I have a farmall cub that won't see alot of use. Just want it to run. Purchased standard rings but probably should have got 0.010 or 0.020 over and filed accordingly. Looking at about a 0.030 end gap. Basically I'm wondering if this will be an issue if I'm not using it much. Will I get enough compression?
- Thread starter ogema1912
- Start date
wore out
Well-known Member
Check out the link below, piston ring GURU Dave Reed says ring groove wear causing side gap is MUCH more critical than end gap.
Piston Rings
Piston Rings
Gary Mitchell
Well-known Member
Oge, I generally consider what I intend to use a tractor for when replacing expensive bits and pieces. In regard to ring gap, you probably know to measure the gap down in the cylinder where it's most worn. I included a link from Hastings that addresses the issue. I'd say you can get it to run on that much gap but you might run into plug fouling. gm
Hastings article
Hastings article
Gary Mitchell
Well-known Member
And that. gm ;-)
Thanks for the reference material fellas. I'm involved with a museum that has over 100 tractors in various stages of operation. I'm relatively new to the board and am quite new to tinkering with these older units. With dwindling volunteers(and limited funds), I'm essentially looking to do the bare minimum to keep these units running without causing long term damage. The rings I took out of this unit had gaps close to 1/8. And bad exhaust seats on cylinders 2 and 3 so hopefully I can get enough compression to operate in the annual parade this summer.
wore out
Well-known Member
"In regard to ring gap, you probably know to measure the gap down in the cylinder where it's most worn."
You must have meant to say "where the cylinder is LEAST worn".
If you do not check the ring gap in the area of LEAST bore wear and instead "fit" them in an area of greater wear the ring gaps will "but" when the engine heats up and the piston goes down into the "smaller" bore area.
wore out
Well-known Member
"The rings I took out of this unit had gaps close to 1/8."
What REALLY matters is the measure end gap of the NEW rings.
As the O.D. of the old rings wore away they expanded to keep in contact with the bore making for a much larger end gap than new rings will have in the same (worn) bore.
560Dennis
Well-known Member
- Location
- Madison,Ohio
The process begins with inserting the ring into the bore, and making sure it is square using a squaring tool to align it properly. A feeler gauge inserted into the ring gap will show you the existing dimension, and from there you can make your adjustments. For a street engine, multiplying your bore size by 0.004in will give you the top ring gap you are looking for.
004 x 4.00in bore = 0.016 inch ring gap
For high performance engines, the multiplier changes to add more clearance, but the math stays the same:
Modified or Nitrous Oxide - 0.005in x 4.00in bore = 0.020 inch ring gap
High Performance Racing - .0055in x 4.00in bore = 0.022 inch ring gap
Racing with Nitrous/Turbo - 0.006in x 4.00in bore = 0.024 inch ring gap
Racing Blower/Supercharger - 0.007 x 4.00in bore = 0.028 inch ring gap
For the second ring, the process is the same, but with a slightly different gap, based on application:
Street - 0.005in x bore size
Modified or Nitrous Oxide - 0.0055in x bore size
High Performance Racing - 0.0053in x bore size
Racing with Nitrous/Turbo - 0.0057in x bore size
Racing Blower/Supercharger - 0.0063in x bore size
According to wiseco
I think you way out of spec ,your engine
004 x 4.00in bore = 0.016 inch ring gap
For high performance engines, the multiplier changes to add more clearance, but the math stays the same:
Modified or Nitrous Oxide - 0.005in x 4.00in bore = 0.020 inch ring gap
High Performance Racing - .0055in x 4.00in bore = 0.022 inch ring gap
Racing with Nitrous/Turbo - 0.006in x 4.00in bore = 0.024 inch ring gap
Racing Blower/Supercharger - 0.007 x 4.00in bore = 0.028 inch ring gap
For the second ring, the process is the same, but with a slightly different gap, based on application:
Street - 0.005in x bore size
Modified or Nitrous Oxide - 0.0055in x bore size
High Performance Racing - 0.0053in x bore size
Racing with Nitrous/Turbo - 0.0057in x bore size
Racing Blower/Supercharger - 0.0063in x bore size
According to wiseco
I think you way out of spec ,your engine
timcasbolt
Well-known Member
I think you should get new rings and get it closer. Under .015" should be fine.
Hobo,NC
Well-known Member
- Location
- Sanford, NC
[ Basically I'm wondering if this will be an issue if I'm not using it much. Will I get enough compression?[/quote]
Yes it will run, .023 is the most I have ran it never missed a beat ran out well as far as I know its still going strong. If it suffers from low compression valve seal will be your issue.
Yes it will run, .023 is the most I have ran it never missed a beat ran out well as far as I know its still going strong. If it suffers from low compression valve seal will be your issue.
Hobo I rebuilt a old MM tractor. I drove the tractor into the shop but It was smoking bad. The rings had end gap of .375. I measured them three times I did not think a ring could expand that much. The cylinder were so tapered that I had to bore them out .040 and get new pistons. So will It run with that much end gap I say yes but the question is how well.
You got a lot of good advice. I would worry more about cylinder taper and roundness. If a cylinder is round with no taper the end gap mentioned will work fine. You need to run a bore guage in each cylinder. Running a ridgid home through it will tell you a lot also. Running a ball home through it will make it look pretty. I would rather open a cylinder up a bit with a rigid hone and run more end gap. Then try to get rings to seat in an out of round cylinder.
You got a lot of good advice. I would worry more about cylinder taper and roundness. If a cylinder is round with no taper the end gap mentioned will work fine. You need to run a bore guage in each cylinder. Running a ridgid hone through it will tell you a lot also. Running a ball hone through it will make it look pretty. I would rather open a cylinder up a bit with a rigid hone and run more end gap. Then try to get rings to seat in an out of round cylinder.
M-MAN
Well-known Member
- Location
- Bostic, NC
It'll run. I've seen Chevy racing engines built with twice that much gap.
Hobo,NC
Well-known Member
- Location
- Sanford, NC
I dunno I will make a educated guess he will be within 10% of OEM compression> I will also wager everyone's old tractor will not be that close : )
Rings are new pistons will never overcome a deep scratch are gouge if it is that way he will be in the 20/25% lost range. It will suffer but run...
I also want to say I understand what everyone is saying I am not auguring your point.
I will not run a piston with worn ring lands I will ring a cylinder that is at the edge of its normal speck for myself. I got to the point if it had worn ring lands I would order up new 10 over pistons pull my Sunnen adjustable hone out and take the cylinder to 10 over. It would surprise ya how fast it will get to 10 over and to me as good as a bore job. I grantee ya machine shops do this in less than 10 min per hole and hand it back to ya.
This post was edited by Hobo,NC on 02/27/2022 at 06:56 pm.
Rings are new pistons will never overcome a deep scratch are gouge if it is that way he will be in the 20/25% lost range. It will suffer but run...
I also want to say I understand what everyone is saying I am not auguring your point.
I will not run a piston with worn ring lands I will ring a cylinder that is at the edge of its normal speck for myself. I got to the point if it had worn ring lands I would order up new 10 over pistons pull my Sunnen adjustable hone out and take the cylinder to 10 over. It would surprise ya how fast it will get to 10 over and to me as good as a bore job. I grantee ya machine shops do this in less than 10 min per hole and hand it back to ya.
This post was edited by Hobo,NC on 02/27/2022 at 06:56 pm.
gene bender
Well-known Member
just make sure the gaps are spread around and not lined up in a row from top to bottom like i found in one engine i was working on
Fritz Maurer
Well-known Member
You took an engine apart and the ring gaps were all lined up? How is this possible? Last month everyone said that piston rings rotated
dr sportster
Well-known Member
End gaps have been deemed not as critical as once thought, Staggering does nothing as the rings rotate three times a minute, Everyone still staggers anyway. There is a spec something like .003 gap per inch of bore.
dr sportster
Well-known Member
Only boring trues the hole Honing can go bad easily. My gauge reads to the .0001 ,Many honing mistakes are shown
I have had good luck rigid honing and installing new rings as apposed to glaze breaking and throwing in a set of rings. Yes in a perfect world I like to bore .030 over leaving about .003-.005 to rigid hone to size and finish with a ball hone. Use over size rings and file to fit. Oh, and to actually have the new piston in hand before rigid honing to size.
T in NE
Well-known Member
- Location
- Cambridge, Nebraska
Hobo,NC
Well-known Member
- Location
- Sanford, NC
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