Author Topic: Engine Specifications  (Read 8070 times)

wirenutrob

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Engine Specifications
« on: March 09, 2007, 01:40:06 AM »
Here is the situation:

The engine in is a listeroid 20/2. The issue is, I was told that the pistons are not the right size for the cylindes. The pistons have 120.85 stamped on the head and the cylinders mic out at 121.50. Can someone tell me the correct distance of gap between the piston and the cylinder wall. I am getting alot of information but I want to hear it here. I am scheduled to enlarge the cylinder .004 more tomorrow 03--9-07. Thanks  :)

dkwflight

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Re: Engine Specifications
« Reply #1 on: March 09, 2007, 01:50:36 AM »
Hi
I suspect that your machinist is thinking along the lines of modern high speed diesels.
Lister types are slow speed and don't generate as much heat.
I think that you may set this engine up too loose with those dimensions.

Others may have better information than I.
My original type manual does not give a dimension or clearance for the piston to cylinder clearance.

Dennis
« Last Edit: March 09, 2007, 01:54:36 AM by dkwflight »
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Still in devlopment for 24/7 operation, 77 hours running time

Doug

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Re: Engine Specifications
« Reply #2 on: March 09, 2007, 03:00:49 AM »
Slow down wirenut.....

I don't know what your liner size is suposed to be but if you have iron pistons I would be inclined to think that because of the lower expansion rate the clearence might be tighter.

IF you have aluminum then the waters muddy.....

Somebody here must have 20/2 or a 10/1.

John Woods are you out there? ( Candian JKson vender for the newbies )

Try and contact the maker maybe they can tell you the spec and limmits.

Last option Atul Patel at Anand may provide answeres. I'd be inclined to send him a thank you note and stear him some buisness ( if you need parts ) if he was able to provide you some answeres. You know shipping will cost you more than the spares buy some bearings and rings ect its not like your never going to need them.

He may be willing to help...

If you remove metal its gone forever.

I have no financial connection to Anand, they sold Gus and have provided me with a lot of specifications, technical information and sold me two crates of spares. I believe I have probably exchanged something like over 100 emails with them ( PEC is the actual name of the works that built Gus ) and several phone calls. Other people have also done well by them for spares to repair screwed up roids.

Doug
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wirenutrob

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Re: Engine Specifications
« Reply #3 on: March 09, 2007, 04:22:08 AM »
Doug -

Thanks, I will most likely wave off tomorrows events then and contact Anand...
I forgot to say that the pistons are aluminum.
Rob

snail

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Re: Engine Specifications
« Reply #4 on: March 09, 2007, 05:12:33 AM »
Rob,
    I've got some figures for the dursley 6/1 and 12/2 (iron pistons):

"piston to bore clearance at botton of skirt =.006 - .008 initially,.010 max."

 I'd imagine that your alloy pistons will need more clearance just don't ask me how much!  :D
Hope this doesn't confuse the situation...

Brian

Edit: come to think of it, are the alloy pistons (deliberately) oval ? .The original iron ones are a plain cylinder.This is contraryto GF's opinion but is easily measured  ;D ;D.I'd do your own measuring rather than going by the stamping.   
Has anyone measured an indian (iron) piston? I would imagine that they are cylindrical but you never know!

brian
« Last Edit: March 09, 2007, 05:32:28 AM by snail »

Doug

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Re: Engine Specifications
« Reply #5 on: March 09, 2007, 07:35:43 PM »
I have alloy pistons in Gus they are Cam ground cast pistons. Very nice actualy I don't think I could get better without a forging.

Bad picture:
http://www.putfile.com/pic.php?img=4341566
« Last Edit: March 09, 2007, 07:39:27 PM by Doug »
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xyzer

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Re: Engine Specifications
« Reply #6 on: March 09, 2007, 08:29:22 PM »
   
Edit: come to think of it, are the alloy pistons (deliberately) oval ? .The original iron ones are a plain cylinder.This is contraryto GF's opinion but is easily measured  ;D ;D.I'd do your own measuring rather than going by the stamping.   
Has anyone measured an indian (iron) piston? I would imagine that they are cylindrical but you never know!

brian
Brian,...all
I don't believe so on the castiron. They both are oval and small at the top. Definatly measure at the skirt or the largest dia. you can find. I don't have a piston handy to confirm but my castiron 6/1 piston was large at the skirt. I didn't check for the oval part just treated it as a normal piston. All I have come across are slightly oval and large at the skirt. The values of taper will change with the material (coeficiant of expansion)but all suffer from heat on one end of the piston and none on the other.
Dave
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wirenutrob

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Re: Engine Specifications
« Reply #7 on: March 10, 2007, 02:39:07 AM »
Good Evening all -

Thank you for your advise and help it is truly appreciated!  My machineist took closer measurements
and suggested that we hone out only .0002 with a machine then remeasure. I paid for the power honeing and after it was complete the measurements were .004 on both cylinders. He checked the heads for proper valve seating and handed my newly ground lifters and said the engine is ready for assembly now.  :P I feel like I dodged a bullet! I really had a scare there.
 It was true that the cylinders had only .002 to start and that addingan additional .002 was exaxtly this size this engine needs and calls for, the max clearance is .008 . I did find out that the indian cylinders are .002 out top to bottom (like a cone). For aluminum pistons this is correct sizeing. My machinest is standing behind his advice, he said any problems he will assist in its repair. This place does alot of stationary engines for Kohler, Cat, Perkins generators.
Again thank you guys for reaching out to help me!  :)

snail

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Re: Engine Specifications
« Reply #8 on: March 10, 2007, 03:17:51 AM »
xyzer,
      Ok, I'll agree that Mr Lister's iron pistons are smaller at the top, but I can't measure any ovality.I suppose I should have described them as truncated cones, a mistake for which i am truly sorry.... ;D ;D .Serious question: when did people start to cam grind pistons? I've measured a few from the 1920's to 1940's and so far haven't found one.No doubt it started as racing practice. Who was first?

Cheers,

Brian

xyzer

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Re: Engine Specifications
« Reply #9 on: March 10, 2007, 05:28:08 AM »
Brian,
Uhhh Uhhh heck I don't know when they started. I put a new set in my stock 23 T roadster but they really don't count they were aluminum pistons made in the 70's. We have 3 Van Norman piston grinders at work that were made in the 40's we have adapted to be abrasive cutoff saws. They had a cam that rocked the piston in and out from the grinder wheel and the table was adjustable to put in a taper. I was always told the pistons grow more or less in different areas due to the mass around the wrist pin area. Just a thought but Cast iron pistons usually have a full skirt, aluminum pistons usually don't. I think the reason for the funny and complicated grind on modern aluminum pistons is because of the calculated growth of the piston. More growth per degree and the mass is only where they need it. The cast iron piston has a different growth pattern due to the more even dispersal of mass and lower growth per degree.  As I said I did not diesect my cast iron piston and to me it stands to reason like you say they are tapered (truncated) and not tapered and oval.  I'm sure the ring area should be round but i'll just have to mic one up below the ring area someday and see. I have seen some literature on CNC piston turning center and they cut any kind of shape you want on the outside of a piston in about 35 seconds for $750,000, quite elaborate machine. I have to agree from the teens up to the 30's anyway they really didn't have a machine that would grind to complicated of a OD configuration on the piston. Oh........ back to the question!  I bet is was racing!
Dave
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Doug

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Re: Engine Specifications
« Reply #10 on: March 10, 2007, 06:28:51 PM »
Wow....

Could you make me a 102 mm Petter pistom with a small dish rather than the deap diesel cup?

I'll be your best friend and tell you what I'm up too!!!!!

Doug
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xyzer

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Re: Engine Specifications
« Reply #11 on: March 10, 2007, 09:41:44 PM »
Doug,
 Sorry I don't make pistons, they are over the edge with a bunch of unknowns! We have typical turning centers and no piston machines other than the ex-piston grinders. We keep busy trying to make things round. That can be its own pain! How much do you want to raise the existing dish in your piston?
I hope we can still be friends ;D.
Dave
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Doug

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Re: Engine Specifications
« Reply #12 on: March 10, 2007, 11:06:48 PM »
Just playing with an Idea. Slight dish.

I'd realy like something that would give me a 16:1 compression ratio.

I don't know enough to say for sure what kind of shape piston head I need. Seems to me a slight dish and a little quench area around the outside sort of like a Hemi head.

Any ideas where I could find such a think. I have a realy thick liner so if its a little bigger than a 102 mm but could be modified for Petter rod and stand the presure.....

Doug

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snail

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Re: Engine Specifications
« Reply #13 on: March 11, 2007, 02:38:53 AM »
Xyzer,
     I think you're spot in your thoughts about modern pistons.
My question was intended to be addressed to the whole forum, not to put you under pressure :D. Sorry about that, mate! Good answer though! Thanks!

Cheers,

Brian