I have a set of PRW 1.6:1 stainless steel rocker arms that I want to use on a set of edelbrock 6077 heads, but am having clearance problems.

I've swapped the springs with a set of lunati dual springs 73195, with 10 degree locks/retainers.

Is it safe to notch the rocker arms or do I need to search for another solution? I would like to keep the springs I have since they were matched to the cam (lunati 60403).

thanks,
Ray


[img]https://drive.google.com/open?id=14qncSUypfApLo8jidCAT4LzXdHElrtRb[/img]

[img]https://drive.google.com/open?id=1bo0YXP4514eK4prXOIBYd-eJaVB4noxs[/img]

Hey Ray , Welcome to my world . LOL I have a set of HS Rollers and they were machined by HS before I got them. Grind them to fit but take your time and go slow. My 2 cents only.

How close are they.. are you using 1.55 dia
springs.. I have clearanced a couple sets of
rockers to clear for roller springs.. make
sure you get a radius in the corner so they
dont crack... the rockers I did were the
blue MP (Crane) alum ones

Hey Mike I like the pictures of his because they don't look like they need too much work and they also look to be reinforced in the fulcrum area.

Here are the spring specs. for the Lunati web site

Product Description
Type: Dual With Damper
O.D. Outer: 1.437"
I.D. Outer: 1.076"
I.D. Inner: .697"
Coil Bind: 1.050"
Seat Load: 115@1.700"
Open Load: 336@1.150"
Rate (lbs/in): 402
Quantity: 16

What type of tool did you use to clearance the rockers? I have alot more time than money so I thought about using a dremel and going slow.

I appreciate everyone's feedback.

-Ray

Yeah they are decent rockers.. even after I cut
them.. I put them in the mill to do it.. I had to
have a cutter made for the radius that I wanted..
wasnt too bad on price and I still have that bit

FWIW I ran the exact same cam with Comp 901 springs (single with damper) and stock retainers with no problem. Totally different rocker arms, just saying I don't think you need the dual springs Lunati recommends. I think they call for their same dual spring for the voodoo cam that is a step below that too. Before I set mine up I looked at all the other cam manufacturers and no one else was calling for a dual spring for the cams in the 60403's duration and lift range.

What retainers are you using? In the pics you posted it almost looks like the retainer you are using is wider than the spring itself. IIRC retainers are usually slightly smaller diameter than the spring OD. It looks like you're pretty close, if that's the case a smaller retainer diameter may get you where you need to be.

My solution was to find a beehive spring with similar specs. Plenty of clearance.

I use to clearance Harland Sharps and Crane ductile iron rockers. But no matter how well you do the job and how little you take off, it does weaken the rocker. But my applications have been more radical than yours and a little clearancing will probably work well for you. I just decided to get away from that.

You're removing metal at one of the worst possible places: it's always in tension, and near the mid-point (between the rocker shaft and the roller axle) is even worse.
Make the smallest possible notch, only exactly where you need it, and blend it into the remaining shape until it's invisible.
An FEA projection will show the notch in bright red. Yes, that's exactly where it may break.

[quote=polyspheric]You're removing metal at one of the worst possible places:

Just had a buddy cause a bunch of damage to his small block because of this exact thing. The machine shop that built his engine clearanced his HS rockers and left less than an 1/8 " of material at it's weakest spot and when it broke pieces went through the oil system, it's looking like he will go back with HS rockers and they told him they could clearance them without sacrificing strength.

There have been HUNDREDS of guys that did this
with no issues.. I did it running roller cams
and high spring pressures.. hell they tell you
that you can in the Mopar small block book

Lash caps and rocker shaft shims is what I would do. Maybe even look at a different retainer.

It's actually not strength but stiffness - the rocker shape concentrates bending stress right there, and when it bends a few thousand times the aluminum just gives up. Steel would not only be much stiffer (1/3 as much material with equal stiffness - yes, really) but also recover from worse distortion without failure.

Being the OCD that you all love, let me amend their statement: "we can clearance the rocker to safety without compromising the strength... to the point of failure... in your engine".
With a 900 lb. spring, or 10,000 RPM, that wouldn't be safe.

For long mileage with big springs, investment cast steel rockers is the best bang for the buck. Any structural aluminum part will eventually fail in service, it's not a quality or design flaw, they just don't have the "memory" of steel parts.
Pratt Institute has steam engines built in 1900, still running with the original rocker arms.

DO NOT GRIND ON THE ROCKER ARMS.

That's not the correct way to fix it. You don't have enough spring diameter to have an issue.


What you have is a geometry problem. Fix the problem it's your geometry and you won't have rockers hitting the springs. You don't need beehive springs.

Contact Mike at b3racingengines and have him help you correct the geometry.

I run the same rockers as you do and a 1.500 spring. With the geometry correct I can run a 1.625 spring and not hit the rocker.


FWIW I had to raise my shafts .280 and IIRC .100 towards the intake manifold.

Don't grind the rockers.

How old is that kit? The early ones fit perfect on eom heads with oem specs and they were not worth trying to fix for a modified or different head.

If you have a junk oem 318 like head laying around, toss that rocker set on and see how they look. I bet they fit and align with little room to spare.

If you have as delivered length valves in your eddy heads id bet thats the case here, the newer prw-s fit alot better ootb.

Looking at the OD of the spring you should clear
with no issues.. check everything first

I'm inclined to agree. Nothing wrong with the rockers, the shafts are in the wrong location.

On my W-5 heads I had to add a .060 piece
of stock under the mounts to get things right
but those use TD paired rockers and PR oiling..
they are great now.. I dont like to grind on
steel rockers.. they have less material to work
with.. unlike the alum rockers which have a
pretty thick section where it touches(at least
with a 1.55 spring and the Crane rockers)

Anytime you grind on something I agree it looses strength but for the nominal amount needed from what I see on the rockers I would say sure try to adjust your shafts a little but at the end of the day if the rockers are too close grind them if needed. I have seen it done over the years to many , many setups and have not seen them fail yet. Again my 2 cents only

I'd agree with you if he was running a bigger diameter spring. They just aren't that big. The reason the rockers are hitting is because the OP has changed enough pieces in the system that the rocker shaft is now too low, and too close to the springs.

The shaft needs to go up, and towards the intake manifold.

Back in the day, the ONLY way to fix this issue was to mill down the stands and use offset blocks and shafts just like W-2 stuff. It was costly and most guys wouldn't do it, so they ran with geometry wrong.

The only guy I know who makes the pieces to correct geometry without milling the stands is Mike at B3 racing engines. His system is cost effective and works. It's very simple.

I used it with my PRW rockers.

Lash caps and all that other stuff won't correct the geometry.

It just kills me to see guys grinding rockers, running lash caps and doing all kinds of things to cobble the valve train together. Someone has made it simple to correct and we should all be doing it, rather than grind on a rocker arm.