Perfect Circle Piston Rings

R

rfitzpatrick

Well-known member
Back during the Dirty Thirties, how many miles did the engines last before they needed to be replaced/rebuilt. Might the Company: Prefect Circle made them?
 
Perfect Circle made good rings. I never kept track of the mileage you could get out of the, but as good as any other brand.
 
The trademark is now owned by Mahle Aftermarket and sold as "Mahle Original" piston rings. They're in Michigan but I don't know if their product is made there.
 
How to machine piston rings:


  1. Pick a good grade of fine grain cast iron. A cylindrical shape works best.
  2. Machine the inside and outside to size. The OD should be the same size as the engine's cylinders. Machine to a smooth OD. Best to finish grind the OD.
  3. Cut off the rings with several spares off of the machined cast iron. Adjust the thicknesses on a surface grinder. Machine both sides. Use a 0.0005 clearance in the piston groove.
  4. Break the ring in one spot by carefully bending it.
  5. Spread the rings at the break using steel spacers. Spread about 0.10 inch per inch diameter.
  6. Heat the rings in a kiln to a dull red in a flat configuration. Put the rings on a flat surface with the whole ring in contact with the surface to keep it flat
  7. Slowly cool the rings in the kiln.
  8. Remove the spacers and the rings are ready to use.
  9. Put the rings in the bore and check for roundness. Trim the rings for the proper gap using a flat file.
 
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Tks everyone -- I've read 15K miles was about the limits before the engine needed new rings. I was just wondering how close to my readings was reality.
Perfect Circle was a Family owned enterprise, per my readings
 
Back in the 1970's I knew a woman who traced her family's wealth to the Perfect Circle Piston Ring Co. On one occasion, someone asked her what was a piston ring. She drew a blank expression and responded that she had no idea other than it had something to do with automotive parts. She was of the third generation of that manufacturing dynasty.
 
Repco here in Oz were known for their piston rings in the 60's.
I think they had to change the ring design tho for formula one to make them go the distance.

"In the 1960s, Repco was a major Australian automotive powerhouse. They were renowned for their high-quality engine internals, including Repco Super X and Repco Perfect Circle piston rings. Their parts were famously used in the championship-winning Repco-Brabham Formula 1 cars."

"Repco partnered with or produced rings under the Perfect Circle brand. Perfect Circle was highly regarded globally for its oil control ring designs."
 
There's great history behind Perfect Circle piston rings.

Get a copy of "One Man's Vision," the biography of Ralph Teetor, a blind mechanical engineer who ran the family company for many years. He was elected president of the SAE in 1936 and the organization still gives a highly coveted annual award in his honor.

Ralph Teetor
 
nkaminar said:
How to machine piston rings:


  1. Pick a good grade of fine grain cast iron. A cylindrical shape works best.
  2. Machine the inside and outside to size. The OD should be the same size as the engine's cylinders. Machine to a smooth OD. Best to finish grind the OD.
  3. Cut off the rings with several spares off of the machined cast iron. Adjust the thicknesses on a surface grinder. Machine both sides. Use a 0.0005 clearance in the piston groove.
  4. Break the ring in one spot by carefully bending it.
  5. Spread the rings at the break using steel spacers. Spread about 0.10 inch per inch diameter.
  6. Heat the rings in a kiln to a dull red in a flat configuration. Put the rings on a flat surface with the whole ring in contact with the surface to keep it flat
  7. Slowly cool the rings in the kiln.
  8. Remove the spacers and the rings are ready to use.
  9. Put the rings in the bore and check for roundness. Trim the rings for the proper gap using a flat file.
Click to expand...

That's all? I'll just start making my own!:D
 
in our 60s high school auto shop we were awarded a Doctor of Motors degree by the perfect circle piston ring co.
 
I have made a few rings, but for antique model airplane engines. I had to make a few to get ones that worked.
 
Trapdoor2 said:
The trademark is now owned by Mahle Aftermarket and sold as "Mahle Original" piston rings. They're in Michigan but I don't know if their product is made there.
Click to expand...
Mahle also owns Clevite bearings, fwiw. I was kind of surprised to see the last batch of inserts I bought come in Mahle boxes.
 
Steam engin and large model train guys make a lot of rings in there projects, you can see some of it it you search You Tube :)
 
rfitzpatrick said:
Tks everyone -- I've read 15K miles was about the limits before the engine needed new rings. I was just wondering how close to my readings was reality.
Perfect Circle was a Family owned enterprise, per my readings
Click to expand...

The AA welder truck which passed through my hands was used simply to haul a welding machine from shop to jobsite - consequently it has a VERY low mileage for it's age of 26K miles.

The former owner and I speculated that the engine had never been opened. It was "loose" (I drove it while it had the body on it) and you could tell by the "whuppa-whuppa" sound that it was considerably loose - but it started right up, ran fine and I could even sustain the usual AA truck 40 mph (four speed, high speed rear)

A 1930 Model A "cowl/engine" I brought home from Vermont as a teen had an indeterminate mileage on it. The engine was thoroughly worn out though. I measured the taper of the cylinders at up to 0.005. There was no shims remaining anywhere on the crank. Probably the caps had been "filed." It even had installed "skirt expanders" in attempt to tighten up on "whuppa-whuppa." I have no knowledge of original rings. I remember considerable carbon BEHIND the rings.

My own Avatar showed 146K on the odometer. The engine was painted "red" and I took it as an "Allstate" replacement engine. Worn out no doubt. I measured the cylinder taper and found 0.003. The rest of the engine was worn: egg shaped rod journals about 0.003. I tightened the engine by filing the caps and getting it to the point where it "just bound up" as the eggs mis-matched. This latter probably caused one of the rod nuts to break its cotter and nut ended up in the oil sump - and I limped home at no more than 20mph. Lucky to have made it.

I speculated that the red engine had about 70K on it. Probably the original Ford engine did a similar amount. Hence the 146K total.

And this agrees with my experience with the air cooled VW Bug engines. These are good for about 70-80K, the primary limitation being the proper "cooling" of the cylinder walls. In the Model A the engine usually doesn't get to run at the optimal temperature PLUS it typically (during period life) tended to be used without an air cleaner.

As to the cylinder walls or the crank journals being the first to wear in a Model A - I would guess the crank. The AA 26K was probably exceptional. I would think a typical Model A engine perhaps every 20K would require pulling a shim or two.

Todays engines I would not give so much credit. Ford brought "superfinishing" of journals to a high art - much more than modern engine or engine rebuilding. Today's engines benefit from being "floated" on a continuous oil film brought by a hydraulic oil system and oil filter. One can even look at today's "insert" bearings and see the annular "oil gallery" which is designed to offer continuous "circular" oil to the bearing and hydraulically "center" the journal in the bearing.

In a modern insert bearing, the hydraulic oil film exceeds the surface roughness of the bearing/journal. There is (or should be) no metal to metal contact beyond start-up.

Ford relied on superfinishing and more frequent change of oil. His "angular" positioning of the oil groove was attempt to emulate the steam engine practice of his era which included high bearing pressure, direct contact between slippery babbitt and carbon steel, mirror smooth journals AND bearings.

The downside to this is today we rebuild a Model A engine, but we bore and hone to a "modern engine" standard - which is not and can't be as successful as the original engine design standards.

I'm a little critical here. Doubtless there are those who hold their engine efforts to high rebuilding standard. Whether it is equal to a Ford standard is a worthy question IF you know to ask the question.

There are many, and I'm included, who rebuild a car to show in a parade or go to get ice cream on a warm night. If it sounds and runs good perhaps that is as good as you can reasonably do?

There is some of letting the future mind the future in this.

Joe K
 
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rfitzpatrick said:
Back during the Dirty Thirties, how many miles did the engines last before they needed to be replaced/rebuilt.
Click to expand...

A lot depends on how the engines were maintained. Regular oil changes? Short or long runs? Slow speed runs? High speed runs?
 
rfitzpatrick said:
Tks everyone -- I've read 15K miles was about the limits before the engine needed new rings.
Click to expand...
I think 15K is low. I'd wager by the time the Model A rolled around 50-60K was engine life. During that time the cylinder head may have been off to clean the carbon (did the low compression A even have a carbon problem?) and the pan to adjust the bearings. Today engines are lasting 300K with only regular oil changes - with much tighter tolerances and improved materials.
 
Some of the many advancements in today's engines That allow them to go 300,000 miles is the huge advancement in our oils today An electronic fuel injection Prevents a lot of fuel dilution washing the oil off the cylinder walls!!!
 
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