I am restoring a 27 J. When I dismantled the engine one of things I found was that the rollers that run on the cam lobes were badly worn. In fact the whole roller arm mechanism was worn which was leading to slop in the valve train
Aside from ordering the lifter arm roller rebuild kit supplied by Competition Distributing I put this part of the project to one side while I dealt with some other issues with the engine bottom end. I did fire of an enquiry to the forum at the end of March to see if there was information out there. Dan came back with a useful insight on his experience in doing the job but there was little else I could find.
In the intervening period I picked up another set of roller arms (from a well known internet auction site). These were in much better shape than my originals. They were much tighter around the top bush that fits on the crank stud plate, there was little or no wear on the shoulder of each arm where the pins ride and although there was still a little lateral play in the rollers they were all very much better than my originals. Had I not already bought the rebuilt kit I might well have just fitted them as they were.
In the event I rebuilt the rollers using the better set of roller arms and I thought it would be useful to share the experience and add some images for clarity.
The first task is to remove the old roller. This involves grinding away the end of the old pin where it has been peened over to allow the pin to be knocked out with a punch.
That’s ok if you can identify the end of pin from the roller arm itself. The first image shows my old set in comparison with the newer one. It is just possible to see the edge of the peened pin in the old one, much easier in the other less worn one. Dan suggested using some ink to bring up the edge if it was indistinct.
I used a diamond bit dremel to carefully remove a ring of material around the top of the pin. I then used the punch supplied with the CD kit to try and drive the pin out. I found the punch hard to use and in particular to keep vertical over the pin and it soon bent. I substituted a pin punch from my toolbox with a similar diameter. This was a lot easier to hold and less dangerous for my fingers.
Perhaps because I did not remove enough material from the head I found the first pin tough to drive out. It took a number of very firm blows with a 4lb lump hammer onto the punch to shift it.
Once out I could see clearly the underlying structure of the roller arm. The second and third pictures show either side or the arm with the old pin and roller removed. You can see that the pin aperture has a shoulder in the opposite side to the roller which provides space for the peened pin to spread into. Once I could see this I was able to grind out the other three pins with more confidence and the pins were themselves easier to get out as a consequence.
Refitting the new rollers was comparatively straightforward. The fourth image shows the pin, roller and new bushing. The rollers are not all the same – the exhaust rollers being deeper with a longer pin. Be careful not to mix them up!
I found the new bushes were a good tight press fit onto the arm. In one case I had to warm it up before I could tap it home. The bushes were however just longer than the mounting stud, as they should be, to allow the pin to abut the bush and not pinch the roller.
The new rollers were in each case tight on their respective bush. I used one of the old bushes previously removed held tight on a bit of scrap steel bar to create a lap. I mounted the new rollers in the lathe chuck and gently lapped them with fine grinding paste. For final fitment I put some paste on the new bush and worked the roller by hand until they just spun freely. This was the most laborious part of the process but worthwhile to get the precise fit needed.
Finally the new pins were fitted. Again they were a nice tight press fit. I found the inlet roller pins a little short once fitted which meant that they became slightly concave when peened into place – since the picture was taken I have used a smaller diameter ball peen hammer just to spread the pin head thoroughly into the available space to make sure they were absolutely secure.
Final picture show the finished roller arms test fitted into the engine. They lined up perfectly with the cam lobes.
I hope this information and in particular the pictures will help somebody else looking to undertake the same job.
Martin
MAP_4308_8028.jpgMAP_4298_8019.jpgMAP_4295_8016.jpgMAP_4310_8030.jpgMAP_4312_8032.jpg
Here is the last photo relating to my earlier post [above]
Aside from ordering the lifter arm roller rebuild kit supplied by Competition Distributing I put this part of the project to one side while I dealt with some other issues with the engine bottom end. I did fire of an enquiry to the forum at the end of March to see if there was information out there. Dan came back with a useful insight on his experience in doing the job but there was little else I could find.
In the intervening period I picked up another set of roller arms (from a well known internet auction site). These were in much better shape than my originals. They were much tighter around the top bush that fits on the crank stud plate, there was little or no wear on the shoulder of each arm where the pins ride and although there was still a little lateral play in the rollers they were all very much better than my originals. Had I not already bought the rebuilt kit I might well have just fitted them as they were.
In the event I rebuilt the rollers using the better set of roller arms and I thought it would be useful to share the experience and add some images for clarity.
The first task is to remove the old roller. This involves grinding away the end of the old pin where it has been peened over to allow the pin to be knocked out with a punch.
That’s ok if you can identify the end of pin from the roller arm itself. The first image shows my old set in comparison with the newer one. It is just possible to see the edge of the peened pin in the old one, much easier in the other less worn one. Dan suggested using some ink to bring up the edge if it was indistinct.
I used a diamond bit dremel to carefully remove a ring of material around the top of the pin. I then used the punch supplied with the CD kit to try and drive the pin out. I found the punch hard to use and in particular to keep vertical over the pin and it soon bent. I substituted a pin punch from my toolbox with a similar diameter. This was a lot easier to hold and less dangerous for my fingers.
Perhaps because I did not remove enough material from the head I found the first pin tough to drive out. It took a number of very firm blows with a 4lb lump hammer onto the punch to shift it.
Once out I could see clearly the underlying structure of the roller arm. The second and third pictures show either side or the arm with the old pin and roller removed. You can see that the pin aperture has a shoulder in the opposite side to the roller which provides space for the peened pin to spread into. Once I could see this I was able to grind out the other three pins with more confidence and the pins were themselves easier to get out as a consequence.
Refitting the new rollers was comparatively straightforward. The fourth image shows the pin, roller and new bushing. The rollers are not all the same – the exhaust rollers being deeper with a longer pin. Be careful not to mix them up!
I found the new bushes were a good tight press fit onto the arm. In one case I had to warm it up before I could tap it home. The bushes were however just longer than the mounting stud, as they should be, to allow the pin to abut the bush and not pinch the roller.
The new rollers were in each case tight on their respective bush. I used one of the old bushes previously removed held tight on a bit of scrap steel bar to create a lap. I mounted the new rollers in the lathe chuck and gently lapped them with fine grinding paste. For final fitment I put some paste on the new bush and worked the roller by hand until they just spun freely. This was the most laborious part of the process but worthwhile to get the precise fit needed.
Finally the new pins were fitted. Again they were a nice tight press fit. I found the inlet roller pins a little short once fitted which meant that they became slightly concave when peened into place – since the picture was taken I have used a smaller diameter ball peen hammer just to spread the pin head thoroughly into the available space to make sure they were absolutely secure.
Final picture show the finished roller arms test fitted into the engine. They lined up perfectly with the cam lobes.
I hope this information and in particular the pictures will help somebody else looking to undertake the same job.
Martin
MAP_4308_8028.jpgMAP_4298_8019.jpgMAP_4295_8016.jpgMAP_4310_8030.jpgMAP_4312_8032.jpg
Here is the last photo relating to my earlier post [above]
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