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Re: 1928 Ariel Model C [Re: Magnetoman] #728347
03/11/18 11:50 pm
03/11/18 11:50 pm
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Posts: 4,643
U.S.
Magnetoman Offline OP

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As shown in the first photograph, the good news is the combination of hard chrome plating plus a toolpost grinder fills in nearly all the corrosion pits and produces an excellent surface. The bad news is, the spindle was offset enough from the center line of the gear that I'll have to add more Cr and grind again.

I first tried holding the cam between centers but the center at one end is off by just over 0.002" and the other by 0.001" so that was impossible. I then centered it in the 4-jaw chuck using an unplated portion of the spindle as shown in the 2nd photograph. When done this way the TIR of the outer surface of the teeth is 0.0005". In the end I want to grind the spindles "perfectly" coaxial with the teeth and currently they're less than perfect so the meshing would oscillate as the engine ran. I then installed the toolpost grinder on the lathe, attached an 80 grit stone for materials of hardness greater than Rockwell 60, and switched pulleys to spin at the correct rpm for that stone. There were no glitches, but this paragraph represents about an hour's worth of work. Nothing goes fast when you're working to high precision.

I then dressed the stone and removed Cr at a rate if ~0.0005" per pass until most of the surface had been ground. Unfortunately, at that point the diameter would result in a clearance of ~0.005" with the bush. So, I cleaned the end that I just ground, applied RTV to the portions I don't want plated, plus a baggie to protect the rest, and when the RTV is dry will add another ~0.002.5" (0.005" diameter) of Cr to give enough material to grind to the clearance I want. I'll just hang that end in the plating solution and repeat, if necessary, with the other end when I get to it (treating in the oven in between).

I already had the spindle centered in the 4-jaw chuck, but now that I have confirmed the gear teeth are nearly coaxial with the current shafts, next time I'll hold it by the gear. It has 40 teeth so the 4-jaw chuck can hold it directly.

Blueprinting is a bitch, but somebody has to do it...

Attached Files camshaft07.jpgcamshaft04.jpgcamshaft05.jpgcamshaft06.jpg
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Re: 1928 Ariel Model C [Re: Magnetoman] #728448
03/13/18 12:55 am
03/13/18 12:55 am
Joined: Nov 2011
Posts: 4,643
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Magnetoman Offline OP

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I was going to have to confess that I got nothing whatever done on the Ariel today, but then the postman came. So, I get to report an actual accomplishment for today, i.e. opening an envelope. Measurements and other details to follow maƱana.

Attached Files Valves.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #728540
03/14/18 3:11 am
03/14/18 3:11 am
Joined: Sep 2004
Posts: 835
Farnham, Surrey, UK
gunner Online content
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Farnham, Surrey, UK
Hi MM, one thing I don't understand about your chrome plating process is how the base surface is first prepared to ensure good adhesion and how you get away with applying chrome directly onto the surface. I note that many commercial chrome plating companies first use copper, then nickel and finally chrome on top. Perhaps the answer is that you want a thick and solid hard chrome finish which can subsequently be ground back to the desired thickness as required.

P.S. I note your lecture flyer at the University of Arizona, do you have any forthcoming science lectures in the UK?


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: 1928 Ariel Model C [Re: Magnetoman] #728541
03/14/18 4:39 am
03/14/18 4:39 am
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Magnetoman Offline OP

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Originally Posted by gunner
many commercial chrome plating companies first use copper, then nickel and finally chrome on top.
Decorative chrome is a very thin layer of (expensive) chrome over Cu and Ni. Although the steel is polished before plating there are still pits and scratches and a relatively thick layer of (less expensive) Cu does a good job filling those in. The much thinner layer of Cr would just follow the contours of the imperfections. Instead, the underlayers are polished so the thin, hard Cr on top doesn't need to be. "Hard chrome" is plated directly on the steel but is much thicker than decorative chrome to do its job of providing a hard wearing surface rather than just look pretty.

Originally Posted by gunner
any forthcoming science lectures in the UK?
I was in the UK twice last year to speak but there's nothing on the schedule there for this year. That can always change, though.

As shown in the first photograph, the guides that arrived yesterday from the AOMCC are shorter than the ones I removed (exhaust on top, inlet on bottom) as well as have a projecting positioning ring on them that would make them project further into the airstream as well as not so far above the head (old guides marked with paint where they made contact with the top of the head). They also have grooves around the middle as well as an oil hole so are designed for a different head with an oil gallery to feed that oil hole. Before I make my own guides I'll have to decide how far I want them to project into the ports.

The OD of the exhaust valve is 0.0003" larger than the inlet valve, which would result in clearances of 0.0013"-0.0016", respectively, if I could somehow succeed in reaming reaming the guides to precisely 11/32" (0.34375"). How I'm going to size the guides after installing them is subject of ongoing research

A few weeks ago I bought an offcut of G2 cast iron to use to make my own guides. But, what if it isn't G2? I'm glad you asked that question. Today I cut a small slice from the end and polished with every finer grades of SiC, ending with 1 micron powder, it to make a micrograph (following a procedure described in ASM Handbook Volume 9, Metallography and Microstructures). However, the only micrographs of G2 I can find show it after being etched with nital to reveal the grain boundaries so I'll do that tomorrow.

The valves springs in the package are different in length than the ones that were in the engine, and their spring constants quite a bit less. The outer spring is 45+/-2 lbs./in and the inner 37+/-2 lbs. in. Combined they are 76+/-2 lbs./in. In contrast, combined the ones that were in the engine are 136 lbs./in.

Attached Files Guides_OldNew.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #728571
03/14/18 2:58 pm
03/14/18 2:58 pm
Joined: Aug 2001
Posts: 2,001
Greensboro, NC
Alan_nc Offline
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Bit of a difference on spring rates. Were the wrong ones fitted when you got the bike? Would think that any use would show a 'somewhat' reverse of the numbers you are showing.


Alan
Cleared m out....left only
59 BSA Bantam (Trials)
78 Triumph Bonny (UPS)
02 Suzuki GS500
Re: 1928 Ariel Model C [Re: Alan_nc] #728575
03/14/18 4:05 pm
03/14/18 4:05 pm
Joined: Nov 2011
Posts: 4,643
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Magnetoman Offline OP

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Originally Posted by Alan_nc
Were the wrong ones fitted when you got the bike?
The different spring rates illustrate a general principle that applies to other things as well. If you have only one spring, you know exactly what value is correct. If you have two, you have no idea...

Another principle it illustrates is ignorance is bliss. Had I not been able to measure spring constants I would have installed the new springs, which would have either worked or not worked. Had the engine worked, great, but had it failed I wouldn't have known why and would have accepted it as to be expected for a bike that's 90 years old.

I don't know if the original springs are correct, the replacements are correct, or if neither set is correct. However, I have three BSA B31/33 iron heads, and possibly some loose springs as well, so I'll be measuring a few of those to get an idea of what valve springs an iron engine with fairly gentle cam and a modest redline requires. Hopefully, that will tell me which set of springs, if either, I should use.

In a similar vein, while I could blissfully accept that the G2 cast iron that was sent to me actually is G2, I can't. That's why I spent a half-hour yesterday polishing a specimen to prepare it for a metallograph. I ran out of time before being able to etch it, but I'll do that today. If the valve guides wear prematurely I want it to be because of a fundamental limitation of the open-valve engine design, not because I blissfully made the guides from the wrong grade of cast iron.

Re: 1928 Ariel Model C [Re: Magnetoman] #728586
03/14/18 5:06 pm
03/14/18 5:06 pm
Joined: Feb 2014
Posts: 472
Cork Ireland
C
chaterlea25 Offline
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Hi MM and All,
The guides you got are the ones for later Ariel iron head models, I have a set here but with smaller bore from a 350 NH
The guides that were fitted without a shoulder are in my opinion incorrect,
There must have been some other model in between '29 and '50 that had an oil feed to the guides?
Are either or both new valves non magnetic? as both are the same size how do you tell which is which?
I would expect to see the exhaust stem smaller where both guides are identical bore???

If you remember I mentioned to you to check the pushrod cups for wear as our mutual friends 29 Ariel had an issue where the rocker ball broke through the bottom of the pushrod cup


John

Re: 1928 Ariel Model C [Re: Magnetoman] #728606
03/14/18 7:53 pm
03/14/18 7:53 pm
Joined: Nov 2011
Posts: 4,643
U.S.
Magnetoman Offline OP

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Originally Posted by chaterlea25
The guides that were fitted without a shoulder are in my opinion incorrect,
That's good to know. Thanks. I'll include a shoulder on the new ones I make.

Originally Posted by chaterlea25
Are either or both new valves non magnetic? as both are the same size how do you tell which is which?
I would expect to see the exhaust stem smaller where both guides are identical bore???
None of the old or new valves is magnetic. However, they came with tags attached identifying them. The exhaust valve is on the right in the photograph. Note that its stem is reduced in diameter (to 0.302") for a distance above the head. The head itself is thicker as well, 0.154" vs. 0.128", and it weighs more, 91.68 g vs. 89.53 g. However, unless I go Archimedes on the valves to try to accurately determine the densities I won't know if they are made of the same material. I may have mentioned this in an earlier post, but the company George Kaplan pointed me to is the one that makes the valves for the AOMCC.

Originally Posted by chaterlea25
check the pushrod cups for wear as our mutual friends 29 Ariel had an issue where the rocker ball broke through the bottom of the pushrod cup
Thanks for the reminder. I hadn't gotten to this yet but the two photos show both ends of the pushrods, with a higher magnification inset of the worse of the two. Sorry for the quality of the micrographs but they're shot hand-held on my iPhone through one eyepiece of the stereomicroscope on my workbench. The same pushrod is on the R in both photographs. The dark areas aren't discoloration, they're pits of missing material covering what I'd estimate to be ~1/3 the surface. Comments?

Yes, it would be best to have a replacement, but assuming it proves impossible to find one, would you use this as an excuse to abandon the Cannonball folly, or would you be reasonably confident that pushrod is good for 4000 miles?

Turning to cast iron, the next photograph shows the surface after polishing but before etching. The two faces of the cast iron aren't quite parallel, which is a problem with micrographs given the shallow depth of field of the microscope at high magnification. If the image appears on your screen 1.5" wide the magnification would be 90x (3" = 180x, etc.). The flakes of graphite are quite obvious. The top of the next composite shows the surface after a 10 sec. etch in 5% nital, and at the bottom a "100x" image of G2 from the Dura-Bar site..

I put "100x" in quotes because it's not possible to know the actual on-screen magnification of such a micrograph. In any case, the two surfaces appear to be the same (which is more apparent when scanning around different locations) so I conclude the bar of material I got is G2 as I ordered.

The above might seem like a lot of trouble to go to, and it did take over an hour of polishing, etching, and observing but, even if the odds of receiving the wrong material might have been small, the consequences of having guides made of rapidly wearing (or seizing) iron would be large. And, it's not like suppliers have never shipped incorrect or mislabeled product before, so maybe the odds weren't all that small.

Attached Files Valves_new.jpgPushrods01.jpgPushrods02.jpgCastIronMicrograph01.jpgCastIronMicrograph02.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #728613
03/14/18 8:40 pm
03/14/18 8:40 pm
Joined: Oct 2017
Posts: 88
England
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George Kaplan Offline
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England
Originally Posted by Magnetoman
............the company George Kaplan pointed me to is the one that makes the valves for the AOMCC.


When I spoke to them (Andy Grenside) about my valves they told me that they made their exhaust valves from 214N unless they are specifically asked for a different material. I also asked about surface treatment because 214N is an austenitic stainless steel and Andy specifically said that they always plasma nitride treat them so that they will run in any valve guide material.

If yours were made by G&S then the exhaust valve will be as per the comments above. Obviously I cant comment on the inlet valve as I didn't discuss inlets with them but I am sure they will be able to tell you what the material is (my money is on 214N). When I spoke to them they were able to provide a copy of the drawing of the valve I was enquiring after because they had made some previously and the drawing specifically stated the material.

John

Re: 1928 Ariel Model C [Re: Magnetoman] #728621
03/14/18 9:21 pm
03/14/18 9:21 pm
Joined: Feb 2014
Posts: 472
Cork Ireland
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chaterlea25 Offline
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Hi MM,
Re the pushrod cups ?
No, it would not be an excuse to abandon your Ariel project and leave the world at large watching this thread forlorn

What to do?
The failure of the other pushrod reported was when the bottom of the hemispherical cup departed down into the hollow tube
Paddy raided my box of pushrods and went off with some bits and pieces to effect a repair as only Paddy can do

I would check the pushrod cup ends for cracking, magnafluxing or dye pen ?
Best would be to x Ray them to see what thickness of material remains at the pressure points of the cups
It would not be a (another) major project to make up new pushrod ends or complete pushrods

I have sent an email to a friend who has an extensive library of old automotive catalogs asking if he has any info on the valve spring
specs for your Ariel
Engines with exposed valve gear and minimal lubrication will need softer valve springs than those with fully enclosed and positively
lubed cams and valve gear parts (BSA B series)

John

Re: 1928 Ariel Model C [Re: Magnetoman] #728628
03/14/18 10:12 pm
03/14/18 10:12 pm
Joined: Nov 2011
Posts: 4,643
U.S.
Magnetoman Offline OP

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Originally Posted by George Kaplan
When I spoke to them (Andy Grenside) about my valves ...
Andy is the guy who pointed me to the AOMCC for the valves, and in turn they told me G&S makes all their valves and that Andy is a club member.

Originally Posted by chaterlea25
No, it would not be an excuse to abandon your Ariel project and leave the world at large watching this thread forlorn
Damn. I hoped this gave me a great excuse for backing out gracefully. I guess I'll have to keep looking for... er, I mean working.

Originally Posted by chaterlea25
I would check the pushrod cup ends for cracking, magnafluxing ...
Excellent idea. I might even be able to work that in later today.

Originally Posted by chaterlea25
It would not be a (another) major project to make up new pushrod ends or complete pushrods
The pushrods are of very simple construction. What I would need is to find something that has 7/32"-radius, hardened cups that I could cannibalize and repurpose for the Ariel.

Originally Posted by chaterlea25
Engines with exposed valve gear and minimal lubrication will need softer valve springs than those with fully enclosed and positively lubed cams and valve gear parts (BSA B series)
It would be great if your friend can find the specs on the proper springs. However, I suspect the "soft" ones that came with the new valves are correct.

As the photo shows I have no shortage of used BSA valve springs to test (and these aren't the only ones on the shelf). One set (inner and outer) is 1.56" OD x 1.69" long and the pair is 160 lb/in. and another is 1.26" OD x 1.58" long and is 215 lb./in. Another set of the same dimensions as the latter is in a box labeled "used CB Gold Star" and is 225 lb./in.

Addendum:
Originally Posted by chaterlea25
It would not be a (another) major project to make up new pushrod ends or complete pushrods
A not-major project here, a not-major project there, and pretty soon you're talking about major amounts of time. A 7/16"-dia. ball end mill isn't part of my set, but one will be delivered to me on Monday. That, an appropriate case hardening steel, the Kasenite I already have, and 18" of steel tubing are the only things required for me to have new pushrods. Oh, and the time it will take me to make them. Sigh...

Attached Files springs.jpg
Last edited by Magnetoman; 03/14/18 11:06 pm. Reason: Addendum:
Re: 1928 Ariel Model C [Re: Magnetoman] #728643
03/15/18 1:21 am
03/15/18 1:21 am
Joined: Nov 2011
Posts: 4,643
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Magnetoman Offline OP

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The photograph shows the four sides of one end of the pushrod that has the best of the cups. This end has several nicks in it and the rod is indented on opposite sides as if it had been gripped too hard with a needle nose pliers. I've gone through the first six stages of grief over the past few hours and have now reached the seventh stage, full acceptance that I'll have to make new pushrods.

Attached Files PushrodEnd.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #728676
03/15/18 1:28 pm
03/15/18 1:28 pm
Joined: Feb 2014
Posts: 472
Cork Ireland
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chaterlea25 Offline
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Cork Ireland
Hi MM,
I had a reply from my friend who unfortunately has no info going back to 1928 that covers the Ariel :-(

John

Re: 1928 Ariel Model C [Re: chaterlea25] #728692
03/15/18 5:33 pm
03/15/18 5:33 pm
Joined: Nov 2011
Posts: 4,643
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Magnetoman Offline OP

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Originally Posted by chaterlea25
I had a reply from my friend who unfortunately has no info going back to 1928 that covers the Ariel
Thanks for trying. I'll start rummaging through my books and literature as well as the internet to see if I can find something comparable. Unfortunately, most sources just give part numbers, not technical data like spring rates.

Meanwhile, I now have on order is everything I need to fabricate the new pushrods, i.e. chrome moly tubing, case hardening steel, and a 7/16" ball end mill. Plus the Kasenite I already have. Last night I found that the parts manual shows the pushrod ends as available separately but at this point I don't know how they're attached to the tubes. Perhaps they're swedged or an interference fit, in which case the marks shown in my previous post might be due to someone trying to remove it.

I won't know the wall thickness of the current tubing until I remove one of the ends so I ordered 3' of 7/16" tubing in each of the three thicknesses McMaster-Carr has in stock (one of which I know is too thick). What I don't use will be added to my stock for some future need. It greatly helps keep forward momentum on projects to be able to simply pull an appropriate piece of metal from the shelf when I discover I need it rather than having to place an order and wait.

Even with the stronger set of springs that came on the bike the static force to hold a valve fully open is less than 100 lbs. However, the dynamic force on a rod when the cam slams a valve open is greater this. McMaster-Carr lists 70,000 psi as the yield strength of their 4130 tubes. At this value the 0.049" wall tubing could support 1500 lbs. (i.e. ~15x the static force) and the 0.065" could support 1990 lbs (~20x).

For comparison, it seems CrMo pushrods are most commonly 5/16" diameter with 0.080" wall thickness for "performance" street automobile engines, which equates to 1750 lbs. With the steel ends on the Ariel's pushrods the total weight of one made with 0.065" tubing would be less than 20% more than with 0.049" so that points to using the thicker tubing. It also would reduce flex when I hit 10,000 rpm coming down the back side of the Rockies when the brakes fail and I can't get it out of 1st.

Re: 1928 Ariel Model C [Re: Magnetoman] #728708
03/15/18 9:14 pm
03/15/18 9:14 pm
Joined: Sep 2004
Posts: 835
Farnham, Surrey, UK
gunner Online content
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Farnham, Surrey, UK
Hi MM, it might be worthwhile having a chat with Comp Cams based in the US, who sell semi finished push-rods based on your requirements though they advise speaking to one of their technicians first, see This Link.

These guys also sell various tools which may be of use including checking push-rods to determine the exact length needed, see This Link, and also specialized cutting tools to ensure maximum precision when building custom push-rods, see This Link


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: 1928 Ariel Model C [Re: Magnetoman] #728716
03/15/18 10:06 pm
03/15/18 10:06 pm
Joined: Nov 2011
Posts: 4,643
U.S.
Magnetoman Offline OP

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Originally Posted by gunner
semi finished push-rods ... checking push-rods to determine the exact length needed ... cutting tools to ensure maximum precision...
Thanks very much for those links, but I'm afraid I have to make the pushrods myself. Other than having the brakes relined by Vintage Brake shortly after I got the bike, I've made, machined, Magnafluxed, balanced, bored and bodged everything else on the Ariel. As a result I've become thick-headedly committed to doing everything myself. So, other than the very unlikely possibility of brake fade, whether or not the bike makes it to Portland (ME or OR, take your pick...) will be entirely my fault.

Re: 1928 Ariel Model C [Re: Magnetoman] #728797
03/16/18 7:32 pm
03/16/18 7:32 pm
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Magnetoman Offline OP

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Lacking my own Sunnen hone (for now...) I need to solve the problem of properly sizing the valve guides after I make and install them. A related issue is what clearance I should aim for.

The OD of the exhaust and inlet valve stems are such that the clearances would be 0.00125" and 0.00155", respectively, if the guides were sized precisely 11/32" (0.34375") after installation. That certainly would be too tight for the exhaust valve. Something closer to 0.002" might be best for both on this engine, but comments?

Since accurately aligning a reamer with the bore of the guides after installation would be difficult, resulting in some degree of bellmouthing. I think the best approach would be to ream them while in the lathe. The diameter of the reamer would need to be such that, after the guides were installed with a ~0.001" press fit, they would be only slightly undersize from the final desired ID to allow for final finishing with a ball hone. Another issue that needs to be anticipated is that a, say, 0.343000" reamer won't necessarily result in a hole that is precisely 0.343000".

Goodson sells reamers for cast iron guides in step of 0.001" from 0.340" through 0.346". So, factoring in all of the above, what size reamer should I buy?

Re: 1928 Ariel Model C [Re: Magnetoman] #728803
03/16/18 8:14 pm
03/16/18 8:14 pm
Joined: Dec 2004
Posts: 9,497
Scotland
kommando Online content
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Maybe leave 1 or 2 thou on and use a correctly sized hand reamer on the installed guides, these have a very shallow taper on the first section to ensure they follow the original hole alignment unlike a machine reamer that relies on the machine. You have to ensure the untampered full sized section gets to the bottom of the guide, there may not be enough room in the ports for that.

Re: 1928 Ariel Model C [Re: Magnetoman] #728816
03/16/18 9:54 pm
03/16/18 9:54 pm
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Posts: 472
Cork Ireland
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chaterlea25 Offline
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Hi MM and All,
Pressing cast iron guides into iron heads cold can easily shave the guide resulting in a poor fit
I heat the head and freeze the guide and hopefully the guide will slide into place
I would like to see 0.0015 interference (cold figure)
Ream the guide in the lathe and after fitting ream it again, the guide bore will have shrunk where the head grips the guide
I would aim for a clearance of 0.002 on the inlet and 0.0025 on the exhaust

John

Re: 1928 Ariel Model C [Re: chaterlea25] #728823
03/16/18 10:44 pm
03/16/18 10:44 pm
Joined: Aug 2014
Posts: 1,686
OZ
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OZ
John, I've always believed warming an iron head to fit iron guides was beneficial, despite " experts " saying it wasn't necessary because of the two like metals ! A shaving off the guide bore is a real possibiity !
But would freezing an iron guide to fit into a pre heated head induce any cracking ? Would it be better to fit such guides at room temperature to the warmed head ?

Re: 1928 Ariel Model C [Re: chaterlea25] #728830
03/16/18 11:47 pm
03/16/18 11:47 pm
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Magnetoman Offline OP

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Magnetoman  Offline OP

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Originally Posted by kommando
You have to ensure the untampered full sized section gets to the bottom of the guide, there may not be enough room in the ports for that.
There would be no problem passing all the way through and out the other end.

Originally Posted by chaterlea25
I would aim for a clearance of 0.002 on the inlet and 0.0025 on the exhaust
OK, but how much windage should I allow for in order to hit those values with a hand reamer? Kommando's post made me realize I can easily reduce the OD of the first 1" of a reamer by a few thou. to make it a slip fit in the guide and thus, um, guide the reamer straight through the guide. A clever, to-be-though-of, design for the driver could ensure no sideways force is exerted on the reamer, eliminating bellmouthing. The remaining uncertainty is how much oversize a reamer will cut in cast iron.

If I could hit the 0.002" value precisely with a reamer my hope is an inexpensive ball hone would be good for removing 0.0005" even though such hones aren't really intended for stock removal. What are your thoughts on this, especially on what size reamer I should buy? If it cut 0.0005" oversize then a 0.344" would leave a clearance of 0.0018" for the present inlet valve and 0.0.0015" for the exhaust. That would require the hone remove 0.001" to get the 0.0025" you mention.

However, depending on the length of the flutes (which Goodson doesn't give in their catalog, and they are closed for the evening now) I easily could go further and buy "large" reamer that was sized for the present exhaust valve, grind 1" at the end as a pilot, and ~2.5" in the middle sized for the present inlet guide.

Again, with a piloted reamer with no sideways force on it, what's your best informed guess how much larger than its OD it will cut?

Re: 1928 Ariel Model C [Re: Magnetoman] #728843
03/17/18 2:04 am
03/17/18 2:04 am
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Posts: 472
Cork Ireland
C
chaterlea25 Offline
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Hi MM,
Almost all the reamers I have have a taper towards the ends ?
I have not used my recently aquired Bowers electronic bore gauge to "test" any reamed holes (yet?) to check how good they size
I have checked 5/16 reamed holes with a gauge pin and they are good enough for me
multiple runs through with a reamer will enlarge the bore a touch
I have not had any guides crack when fitting from deep freeze temp to heads at 180-200deg C
A half or thou loose fit to the valve stems will not matter, but the same too tight will
You are likely to find that due to previous eccentric guides and wear that the valve seats will not be near
true to your new "precision" guides
With open valve gear you should be able to feel a little movement of the valve heads when lifted clear of the seats
I can "feel" when they good (or bad)

The original books on the recent Indian Chief engines I rebuilt suggest 4 thou clearance with new parts
Newly manufactured parts reduce this to a more acceptable figure

John

Re: 1928 Ariel Model C [Re: chaterlea25] #728847
03/17/18 4:04 am
03/17/18 4:04 am
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Magnetoman Offline OP

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Magnetoman  Offline OP

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Originally Posted by chaterlea25
Almost all the reamers I have have a taper towards the ends ?
Yes, but the longer the pilot the less bell-mouthing of the entrance to the guide.

I forgot to mention earlier that you though the guides I removed weren't of the original type, but now looking at the parts book I think they might be. However, if the parts book is accurate, the inlet (A6/209) and exhaust (A6/100) were switched. Note the lack of shoulders on them.

Attached Files ValveGuides.jpg
Re: 1928 Ariel Model C [Re: Magnetoman] #728866
03/17/18 10:11 am
03/17/18 10:11 am
Joined: Dec 2004
Posts: 9,497
Scotland
kommando Online content
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Quote
Almost all the reamers I have have a taper towards the ends ?


http://www.taylorandjones.co.uk/wp-content/uploads/2014/03/31-40_technical_section.pdf

Page 4

Quote
MACHINE REAMERS have either a Morse Taper or Straight Shank, but are never square ended.

HAND REAMERS always have a square-ended shank for fitting a Tap Wrench. They also have an additional taper lead behind the 45 degree
cutting bevel to help the tool centralise itself in the hole if there is any misalignment.


So have a look at you reamers and what type of end will identify them as machine or hand.

If like me your reamers are cast off's or good second hand then as the wear is on the front section a used machine reamer will show a slight taper too, but new machine reamers should be straight after the initial 45 cutting bevel.

Re: 1928 Ariel Model C [Re: kommando] #728902
03/17/18 3:51 pm
03/17/18 3:51 pm
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Posts: 4,643
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Magnetoman Offline OP

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Magnetoman  Offline OP

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Originally Posted by kommando
So have a look at you reamers and what type of end will identify them as machine or hand.
All but two of my Imperial and metric are machine ("chucking") reamers, with those two from a failed experiment some years ago to fine-tune jetting using an air/fuel meter and my own bespoke needle jets. The experiment failed because of the difficulty, if not impossibility, of working to tenths with reamers when a hone is the right tool for that job.

One issue is having the reamer precisely on axis with no tilt whatever. The initial taper on a hand reamer is there to help with that issue, but it doesn't solve it completely. Even if it were precisely inserted in the hole, a second issue is twisting the reamer while applying downward force without applying any sideways force whatever.

The above two issues could be solved, but a third issue is whether the hole produced in, say, brass will be precisely the same diameter as in cast iron, and if either is precisely the diameter of the reamer itself. These three issues are always present when using reamers but aren't likely even to be noticed since most people are happy at a few thou., and most don't have the instruments to measure the bore, taper, waviness, bell-mouthing, etc. to tenths anyway to notice the problem.

The exhaust valve stem is larger by 3 tenths and chaterlea25 wants me to make its guide larger than the inlet's by 5 tenths. Even if I knew how much oversize an individual reamer will cut in cast iron so I could look for a smaller one to compensate, hand reamers are available over this range only in steps of 10 tenths (0.001"). And, I would need two of the $47 reamers to deal with the current stem diameters along with chaterlea25's demands on the final results.

Again, these are the problems when using a pocket knife to do a scalpel's job. I started thinking of a Sunnen hone when I sized the small end bush, but a big deterrent was that floor space is at a premium. Sizing the crank and cam bushes softened me to the idea of rearranging things to find the space, and then I got serious as a result of honing the cylinder.

I've had the space for a Sunnen hone mentally marked out on the garage floor for a month but an appropriate one has yet to turn up within any reasonable driving distance. Well, one did turn up in a local auction but I should have bid higher. Of course, given where the rebuild is now it makes no sense for the Ariel (as if any of this makes sense...), but amortized over the number of bushes and guides in the bikes I hope to rebuild in the years to come... well, one could argue it still makes no sense, but it makes enough less no-sense that I decided it makes sense.

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