New Followers don't drop into tunnels! very tight (2014)

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SteveA

SteveA

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Ok, so I inspected the new AN 067820 Cam followers I have. I can only find one part number available for all Commandos, so I expect these to be standard size.

Very nice and none of the worries raised elsewhere, so as directed in the packing I have cleaned and deburred them and am ready to drop them in....Ahhh, they don't drop in....they don't even push in.....

Actually they don't drop or push in to either sets of barrels I have, which both have very clean original follower tunnels.

Paired together the followers measure 30.1mm or 1.185" as I believe they should....now what do I do?
 
I just went out to shed & mic'd Ms Peel's still shiney ex-liters to get 1.280". I've been though like 3 sets but only bought used ones from vendor piles, some needed comnoz bottoms refinished but all just slipped in either barrel of my 2 Combats. Both Combat got run into 2S breathing zone and either got over rev'd WOT stuck or comma slot piston or corroded rod bolt traumas but the lifters and bores were fine so lucked out factory parts all fit good enough w/o a second thought by me to know better till now.
 
1.280!? are you sure?



hobot said:
I just went out to shed & mic'd Ms Peel's still shiney ex-liters to get 1.280". I've been though like 3 sets but only bought used ones from vendor piles, some needed comnoz bottoms refinished but all just slipped in either barrel of my 2 Combats. Both Combat got run into 2S breathing zone and either got over rev'd WOT stuck or comma slot piston or corroded rod bolt traumas but the lifters and bores were fine so lucked out factory parts all fit good enough w/o a second thought by me to know better till now.
Click to expand...
 
SteveA said:
Ok, so I inspected the new AN 067820 Cam followers I have. I can only find one part number available for all Commandos, so I expect these to be standard size.

Very nice and none of the worries raised elsewhere, so as directed in the packing I have cleaned and deburred them and am ready to drop them in....Ahhh, they don't drop in....they don't even push in.....

Actually they don't drop or push in to either sets of barrels I have, which both have very clean original follower tunnels.

Paired together the followers measure 30.1mm or 1.185" as I believe they should....now what do I do?
Click to expand...

If the followers are the correct dia. then you could try putting a flexhone through the follower tunnels if they're only undersize by 0.0005" or so.
 
Well they fit now.... :D

And the tunnels are the same size as the were.....
 
Ok FE I used glasses and light this time to get 1.186". Must of held them crooked prior. Oil drain bevels face forward.
 
So......are you happy with the fit, or just because they fit?
What amount of slop is actually required?
is looser better?
how tight is too tight?

I know that the hotrod engine builders here have it figured out.
 
Make clearances .015" then Bore Tech carbide burnish the liter bores then cryo temper the lightened lifters and have dry friction coating applied. I've always been tempted to drill tiny oil drain hole in bottom of lifter though likely splashes out as well.
 
Mark said:
So......are you happy with the fit, or just because they fit?
What amount of slop is actually required?
is looser better?
how tight is too tight?

I know that the hotrod engine builders here have it figured out.
Click to expand...

If they have perhaps they will tell.

For me too ticgh was simply the would not go into the tunnel at all without more force than i was prepared to apply just to have a set of followers jammed in the bore.

I don't think you need .015" here, the barrel and the follower body are both cast iron, so expansion rates are similar. And if you look at this thread, .0015 to .0025 seems more like...not much clearance.

cam-follower-and-tunnel-dimensions-t11107.html?hilit=oversize%20cam%20followers#p125754

I didn't want to remove material from the bore because I have two sets of barrels that are clearly the same size, so I had to conclude the new items were a little over sized, or perhaps just with high spots.

I did clean up the tunnels to make sure they were clean and free from any rusting as they have been unused for some time. I don't have suitably sized hones laying around, or a machine shop, but I have abrasive paper....it took some time and care but I just hand worked each pair and lapped them in until I was content that they travel the required range without force! I don't know if that amounts to .0015 but it should be close. They don't drop under their own weight but it is a very light push needed now.

I then found that the new retaining plates did not slide in either, but it was pretty clear there were high spots round the edges where they are stamped out...flat surface with abrasive paper sorted those in just a few minutes.

From an engineering standpoint I am sure some of you will be disappointed at my approach. But I suspect the method suites the period the design originates from.
 
SteveA said:
Mark said:
So......are you happy with the fit, or just because they fit?
What amount of slop is actually required?
is looser better?
how tight is too tight?

I know that the hotrod engine builders here have it figured out.
Click to expand...

If they have perhaps they will tell.

For me too ticgh was simply the would not go into the tunnel at all without more force than i was prepared to apply just to have a set of followers jammed in the bore.

I don't think you need .015" here, the barrel and the follower body are both cast iron, so expansion rates are similar. And if you look at this thread, .0015 to .0025 seems more like...not much clearance.

cam-follower-and-tunnel-dimensions-t11107.html?hilit=oversize%20cam%20followers#p125754

I didn't want to remove material from the bore because I have two sets of barrels that are clearly the same size, so I had to conclude the new items were a little over sized, or perhaps just with high spots.

I did clean up the tunnels to make sure they were clean and free from any rusting as they have been unused for some time. I don't have suitably sized hones laying around, or a machine shop, but I have abrasive paper....it took some time and care but I just hand worked each pair and lapped them in until I was content that they travel the required range without force! I don't know if that amounts to .0015 but it should be close. They don't drop under their own weight but it is a very light push needed now.

I then found that the new retaining plates did not slide in either, but it was pretty clear there were high spots round the edges where they are stamped out...flat surface with abrasive paper sorted those in just a few minutes.

From an engineering standpoint I am sure some of you will be disappointed at my approach. But I suspect the method suites the period the design originates from.
Click to expand...

Nowt wrong with hand finishing in my book Steve, provided its done by an experienced, and patient hand that is!
 
You want them to slowly slide in the bores under gravity alone, with a very light coat of oil on everything. Or VERY slight finger pressure.

They should almost in the bores fall if dry.
 
grandpaul said:
You want them to slowly slide in the bores under gravity alone, with a very light coat of oil on everything. Or VERY slight finger pressure.

They should almost in the bores fall if dry.
Click to expand...

Sounds good to me, I think I have a few more minutes work to get there. Not far away, 3 out of four slide down, with a heavy coat of assembly paste on them, so clean and retry with light oil an we should hav ethat with all four.

But one thing always leads to another.....putting the bottom end together and the new AN cam nut is tight on the PW 3, don't want to tighten that very hard.....oh well, that why we do trial assemblys I suppose....exept I din't take this particular nut out of teh pack till I needed it...oops!

Must be enough for one weekend....
 
Went back to the shed, picked up the barrels, turned them up and then down a few times....all four follwers fall under their own weight...

That'll do....why different? well temperature is up a but and probably some of the assembly paste has dispersed.

Will be doing this a few more times before I put the barrels on....which won't really be until I sort the PW3 nut.....
 
Steve A I've been in your situation, ie: seeming impossible fitting or removals being brought to interested collective attention then next attempt its like magic! I use magic marker on lifters and other stuff to see the hang ups.
 
I've stopped using Lubriplate a few years ago, just the same oil I'll be running, except cam lube from Megacycle on cams and followers.
 
New Andover lifters are normally slightly oversized. Which I prefer. Then I can run a hone through the lifter bore and get rid of any old scratches. I go for 1 to 1.5 thou fit. Jim
 
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