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British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on July 01, 2026, 01:21:30 PM »When was I last here... sheesh.... I need to pull my finger out.
So: I bought myself a new cam-follower.
And today I tried it out to see if it made any difference to that annoying "clickety-clack" noise I'm getting.
It didn't. (ffs)
However the follower DOES sit on the spindle MUCH tighter, so I'm going to use it. It also seems to fit nicely when the cover is on, ie the float of the cam-followers along the spindle is well within the desired tolerance (ie there's a tad of movement
), so I'm happy to use it. Next job with that is to try assembly "wet", with some oil dribbled onto it.
I also want to file a notch into the lug of it - I noticed that one of the old followers has such a notch (see below), and what it does is allow oil to get onto the spindle. There's no direct oil feed, the oiling is done by "splash". Having said that - the cam-follower-spindle actually has a channel cut into the top of it, which I can only assume is an oil "trap" to keep the spindle lubricated. Cutting a notch into the cam-follower-spindle lug will allow the oil that is splashed about to get into that channel, and from there it would lubricate the cam-followers on the spindle. So - I kinda wonder why the followers don't have that notch as they come, but it is easily something that could be missed when making up a pattern part, especially as it could well be that (like my engine) only 1 of the followers in the engine the pattern maker had, had a notch.
Job for the next visit anyway, because while I was pondering the clickety-clack, I decided to have a go at refurbing/remaking the push rods.
First I took some highly accurate measurements, to ensure that I had the original lengths of the two push rods BEFORE I took the caps off.
(ahem).
I decided to try "safe" heat first to remove the caps, I wasn't sure exactly how they were secured, the normal method is soldering, but the Guru told me that it's also perfectly valid to use epoxy, so these could be either.
This one was epoxied!
The other end was soldered! go figure!
Re-usable push-rod caps, steel.
Did my best to give everything a good clean up
New pipe on left... old on right.
These new ones should be a tad stronger by the looks of it!!
The new pipe came a tad long, 12", but that's cool
Precision marking for cutting (ahem)
And some hack-saw action
More high precision measurements....
Close enough for government work?
I always like to dress a hole nicely.... (ahem)
Using Meths to clean up the dust and dirt
The original plan WAS to try to solder the caps onto the push rods, I promise you. However... I never been good at soldering, but I did give it a try with a propane can (and yes, I DID burn my $%^&&ing finger tips, again), unsuccessfully... so err...
i cheated.
Trigger clamps for the win.
The second one was a bit of a bugger, for some odd reason the upper cap (the "cupped" one) refused to go onto the rod easily, no matter how much I cleaned up the pipe, or scrapped out the fitting on the cap. In the end I just gave it a bit of a bash...
They're roughly the same length, visually anyway.
To be fair, the "exact" length isn't terribly important, as long they fit between the cam-follower and the rocker arm within the range of movement of the adjuster on the rocker arm - there's at least 1/4" of play in there..... And now I know how to do the job, I can disassemble them, file a bit more off the ends and re-glue them if they're too long.
While I was in the workshop I figured I'd also swap the oil feed fittings which I bought replacements for.
First I pulled the old, utterly knackered fittings off: using my "new" flare spanner found and bought specifically for this job!
Shiny new fittings installed!
I gave the feed tubes a clean while I was here. They feed an oil dribble from the rocker box to the valve stem.
Fitted the dribble-tubes.
These are the old fittings for the dribble tubes, they're utterly shot.
As is the main inlet feed fitting, new one behind it with the oil feed banjo being tested.
A couple of these should fit..... (despite being metric!)
But.... and here's the rub.... the sodding main thread is wrong.
They're both 3/8" diameter thread, but the OLD one is 26tpi (and so BSC), the new one is 28 tpi... and I can't for the live of me figure out what that is supposed to be. It's not BSF, it's not BSW, it's not UNC and it's not metric (I don't think ? ). So I may well be phoning the supplier tomorrow to find out just what tf it is!
Tune in next time for some lubed up action!
So: I bought myself a new cam-follower.
And today I tried it out to see if it made any difference to that annoying "clickety-clack" noise I'm getting.
It didn't. (ffs)
However the follower DOES sit on the spindle MUCH tighter, so I'm going to use it. It also seems to fit nicely when the cover is on, ie the float of the cam-followers along the spindle is well within the desired tolerance (ie there's a tad of movement
), so I'm happy to use it. Next job with that is to try assembly "wet", with some oil dribbled onto it.I also want to file a notch into the lug of it - I noticed that one of the old followers has such a notch (see below), and what it does is allow oil to get onto the spindle. There's no direct oil feed, the oiling is done by "splash". Having said that - the cam-follower-spindle actually has a channel cut into the top of it, which I can only assume is an oil "trap" to keep the spindle lubricated. Cutting a notch into the cam-follower-spindle lug will allow the oil that is splashed about to get into that channel, and from there it would lubricate the cam-followers on the spindle. So - I kinda wonder why the followers don't have that notch as they come, but it is easily something that could be missed when making up a pattern part, especially as it could well be that (like my engine) only 1 of the followers in the engine the pattern maker had, had a notch.
Job for the next visit anyway, because while I was pondering the clickety-clack, I decided to have a go at refurbing/remaking the push rods.
First I took some highly accurate measurements, to ensure that I had the original lengths of the two push rods BEFORE I took the caps off.
(ahem
).I decided to try "safe" heat first to remove the caps, I wasn't sure exactly how they were secured, the normal method is soldering, but the Guru told me that it's also perfectly valid to use epoxy, so these could be either.
This one was epoxied!
The other end was soldered! go figure!
Re-usable push-rod caps, steel.
Did my best to give everything a good clean up
New pipe on left... old on right.
These new ones should be a tad stronger by the looks of it!!
The new pipe came a tad long, 12", but that's cool
Precision marking for cutting (ahem)
And some hack-saw action
More high precision measurements....
Close enough for government work?
I always like to dress a hole nicely.... (ahem)
Using Meths to clean up the dust and dirt
The original plan WAS to try to solder the caps onto the push rods, I promise you. However... I never been good at soldering, but I did give it a try with a propane can (and yes, I DID burn my $%^&&ing finger tips, again), unsuccessfully... so err...
i cheated.
Trigger clamps for the win.
The second one was a bit of a bugger, for some odd reason the upper cap (the "cupped" one) refused to go onto the rod easily, no matter how much I cleaned up the pipe, or scrapped out the fitting on the cap. In the end I just gave it a bit of a bash...
They're roughly the same length, visually anyway.
To be fair, the "exact" length isn't terribly important, as long they fit between the cam-follower and the rocker arm within the range of movement of the adjuster on the rocker arm - there's at least 1/4" of play in there.....
And now I know how to do the job, I can disassemble them, file a bit more off the ends and re-glue them if they're too long. While I was in the workshop I figured I'd also swap the oil feed fittings which I bought replacements for.
First I pulled the old, utterly knackered fittings off: using my "new" flare spanner found and bought specifically for this job!
Shiny new fittings installed!
I gave the feed tubes a clean while I was here. They feed an oil dribble from the rocker box to the valve stem.
Fitted the dribble-tubes.
These are the old fittings for the dribble tubes, they're utterly shot.
As is the main inlet feed fitting, new one behind it with the oil feed banjo being tested.
A couple of these should fit..... (despite being metric!)
But.... and here's the rub.... the sodding main thread is wrong.
They're both 3/8" diameter thread, but the OLD one is 26tpi (and so BSC), the new one is 28 tpi... and I can't for the live of me figure out what that is supposed to be. It's not BSF, it's not BSW, it's not UNC and it's not metric (I don't think ? ). So I may well be phoning the supplier tomorrow to find out just what tf it is!
Tune in next time for some lubed up action!