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Re: 1928 Ariel Model C [Re: chaterlea25] #732111
04/16/18 10:25 pm
04/16/18 10:25 pm
Joined: Oct 2017
Posts: 63
England
G
George Kaplan Offline
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England
Originally Posted by chaterlea25

I am sorting out the 23 HD F for its owner / rider to use on the Cannonball
I will be with the traveling circus as acting "spannerman" and support vehicle driver


Ah, I missed that detail, I had mistakenly assumed that you were the other rider.


Originally Posted by chaterlea25

I was not referring to the HD in the earlier post but thinking about the other engines that are in the "shed"


I too need to think about how to tackle engine work in the future after following this thread.

John

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Re: 1928 Ariel Model C [Re: George Kaplan] #732137
04/17/18 2:55 am
04/17/18 2:55 am
Joined: Nov 2011
Posts: 4,480
U.S.
Magnetoman Online content OP

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Magnetoman  Online Content OP

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Originally Posted by George Kaplan
I too need to think about how to tackle engine work in the future after following this thread.
I'm surprised no one has commented that plenty of motorcycles have been rebuilt using little more than adjustable spanners and hammers and "they ran just fine." Those people will get to gloat when my Ariel dies of unknown causes 500 yards from the starting line.

The only progress today was reading the UPS tracking information that says my Neway cutters are due for delivery Thursday afternoon.

Re: 1928 Ariel Model C [Re: Magnetoman] #732139
04/17/18 3:27 am
04/17/18 3:27 am
Joined: Aug 2001
Posts: 1,878
The Northwoods... Michigan
Steve Erickson Offline
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The Northwoods... Michigan
..."adjustable spanners and hammers".... well, let's not forget beer.

In the Big Bang episode you spoke of, remember Sheldon said "The best decisions are made with a full bladder".

Re: 1928 Ariel Model C [Re: Steve Erickson] #732196
04/17/18 4:50 pm
04/17/18 4:50 pm
Joined: Nov 2011
Posts: 4,480
U.S.
Magnetoman Online content OP

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Originally Posted by Steve Erickson
... well, let's not forget beer. ...remember Sheldon said "The best decisions are made with a full bladder".
Yes, we musn't forget all the bikes that were rebuilt aided by decisions made with a bladder full of beer and that are claimed to "run just fine."

Re: 1928 Ariel Model C [Re: Magnetoman] #732217
04/17/18 7:50 pm
04/17/18 7:50 pm
Joined: Aug 2001
Posts: 3,910
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
I cant wait to see the cam base circle correction grind set up, that 4 thou would bother me. i spent an age on the BSA cams with a clock with 0.0001" resolution, there was nary a waver on the base circle with the clock tip in the push rod top cup , not straight off the cam..There was a very slight dip just before the quietening ramp but only for a couple of degree, presumably where the follower makes 1st contact.

The valve seat distortion is v interesting, when its up to temperature? What you dont know cant hurt you perhaps.


71 Devimead A65 750
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Re: 1928 Ariel Model C [Re: Magnetoman] #732234
04/17/18 10:13 pm
04/17/18 10:13 pm
Joined: Nov 2011
Posts: 4,480
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Magnetoman Online content OP

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Originally Posted by gavin eisler
I cant wait to see the cam base circle correction grind set up, that 4 thou would bother me.
It bothers me as well. The reason I haven't done anything yet about the wobbly base circle is my measurements were of a single line around the cam. I need to repeat the measurements at the top of the pushrods since the wide surfaces of the lifters will average over the full width of the cam so there will be significant averaging of the peaks and valleys of the cam (as well as of any peaks and valleys of the lifters). At that point I'll know if I have to deploy the toolpost grinder again and, if I do, decide how best to attack the problem.

Originally Posted by gavin eisler
The valve seat distortion is v interesting, when its up to temperature?
Ideally, I would make the measurements with the head bolted to the cylinder and wrapped with heating tape so everything could be brought up to a normal operating temperature with a temperature profile down the cylinder to the base. Such a measurement could be done via a custom-made linkage mechanism operating through a valve guide. Actually, if I were to do this I'd design an optical metrology instrument to do it.

I would be quite interested in having the results, but this isn't the time to pursue this. I have to take comfort in the fact that it's an iron head bolted to an iron cylinder so differential thermal expansion will be small to nil and so the distortion at room temperature should stay the same at elevated temperature.

Re: 1928 Ariel Model C [Re: Magnetoman] #732235
04/17/18 10:24 pm
04/17/18 10:24 pm
Joined: Dec 2013
Posts: 3,998
ohio, usa
kevin roberts Online content
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Originally Posted by Magnetoman
Ideally, I would make the measurements with the head bolted to the cylinder and wrapped with heating tape so everything could be brought up to a normal operating temperature with a temperature profile down the cylinder to the base. Such a measurement could be done via a custom-made linkage mechanism operating through a valve guide. Actually, if I were to do this I'd design an optical metrology instrument to do it.

I would be quite interested in having the results, but this isn't the time to pursue this. I have to take comfort in the fact that it's an iron head bolted to an iron cylinder so differential thermal expansion will be small to nil and so the distortion at room temperature should stay the same at elevated temperature.


i once asked a race car machinist if he ever thought about boring and honing his blocks with coolant running through the passages to mimic the distortion of a running engine.

he said, with cylinder leakage at about one percent or so already, what would be the gain?


i have no idea what i'm doing.
Re: 1928 Ariel Model C [Re: kevin roberts] #732245
04/18/18 12:01 am
04/18/18 12:01 am
Joined: Nov 2011
Posts: 4,480
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Magnetoman Online content OP

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Originally Posted by kevin roberts
he said, with cylinder leakage at about one percent or so already, what would be the gain?
For me, at least, gaining knowledge of what happens and why it happens is at least as important as the result itself. In the case of the valve seats, making the "discovery" that a torque plate, and even just installing a spark plug, makes a measureable difference was very pleasing, whether or not the distortion has an effect on performance or longevity.

Re: 1928 Ariel Model C [Re: Magnetoman] #732408
04/19/18 1:14 pm
04/19/18 1:14 pm
Joined: Aug 2006
Posts: 466
Dallas Texas
RPM Offline
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Dallas Texas
Since the side valve Norton does not have head bolts and the valve seats are very far from the spark plug hole no distortion was found either place. That fancy OHV stuff is just a passing trend. Much to complicated. Ha Ha !
I will be checking for distortion of the valve seat on my new T140 race head. Very interesting thought and I can see it is possible especially when over tightening the spark plug.
The results that makes me happy or unhappy is at the end of each race day. However the more results you come up with in the shop the better your results at the end of each day.
Carry on the outstanding work!

Ready for for test run.
https://www.facebook.com/1901197843...103/1621850327851874/?type=3&theater

Re: 1928 Ariel Model C [Re: RPM] #732430
04/19/18 4:43 pm
04/19/18 4:43 pm
Joined: Nov 2011
Posts: 4,480
U.S.
Magnetoman Online content OP

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Originally Posted by RPM
That fancy OHV stuff is just a passing trend. Much to complicated.
I agree that fewer moving parts can be an advantage, but if along the way your Nortons take it to the limit of no moving parts that advantage will be lost...

Originally Posted by RPM
Carry on the outstanding work!
Thanks very much for the compliment. I've had to take care of other things this week but I should be back in the garage as of tomorrow. UPS tracking updates show the Neway cutters are scheduled for delivery this afternoon.

Re: 1928 Ariel Model C [Re: Magnetoman] #732469
04/20/18 3:14 am
04/20/18 3:14 am
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Posts: 4,480
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Magnetoman Online content OP

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The only Ariel progress I made today was opening a package that arrived. However, now that the seat cutters are here it's back to the, um, grindstone. Although, with cutters, not grindstones.

Not Ariel related, I spent a little time yesterday starting to rebuild a Gold Star's oil pump for a friend. I'll work on it during spare time the next week or so and will use the opportunity to make careful photographs and measurements since I haven't found the specifications or rebuild process documented anywhere.

Attached Files IMG_7264.JPG
Re: 1928 Ariel Model C [Re: Magnetoman] #732552
04/21/18 1:41 am
04/21/18 1:41 am
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Magnetoman Online content OP

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The Neway cutters worked out very well for me. They cut fast so the key is to take it slow and pause frequently to check progress with Dykem. And by taking it slow, I mean just a few revolutions of the cutter between checks. Having a heat gun handy speeds things up by drying the Dykem fast. However, like many other tasks, if I were my supervisor in a motorcycle shop I would fire me for being too cautious, i.e. slow. I did the cutting with the torque plate and spark plug in place and before I started I checked to be sure the bolts were still at 20 ft.lbs.

Both seats were a bit off center from the guides so the cutters definitely earned their keep (which, at ~$400, wasn't cheap keep). Since the IDs of the guides differed by ~0.001", instead of buying two solid pilots I bought a single adjustable pilot. This wasn't because I was attempting to cut corners (an adjustable pilot is approx. the price of two fixed pilots), but because I was uncertain whether the 0.001" steps in solid pilots implied being off by half that would result in a pilot sitting to high or too low. Although warnings said the solid pilots were more rigid than the adjustable, which I believe, I didn't feel any flex whatever in the adjustable pilot.

I proceeded according to the Neway instructions starting with the 60-deg. exit angle. In the first photograph the darker area around 11:00 isn't because of the lighting, it's because the seat is slightly off center so that part hadn't been touched by the cutter as yet.

After cutting the 60-deg. exit I turned to the 30-deg entrance, shown in the second photograph. It can be seen that the ring is narrower near 11:00, again because the seat is slightly offset. If I stopped at this point and cut the 45-deg. seat it would occupy the area still covered with Dykem, i.e. it would be quite wide. However, I was still becoming one with the cutters at this point so I was removing small amounts of material at a time, knowing I could always easily remove additional material (but not put it back).

When it was time to turn to the actual 45-deg. seat on the exhaust port the cutter stopped cutting while there was still material to remove between ~10:00 and ~12:00. After puzzling over this for a minute I realized the "nut" for driving the 15-deg. end of that double-ended cutter must be hitting the guide, which projects further into the port than does the one in the inlet port (where I didn't have this problem). Since only a thou. or two remained to be removed I put the cutter in the lathe and took 0.015" off the end of the "nut." Even factoring in the 45-deg. angle I suspect 0.005" would have been sufficient but I took a bit more to be done with it.

In addition to the 30/45/60-deg. cuts I also used the 15-deg. cutter (the 45-deg. is dual-ended, so the 15-deg. cutter came for free). Not because it will make any performance difference, but so when someone proudly tells me of their "three-angle valve job" I can scoff piteously at them for only having three angles.


Attached Files Neway01.jpgNeway02.jpgNeway03.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #732664
04/22/18 12:51 am
04/22/18 12:51 am
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Magnetoman Online content OP

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I found the long-missing box spanner. I had a large box spanner attached to the crankshaft to make it easy to turn the engine over to precise values on the protractor for measuring pushrod lift. Its slot in the holder in the toolbox managed to get filled in with another spanner and several of the others also moved up one position making it appear as if one of the smaller spanners was missing. Sigh...

I cleaned the head thoroughly in hot soapy water, sprayed the valve stems and guides with assembly lube, and assembled the heads. If it's not one thing, it's another, and the thing it is this time is the lash caps are ~0.006" too small in ID to fit over the valves (the ends of the old valves are smaller than their stems). Since I have other things to do I squandered too much money ordering a pair of 11/32" lash caps in the hopes they fit. If not, I'll have to enlarge them by a tiny amount, again using the toolpost grinder.

There are three keyway slots on the mainshaft pinion, and I had marked the one punched with a dot as the one that was in place when I got the bike. However, that doesn't mean it is the correct one so I needed to check. However, I discovered a timing problem at that point. As you might be able to see from one of the photographs, the inlet and exhaust lifters are interchangeable. This makes it easily possible to have the inlet cam drive the exhaust valve and vice versa. The only clue to the correct positioning was a drawing in a 1928 magazine article. No matter what I would be checking, but it would make it faster and less frustrating if I got it right on the first try.

I installed the crankshaft pinion using an air impact wrench rated at 75 lbs. Interestingly, the left-hand nut is 19 mm so it has been replaced at some point in its life. There are 20 teeth on the crankshaft sprocket, broached with three keyways to to allow the valve timing to be advanced or retarded by 1/3 of a tooth (6-deg) or 2/3 (12-deg.) from the nominal keyway marked with a 'dot'. I installed it in the 'dot' orientation.

I slathered Mo assembly lube on the cam, installed it, and measured lift vs. crankshaft angle (which is how I "discovered" the missing spanner). The results with the pinion set on the 'dot' position are shown in the graphs, with the arrows showing the opening and closing angles according to the Ariel manual. Keeping in mind that both cams are on one shaft so whatever I do to one is also done to the other, advancing or retarding the timing by 6-deg. or 12-deg. might make several curves "better," but they would make the others "worse." It seems like the stock ('dot') timing of this possibly-reground camshaft is "best."

Unless something goes wrong I should have the engine completely assembled (minus rocker box, due to the valve lash caps) tomorrow and begin work on the gearbox.

Attached Files LashCap01.jpgValveTiming01.jpgValveTiming02.jpgValveTiming03.jpgValveTiming04.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #732715
04/22/18 5:10 pm
04/22/18 5:10 pm
Joined: Nov 2011
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Magnetoman Online content OP

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I was curious how the Ariel's camshafts compared with those of a completely modern bike, i.e. a Gold Star. Examining the specs of the latter, the only models it makes much sense to compare it with are the 1949 Trials and the 1952-56 Tourer:

_________BTDC___ABDC____________BBDC___ATDC
________In. open_In. close_duration___Ex. open_Ex. close_duration___overlap__lift
Ariel_____ 5 ______ 50 ____ 235 ______ 55 _____ 20 _____ 255 _____ 105 __ 0.348"
Trials ____ 25 _____ 65 ____ 270 ______ 65 _____ 30 _____ 275 _____ 130 __ 0.300"
Tourer___ 43 _____ 73 ____ 296 ______ 70 _____ 45 _____ 295 _____ 143 ___ 0.386"

Comparing the Ariel to the Tourer, the Ariel's inlet valve is open for 61 fewer degrees and it has 10% less lift so even without dyno testing I'll go out on a limb and predict the Ariel has less h.p. than those Gold Stars.

However, the h.p. gain due to the greater duration of the Trials cam must be somewhat offset by the 15% greater lift of the Ariel's. It happens that the iron-head ZB33 and BB33 used the same 65-2420 cams for the inlet and exhaust as did the Trials Gold Star so in a race against a B33 the Ariel would... well, it would lose, but not by as much as in a race against a Gold Star.

Addendum: The curve below is of the opening of the exhaust cam. Both cams are symmetrical and the same so by mirroring this curve around the midpoint (72.5-deg) the shapes of the full cam profiles can be obtained. It would be nice to have the curve for a BSA B33 on the same plot for comparison but I couldn't find any such data on line.

Note: Note, because of the lifter geometry the lift measured directly on the cam (0.348") is greater than the lift of the pushrod (0.311"). Although I haven't plotted it here (...yet) the profiles will be different as well due to the finite size of the lifter pad vs. the point of the indicator when measuring directly on the cam.

Attached Files ValveTiming05.jpg
Last edited by Magnetoman; 04/22/18 6:44 pm. Reason: Addendum: and Note:
Re: 1928 Ariel Model C [Re: Magnetoman] #732749
04/22/18 10:28 pm
04/22/18 10:28 pm
Joined: Mar 2013
Posts: 328
Irene, South Africa
robcurrie Online content
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Irene, South Africa
Originally Posted by Magnetoman
Note, because of the lifter geometry the lift measured directly on the cam (0.348") is greater than the lift of the pushrod (0.311").

For that reason alone, I would recommend converting it to overhead cam before the Cannonball ;-)
That way you will keep us enthralled for a bit longer because after you sort the gearbox, there's not much more left to do.

Rob C

Re: 1928 Ariel Model C [Re: Magnetoman] #732783
04/23/18 2:44 am
04/23/18 2:44 am
Joined: Nov 2011
Posts: 4,480
U.S.
Magnetoman Online content OP

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Note to self: insert center bolt in rocker box before slipping box into place on the head, because otherwise the frame is in the way (see first photograph). However, despite that little glitch the engine is now back together with only one washer left over. Unfortunately, I hit a roadblock thanks entirely to robcurie:
Originally Posted by robcurrie
there's not much more left to do.
You jinxed me. It was going smoothly until you wrote this.

As the second photograph shows, even with the rocker adjusters at the short end of their travel the rocker cover still cannot be bolted down without negative clearance on the valves. How can this be? I don't remember measuring the lengths of the two arms on the followers but the answer has to lie with them. I swapped the orientations of the cam followers so the ends that had been in contact with the cam are now in contact with the lifter and vice versa. The ends are different and for several reasons I convinced myself that the previous restorer had installed them incorrectly. For example, if you look at one of the photographs I posted yesterday you'll see the follower is pressing directly in the center of the lifter which implies it is installed correctly.

There's also an adjustment at the other end of the pushrod. But, as the next photograph shows, those adjusters already are at the short end of their travel. If I move that adjuster out, but still leave 5 threads engaged for strength, that gives it over 1/4" of travel. Similarly, there is over 1/4" of travel in the adjuster on the rocker arm. Together, this means the pushrods need to be ~1/2" shorter. So, thanks entirely to robcurrie's jinx, I'll have to make the new pushrods sooner rather than later in order to complete the engine.

Attached Files Head01.jpgPushrods04.jpgPushrods03.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #732803
04/23/18 9:41 am
04/23/18 9:41 am
Joined: Aug 2001
Posts: 3,910
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
Arrgh!, dimensional instability, . You were the last person I thought would be afflicted by this, goes to show, it happens to everyone.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: 1928 Ariel Model C [Re: gavin eisler] #732835
04/23/18 5:08 pm
04/23/18 5:08 pm
Joined: Nov 2011
Posts: 4,480
U.S.
Magnetoman Online content OP

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Originally Posted by gavin eisler
Arrgh!, dimensional instability, .
I hate it when that happens, because it also leads to fits of emotional instability and frustration.

I've had an evening to sleep on this, and an hour to make additional graphs. I think I now understand why the pushrods are too long despite them having been OK when I got the bike.

The lobes on the cam itself are offset from each other by 14-deg. (28-deg. engine), which is how far apart the valve openings would be were it not for the followers also being offset from each other. This means that if the positions of the followers were swapped the valve timings would be changed by 28-deg., with the inlet now opening that much earlier and the exhaust that much later.

Instead of the inlet opening at 5-deg BTDC as it does now it would open at 33-deg. BTDC. How could the engine have run when I got it if the inlet valve were off by that much? Looking at the values I posted a couple of days ago, a B33 has its inlet open at 25-deg., which isn't that much different than this incorrect setting of 33-deg. (the Gold Star is 43-deg.). Of course, it also would close 28-deg. sooner, at 22-deg. ATDC (vs. 65-deg for the B33), so with a lot less time to suck fuel in it certainly would be down on power. While the bike ran when I got it, I only puttered up and down a potholed road at maybe 20 mph so I know that it ran, but I have no idea of the h.p.

As for the exhaust cam, if the followers were swapped it would open at 83-deg BBDC (vs. 65-deg. for the B33) and close at 58-deg ATDC (vs. 45-deg. ATDC). Again, it should -- did -- run under those conditions.

Anyway, given that with the way I decided to assemble the followers the valve timings I measured from the pushrods are collectively what they should be according to the manual (and individually each within ~+/-5-deg.), it must be correct. I know for two reasons that the previous rebuilder assembled it incorrectly: 1) I marked the positions of the followers in paint when I removed them so it would be easier to reassemble the engine, and 2) the pushrods are ~1/2" too long with the followers in the present, correct positions. The latter must also mean the current pushrods aren't the ones that came from the factory.

p.s. I remembered that when I first got the bike, after I sorted out the leaky carburetor, I was gently pushing the kickstarter lever through to find TDC when the bike started. The piston in it didn't have an incredibly low CR so the fact it was so easy to accidentally kick right through TDC is consistent with relatively low pressure in the cylinder. This would be caused by incomplete filling on the intake stroke, i.e. it is consistent with the incorrect valve timing discussed above.


Last edited by Magnetoman; 04/23/18 5:33 pm. Reason: p.s.
Re: 1928 Ariel Model C [Re: Magnetoman] #732999
04/25/18 2:17 am
04/25/18 2:17 am
Joined: Nov 2011
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Magnetoman Online content OP

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I started to make the new pushrods today but got called away before I got very far. But, I did manage to make some progress.

The first thing is to determine how long the new pushrods need to be. To do that I made an adjustable faux pushrod from a piece of 5/8" Al rod in the scrap box. I machined one end flat and tapped the other end 1/4-28 for a bolt whose head I had faced flat. With the rocker box bolted in place, and with the adjusters at their midpoints, I inserted the rod and turned the bolt to make contact, allowing room for the lash caps that are due for delivery tomorrow. As the third photograph shows, with the same adjustment on the rod the gap at the exhaust valve is larger. This might seem to indicate the exhaust cam lobe doesn't have as much lift as the intake but the measured difference is only 3.5 thou. This means the difference in gaps is due to slight differences in the followers; one must have been ground a bit more than the other, reducing its leverage.

Next, to copy the design of the current pushrods, which look like the ones in the Ariel Parts Book, I cut four 1" lengths of 5/8" 1117 carbon steel. As I mentioned in an earlier post I originally decided on this steel when intended to case harden the ends but later decided to apply Stellite instead. I got as far as "drilling" (with a 7/16" carbide round end mill in the tailstock of the lathe) a recess in one of them. My plan is to fill the bottom with Stellite and then use the same carbide end mill to drill to a depth 0.05" less than the original hole. To be continued...

Attached Files Pushrods05.jpgPushrods06.jpgPushrods07.jpgPushrods08.jpgPushrods09.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #733109
04/26/18 1:43 am
04/26/18 1:43 am
Joined: May 2013
Posts: 743
Overland Missouri
O
old mule Offline
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Posts: 743
Overland Missouri
"Called away"? That's how southern Baptists describe the unpleasant process of death. As in "Brother Mag was called away!". Please finish the Cannonball First, first!

Re: 1928 Ariel Model C [Re: Magnetoman] #733134
04/26/18 6:12 am
04/26/18 6:12 am
Joined: Nov 2011
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Magnetoman Online content OP

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Magnetoman  Online Content OP

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Originally Posted by old mule
"Called away"? That's how southern Baptists describe the unpleasant process of death.
Death was involved, but it was my aged home computer that was in the throes of rapture. Its hard disc was shedding bits faster than a 441 Victor sheds parts on a freeway. The new computer arrived and, being my house's Senior IT Manager, I wanted to get it fully operational before the old one breathed its last. Software downloads and updates, deauthorizing programs, etc. over a slow DSL line and an ever-slower rapturing hard disk, means I was still at it today, but there was still time to make some Ariel progress.

Turning to the Ariel, I used a 7/16" carbide ball end mill to drill the cavities in the pushrod endcaps 0.275" deep (2-3/4 turns of the lathe's tailstock), so that after adding the Stellite I could drill it 0.225" deep (2-1/4 turns) to leave a 0.050" layer of Stellite.

The first photo shows one of the pushrod ends cooling down after being filled with Stellite. I held the end in the welding vise that I had sitting on a fiberglass insulating blanket and preheated the vise and the end (for the reasons discussed in an earlier post) with an acetylene torch. Just out of sight is the clamp that grounds the vise to the welding table. Within maybe 15 sec. after I was done heating it I was hitting it with the TIG torch. As soon as I was done I flipped the blanket over the top to slow the cooling rate (although I opened the blanked for a moment after I had my iPhone ready for this photo). This pre-heating and cooling was to avoid cracking of the Stellite, and it was successful at that.

Next I drilled it again with the ball end mill. At this point the end mill was barely cutting but, luckily, I had a second one. Unfortunately, as the third photograph shows, I had done a poor job with the TIG on my first attempt, with a void hiding under the surface. In my defense, it's not easy to weld this stuff at the bottom of a fairly deep hole without melting the sides or touching the Stellite rod to the electrode.

Not shown is now that I had experience I knew what to look out for and the next one was fine. Again I drilled it, but this revealed the next problem. The end of the ball end mill isn't as nicely finished as I need, resulting in ridges and grooves in the Stellite.

I then brazed a 7/16" ball bearing to the end of a piece of tubing and used it in the lathe to lap the Stellite with 280-grit grinding paste. Five minutes with the paste made a dent in the surface but it was going to take at least another 5-10 minutes, and that would have to be followed by finer paste. So, I've now ordered a 7/16" carbide burr that won't be here until next week, and two 7/16" carbide grinding stones that will be here Friday.

My plan is still to do the major work with the ball end mill, but my hope is the grinding stones and/or carbide burr will much more quickly reduce the surface roughness to a point where grinding paste can finish the job

Attached Files Pushrods10.jpgPushrods11.jpgPushrods12.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #733291
04/27/18 3:49 pm
04/27/18 3:49 pm
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Magnetoman Online content OP

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Magnetoman  Online Content OP

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Off line someone asked why I’m doubling my work in order to add Stellite to both ends of the pushrods since the bottom end only is pushed straight up and down and so no relative motion is involved. There are two reasons:

One reason is that by making both ends the same, and both pushrods of identical length, it eliminates a source of possible error if the team mechanic finds himself rebuilding the engine at 3:00 am while I’m sleeping soundly and not there to provide real-time constructive criticism of his efforts.

The other reason is there will be no relative motion of the bottom end of the pushrods only if the pad on the rocker shaft at the top end is perfectly symmetric. Since that pad moves in an arc it is dragged a short distance across the pushrod allowing for the possibility of imparting a twisting force on the pushrod (if not symmetric).

The 7/16” grinding stones are due this afternoon. If they work, great. If not, it may be time to turn to Plan B – case hardening.

p.s. The stones will “work” if they reduce the peak-peak roughness left by the end mill by enough that grinding and polishing paste can finish the job in a reasonable time.

p.p.s. The lash caps arrived yesterday and, unlike the ones that came on the bike, fit on the new valves

Last edited by Magnetoman; 04/27/18 6:28 pm. Reason: p.p.s.
Re: 1928 Ariel Model C [Re: Magnetoman] #733339
04/28/18 1:53 am
04/28/18 1:53 am
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Magnetoman Online content OP

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Magnetoman  Online Content OP

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The 7/16” grinding stones arrived this afternoon, resulting in a few developments. First, the stones work, so I’m proceeding with Plan A (Stellite).

As the composite photograph shows, the grooved surface left on this test piece by the ball end mill was taken care of in less than 10 sec. by the grinding stone. I’ll return to the features in this composite, but why is the end mill leaving such a bad surface?

I put the carbide end mill under the microscope, discovered it was ‘Made in Korea’, and that it is chipped. All of the surfaces, even the first one I cut, look this way but at this point I can’t tell if the end mill came to me “pre-chipped” or if it chipped the first time I used it when it hit the hollow under the surface of that one. Anyway, the chipped cutting face explains the grooves. I looked at the other end mill that ceased cutting and discovered it is made of HSS rather than carbide. I had used it on the bare steel to form the hollows for the Stellite and forgotten that it wasn’t carbide. Anyway, the fact it’s HSS explains its refusal to cut Stellite. If the chipped carbide end mill can hold up for one final end piece I should be fine since I now know the grinding stone can take care of the fixing it well enough to allow me to move on to the polishing stage.

Back to the features shown in the photograph. It appears that there are two diameters; one slightly smaller at the tip and the other slightly larger further out. That's certainly possible since there's no expectation that the grinding stone will be precisely the same diameter as the end of the end mill However, the diameters are very nearly the same and cannot be felt by running a scribe up and down the walls. But, if there are two diameters the balls will be supported only by the smaller of the two, so is that something of concern?

Measuring the ratio of the largest dia. to that of the inner one times the 7/16” actual dia. gives 0.33” as the smaller dia. As will be seen below, this gives it an area larger than that of the CrMo tubing that I’ll use for the pushrods. Hence, even if this is the only portion of the Stellite the balls on the lifters and rocker arms push against, it has strength to handle the pressure without yielding. I should add that there's no reason to expect the grinding stone to be precisely 7/16" in diameter, in which case a smaller area at the tip, or a ring around the surface, will support the ball. However, if this is the case, it will be revealed as soon as I start lapping with grinding paste and I'll be able to deal with it.

CrMo pushrods for performance cars are sold in several diameters and wall thicknesses, including 5/16”x0.080”. The cross-sectional area of one of those is 0.079 sq.in. (0.094” for 3/8” pushrods). I’ll be using 7/16” tubing with 0.065” wall thickness. The area of that tubing is 12% greater at 0089 sq.in. (5% less than 0.094”). Further, the Ariel’s pushrods will be dealing with less powerful springs as well so this calculation shows tubing of this thickness should be up to the task.

Attached Files Pushrods12.jpgPushrods11.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #733446
04/29/18 5:20 am
04/29/18 5:20 am
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Magnetoman Online content OP

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Magnetoman  Online Content OP

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I welded the first few pushrod ends using 3/32" Stellite, the smallest size normally available. However, I also have 5 rods of 1/16" kindly sent to me as a sample by Polymet which I should have been using all along because of the small clearances. Instead of saving the 1/16" material for some possible future use, I used it now and the results were great, as shown at the left in the composite below.

After filling this ~1" pushrod end with Stellite I used the chipped carbide ball end mill to drill it to a depth that left 0.050", shown in the center of the composite. As can be seen the end mill did an OK job, but yesterday I ordered another one for Monday delivery just in case things didn't work out today. I won't be needing it. I then used the grinding wheel to smooth the cavity as much as possible.

I brazed a 7/16" ball to a piece of stainless tubing, held it with a small vise grips, and used it with the lathe at 400 rpm with the following grinding pastes:

280 grit (42 micron)
400 grit (22 micron)
800 grit (15 micron)
Simichrome (8-10 micron)
3 micron

The result is shown in the next photo. It is smoother and shinier than the pushrods that came on the bike, as well as the balls they push against. The polishing probably took two hours because I stopped frequently to check progress, and had to clean the pushrod end and lap after every grit. However, once I had refined the procedure on the first pushrod end I did the other three in an assembly-line way, finishing all of them in a little over an hour.

After I had the four ends polished I drilled the opposite ends 0.5" deep with a 7/16" drill bit for the CrMo tubing. I used the faux pushrod to determine I needed the pushrods to be ~8.14" between their concave surfaces and based on measurements using 7/16" balls determined I needed the tubing to be ~7.45" long to accomplish this, so I cut a piece 7-3/4" and silver soldered one end to the pushrod end. After soldering it in place a second measurement showed how much I needed to remove from the tubing, after which I silver soldered the other end on. I repeated this with the second pushrod, and they ended up only 0.002" different in length so they are interchangeable, as was the plan. The final photo shows them in place.

Tomorrow I'll remove the rocker cover to add the pushrod covers, and finish bolting the engine back together. Then on to the gearbox.

Attached Files Pushrods13.jpgPushrods14.jpgPushrods15.jpgPushrods16.jpgPushrods17.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #733534
04/29/18 11:58 pm
04/29/18 11:58 pm
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Magnetoman Online content OP

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Magnetoman  Online Content OP

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As you can see from the photograph, the engine is back together. Some time ago I made a larger diameter knurled brass knob to replace the smaller steel one for the rocker cover to make it easier for me to remove it at fueling stops for frequent greasing. The slot in it is for a screwdriver, if necessary, as well as for a length of safety wire to keep it from vibrating off.

With the engine together, it’s time for the gearbox. The first thing to remove is the clutch. As I described in my BSA 6-spring clutch restoration thread life is easier, and more precise, if the springs can be set using some sort of gauge. That gauge being the torque required to move the actuating arm through a given distance. Since the clutch seemed to be OK when I got it, machining a socket to fit over the actuating arm let me determine that it takes 6 ft.lbs. to move the end of the arm 3/4”. I can now reset the springs to give that value while also minimizing runout and it should be very close to perfect, if not spot on, without any further adjustment.

The clutch is very much like that of a BSA, except for the details of the driven and driving plates. Because they’re different I can’t use a BSA tool (a pair of plates bolted together) to keep things motionless while I loosen the center bolt. So an impact wrench to the rescue, since inertia of the rotating parts does the same job the tool otherwise would. One rated at 75 ft.lbs. didn’t budge the nut, but another at 320 ft.lbs. had it off immediately.

The next problem is pulling the clutch hub off. There aren’t any threads for a BSA-type puller but luckily I have a 3-jaw puller whose arms fit between the various pieces. It took quite a bit of torque on the puller before the hub let loose with a bang and ended up on the floor, luckily without any apparent damage. However, whatever bearing is inside it feels a little rough so I’ll be looking into that before I’m done. To do that will require removing a nut that appears to have been peened over rather securely (although I only glanced at it for a moment).

Once the hub was off the sprocket was visible. As can be seen, it is a “custom” item complete with a bespoke retaining fixture for the nut rather than a locking washer that fits over the splines. I’m going to be making a “custom” sprocket of my own, with more teeth, and I can only hope that my welding job ends up somewhat more aesthetically pleasing than this one.

At this point I only had another hour I could have worked, but I hit a roadblock. To remove the nut that is retaining the sprocket requires a 1-1/4” BSF socket. I actually have one this size, but it isn’t deep enough for the drive end to clear the end of the gearbox shaft. Tomorrow I’ll stop at the used tool store and hope they have a 1-7/8” A/F 6-point, deep-drive socket since it will be only 0.015” larger than the proper BSF size. Off line today I had a Gold Star "consulting job" that prompted me to machine a piece of steel for a BSA special tool that also will require a socket, so I'll kill two birds at that tool store tomorrow.

Attached Files Ariel_engine_assembled.jpgClutch01.jpgClutch02.jpgClutch03.jpgClutch04.jpg
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