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Discussion Starter #1
I picked up some information from a local harley dinosaur a few years ago, about the ‘misallignment’ from the rockers in the rockerbox, at this moment i have a few rockerboxes available for an exploded view to check the myth , wich tells the factory intentions where to angle the rockers a bit compared to the head top surface with the intention that every time the rocker pushes the valve it will spin the valve around his own axis to keep the valve seating clean. Resulting more in wrongly loaded valve stems and guides and rocker tips. It is even an 3 dimensional angle because the inlet and outlet side differ as well, i made a steel block with 2 arbors that will line up the rockershaft holes perpendicular in every direction so i can remill the rockerbox gasket surface to get rid of that angle, no way a valve would spin its own axis anyway.
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F4091E28-41A0-41C3-B987-F104AB3AF234.jpeg
B49D86A0-AE2B-4D9D-BA4F-27968C9E81A2.jpeg
B69E261E-AA4B-47B8-A9E8-5E2881D1012A.jpeg
 

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someone said the shaft angle was intended to spin the valve during use?

my guess is that the springs, retainers and keepers all locked together will prevent any rotation.
i also guess it's a compromise to help correct the angle of the rocker and push rod to cut down some of the clatter or maybe wear on one end of the rocker.
yes, i could be way off on that guess, i have been so many times.

lets us know how it works for you if you alter the boxes to correct the shaft angle.
 

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Discussion Starter #3 (Edited)
Dan , it is not a wrong idea , only they normally use a dedicated mechanism for this rotation with all the moving parts in one centre-line, not an angled rocker. Check out the link. VALVE ROTATORS edit , while searching the net i ran into Dan Baisley Hi performance Portland , i requested his opinion and he confirmed my suspicions. I will fire up the mill very soon.
 

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I looked at the link. I have seen valve rotators in many engines and yes they may extend valve life. Many diesel engines of all brands use them mostly today. When I worked for Ford in the early to mid 70's there were many truck engines with the positive rotators on exhaust valves. In the late 70's they used a different method called the split collet type like what is shown in that article you listed. Those split collet type valve keepers come together and wedge into the spring retainer and the valve stem will still rotate in the keepers. Shovelheads, well, all Harleys really, the valve keepers wedge into the spring retainers and clamp onto the valve stems and yes, prevent rotation. While I'm no big name shop owner or wrench in the back room of one, I have been doing valve jobs on shovels close to 40 years. I have never seen any evidence that the rocker shaft angle induces valve spinning in the guides. Wear on guides and valve stems of shovelheads clearly show only straight line wear patterns. Most often in bad worn heads the stems show wear much more on one side, not even all around as if it was spinning.

Any way... What is your end goal if as you say the rocker angle spins the valve. If you change the angle to 90 degrees there will be no spinning of a valve right? What do you hope to gain? The picture of the rocker arm you show above has a wear spot, is that what you hope to prevent? That rocker arm in your pic has had that pad reground btw and they are case hardened to start with...

yes, testing to see if I can post pix here yet, maybe...
heads 001.jpg
 

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Discussion Starter #5 (Edited)
Dan thanks for the reply , appreciated.
I started this topic not to tudor but to get to know some opinions , mine is that if this design was deliberately for that purpose the might have missed it ( i think we agree on that) and the modification is relatively easy. The geometry could be optimised.
I just learned the pan and evo heads do not have this addtional angle ,no doubts about your experience, to be honoust... when you did your first head i was learning square from rectangular. 1B591F11-8BD6-49D2-8C7A-B112867EC108.jpeg
 

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That last picture clearly shows each rocker shaft is at a different height, the other box will lean the other way.

I ask myself why would they do that? Could it be because of the camshaft centerline is above crankshaft centerline? The total valvetrain system on harleys uses angles that are less than ideal. If you look at just rocker arms, you will notice there are two different types, one of each for each head. Making only two types is a production compromise. It makes parts that are somewhat universal (lower cost) but yes, less than ideal for each location they are used in. My guess the side to side angle and the different heights is a compromise to help but not totally correct the working angles. One could then say, best we can do with what we have. I'm only guessing that it was a compromise to keep costs down yet make something that would still perform somewhat reliably.

I'm very interested in how your modified version will perform.

Here are a few old prints you may find useful...
272266


272267
 

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Discussion Starter #8
Thanks for the drawings , very interresting. I have a few days of but when i get back to work i will get in to it a bit further.
 

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for me the greater point is the fact that the rocker pad does not follow the correct location being in the center of the valve at 1/2 camshaft lift - i would think a tool to mimic the rocker box and an angle changing grinder to finesse the pad is a better idea

they never intended the engine to be a million mile 12 valve Cummings - and they have always benefited from massive replacement of parts as a means to more profit
 

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Discussion Starter #10 (Edited)
Hi gents , it seems like i opened a pandora’s rockerbox on myself 😬 i inquired some information here and there and i learned a lot in the last few days , the valve train set up is really a compromise for every valve to be a bit effective ...maybe i am to eager on it now.
But there is still a lot to gain, even for streetwise machines , the additional angle of 1 degree as seen on the drawing compromises the push rods positioned a bit more inward at the bottom. The rocker to valve surface has to give in a bit for that detail. i choose the opposite. @Dan , where did you get that blueprints from?? Are there more available? @johnjzjz , perhaps a tunable rocker set up could be something , some tuners do this by welding. Al we need is to find a proper macineshop...
C2CD0ED6-5997-40F0-84F6-4E3D852610C7.jpeg
 

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I found the prints years ago on a shovelhead forum. I don't remember just who posted them. I seem to think is was someone who was connected to STD but I could be wrong.
stddevelopment.com
Yes, as you are finding, all Harley rockers are a compromise.
Many years ago there was a company who made rockers for evo engines that were adjustable. It might have been Rivera but brain fade is kicking in again.
Quality, Performance Parts and Accessories for V Twin | Harley – Rivera Primo
Both companies have evolved, changed ownership and well, they are not the same companies they were 25-30 years ago.

Ok, back to the subject... If you perfected each rockers angles you will no doubt end up with four that are distinctly different. During the process you will then learn that valve stem protrusion will be off I'm guessing 100% of the time. So after that second stumbling block it will then hit you, everything changes completely again with different camshaft lifts...

Now lets talk about a few other disadvantages and also other possible advantages. You must look at every thing from cam lobe to valve stem if you want to make worth while improvements. One thing I have noticed with some aftermarket designs, they are blending what they have learned from the evolution engine. The evo has different/larger diameter tappets with larger rollers that will follow a camshaft lobe easier. The evo hydraulic tappet is also a much more modern (read efficient) design. Another advantage is top end oiling, up through the pushrods vs outside oil lines. There are retro fit kits from the aftermarket to adapt evo design cams, tappets and blocks, pushrods and rocker arms into shovelheads.

The point I getting to in a round about way is. If your going to play with rocker arm angles, might as well blend in other improvements at the same time. I look at your splined rocker drawing and say ok on paper, what is it going to cost to produce?

Sooo... Blending in evo cams, tappets, blocks and rockers will be more cost effective and will at the same time will give you a more modern camshaft profile design. Then take the more readily available evo rockers, saw them in half, adjust for angles and then weld them back together.

Here are a few more prints I have for shovelheads and rockers, all I have. I noticed this head print has the valve stems at different angles...
head.jpg


and here's a rocker...
rocker.jpg
 

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Discussion Starter #12
Dan , thanks for the reply and feedback .
Very usefull , the valve stem angles are different indeed , in 40.25 and out 38.25 degree.
I am aware its not an single part modification by now , but i am always curious about the do’s and dont’s and sometimes have a costly way of learning. But learning never stops.
 

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The shovel evo conversion turns a shovel into a power house - but the rocker arms from S&S are proprietary to the new cam and lifter via the push rods and instead of the stock 1.43 rocker ratio its 1.5 for the shovel evo combo — evo is 1.625 so any given cam produces less lift and a couple degrees duration is also lost in the ratio change

they seen something when doing that besides the different valve stem heights they dont Share - is my guess
 

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272295


I have never measured it, many other things to do, but it's obvious that both the shovel and the Iron Head Sportster have compromised rocker geometries cause nowt is in line with nowt when it comes to valve actuation!!!

What you describe in the drg above is just what Harley did in 1972 with the then new alloy XR engine. Since the stroke was much shorter than the previous Waffle Iron XR and its predecessor, the XLR-TT, the geometry was much worse and needed attention.

So they forged 2 rockers, Front and Rear, then cut them both in half. Then 4 different jigs were used (one per valve) to reangle and weld each F and R rocker to the right angle in the new location.

This was so critical on an engine turning 9500rpm that the eccentric adjustment of valve lash on the rocker shaft only allowed 1/4 turn adjustment. Past that, new valves or valve tip grinding required to bring back the geometry within its tolerances.

Which is why the price of XR rockers these days is so high in the collector market, the jigs are long gone...

Patrick
 

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Discussion Starter #15 (Edited)
@ johnjzjz Yeah , in my own bike i have jims roller rockers for at about 18 years now , combined with a unknown sifton cam wich was already in it , it is easy starter and smooth ride .
That makes me curious about the rockers geometry, if only the lever is longer in this ratio it will be way off the valve stem centre line....better leave it untouched for now Dennoz.
First i will exam Dan’s blueprints a bit closer and get that visualized.

french owl , merci beaucoup . Turns out i am not that crazy, i did knew about the welding but i guess i had a commercial potention in the back of my mind....what if a respected company would provide such parts ...i know they will charge too much , but i think more shops or ‘tuners’ will consider this as more easy acces compared to welding....ooh well , i am no respected company.
 

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Yes, but the costs of the alloy XR 2 x forging dies plus 2 jigs for machining, then cutting and welding in 4 jigs, was cheaper than 4 x forging dies and 4 machining jigs.

The HD race dept was also up to scratch for welding hardened stuff, they had been doing that for years to KR cams to index them dead on... (in my KHK, one OEM exhaust cam is 10 degree off the other OEM cam, same duration but advanced... std machining tolerance for HD cams is + or - 2 degrees, so that's 4 deg max, not 10!!!)

Patrick
 

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Dutch the spot when building race engines we looked at very close is the 1/2 cam shaft lobe lift to the rocker pad center ( of its ratio ) matches the valve at location of 1/2 camshaft lift is also in the center of the valve - valve harmonics is lessened we feel no proof not wealthy enough

i am convinced this on a engine dyno shows the speed of torque was increased when you have this correct along with exact valve weight to valve springs rate - an increase is shown only a frizzle increase - its the speed that counts

when the rocker is allowed to be negative or positive to the center - the valve rub wear is seen on the top of the valve and the valve guide is being egg shaped - ( side load ) we have also see the seats 45 degree angle flatten a bit 90 degrees to the rub mark line - when this is seen in a used race engine the valve on the grinder at .0002 to .0003 is showing a valve warp - it was loosing power
 

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I don't have the Shovel dimms, but I drew a similar set up with the same valve angles and correct geometry when all is at right angles at 1/2 cam lift.

Just to show the disadvantage to have a camshaft above the crankpin!!!

Rear Exhaust: Rocker Arms angle 162 deg, Push Rod length 261.7mm
Rear Inlet: Rocker Arms angle 147 deg, Push Rod length 246.2mm

Front Inlet: Rocker Arms angle 141 deg, Push Rod length 243.7mm
Front Exhaust: Rocker Arms angle 158 deg, Push Rod length 260.3mm

Also worth noticing since the 4 cams are on the same axis, so that, viewed from the front of the engine, each push rod attack each rockers at a different angle... More unwanted side trusts...

Patrick
 
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