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Vanapplebomb Samba Member
Joined: November 03, 2010 Posts: 5412 Location: Holland, MI
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Posted: Thu Dec 02, 2021 7:47 am Post subject: Re: Bushings for carb butterfly shaft? |
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The biggest problem with Delrin is it’s nature to cold flow under consistent pressure. It won’t hold its shape well and will go oval over time from the return spring on the throttle, resulting in leaky bushings. This is true of UHMW, Teflon, Nylon, etc… great natural lubricity, and pretty good west resistance, but won’t retain its shape long term due to cold flow. _________________ 1800 Type 4 Berrien 295
http://www.thesamba.com/vw/forum/viewtopic.php?t=487021
Last edited by Vanapplebomb on Thu Dec 02, 2021 7:50 am; edited 1 time in total |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21519 Location: Oklahoma City
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Posted: Thu Dec 02, 2021 7:48 am Post subject: Re: Bushings for carb butterfly shaft? |
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oprn wrote: |
Interesting about Delrin. I have some shaving from it on my lathe bed yet. I will put them in a jar with pump gas and see what happens. My stock of Delrin is from used displacers that were in service in oilfield vessels that were filled with crude oil and in some cases natural gas condensate so I am a bit sceptical about Delrin not being compatible with gasoline. We have used it extensively in this service for many decades. |
Basic black Delrin (acetal) in the lists I have.....lists as "good" in "leaded gasoline".....just OK with standard no lead.
Make note.....I did NOT say it had big issues with gasoline (but it does have issues over a period of time). I noted that it does poorly with standard carb cleaners.
The two main groups that Delrin has BIG problems with are "KEYTONES" and greases and some oils. The saponifying chemicals and surfactants in greases....even some food greases.....slowly turn Delrin gummy. It starts to swell.
Toluene is a slow delrin killer but one nonetheless. Same issues with a lot of fuels and oils. Gasoline has about 130 hydrocarbon components some in smaller some in larger amounts in it.
I love Delrin.....but I have had too many complex chemical mixtures that affected it in odd ways....and this is even before adding heat .
That's the other issue. Delrins softening point.....even without any added attack from greases or solvents....is about 240-ish. Check parts under your hood on a warm day and a long drive. Typically I find my distributor on a type 4 can be between 200-225 in mild weather and pushing 300 in hot summer.
The carb will not get that hot when running....if it's a center mounted carb....but will get much hotter on duals depending on manifold length. Still not horribly hot while runnijg with a good spacer. But after shut down.....hot.
Also.....the severe risk of issues when adding grease.
Thats a good test....soak a piece of Delrin in gasoline. What you will usually see is a surface softening where you can easily scrape or gouge penetrated plastic away. Also check for swell. Ray |
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Brian_e Samba Member
Joined: July 28, 2009 Posts: 3292 Location: Rapid City, SD
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Posted: Thu Dec 02, 2021 10:02 am Post subject: Re: Bushings for carb butterfly shaft? |
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Or you could just use short piece of an old push rod, or chunk of a valve guide and machine it to size and be done. It will long outlast the rest of the carb or the engine its going on. It may not be the most exotic, but we ain't going to the moon here.
Brian _________________ www.type-emotorsports.com |
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Chickensoup Samba Member
Joined: January 06, 2018 Posts: 5368 Location: Good Hope, GA
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Posted: Thu Dec 02, 2021 10:12 am Post subject: Re: Bushings for carb butterfly shaft? |
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sorry, but im not seeing how using old worn engine parts is cheaper. I dont have an unlimited stash of push rods and valve guides.
If customers found out I install "used" parts, they will freak. Carb buyers are not easy to deal with. _________________ -'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge" |
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Brian_e Samba Member
Joined: July 28, 2009 Posts: 3292 Location: Rapid City, SD
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Posted: Thu Dec 02, 2021 10:42 am Post subject: Re: Bushings for carb butterfly shaft? |
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You have never taken a piece of good material from the scrap bucket, and turned it into something very useful for a different application?
My point is....you don't need to re-invent the wheel with questionable space age materials, when a small piece of aluminum, or brass, or bronze will work 100% and most likely be cheaper and easier. With one old push rod tube, you can probably re-bush 6-8 Kads. Sleeve bearings from Mcmaster are less than $1 each and they also last forever.
I have been re-bushing and O-ringing Kads and other carbs for 12+ years, and never had an issue with non-plastic bushings. They work 100% every time, and I have yet to see one wear out.
Brian _________________ www.type-emotorsports.com |
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Lingwendil Samba Member
Joined: February 25, 2009 Posts: 3988 Location: Antioch, California, a block from the hood
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Posted: Thu Dec 02, 2021 10:56 am Post subject: Re: Bushings for carb butterfly shaft? |
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Chickensoup wrote: |
sorry, but im not seeing how using old worn engine parts is cheaper. I dont have an unlimited stash of push rods and valve guides.
If customers found out I install "used" parts, they will freak. Carb buyers are not easy to deal with. |
Don't tell them it's a used pushrod, call it old stock high quality aluminum tubing.
I've made linkage downrods with it. Put the tubes in the chuck of a drill and polish them up with some scotchbrite. Tap the ends and thread in a male heim joint. Looks better than most aluminum tubing you pick off the shelf at the local metal shops _________________ 73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!
Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884
Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087! |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Thu Dec 02, 2021 11:14 am Post subject: Re: Bushings for carb butterfly shaft? |
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We have been recycling metal for 2000 years
your valve guides might have some bronze from the "bronze age" in there, used to be a hatchet, used to be a cannon, used to be a church bell?
you prefer nu-metal?
Aluminum is very "new" |
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liquidrush Samba Member
Joined: July 18, 2018 Posts: 588 Location: MO
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Posted: Thu Dec 02, 2021 11:45 am Post subject: Re: Bushings for carb butterfly shaft? |
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I do a lot of Quadrajets for guys and I use silicon bronze bushings from mc master. Measure your shafts OD for the bushing ID, then look for a chucking reamer about .1 or .150 or so over. Search mc master for bushings in that size and there you go. Their bushings have .0005 over for a tap in fit. I chuck my reamer in the drill by the flutes leaving the length of the bushing exposed, then let the shaft of the reamer act as a guide in the T-body and spin the drill in reverse to ream the hole. Works perfectly every time. I put the bushing on a 5/16 x 4" bolt and tap it in again using the center holes as my guide. Done. I know this is a Q-jet but the principle applies. |
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Chickensoup Samba Member
Joined: January 06, 2018 Posts: 5368 Location: Good Hope, GA
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Posted: Thu Dec 02, 2021 12:21 pm Post subject: Re: Bushings for carb butterfly shaft? |
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The valve guide idea, im concerned about proper fit when using used guides. Obviously i will adjust the OD/crush, but for the ID, Results would be inconsistent right? Since the ID already is 8mm.
As for push rods, for me at least, finding non bent examples has been a challenge. I can chuck a few up in the lathe and watch how blurry they spin. Although, if I cut them into smaller chunks before hand...
new valve guides go for 5-7 bucks a piece. that could make about 4ish bushings?
I can get push rods for 3 bucks a pop. And they can make a billion per push rod.
Igus... well idk. Their website has been down.
Quote: |
You have never taken a piece of good material from the scrap bucket, and turned it into something very useful for a different application? |
Yes, Thats how i made my rocker chamfering jig. Quality control is number 1 for me tho.
I didnt think this would be such a hard decision lol. _________________ -'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge" |
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Chickensoup Samba Member
Joined: January 06, 2018 Posts: 5368 Location: Good Hope, GA
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Posted: Thu Dec 02, 2021 12:37 pm Post subject: Re: Bushings for carb butterfly shaft? |
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ok new idea. What are yalls opinions on pushrod grade aluminum bushings, and nickel plated shafts? Would the nickle plating be a better option that polished steel? zinc plate is also an option. I guess what im asking is what happens when the two metals contact each other over time? _________________ -'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge" |
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Vanapplebomb Samba Member
Joined: November 03, 2010 Posts: 5412 Location: Holland, MI
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Posted: Thu Dec 02, 2021 1:07 pm Post subject: Re: Bushings for carb butterfly shaft? |
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There is a good reason you don’t see aluminum bushings and aluminum faced bearings. Aluminum is sticky, gummy, and galls easily to harder materials.
Also, the aluminum will wear out fast, no matter what grade it is. It’s soft with no natural lubricity in and of itself.
If you want to see how metals react with each other, look up tables of the galvanic series. More cathodic elements “galvanize” more anodic materials. This is why magnesium, aluminum, (raw) beryllium, and zinc protect steel components for corrosion. _________________ 1800 Type 4 Berrien 295
http://www.thesamba.com/vw/forum/viewtopic.php?t=487021 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Thu Dec 02, 2021 6:24 pm Post subject: Re: Bushings for carb butterfly shaft? |
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So why are most engine bearings aluminum then?
Ok to be fair there are lots of different kinds of aluminum, and lots of different kinds of bronze.
Some are soft, some contain hard particles like silicon, some are SUPER hard, some are alloyed with tin or lead.
If you want to buy something universal look up....
660 aka 932 bronze, or phosphor bearing bronze
That's the classic for low speed bearing on a soft steel shaft.
You don't HAVE to make the bushings to fit, but it is handy because.....
You can make the bushing to fit whatever size the hole comes out, and fit whatever size the shaft IS after it's polished up. |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Thu Dec 02, 2021 6:31 pm Post subject: Re: Bushings for carb butterfly shaft? |
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I don't know about nickel plating, sounds good but i wonder why isn't it used? |
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Brian_e Samba Member
Joined: July 28, 2009 Posts: 3292 Location: Rapid City, SD
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Posted: Thu Dec 02, 2021 6:52 pm Post subject: Re: Bushings for carb butterfly shaft? |
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Make it easy on yourself and order a 7/16OD x 5/16ID oil impregnated bronze sleeve bearing from McMaster for less than $1 each. Use a 7/16 end mill to bore the hole, put a drop of sleeve retainer on it, tap it in, and then run a long .314” reamer through both bushings. Polish the shaft, reassemble, and go drive.
Easy peasy. No need to make it harder than it needs to be.
Brian _________________ www.type-emotorsports.com |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21519 Location: Oklahoma City
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Posted: Thu Dec 02, 2021 11:06 pm Post subject: Re: Bushings for carb butterfly shaft? |
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modok wrote: |
I don't know about nickel plating, sounds good but i wonder why isn't it used? |
It is used quite a bit....just not on master cylinders!
Its actually used on fairly modern industrial carburetors and on fuel injector internal parts.
Its not used on factory made master cylinders because its a little expensive.....electroless nickel I mean....which is VERY accurate in plating to a uniform surface thickness on any shape...as compared to electro-plating.
This is why they use it on carbs with all the small passages. To be precise.....they use zinc-nickel electroplating. It has the sacrificial anode capability of zinc...but has the rockwell hardness, fine grain and accuracy of nickel.
Electroless nickel is used for repairing expensive and hard to repair bores, shafts and bearing journal surfaces on ferrous metals. There is an awesome video I have a link to of a very large lathe having a bearing journal repaired...in place...by a technician.
He cleans the worn away and cracked metal, then makes a small dam aroun the area with clay. Heats it to about 225* F with a radiant heater....then pours in the nickel solution. Every 15 minutes at 206* gives a plating of about .0005" thick. He plates....cleans....buffs....files or grinds to feather then repeat. In the end....he gets a layer that fills in the dent, or ding flush...and ends of with a rockwell hardness over 70.
If you wanted to have an original master cylinder that would last forever....meaning no rust....ever.......just needing a cleaning every few years and new seals...First hone it oversize by about 0.003" and polish the bore.
Then .you can mask off the cylinder with peelable masking rubber (fairly cheap for a quart)...then drop the cylinder in the tank at 206* F....replenish every 30 minute by stopwatch. Just keep agitating.
It will emerge with a pating of 0.001" after 30 minutes. So the bore....if it was 0.750" stock....and you honed it to 0.753".....in 45 minutes it would be back to 0.075".....would be smooth as glass so you can lap a fine 600 grit tooth on to it.....and it would last forever.
If you wanted to do one at home (you can buy a kit)....it would cost about $275. But in that same bath, you can do several master cylinders, all of your brake cylinders and a few clutch slave cylinders. Price comes own to cheap.
And....for cars like mine (my 412)...you cannot buy new master cylinders or clutch slave cylinders.
The one drawback of nickel plating n ferrous metal. While nickel will NEVER rust....if you scratch through the surface....since it is not a sacrificial anode like zinc.....the metal underneath will start to rust and will rust away under the nickel...leaving hollow areas that collapse.
By the way...nickel electroless was and is used on ATE caliper pistons and on the metering plates in fuel injection fuel pressure regulators. Very hard, very rust free. Its why old abused caliper pistons get those crazy rust pits in them. Usually a previous owner during a rebuild scratched the piston.
Ray |
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tisius Samba Member
Joined: July 11, 2011 Posts: 1570 Location: Rotterdam,NL (+Chicago,IL)
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Posted: Fri Dec 03, 2021 2:23 am Post subject: Re: Bushings for carb butterfly shaft? |
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modok wrote: |
So why are most engine bearings aluminum then?
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lubricated by the engine oil.
carb throttle shaft bushings are not lubricated (continuously). _________________ drive it like you just robbed the bank
you don't have to be crazy to be into VW's, but it sure helps!!
.... if it ain't dutch, it ain't much! |
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Vanapplebomb Samba Member
Joined: November 03, 2010 Posts: 5412 Location: Holland, MI
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Posted: Fri Dec 03, 2021 6:05 am Post subject: Re: Bushings for carb butterfly shaft? |
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modok wrote: |
So why are most engine bearings aluminum then?
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I should be more specific. When I referred to aluminum bushings/bearings, I am referring to non-hydrodynamic bearings, like we use in throttle shafts. Hydrodynamic bearings like we see on cranks/rods and other industrial applications are another animal entirely. They are a fluid bearing, and do not depend on the bearing material for lubricity.
Also, not referring to cast bearing grade aluminums alloyed with Tin, Zinc, Lead, or silicon. These alloys can work at lower surface speeds with a healthy dose of hydrostatic lubrication, such as an oil wick or splash lubrication.
Pervious poster was talking about machining down pushrods, which are commonly 2024-T3, 6061-T6, or 7075. Those alloys have no place as a bushing or bearing.
Sorry for nerding out, but materials are kind of my jam. _________________ 1800 Type 4 Berrien 295
http://www.thesamba.com/vw/forum/viewtopic.php?t=487021 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26788 Location: Colorado Springs
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Posted: Fri Dec 03, 2021 7:13 pm Post subject: Re: Bushings for carb butterfly shaft? |
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Yes I agree that is not an ideal material to use but it does NOT need to be ideal to work.
the zinc alloy the carburetor is made from is a bad bearing material also, but yet it worked good enough for most people.
I think most ideas discussed here would work well.
Bearing bronze and hard aluminum are a joy to work with, but some of the others are more troublesome.
My scrap bin currently has lots of 6&7mm id bronze guides from vw and bmw, actually 8mm is getting a bit rare, but I have a few left in the bottom perhaps. |
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esde Samba Member
Joined: October 20, 2007 Posts: 5969 Location: central rust belt
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Posted: Fri Dec 03, 2021 8:13 pm Post subject: Re: Bushings for carb butterfly shaft? |
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Or, here is the really easy answer
https://www.thesamba.com/vw/classifieds/detail.php?id=2324257
https://www.thesamba.com/vw/classifieds/detail.php?id=1929455
I know that in the VW community claiming you fixed something better than new with leftover bits for no money is a point of pride. And I get it, my dad was never one to spend if he could DIY a thing, consequently everything we owned needed work, and we made a lot of our own tools and parts. SO surely these throttle shafts are not the cheapest or thriftiest way to do the job, but it does cut it down to one operation. Surely being the fastest option is worth something? I used these on a 30pict and two 28pci carbs, and man it was easy.
SD _________________ modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that. |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21519 Location: Oklahoma City
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Posted: Fri Dec 03, 2021 9:59 pm Post subject: Re: Bushings for carb butterfly shaft? |
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modok wrote: |
Yes I agree that is not an ideal material to use but it does NOT need to be ideal to work.
the zinc alloy the carburetor is made from is a bad bearing material also, but yet it worked good enough for most people.
I think most ideas discussed here would work well.
Bearing bronze and hard aluminum are a joy to work with, but some of the others are more troublesome.
My scrap bin currently has lots of 6&7mm id bronze guides from vw and bmw, actually 8mm is getting a bit rare, but I have a few left in the bottom perhaps. |
If its guides you want to use.....the guys from SI can get you anything you want.
As for other machinable things....the bearing grade plastic that was suggested...machines like butter. The graphite does wear a little on the tools but it machines very clean and accurately. It also blows oilite bronze away in "most" applications. As with anything....it depends on what you want to play with.
Ray |
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