Author Topic: Clinder Honing, Head Clearance, Cylinder milling  (Read 15177 times)

hotater

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Re: Checked my head clearance, cylinder looks USED.
« Reply #15 on: January 25, 2006, 02:04:45 AM »
Bruce---

I have a dingleberry brush too.  What I need is the help of a cylinder lifter and wrench getter!!

I honed with a 240 and hand wiped with 400 wet or dry before start-up.  The cylinder was last off at 3200 hours and the crosshatch was still visible and no ridge at the top.  Cylinder= 4.497  Piston= 4.485  Head clearance=.055

There's a noticible difference in sound and cranking between .055 and .065.  Smaller is better at high altitude.
.052 clearance will leave the imprint of the intake valve in the carbon layer of the head, but it run good!
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

GerryH

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Re: Checked my head clearance, cylinder looks USED.
« Reply #16 on: January 25, 2006, 04:44:23 AM »
Tom,
Like everyone else, when I was first told to use Bon Ami, I thought they were idiots. One day I was at a friend's place who is a automotive machinist. He had guided his son thru a rebuild of a 250 cc bike engine and the thing had to be run down a hill to start it as the rings refused to seat after 2 weeks of the kid riding. Right in front of me he fed it a tablespoon of Bon Ami and the cure was instant. It kickstarted first try every time after that.

Gerry

Tom

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Re: Checked my head clearance, cylinder looks USED.
« Reply #17 on: January 25, 2006, 06:16:59 AM »
Well some idiot had to be the first one to suggest Bon Ami. :P
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

BruceM

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Re: Checked my head clearance, cylinder looks USED.
« Reply #18 on: January 25, 2006, 04:34:51 PM »
Jack,, yea, I'm lucky to have a bigger than me 14yr old home schooler nearby. I don't know how you manage head/cylinder lifting solo! He even gets school time credit for this sort of work, and wants more.  His enthusiasm is fun to be around.  I had pictures of your oil filter and Steve's version up in my shop for inspiration and he got a kick out of that.

Sounds like the plateau type finish worked like a champ on your engine. Should have known a master gunsmith would have already done that!

George B had a great idea for compression adjustment. He says the fixed cylinder head plug (where the original adjustable compression setup was)  is concave and seats on a gasket.  Not a big deal to hand hone off some of the edge to raise compression, or add gasket thickness to lower it if I went too far.  Just need to calculate the area of the plug surface relative to cylinder to be able to convert it to "equivalent head clearance".  This would let me to get below 0.057 (where I'm at now) if needed. Even at .057 head clearance  I can already see a very slight shadow of the valve edge on the piston surface carbon.




BruceM

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Cylinder Hone and Haircut
« Reply #19 on: January 31, 2006, 01:03:12 AM »
Honed the cylinder today with a 240 grit flex hone followed by a light 400 grit by hand  Sure makes for a  nice looking finish!  The "dingle berry brush" type hones are very easy to use. 

My cylinder is now at the machine shop to get a "haircut" of 0.045 mils.  My Metro manual calls for head clearance of 0.045-0.050 inches (45-50 mils) at sea level. Normally one 16 mil paper shim under the cylinder should be removed for 8000 feet elevation. For 5600 feet that would proportionally be 11.2 mils.  My  6/1 will be running at 5600 feet so that makes for 36 mils head clearance, adjusted for elevation.

My question:  Will I have problems with valve clearance to the piston at only 36 mils??? 

I looked into modifying the cylinder head plug to adjust compression.  The cylinder head plug seats on a shoulder about 0.75"  back, not on the concave surface edge.  To lower compression, grinding off some of the concave edge would work, or adding copper gaskets.  To raise compression, both the shoulder and the thread would have to be cut back, or the concave face would have to be filled in with ??? or material added via arc/mig welding.

   



Bruce
« Last Edit: January 31, 2006, 01:33:35 AM by BruceM »

hotater

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #20 on: January 31, 2006, 03:24:51 AM »
Bruce--

.036 is almost sure to be an interferrence fit with the valve.   :(

Mine is at .058 now and I can tell the difference.  I'll be pulling it apart of cleaning and looking as soon as the blizzards stop and will adjust down to .052.  That was the best I tried on mine.
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

BruceM

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #21 on: January 31, 2006, 04:01:41 AM »
How about I back off to the Metro minimum head clearance spec of 0.045 with a .027" gasket, and then valve clearance test it at 0.036 head clearance... (with a .016 gasket under the cylinder)?

Is it safe to do a lead squish test (very small bit) on the valves?

Which valve is the likely interference fit??? 


hotater

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #22 on: January 31, 2006, 04:49:26 AM »
Bruce---

The real danger or a valve hitting the piston is in the rest of the valve train.  It puts a BUNCH of pressure on the push-rod ends and the cam shaft and lobes and bushings, as well as the rocker arm and shaft, lash cap, and the valve itself.  Under that pressure the lube gets wiped or mashed off which heats the part which makes it bigger and more of an interference fit which causes more pressure and less lube and more heat.......noise.

You can measure the valve clearance with a depth micrometer with the head on but the rocker arms off.  Torque the head bolts and measure the valve stroke.  (Much easier with just one spring or no springs).  Now rotate the engine and measure the stroke of the intake tappet...thats' the valve that will hit the piston.  Since the rockers are a 1:1 ratio pivot, you can figure where the metal starts to bang pretty easily.

Since two masses cannot occupy the same space at the same time, just a *little* interferrence is way too much.   ;)
Use plasti-gage instead of lead to measure valve clearance.  I use small split shot for piston to head clearance.  They're dead soft and plentiful.

7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

BruceM

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #23 on: January 31, 2006, 03:28:33 PM »
Thanks for your help, Jack. My last engine rebuild was in '71 and I'm very grateful for you expertise and experience.  I'll start out with an extra .010 manilla folder gasket (.037 total), that will get me to within 1 mil of the METRO minimum head clearance spec of .045.  Then I can measure valve clearance with plastiguage and think about removing the extra 0.010 or something less.

On my Metro head, the seated valves are recessed quite a bit, something like 0.17" or so. Maybe that will buy me some extra valve clearance for raising compression?

Once concern-  could someone please measure the hot (full normal operating temp) valve lash? I need to know how much this is changed from cold for the typical Listeroid for this exercize as well as the carbon fiber tube push rods. I don't have the generator or compressor mounted anymore as the engine was supposed to be moving to the "House of Lister" soon, so have no way of getting her hot.










« Last Edit: January 31, 2006, 03:46:09 PM by BruceM »

hotater

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #24 on: February 01, 2006, 12:07:39 AM »
Bruce---

With lash set cold at .016 intake and .018 exhaust, both have .005 clearance when hot.
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

BruceM

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #25 on: February 01, 2006, 01:46:33 AM »
Thanks very much for the hot valve lash data, Jack!  In my Metro book the cold lash is:
 0.017 (intake),  0.032 (exhaust).  George's CD and the original Lister book have the same figures.  Is your 6/1 different???  (I know 8-1s and 10-1s are different.)

That's quite a change, more than I would have guessed.  (0.012 elongation of the cylinder and valve stems).  We'll see how the carbon fiber push rods work out. 

Best Wishes,
Bruce McCreary
Snowflake, AZ
Topless Metro 6/1 waiting for newly milled cylinder.

« Last Edit: February 01, 2006, 02:16:34 AM by BruceM »

hotater

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #26 on: February 01, 2006, 03:55:51 AM »
Bruce---

I tried what the book said and found out it was too much.... so, I set the clearance hot, at shut down, then measured again the next morning.  Now I know where to set the lash hot or cold.    ;)

  BE SURE TO CHECK ROCKER TEMPERATURES AFTER TEN MINUTES OF ANY ADJUSTMENTS!!
Rocker arms are always hot, but you shouldn't be able to smell them.
I think tight lash adjustments could wreck an engine in a hurry.

My Listeroid (the only one I've ever heard run) has a certain amout of clatter about it when using the old broomstick stethescope. I can distinctly hear an extra clack when lash is too loose and the valve train parts do the old 'freight train reversing in the middle of the night' sound. Its' gotta be hard on keepers and caps.

BTW-- you can feel as lot of what's going on in your valve train by holding the shim gage while it's running.  I'm convinced I *felt* the worn valve guides ......it's neat to *feel* the tappets twirl.

I'm easily entertained.   ;D ::)
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

BruceM

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #27 on: February 01, 2006, 08:54:46 PM »
Got my cylinder back today from the machine shop.  The owner/machinist told me the base and head surface were not parallel- off by 0.006".  He got it to within 0.002 when he made the cut.  Of course which surface the cylinder bore was perpendicular to is another question. 

Tomorrow I'll put her all back together and check the head and valve clearance (several times I'm sure).

Bruce M
Snowflake, AZ
Metro 6/1


GerryH

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #28 on: February 02, 2006, 01:01:37 AM »
Bruce,
I don't have a cooling system yet, so I have always run the engine for short periods (-5min) I have noticed, as it's inside my shop, it puts out a lot of smoke, grey stuff. I figured it will clean up when hot and broken in.
Today, as I have an extra head plug, I decided to experiment. I chucked it up in the 4 jaw by the wrench flats, and cut .050 off the seating shoulder. I installed it and started it up and loaded it. The exhaust was now clear. Ambient Temp -5C. The shop was smoke free.
 
I monitor the plug and when I put my fingers on it and don't want to keep em there, I shut it off. It seemed the plug got hotter more quickly. This is a good thing.

I have no idea what the compression ratio is, someone with more brains will be able to figure it out, but I am going to break in the  motor and then experiment in cutting til I get a Knock.

Gerry

BruceM

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Re: Clinder Honing, Head Clearance, Cylinder milling
« Reply #29 on: February 02, 2006, 02:18:23 PM »
Gerry, you should pull the head and check your head to piston clearance with a snip of solder. 
I seriously doubt that the assemblers check this and adjust the cylinder shims.  Mine was off by 0.060 or so!

While you're there you can lap the valves and check your cylinder bore honing.

To calculate the plug shoulder cut for an equivalent cylinder shim:

Volume of a cylinder is heightx Pi x radius squared.  Figure your change in head height in inches x 3.13 x2.25 x2.25  (assuming your bore is .5"). This will give you the volume of the change in head height in cubic inches.

Divide that result by the area of the plug concave insert (plug concave insert radius (half diameter) squared  x 3.14).  This will give you the shoulder cut dimension for an equivalent cylinder shim.
 
Best Wishes,
Bruce