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E: Engine ET26/2 Extra Long Rocker Bearing


ClassicBiker

Well Known and Active Website User
VOC Member
A while back I complained of the Shadow smoking badly. Personal circumstances prevented me getting to it straight away. So as part of my plan to cure the issue I purchased four new rocker arms, pins, locking rocker feed bolts, and ET26/2 Extra Long Rocker Bearings. They arrived over the Xmas holiday:). Obviously "some assembly required" as with most Xmas presents. Trying to do a dry fit of all the components it became apparent that I needed to enlarge the feed bolt hole from 5/16" to 3/8" to receive the trapped nut and I will then need to produce a slight counter sink for the oil feed holes in the bearing. But what direction does the extended length go? Towards the valve or towards the push rod? I've searched the forum and caught a passing mention that it is towards the push rod, but nothing definitive. Using an undersized 1/2" transfer punch as makeshift rocker pin to look at the assembly it makes sense that the extra length is towards the push rod, but I would like to hear from someone who has actually fitted them.
Thanks
Steven
 

greg brillus

Well Known and Active Website User
VOC Member
Steve, just a couple of points you may or may not know for carrying out this mod. As you might know the top center section of each rocker will need grinding/linishing down so the rocker can pivot freely to clear the inner anchor nut you mentioned. If you grind some away, you can check for travel but installing the rocker temporarily with the ET 100/1 mod in place in the rocker bearing whilst just holding a rocker pin from one side and move the rocker up/down and you want a good 12 to 15 mm of travel at the fork end. When you bore the holes larger for the anchor nut, be sure the hole is centered as best you can, and deburr the inside of the hole with a small square file, then check visually that the anchor nut with the bolt screwed into same pulls up neatly and fully home in the roof of the rocker bearing.......Sometimes they can sit slightly to one side and this will cause the rocker/bearing assembly to sit cockeyed in the head. Before you finally press the new pins into the rockers, linish a slight bevel/chamfer onto one end of the pin and polish on a buffing wheel. Lube the parts with clean engine oil and press the pin in squarely, and I use an old cam follower spindle to do this. As the pin is an interference fit in the rocker bore, the sharp edge of the new rocker pin can broach slightly and pick up a small amount of metal that tends to grab as it passes into the other side of the alloy rocker bush, and this then makes the rocker very tight when you try to pivot the rocker in the bearing. This is why I tend to bevel and polish the pin on one end to stop this from happening. On final assembly into the head, do not over tighten the holding bolts, just a nice firm nip up is enough, the thread into the anchor nut is small and could damage easily if one gets too carried away. It is a good idea to blow through the feedbolt holes with some compressed air just in case any manufacturing swarf is still present. Good luck with it all..............Greg.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Hi Greg, I had heard of the need to relieve the rockers clear the inner nuts. I am hoping that the new rockers I purchased from the spares co. are relieved enough, they are advertised as such.100_3039.JPG
I also purchase new rocker pins. They appear to have a bevel on them, do you think this is sufficient or should aim for a bit more?100_3047.JPG
I was consider making stepped pin to guide the new rocker pin as it is pressed in or even a threaded one that I could gently draw it in with. I was also thinking about warming up the rockers in an old toaster oven and chilling the pins in the fridge along with a little light lube. Thoughts?
Steven
 

ClassicBiker

Well Known and Active Website User
VOC Member
Greg, I took a rough measurement to see if I got the range of motion you mention.
100_3049.JPG
100_3050.JPG
100_3051.JPG
I used a 1/2" transfer punch which was a nice sliding fit in everything and a second bearing to keep things level. I travel from 14 mm to 36 mm on my pocket scale. Hopefully that is enough. When the forked end of the rocker is right down the push rod end is in contact with the bearing. When the forked end it at 36 mm the relief at the forked end is in contact with the bearing.
Does this sound about right?
Thanks
Steven
 

greg brillus

Well Known and Active Website User
VOC Member
Hi there Steven, You will be fine with all you have, the parts will go together very nicely. Your point about heating the rocker, cooling the pin is probably not necessary given these parts are steel not alloy. I would still definitely linish a small bevel on one end of the pin, as the bevel you see is more so the pin does not rub against the side walls of the cylinder head tunnel. It is very important that you check that the pin does not protrude out one side even a small amount, as the pin will gouge its way in leaving a scar down the tunnel side wall and this will make the final fit very difficult. This extra bevel I mention is only about a mm long not much more would be unnecessary, and they can be quite a tight fit into the rocker itself. Some support the rocker bush in a custom made cradle with a hole in it for the pin to pass through, but I prefer to support the rocker itself across the top of the jaws of a good bench vice, and open the jaws just enough so the alloy bush slides between the jaws. Remember to lube all the parts with oil and the pin should tap in nicely. If you do go too far, just flip it over and tap back the other way.........
 

vibrac

Well Known and Active Website User
VOC Member
I used lanolin to ease the pin insertion that bevel is essential new pins from Vs should have the bevel I have seen the side of the rocker fracture off without it I use one half of the aluminium exhaust pipe bevel collar to cushion the far side of bearing in the vice
Extended bearings are only really useful on worn tunnels from pre et100 mod
 

stu spalding

Well Known and Active Website User
VOC Member
Here are a couple of my rockers. The front rocker has had far too much metal taken off it and, as supplied, gives 1 1/4" valve travel, the back rocker has been ground by myself to give sufficient clearance under the locknut. Cheers, Stu.Rockers.JPG
 

ClassicBiker

Well Known and Active Website User
VOC Member
Hi Greg, I'm following what you're saying. The pin needs more bevel than what it is supplied with, don't bother with heat/cooling, some lube is more important. Some form of support for the rocker.
Thanks.
Steven

Vibrac, Fracture!!! o_O Bevel is top of the to do list!!!
Thanks.
Steven

Stu, The front rocker in your photo looks very similar to the Spares Co. rockers I just purchased, which definitely has more material removed than that which is in the rear of your photo. Si I'm feeling good about that now. I followed the 1 1/4":)
Thanks.
Steven
 

stu spalding

Well Known and Active Website User
VOC Member
The best thing to do with the pins ET28 is spin them in a drill and break the edges with a fine stone. They then won't pick up in the bushes or rockers. Cheers, Stu.
 

Vincent Brake

Well Known and Active Website User
VOC Member
Hi Greg, I had heard of the need to relieve the rockers clear the inner nuts. I am hoping that the new rockers I purchased from the spares co. are relieved enough, they are advertised as such.View attachment 25436
I also purchase new rocker pins. They appear to have a bevel on them, do you think this is sufficient or should aim for a bit more?View attachment 25437
I was consider making stepped pin to guide the new rocker pin as it is pressed in or even a threaded one that I could gently draw it in with. I was also thinking about warming up the rockers in an old toaster oven and chilling the pins in the fridge along with a little light lube. Thoughts?
Steven
Well one could take out a bit more metal and get really light ones.!

It sure looks not all right. Part taken out where they need to be stiff.
But one never knows.
If they hold one let me know plse

Cheers
 

greg brillus

Well Known and Active Website User
VOC Member
The stock rockers I generally grind them so they look similar to the one in the picture above to the rear of the photo. And I usually polish the grind marks out and radius the edges, I don't like sharp edges or burs on holes. The new rockers that Neal supplies are like the originals but the hole is higher up and does not have the cutaway sections like the ones shown in the above picture.
 

Bill Thomas

Well Known and Active Website User
VOC Member
I wonder how many people have not known of this problem, And put an Engine together, As is ?.
I was worried about how much I had to grind off the rockers, When we did one in 2015, Although I have used this Mod' for many years, Even made my own version, And used Spares Company ones as well.
I thought I was grinding too much !.
Nice to see the Spares Company parts are ground like this now.
I think it's how deep the valve seats are part of the problem. Cheers Bill.
 

timetraveller

Well Known and Active Website User
VOC Member
Has anyone on here got access to a 'Finite Element Analysis' program? Even knowing that the forces along the top edge are 'compressive, it still does not look right to me. In the past I have ground them as the rear one in the photograph.
 

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