Pistons and Rings - opinions? Stay calm..

[Bryan]

Not looking to hop up, just started looking into pistons and rings.  Seems like there are sealed power, silvo-lite and NOS pistons out there. Any opinions on these?  Also chrome, cast, and ductile iron rings. I know chrome rings are hard..seems like you would want the rings to wear more than the cylinder walls.  Any opinions?   Any other good sources of "normal" pistons and rings? 

[Sniper]

Given what JE Pistons has to say, I'd go ductile.  I'd prefer moly based on what I've seen cast vs moly ring wear on the cylinder look like but that's not an option.

 

https://auto.jepistons.com/blog/piston-ring-materials-explained

Edited December 19, 2021 by Sniper

[Bryan]

And contrary to Rock Auto description the pistons are not cast iron. Both sealed power and silv-o-lite are cast aluminum pistons.

[Bryan]

Looking at forums: Silv-o-lite are Keith Black pistons, (United Engine & Machine) supposedly heavier than others.   Sealed Power are same company as Federal-Mogul, Speed-Pro, TRW.

[KevinF77]

I’d be willing to bet sealed power could make you a set of moly rings. Probably wouldn’t be overly expensive, as I’m sure they have stock rings in the right sizes, just not in the right kit form. Guess it depends what your expectations for the engine are. Certainly any of the options will seal well. Pay attention to hone pattern/grit as it pertains to different ring materials. 

[Bryan]

There's about 3 ring manufacturers that do custom rings by request quote only.  Anyway, found another ring brand..  TotalSeal Catalog

[47 dodge 1.5 ton]

I have used totalseal rings in several engines (not flatheads) and have been pleased. More consistent  compression readings, slightly higher PSI and much less blow by. Just had a 340 apart that got the first set installed around 1994 had just over 40k miles. Cross hatching still in cylinder walls, motor measured 245psi  same as it did in 94’. Engine saw RPM’s over 7200 many times as is a stick car. Oil has always be 20/50 Castrol. Original TRW’s had a lot of blow by over 6500rpms. 
 

 I know these engines will never see that kind of rpm’s but believe there is still some benefit.

Edited December 20, 2021 by 47 dodge 1.5 ton

[Loren]

Silv-O-Lite pistons used to be made in Carson City, NV (just like Mallory Ignition) but they are now made in Mexico.

Keith Black is a brand of their's. The KB pistons are a cast type made with an advanced alloy which supposedly approaches the forged alloys for strength.

 

For my money, for a street car I don't think you can do much better than the government surplus pistons from VPW, provided they have your size. Same thing with the rings.

As odd as it seems I've seen engine parts made in India that were first rate quality. If you will pay for quality you can get it there. Remember they have the bomb so they are capable of very high standards.

I've seen pistons being made and it's not rocket science. The alloys are well known and there isn't enough difference between brands to worry about. Your machine shop is going to hone the bores to fit each piston anyway.

 

In the old days machine shops used to get "semi-finished" pistons then grind them to the size they needed. Which allowed to them "recycle" used ones as well.

I had two Van Norman model 101 piston grinders which had a rocking table and a cam master like a camshaft grinder to put the oval "cam ground" shape to the skirt of the piston. I rebuilt one of them for use as a "between centers" grinder when I manufactured turbocharger turbine wheels.

 

[Bryan]

50 minutes ago, Loren said:

For my money, for a street car I don't think you can do much better than the government surplus pistons from VPW, provided they have your size. Same thing with the rings.

I

 

When you say government surplus do you mean their NOS pistons?  Or the regular ones they list?

[Loren]

I think the government buys good stuff even if it is the commercially available stuff.

NOS stuff is very likely American made and very likely good stuff. They buy NOS stuff at clearance prices, regular stuff at regular wholesale prices and they could be foreign made.

Piston rings are like the pistons, they are commodities. Which means there are not a lot of variations even between brands or countries manufacturing them.

For the street NOS stuff is plenty good enough and I'd look for it.

 

If you want premium stuff and are willing to pay big bucks for it there are any number of custom manufacturers who would love your business.

I'd say have a look at the beautiful pistons and rods offered by Tony Smith. At least one of my treasures is going to get a set. Hold on to your wallet cause they are $2,600+ and worth it! Everybody wants a 230 23" engine because of the torque (or a 265 25") but that longer stroke comes at a price. Piston speed goes up with the longer stroke. Tony's rods & pistons are lighter so the driver will want to rev higher which makes the problem even worse. You will note that he has had the piston skirts coated and lengthened the rods to accommodate the piston speed. (longer rods have a smaller angle of pivot at the piston and therefore less piston rock at the top and bottom. Piston speed is the speed of the piston in the middle of the stroke. Lengthen the stroke and the piston speed goes up)

 

More information than the average person can process I am sure. For the street keep it simple, these cars have been around a long long time because as the ads say "Plymouth builds Great Cars". They aren't over-powered but you can put a lot of happy miles on them.

[Bryan]

For how I'm going to drive my car and where I'm driving I'm not needing anything like that. Just wanting more info on the differences between Silv-o-lite, Sealed power and NOS types.   As for NOS maybe someone knows the difference between 1940s-50s machining technology in the USA vs modern machinery in piston making factories today, no matter where located.  

[Loren]

I believe I answered that question at least twice.

Replacement pistons are made to factory standards so you could run one piston from every source you can think of until you filled all 6 holes and the engine would never know the difference!

Pistons and rings are commodities, especially for 70+ year old Plymouths. Which means there isn't a dimes worth of difference between any brand of standard replacement piston. They are all made to replace the original equipment directly.

That being the case, buy the cheapest available: NOS, Government Surplus, or whatever.

New Pistons are (and were) available singly which means you can replace just one if you need to, without even knowing what the other 5 were. 

They would not do that if what I've said weren't true.

If there is someone out there who can tell what brand of piston is in an old Plymouth by driving it, I'd like to meet them.

[47 dodge 1.5 ton]

Loren,

 

So back to the rings, do you have an opinion to the 2 pc Totalseal rings for these motors? I only know about the ones I have had experience with, and my brothers turbo charged slant six that he used them in. They are certainly not inexpensive compared to Hastings or such 
 I had posted questions on them some time ago and the general idea I received was that they were not necessary. In my mind, they are a win unless it causes future issues with the engine that I’m unaware of such as less oiling of the valves or along those lines. I only mentioned that because they definitely reduced blow by in the V8’s. 

[Bryan]

Yes, if a machinist bored & honed each cylinder for that piston you probably couldn't tell a difference immediately.  Run it 80K miles and you might see one or two cylinders that are more worn.   So the Silv-O-Lite (possibly made the same as the KB advanced alloy) are exactly the same quality as 1940s NOS pistons.   All brands are exactly the same metals, tolerances, weights etc..and everybody on the forum has had exactly the same experiences with all the "normal" brands..

[kencombs]

14 hours ago, Bryan said:

Yes, if a machinist bored & honed each cylinder for that piston you probably couldn't tell a difference immediately.  Run it 80K miles and you might see one or two cylinders that are more worn.   So the Silv-O-Lite (possibly made the same as the KB advanced alloy) are exactly the same quality as 1940s NOS pistons.   All brands are exactly the same metals, tolerances, weights etc..and everybody on the forum has had exactly the same experiences with all the "normal" brands..

I think the message is not that precise, but that whatever differences may exist are to minute to make any material difference in the usage common to our type of vehicles.

 

As far as bore wear is concerned, IMNSHO the piston used has almost no bearing on bore wear.  The rings, oil used and operating conditions are the major contributors.  Most of the piston face doesn't even touch the wall, and the thrust faces that do are aluminum on cast iron, not likely to cause wear on the harder of the two.

[Bryan]

Understand that, don't know why I wasn't thinking about aluminum on cast iron not having much effect. Sitting around sick waiting to get back outside one day this week. Rings are main point of contact.  Reckon only other considerations would be how a piston holds up under pre-detonation and the weight of the piston (rotating mass).  If kept below 4000 rpm maybe it wouldn't make a difference.

[Matt Wilson]

One thing to be aware of is that pistons prior to the 1970's were not made with hypereutectic alloys.  Hypereutectic alloys have a much greater silicon content that their predecessors.  The large amount of silicon content within hypereutectic aluminum alloys causes them not to expand nearly as much as prior alloys as their temperature increases.  Also, the excess silicon (there's enough that it can't all stay in solution within the aluminum) congregates on the surfaces of the parts, forming a barrier to the heat, and further inhibiting thermal expansion.  As a result, the clearances between the piston and mating parts (cylinder wall, rings and wrist pins) are somewhat different from the original clearances specified in the factory manuals, which were written in the days prior to hypereutectic aluminum materials.  Having said all this, I contacted Sealed Power a few years ago, and asked them what alloy they used to make the pistons I purchased, and they replied by saying they are made of a eutectic cast alloy.  Note they didn't say "hypereutectic" alloy, but just "eutectic."  After a little further digging, I found that Sealed Power uses a proprietary alloy called FM132, which is described as a "eutectic" alloy.  Eutectic alloys have less silicon content than hypereutectic alloys, but still a lot more than traditional alloys, and this means they still don't expand nearly as much as the traditional alloys as temperature increases.  Apparently, the silicon offers anti-scuffing properties as well, which is a benefit, but the hypereutectic alloys tend to be brittle, while eutectic alloys are not so brittle.

 

Anyway, the main point of all this is that there are differences in pistons, and the cylinders have to be bored accordingly, depending on the piston alloy used.  It's also worth mentioning that if you're detailed-oriented/OCD, like me, and you perform checks of the clearances between wrist pins and pistons, and ring side clearances, you'll find that these clearances are larger than specified in the manuals.  When I first discovered this, I was concerned that my pistons were mis-manufactured, but after I did some research, I realized what I just outlined above.  As best I can tell, they start off with clearances at room temperature that are practically the same as the clearances needed at operating temperature.  Another benefit (though minor) is that the eutectic pistons don't have a tendency to make piston slap noises when cold, while the factory pistons sometimes do, since they are smaller in relation to their bores until they warm up.

 

One other thing is that the factory original pistons had slots in one side of the skirt, whereas the Sealed Power pistons do not.  I don't recall the purpose of these slots, but I guess Sealed Power (and maybe other aftermarket manufacturers) decided they weren't needed.

Edited December 21, 2021 by Matt Wilson

[wayfarer]

As noted, there are advances in material sciences since the day your engine was built and although you could mix-n-match various brands of pistons it would be foolish to do so as the actual piston weight can and will vary from source to source due to variations in the initial piston blank and subsequent machine operations. Perhaps, if you don't mind some minor imbalance, mixing would work out but, any imbalance in a rotating assembly will add odd stresses to the parts.

I am reminded of a customer who had bought a 350 crate engine from his gm dealer; upon disassembly, for the purpose of verifying what he had, the off-balance was measured in ounces...not grams. So, apparently, gm didn't think an out-of-balance condition was an issue. YRMV

[Loren]

Aren't we glad that Chrysler engineering was advanced enough to produce engines like the Plymouth/Dodge 23 inch and the DeSoto/Chrysler 25 inch?

 

Over at Chevrolet they were still using Cast Iron for their pistons!

I seem to recall that the first Corvette had cast iron pistons.

I heard one story of a Corvette entered in the Mexican Road Race that didn't make it to the first turn before scattering the engine.

 

Ford stopped using cast iron pistons after the Model T, two and a half decades before Chevrolet.

 

In an engine that was designed to turn 3,600 rpm at peak hp, I really don't believe there's much to worry about in the piston dept.

We have better motor oil that can serve engines that routinely turn twice the rpm of a flathead Mopar with few problems.

The only issue that seems to be troubling for the modern crop of engines are low pressure piston rings. The idea being that low pressure rings lessen the internal friction of the engine thereby improving fuel economy. The problem is they burn oil at a rate of 1 quart every 600 to 800 miles!

Older engines don't begin to burn oil like that until they're pretty worn or neglected.

 

The splits in the skirts of old pistons were designed to allow for expansion. As the pistons wore they developed "piston slap" which was a kind of clicking sound as the pistons rocked in the bore. Tool suppliers actually made a tool that used car lots could use to expand the pistons by wedging the slots open with a kind of chisel and an air hammer. The parts manufacturers made "piston expanders" which could be driven into the piston. The best solution seems to have been Knurling the skirt of the piston to take up the loose fit. I would not use pistons with slotted skirts. They are hopelessly antique.  

[Bryan]

On 12/19/2021 at 6:55 PM, Sniper said:

Given what JE Pistons has to say, I'd go ductile.  I'd prefer moly based on what I've seen cast vs moly ring wear on the cylinder look like but that's not an option.

 

https://auto.jepistons.com/blog/piston-ring-materials-explained

Here's Sealed Power ring sets DRiV - Vehicle Look-up (drivcat.com)

Edited December 21, 2021 by Bryan

[Bryan]

Silv-o-lite : Shows 2 different compressions and same part #. UEM website UEM Pistons

[kencombs]

Compression ratio changed a lot over that fitment year span. Same piston, different chamber volume.  I don't understand how they can list a specific number without any added info.   I would ignore that altogether.

[James_Douglas]

Tony lost his access to a machine shop for small weekend work like doing rods. His day job is in a manufacturing plant. He is sourcing Carrillo Rods and forged pistons for the small flatheads. But the cost is steep like in the $4K to $5K range.

 

He said he would do Carrillo Rods and forged pistons set for my 265 but it would take six months and about $4500. 

 

Now that IS a lot, but I REALLY want to get the bore wear down. On the big Desoto after about 50K miles went from about 140 down to about 80. In the big Desoto it is very noticeable as the pressure is goes down. Tony tells me that the Carrillo Rods and forged pistons have a weight saving is 25%. That is a LOT. Also, remember what Tom Hoover said when asked what if anything he would do different in the development of the Max Wedge and the 426 Hemi. He response was to do one thing and that is to lower the engines reciprocating weight.

 

Since I run the engines hard to push that heavy 140 inch wheelbase Desoto around, anything that lowers the load on the wrist pins or the crankshaft is not a bad thing and the bonus would be more HP out the crankshaft.

 

James

[Bryan]

1 hour ago, James_Douglas said:

Tony lost his access to a machine shop for small weekend work like doing rods. His day job is in a manufacturing plant. He is sourcing Carrillo Rods and forged pistons for the small flatheads. But the cost is steep like in the $4K to $5K range.

 

He said he would do Carrillo Rods and forged pistons set for my 265 but it would take six months and about $4500. 

 

 

James

This might help you.  Click on the first link  September 16 2017.

Edited December 22, 2021 by Bryan

[thebeebe5]

On 12/21/2021 at 5:13 PM, James_Douglas said:

Tony lost his access to a machine shop for small weekend work like doing rods. His day job is in a manufacturing plant. He is sourcing Carrillo Rods and forged pistons for the small flatheads. But the cost is steep like in the $4K to $5K range.

 

He said he would do Carrillo Rods and forged pistons set for my 265 but it would take six months and about $4500. 

 

Now that IS a lot, but I REALLY want to get the bore wear down. On the big Desoto after about 50K miles went from about 140 down to about 80. In the big Desoto it is very noticeable as the pressure is goes down. Tony tells me that the Carrillo Rods and forged pistons have a weight saving is 25%. That is a LOT. Also, remember what Tom Hoover said when asked what if anything he would do different in the development of the Max Wedge and the 426 Hemi. He response was to do one thing and that is to lower the engines reciprocating weight.

 

Since I run the engines hard to push that heavy 140 inch wheelbase Desoto around, anything that lowers the load on the wrist pins or the crankshaft is not a bad thing and the bonus would be more HP out the crankshaft.

 

James

That sounds like ridiculous money... ?