for excessive wearing and or missing or lose bearings.  PRW also makes reasonably priced roller rockers.  As Runcharger stated a lot depends on which cam you're going to run.  Lunati has an excellent selection of cams for all purposes.  Keep in mind, that depending on which cam you use you may have to buy custom built push rods.  I ran a high performance Lunati street cam in my 440/512 stroker with PRW rockers and needed custom built push rods.   I later changed to a Bullet custom ground cam with roller lifters and needed custom push rods again even though I'm still running the PRW rockers.  Good luck and keep us posted on your decision.  :wrenching:

JS29

Roller rockers alone will increase horse power by freeing up friction! I would buy them.  :yes:


Chryco Psycho

 :iagree:
For $200 if they are in good shape I would use them .
I do prefer the Iron rockers if you can find a set tho .
The Chev rockers do allow individual adjustment But they limit travel if the slot is not long enough.
the shaft style do not limit travel & are far more stable overall & provide better oiling .
Lunati does offer some great grinds for Mopar so you can get a lot of lift / duration due to the wider Mopar lifter without the need for 1.6 rockers

Chryco Psycho

I was also going to mention that the ratio on a roller rocker is generally far more accurate than a stamped rocker & you can control the lifter preloadfar more accurately .

GoMangoBoys

My opportunity in the Crane roller rocker assemblies did not work out.  They were sold before I could get them.  Has anyone had any experience with these?  They seem like a good value, especially given that they include the pushrods.
https://www.manciniracing.com/mre5700192841.html

Chryco Psycho

I would look for a set of PRW rockers , Stainless are better for long term street use or find a set of the Iron rockers , alum are more of a race part


Chryco Psycho


Chryco Psycho

Prw , I have used htese in a lot of the engines I have built , never had a problem with them . Both the Crane Iron & the PRW Will fit under stock covers too .
https://www.ebay.com/itm/PRW-3244011-Stainless-Steel-1-5-Ratio-Rocker-Arm-System-Big-Block-Mopar-361-440/133383005305?epid=19017020146&hash=item1f0e3f2479:g:mR8AAOSwsidejyVJ

RUNCHARGER

I generally source used ISKY or Crane iron rockers and use new adjusters on them. They'll never break and usually they sell in the $200 range.
Sheldon

GoMangoBoys

Does anyone know where the PRW rockers are made?