1971 340 Build - Choosing piston rings dilemma

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Ask the guy who honed your block what rings you should use.
Good idea if he was into performance engines and had that type of knowledge but he's 74 years old and runs just a regular machine shop. One day he's be doing machine work on a Toyota 4 cyl engine, next will be rods from a Top Fuel drag car, next day will be will be a rebore on a lawnmower engine.

He doesn't have much interest in the parts. He would just say throw in some no-name cast rings.
 
I like Total Seal for race motors but RaceTec supplied moly std. rings so thats what Im using in my 388 SBM.

Any name brand moly ring will work good in your app. Bore finish is important.

Most private label rings are made by the big names.
 
Glad to help, even though I'm sure you're disappointed to have to hunt more pistons. KB243's are what I have bought for a future 340 build. You could do.... Sorry you have to get new pistons or fool with the crank, but I'm glad it was caught now instead of later.

Yes you saved me considerable angst, if you were close by I'd by you a coupla beers! - Imagine getting to the stage of having one or more fitted in a bore and rotating around the assembly to see them misbehaving in the hole. I will just get new 340 pistons - I don't have the original ones to compare (think I sold them 10 years ago). However it's interesting, I have one of these new KBs here on my desk and I remember a thought flitting through my mind that it looked a bit odd. As I am not greatly experienced and have never built a 360, only 340s and 318s. So I am used to seeing the look of those pistons. That stroked unit of yours you described was a success story. You are lucky to have those competent machinist guys around. The state I live in is one of the largest in the world (by land area) but has a small population and a very small capacity for things like this. The places around that can do it are not many and not cheap either. Just to get a dynomometer run costs over $1500 and it's a big deal. The cost to get a 360 turned down to what you describe with internal balancing etc would cost over $700 and that money could be used for a new one. Plus the knowledge about Mopar engines here is so low, I wouldn't trust anyone to do it!! I picked up some 440 pistons for a friend once, from a machine shop he always used. They had put every rod on each piston the wrong way! My friend was spewing, but they denied it! He had to do them all again himself. No great drama, but that gives an indication of competency. Last time I went in there they were still using old scales and counterweights from 1965 to weight match rods! Couldn't even be bothered to buy some digital scales with +/- 0.1gram accuracy which you could get for under $50.

I would not even consider stroking this engine, and it would even be hard to find a 360 crank these days. Even though we (as in Chrysler Australia) have had quite a few 360s over the years. But they are sought after and drying up quickly. I already have the original really nice forged one for it all machined up and the new bearings etc. Plus as I mentioned before in another reply, 340 engines are quite rare here, we only got one model car with them and only for 2 years. The number of Australian designated 340s would be less than 400 in the whole country. Many have been imported in. They are quite revered and it would be sacrilege to many Mopar guys here - me included - to stroke a 1971 340 with a cast crank.
 
I like Total Seal for race motors but RaceTec supplied moly std. rings so thats what Im using in my 388 SBM.

Any name brand moly ring will work good in your app. Bore finish is important.

Most private label rings are made by the big names.
Thanks for the input, I have been looking at Total Seal a few times now.

Hastings have a broad range. Their premium Plasma Moly range is over $160 for a set. The higher price seems to be for the ductile iron top ring as opposed to just iron. Then they have phosphate coated for the cheaper ones. I still have not heard what the difference between Plasma Moly and just "Moly" is. Is it a different or better facing process? Or just technical jargon to make things sound like higher quality? I would like to be better informed in this area where there are so many brands and such a high range of prices, for basically a part that all do the same thing. I have a feeling that in the $300 and under range, mostly it all comes down to "Names and Claims". A $900 set of rings for a Top Fuel Dragster would certainly be in a different league of quality.
 
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Interesting... that was about the limit I was thinking of too. 360 engines are very popular here so it will be interesting to see if they sell or not. But compared to the US market for Mopar engine stuff, our market (supply and demand) is tiny.
I wouldn't have went that far if I didn't have too. 30 was a no go so we tried 40 and it almost got there. There was two tiny spots in the 1 and 8 cylinders that didn't clean up and probably it would have been fine to run it like that but I didn't want to chance getting blow by, a weak cylinder or even worse a broke ring.
 
Good idea if he was into performance engines and had that type of knowledge but he's 74 years old and runs just a regular machine shop. One day he's be doing machine work on a Toyota 4 cyl engine, next will be rods from a Top Fuel drag car, next day will be will be a rebore on a lawnmower engine.

He doesn't have much interest in the parts. He would just say throw in some no-name cast rings.
Right on. Kinda how most shops run, whatever you take in that's brought to you

I worked at a machine shop long ago...and as I was being run through the operating of the sunnen hone..i remember Toyota came up in regards to which stones to use and hardness of diff blocks..so on that block you would use a fine stone because they have pretty hard castings...and on a a 350 etc a course stone in comparison. So he would know what grit and then and wether he used a plateau brush etc. Therebis more to that story, of course...but more than likely he could use a basic moly ring, or cast and maybe notice a duration diff in break in with regular cast seating almost instantly as where the moly might take longer. Too rough and it will take many mile to seat a moly ring in my experience. I did it with a 225... must have what seemed like 10k.
I got 160k or so out of it before I sold it. It had a ridge at about 70k when I changed the head for a big valve upgrade.
 
Thanks for the input, I have been looking at Total Seal a few times now.

Hastings have a broad range. Their premium Plasma Moly range is over $160 for a set. The higher price seems to be for the ductile iron top ring as opposed to just iron. Then they have phosphate coated for the cheaper ones. I still have not heard what the difference between Plasma Moly and just "Moly" is. Is it a different or better facing process? Or just technical jargon to make things sound like higher quality? I would like to be better informed in this area where there are so many brands and such a high range of prices, for basically a part that all do the same thing. I have a feeling that in the $300 and under range, mostly it all comes down to "Names and Claims". A $900 set of rings for a Top Fuel Dragster would certainly be in a different league of quality.
Dont overthink this... Plasma is the process used to spray the moly on the ring... All the same.

Any high quality ring will work. I have used simple cast rings when the budget was tight even on modern engines.

Years ago we only had chrome or cast. Top fuel cars ran cast back then...went 250 mph!
 
Thanks for the input, I have been looking at Total Seal a few times now.

Hastings have a broad range. Their premium Plasma Moly range is over $160 for a set. The higher price seems to be for the ductile iron top ring as opposed to just iron. Then they have phosphate coated for the cheaper ones. I still have not heard what the difference between Plasma Moly and just "Moly" is. Is it a different or better facing process? Or just technical jargon to make things sound like higher quality? I would like to be better informed in this area where there are so many brands and such a high range of prices, for basically a part that all do the same thing. I have a feeling that in the $300 and under range, mostly it all comes down to "Names and Claims". A $900 set of rings for a Top Fuel Dragster would certainly be in a different league of quality.
Hastings I like and have used in about everything.. I just put a set of those in a 340, havent run it yet. Was the steel ring vs iron diff in the set I bought. I wanna say they were 70 bucks. I'll try to dig up the part #
 
I wouldn't have went that far if I didn't have too. 30 was a no go so we tried 40 and it almost got there. There was two tiny spots in the 1 and 8 cylinders that didn't clean up and probably it would have been fine to run it like that but I didn't want to chance getting blow by, a weak cylinder or even worse a broke ring.
Yes well good luck, hope the tough Mopar blocks reputation doesn't let you down. But I'm surprised that the machine shop didn't suggest that you sleeve those bores. If they were the only two bores that were stopping you leaving it at a healthy 030 or 040 then that would have been an easy solution. Or even if it had been three or four bores like that, then sleeving, if done properly, and then machined down, is a great way of restoring a block with doubtful walls.
 
Dont overthink this... Plasma is the process used to spray the moly on the ring... All the same.

Any high quality ring will work. I have used simple cast rings when the budget was tight even on modern engines. Years ago we only had chrome or cast. Top fuel cars ran cast back then...went 250 mph!

Yeah true, wise people have to cut through the advertising jargon B.S. and see things for what they are. That's why I was asking the questions. In the case of rings I don't think the simple rule of "you get what you pay for" totally applies here. You could pay literally twice as much for a set of rings from an expensive brand (eg JP Pistons or Manley) than someone else and not get any difference at all in performance or engine longevity. However if Summit Racing brand rings are made in China, then I would draw a line there and not use them, since the metal composition is pretty important in such a high stress component.
 
Hastings I like and have used in about everything.. I just put a set of those in a 340, havent run it yet. Was the steel ring vs iron diff in the set I bought. I wanna say they were 70 bucks. I'll try to dig up the part #
Ok thanks, will be interested in that. Although I could probably go to the Summit website and see, they seem to have a lot of Hastings rings.
 
Yes well good luck, hope the tough Mopar blocks reputation doesn't let you down. But I'm surprised that the machine shop didn't suggest that you sleeve those bores. If they were the only two bores that were stopping you leaving it at a healthy 030 or 040 then that would have been an easy solution. Or even if it had been three or four bores like that, then sleeving, if done properly, and then machined down, is a great way of restoring a block with doubtful walls.
That was discussed. He gave me a couple of options to choose from so I did the right thing and went the cheapest most risky way! Lol
 
It needs to be remembered that the 340 came with moly rings from the factory, and the 340's never seemed to have the bore wear that the 360's did.
 
Good idea if he was into performance engines and had that type of knowledge but he's 74 years old and runs just a regular machine shop. One day he's be doing machine work on a Toyota 4 cyl engine, next will be rods from a Top Fuel drag car, next day will be will be a rebore on a lawnmower engine.

He doesn't have much interest in the parts. He would just say throw in some no-name cast rings.

What does that have to do with the price of tea in China? ASK the guy how he honed it. There are a few different methods, all of which dictate which style rings to run. Moly rings take one style of finish while cast rings take another. My suggestion would be ask your machinist. If he "doesn't know" then what I suggest is re-honing it yourself based on what rings you plan to run.

If you simply make a decision and sling it together, the rings may never seat, as the type of ring you choose may not match the particular finish your cylinder has. If he's 74 and been a machinist a long time he may know more about performance machine work than you give him credit for.
 
Hastings I like and have used in about everything.. I just put a set of those in a 340, havent run it yet. Was the steel ring vs iron diff in the set I bought. I wanna say they were 70 bucks. I'll try to dig up the part #

Those are a brand I usually look for on eBay. I try to find good deals on older NOS American made brands. Had good luck so far. ......and gotten some really cool old boxes too. lol
 
It needs to be remembered that the 340 came with moly rings from the factory, and the 340's never seemed to have the bore wear that the 360's did.

Moly rings eh? That's new to me, wow, the 340 really was special then. Maybe they upped the nickel content on the 340 castings if they knew that many of them had a good chance of being raced. While I'm here, do you know if they did anything to the oil pump? All I have heard is that it was "revised", whatever that means. They couldn't really make it a HV pump as that oil pan was pretty low at 4 quarts. For the high revs it was capable of I was a bit disappointed they didn't do more with the oiling system, such as Ford did with theirs.
 
Moly rings eh? That's new to me, wow, the 340 really was special then. Maybe they upped the nickel content on the 340 castings if they knew that many of them had a good chance of being raced. While I'm here, do you know if they did anything to the oil pump? All I have heard is that it was "revised", whatever that means. They couldn't really make it a HV pump as that oil pan was pretty low at 4 quarts. For the high revs it was capable of I was a bit disappointed they didn't do more with the oiling system, such as Ford did with theirs.

Nickle content in Mopar blocks was already high compared to all the rest.
 
Moly rings eh? That's new to me, wow, the 340 really was special then. Maybe they upped the nickel content on the 340 castings if they knew that many of them had a good chance of being raced. While I'm here, do you know if they did anything to the oil pump? All I have heard is that it was "revised", whatever that means. They couldn't really make it a HV pump as that oil pan was pretty low at 4 quarts. For the high revs it was capable of I was a bit disappointed they didn't do more with the oiling system, such as Ford did with theirs.

Every 340 pump I have ever dealt with appeared identical to every other stock SB pump, they may have raised the pressure a little though.
 
Im always reading and looking for new better things to try...these were the last set I bought.

Hastings Steel Series Performance Ring Sets SM139030

And here is some good read. @Jadaharabi
https://www.google.com/url?sa=t&sou...FjABegQIARAE&usg=AOvVaw0GPKHKoZGNxHyAO0SB1dwU
Hi thanks for those links - the Hastings rings seem a very good price for their claims. First I have seen with stainless steel top ring at that price. I will definitely be considering them. The article about piston rings is just what I have been searching for and really enjoying reading it. Muy apreciado gracias!
 
Are these companies all making their own rings or do they all buy generic rings from a couple of manufacturers and put them in their own box with their own advertising?

Also is "Plasma Moly" and just "Moly" the same thing, or is Plasma Moly better?

Lots of questions (maybe too many for one post!?!), hoping for some guys who have knowledge and had experience with different brands of Moly ring sets for the common KB Hypereutectics.

Thanks.

Most make their own but I’m sure like all things some are re-boxed. In a mild application there’s not much you “need”, aside from buying rings that will work with the cylinder wall finish the shop gave you. A picture of the bore might help eyeball it if you don’t know how they left it.

Cast rings are the basis for all types you might be interested in. The coatings and ring design comprise the price swings.
In order of performance (at least imo)
1. Cast top and standard design 2nd with no coatings
2. Cast top and 2nd with moly coated top ring (2a. Is file to fit rings)
3. Cast top and 2nd with plasma moly coated top (3a is file to fit)
4. Cast top with cast Napier design 2nd, with moly or plasma moly coated top ring (4a is file to fit)

You don’t need gapless, chrome, or any other gimmick.

Assuming the bore are prepped right- the cast top and std design 2nd with a moly coated top would be fine (#2a).
If you’re not sure or the bore is too rough, cast top and cast 2nd with no coating is fine (#1). That’s because if the bore is finished right a moly ring will seat fast. If it’s too rough it will just strip the moly off and then break in like a plain iron ring and you paid for moly for nothing...

Last- on the ring gaps: follow the spec sheet for the top ring especially, and add .004” to the 2nd ring gap. I like file to fit but to be honest you should be giving them bigger than the stock part anyway so you could go non file to fit and be fine.
 
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Thanks Moper for writing out all that info. Good idea, I might take a couple of high res photos of the bore finish and send them here. The machine shop is 40min drive away and don't particularly feel like lugging the block all the way there just for them to look at the bore. (it was machined about 6 years ago!).

Good advice about the ring gaps, I will take note of that. Also I just learnt that the second ring has to go the right way around, as it is tapered in one direction to push oil downwards.

The article that MOfficial gave the link to has some very good info about ring materials, ring coatings and ring profiles, and I can compare that info to what I see on the Summit site. I only use Summit Racing, they have been superb over the last 15 or so years for me and have never let me down.

It's quite amazing that cast iron (grey cast) rings are so good, as you would think that for the amount of movement and heat cycles they go through, for sometimes 500,000 miles or more, that brittle cast iron would not be up to the job. But they do.
 
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