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Triumph TR3 FAQ page

Chrome on chrome and getting the most out of rings

"The advantage of ring lapping is that it increases the likelihood that your rings will seat by a bunch."

> Always wanted to try chrome rings in a chrome block when the cylinder > walls were mirror smooth, but never got to that point.
> Are there high chromium liners for the TR-4?

One of the things I was taught by others of the "old time guys" is "NEVER, NEVER use chrome on chrome".

In all of the last engines I did for the TR-4's I used chrome top rings and found that they did not want a long break-in but responded to a fast run of about five minuets on the dyno at half speed and power.

In the end to make the most power I found it best to lap the rings into the bores of the sleeves on the bench then fit to the block. It's a pain in the neck with pans of gas or whatever but very very effective.


Because of a bunch of inquiries on the lapping business, this is what I did.

After assembly of the rings to the pistons and the honing of the sleeves: I used a mixture of BonAmi and 30 weight oil just gritty, not a paste. I'd coat the assembled rings with this mixture, insert into the sleeve and give it ten strokes , remove from the sleeve and dip into a deep pan of gas (or thinner) and carefully turn the rings on the pistons to remove the brunt of the compound, then go to 3 more seperate pans of clean lacquer thinner then finally a bucket with hot soap suds. Blow dry and quickly spray the assembly with WD-40. All the while being very carful not to "spring" the rings in any way and of course you do not remove the rings.

Remember to number the sleeves so they match the ring and piston sets. Clean the sleeves in much the same manner. This saved a lot of run-in time on the dyno and gave by far the best performance.


I hate to thrash through this again but JIC ... there are two different varieties of Bon Ami, "cleaning powder" and "cleanser". The "cleaning powder" is safe for use on glass, and is almost impossible to find in stores today. (I found some at OSH but I don't know if they still carry it.) The "cleanser" is not safe for glass (says so on the back of the can), and is available at any supermarket.


Chlorine causes stress corrosion cracking, especially in magnesium/aluminum alloys. A lot of cleaners also use silica-based abrasives whereas Bon Ami uses Feldspar. Further search reveals that Feldspar is a relatively soft silicate (a hardness of about 6).

Bill Babcock

At the Engine Room we have always used chromed top compression rings and have had no problem getting them to seat. We hone the cylinders with a "Brush Hone" with the little abrasive balls on flexible plastic stalks. We use the appropriate grit for chrome rings, I believe it is 280 or so and then wipe the cylinders with atf and a white paper towel until there is no more grey color comming off onto the paper towel.

The rings seat in 20 minutes of running. the ring manufacturers say the the rings are "lapped in" to a cylinder of the correct bore during the manufacturing process and so are actually "pre broken in".

The main advantage of "ductile iron" top rings is that they are very resistent of breakage caused by detonation. Sealed power, now owner by Federal Mogul Corp. used to make 1/16" ductile iron chrome plated riings in 87mm, but have not done so for a number of years. I have looked into having them made, but they want a min. order of 1000 rings or so. The rings are available in metric widths and an 87 mm bore so it is possible to have custom pistons made the will accept these rings.

The only "seating " problems we have had, and they have occured enough times to have been a real problem, is with the cast oil rings not seating and the engines burning oil and smoking out the exhaust. We no longer will build an engine using the cast, 1 piece oil control rings that come on the "Hepolite Powermax" pistons. We replace the oil rings only with modern, American 3 piece oil control rings, and have never had an oil consumption or smoking problem siince.

We normally us either sealed power rings, which we buy in separate pieces and make up for the specific application based on race or road use, or we use offf the self Hastings oil control rings.

We ahve never used any "gapless " rings of any sort. With the proper end gap, about .013" top ring on an 87mm bore, and around 12:1 or higher compression ratio with a 300 degree raciing cam, we get cranking compression figures of around 240 psi and cylinder leakage of about 4-6 %. when the engine is hot.

The sealed power ring engineers say that it is very important the there be a high differential pressure between the area above the top ring and the area below the top ring. It is this pressure that presses the ring out against the cylinder wall and down against the 2'nd ring land of the piston. With a gapless 2'nd ring, the 2'nd ring seals to well and causes the pressures above and below the top ring to be more nearly equal and this actually degrades the seal of the top ring to the piston and cylinder wall. According to those engineers that I have talked to, the primary purpose of the 2'nd ring is oil control and not cylinder pressure sealing.

Greg Solow

Yes, the same technique will work with a dry block as I did on the TR-4 sleeves. And yes, you can use Comet or Ajax (or like stuff) with equal results. You need to do a very very through job of cleaning if you lap into a dry block 'cause the cleanser will not be friendly to bearings and smooth surfaces.

I found that the chrome rings were almost impossible to seat if you did the usual break-in at slow running and low revs. They would pass pressure and oil forever. What I found that worked every time, operate the engine at low speed for a bit, like three or four minutes, then take it out and run the devil right out of it for a couple laps. The chrome rings seem to like this abuse and they sealed up immediately. The slow running on the chrome seemed to glaze the cylinder walls and never let a full seat occur. Yup, that's my opinion.

"Never be beaten by Equipment"
Kas Kastner

A couple of years ago I installed Total Seal rings in my engine and just couldn't get them to seal at all. Turned out that it wasn't the rings' fault, but rather the surface of the sleeves had a poor finish.

In the process of solving this problem, I talked to a motorcycle guy who said that BMW motorcycles had this problem a couple of years ago, and when he went to the BMW school they taught them their recommended startup procedure to prevent this problem.

This procedure is to install the pistons in the cylinders with virtually no oil on the walls and no oil on the rings. Just put one dab of oil on each skirt. Then, upon startup, run the engiene 2500 - 3000 for two to three minutes -- just what cam manufacturers recommend anyway.

I tried that on my own engine with great trepidation (I've been looking for a chance to use that big word) and it worked fine. Since then I've built a half dozen engines using that procedure and everything is cool. There has been no evidence of early ring wear, either.

uncle jack

> This procedure is to install the pistons in the cylinders with virtually no oil on the walls and no oil on the
> rings. Just put one dab of oil on each skirt.

I don't even dab the skirt. I have built my race engines with no oil added to the bores or rings for a couple years now. I use Deves rings, they seem to seat fast and well. I forgot how I figured this out or who told me, but it seemed like a good idea at the time. Works for me.

Funny, I didn't feel any trepidation about the pistons seizing at startup, just the typical angst whenever I start a fresh engine build...

Henry Frye

If I had just remembered this stuff before I'd have had another ten pages for my book. I used chrome rings in my TR-4 engines and found that lapping them in first saved a lot of breaking time on the dyno and always gave a higher power number and a lot less blowby and early loss of pressure. My system is not fun to do but here is how I did it successfully for lots of years & engines:

With the pistons you are going to use fit all the rings making sure to already have the end gap checked. Fit the correct rod.

Then lay out four pans that will hold about a quart of your favorite cleaning fluid. ( I used lacquer thinner cause it was there and no one was lighting fires in the shop)

Mount the sleeve in a fixture to hold it . (such as easy gripping in the vise)

Make up a thin paste of kerosene and Bon-Ami ( yup, the old time cleaning powder) The paste should be about the consistency of cold 50 weight motor oil.

Apply a lite coating to the rings of the piston that matches the sleeve in the vise, and a lite smear to the bore of the sleeve

Fit your ring compressor to the rings just as normal.

Fit the piston into the sleeve and give it ten strokes , one up and two down and so on.

Remove the assembly from the sleeve, carefully remove the compressor and ABOVE ALL, DO NOT TAKE ANY OF THE RINGS OFF THE PISTON. DO NOT DISTURB THE RINGS.

In the first pan of cleaner use a small paint brush to start cleaning the paste off the piston and the rings. After the worst is removed go to the second pan, DO NOT TRY TO MOVE THE RINGS. Work with a brush again to clear the paste residue.

Now go to the third pan and very carefully by gripping the ring away from the ends move it slightly and a little more and a little with the head of the piston submerged in the liquid more until the ring is free to turn easily. Do one ring at a time, this is not the time to be lazy.

On the last pan of fresh cleaner. Move the rings as above several rotations on the pistons making sure there is no gritty feeling.

Now that the pain part is over, wash in hot soapy water and blow dry and immediately coat with WD-40 or similar type oil. Do not try to remove or bend the rings or pull on the ends.

You will see a fine grey line on the top edge of the rings showing that they indeed are lapped into the bore. Not only that the rings are ROUND. (keeping them round after the lapping is why you don't want to carelessly try to move them too soon while cleaning.)

Wash the sleeve in the same manner, you can eliminate a couple of the cleaning steps as there is no finesse involved,. Finish though with soapy water and blow dry and coat with lite oil. Both the piston assembly and the sleeve should be immediately put into a plastic bag or sack to keep clean and dust free until time of assembly. Remember each piston has it's own sleeve and should not be changed out to another part.

Clean the ring compressor some before starting on the second piston assembly.

When fitting to the engine just a lite oil on the rings and bore, finish up and stand on the gas after about four or five minutes.

Done in this manner my rings lasted longer than any other method and gave the best perforce all round.

I did make up a torquing plate for the dry blocks and did everything in much the same manner. My torquing plate was made of 1" thick mild steel.

"Never be beaten by Equipment"
Kas Kastner

We have been building TR-3,4, MBG, Lotus, Ford, etc. engines as part of our business at The Engine Room here in Santa Cruz since 1971. In newly rebored or otherwise very round (unworn ) cyinders, we have always used chrome top compression rings. We have never had a compression ring seating problem! The only ring seating problems we have had were with the cast iron oil rings that come on many english pistons . We have for many years now used Hastings or Sealed Power (now Federal Mogul) 3 piece oil rings and have never had any oil consumption problems with these rings. The Preparation we use is when boriing a cylinder, we leave .003" to hone the cylinder to size. The last hone is done with a Sunnen 300 grit stone being carefull to leave the hone marks at 30 degrees up and down from horizontal. After this, we final hone in a bath of solvent or honing oil with a "Brush Research" "dingel ball" hone. These are available in different grits and different sizes depending on the exact ring type and bore size. Again we make sure there is a 30 degree angle to the horizontal to the honning marks. Finally we clean the cylinders using automatic transmission fluid, wiping the cylider with a soft white rag and lots of atf until there is no more grey color comming off of the wall. At that point the pistons are ready to install. We lubricate the pistons and rings liberally with an assembly fluid made up of Kendall GT-1 40 SAE and Molybdinum di Sulfide in an oil base (ie MR. Moly Break in Lube or a similare product) and assemble the engine. Before start up, we crank up oil pressure with no plugs in the engine after getting oil pressure, we fire up the engine and immediately bring it up to about 2,000 rpm and run it for about 10 minutes to break in the cam and lifters. We then shut the engine down, retorque the head & manifolds&adjust the valves. (This is with a TR that has an iron head). Then the engine is put under about 30 - 40 ft. lbs. of load (if on a dyno) for about 30 to 45 minutes with the speed beginniing at around 3000-3500 rpm and gradually increased to 4500 rpm or so. The engine is then ready to load. If the engine is not going to be run on a dyno, but is going to be used on the road, then it is taken out and driven. If it is a road engine, we load it at WOT fron 2500 rpm up to 4,000 rpm 10 times in succession allowing the engine to coast down from 4,000 to 2500 in gear each time. This creates a high vacuum in the cylinder and pulls oil up into the ring area to cool the rings between each time the load is applied. This process seats the rings. The car should now be driven for the next 500 miles with the engine speed varying as much as possible (like continuous miles on curvy mountain roads) gradually using more rpm up to whatever your rev limit is to be. If the car is a race car, then out onto the track. A couple of laps using 5,000 as a rev limit, then a couple of laps at 5500, and so on up the rev limit you are going to use. Then readjust the valves to your hot setting. Change the oil filter and oil after the initial track session. According to the ring manufacturers, the rings are "lapped in " during the manufacturing process and so they claim there is nothing to be gained by more lapping.

Greg Solow

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