Mercury flathead pistons

[3twinridges]

Anyone know a source for Merc pistons 60 over that are three ring? I know an option would be a 4 ring leaving a ring off, but a 3 ring would be good to find.

[WestCoast]

egge makes pistons for almost any engine, google them

[Binx]

Be sure your machine shop has told you .060" before you buy. I've brought blocks and pistons to a shop certain of my needed oversize and they proved me wrong due to a weird wear in one or two bores.

Lonnie

[3twinridges]

Thanks Lonnie, they told me 60 over! Machinist was not sure of a source for 3 ring but it sounds like egge has them. Any downside to running a three ring?

[40cpe]

Jim at Red's Headers has the Egge pistons. He is great to work with.

[Binx]

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Originally Posted by 3twinridges

Thanks Lonnie, they told me 60 over! Machinist was not sure of a source for 3 ring but it sounds like egge has them. Any downside to running a three ring?

No problem with 3-ring Egge, but if you're planning on milling heads for absolute best possible compression, Egge pistons have a pointed dome that don't conform to the head.

Lonnie

[Ol' Ron]

I use alum balls to measure the piston clearance in several areas of the piston. Now I mill the heads to give the .045/050" over the largest area. Then using a dremmel I remove the material from the tightest area. This takea alittle thought process, but give better throttle response and economy. This way the dome shape is not very important. I also ise best copper gaskets with copper coat sealant.

[Bored&Stroked]

Another option is to go to a forged piston - talk to ROSS if that is an option. Personally, I like to run the 1.5, 1.5, 3.0 mm ring packs . . . but I have not checked with Ross to see if they have mm rings in this diameter. You might give their tech folks a call.

Also, as others have noted - the piston crowns of some of the Egge pistons are not a consistent radius like the aftermarket heads are . . . this can be a real pain. You save some money on the pistons, but then need to have your heads reworked so the domes don't hit. You won't have this issue with Ross - they have a consistent radius dome that works on all the various heads (as long as you order the right compression height pistons!).

Also, if this is a performance build, then consider boring to a 3 5/16 bore (.125 over), running the Ross pistons and ask for the 1.5, 1.5, 3.0 ring package. Is a bit more expensive, but I sure like the results. Your machine shop needs to have the 'pistons in hand' before they bore/hone and need to hone to match the ring manufacturer's specifications. Different bore finishes are needed for different ring types.

Good luck,
B&S

[Tony, NY]

Arias is an option. https://ariaspistons.com/search?q=me...athead+pistons

[rotorwrench]

I thought the 3-ring Egge's were only available in larger sizes?

[3twinridges]

I talked to both Ross and Arias. Ross has a 3.2475 and arias has a 3.248 3 ring on the shelf for my stroke. How much more power am I likely to see (ballpark) in using one of those vs a cast 4 ring?

[flatheadmurre]

Do you need forged pistons for your engine ?
Going from normal rings to low tension moly makes a difference...just going from 4 to 3 normal ones...i wouldn´t spend the money if it was for that reason only.

[scooder]

I've made the change on an engine, ok not a flathead, it was a 2.0 Pinto engine that stock make circa 100 hp (UK spec high compression). It had stock size early style (fatter) piston rings. The later engines came with the more modern much
thinner, lower tension "metric" rings. Engine was a nice fresh good performing relatively low (sub 50000 mile) motor.
I had a set of the "metric" piston/ring combos. So I tugged the engine, honed the bores stuck in the "metric" things, and put it back together. Now I checked all the bearings and journals, no wear, miked perfect. Fully checked bore for taper and roundness, perfect. Cross hatch was still there over the entire bores. Checked pistons for compression hight and size, really wanted to see a fair comparison of just the piston/ring combo. Original Ford pistons, standard bore both sets. The old fat ring slugs had no measurable wear on skirts or pin holes or ring lands. Thin ring slugs were new and measured the same as the fat chaps in all areas.
This was a great little engine.
The difference with just this change? Couldn't feel any difference, anywhere. Wether I used the car as normal driving to and from work, or kicking its arse. Which was a pain, it's a time consuming job "just changing piston style"
The only difference I did notice was the engine was slightly better on gas. And the exhaust sniff tester showed slightly clearer emissions. This last bit made me then play with ignition and fuel settings to see if I could optimize the thin ring setup. A blind alley there.
Now I fully understand why the thin rings are better, and why they should make more performance, even if slightly, but none was found.
This testing was with a four cylinder over head cam engine, so we could look here. Half the cylinder number, half the friction. So the "gain" would have been less in an A/B test. But this four cylinder engine when compared to a Flathead V8 is using getting on for double the rpm in use, especially when kicking is arse!

I'll leave the is it worth it question to whoever asks, in my opinion, it was not.
I'm currently building another one of these engines for my mk1 Cortina. It's getting fat ring pistons, as I can usually get these "old fat ring ancient technology" slugs for under half the price.


As for performance difference between cast or forged pistons, all else being equal, in an unblown engine, nothing at all.
In a blown or N2O setup, they are better as they are more resilient to detonation damage. They will still fail if held in detonation for to long though, just a bit longer the cast or hyperwhatsit slugs, if the cylinder pressure isn't crazy. They will last better in higher cylinder pressure applications. And last longer in badly tuned setups.
Luckily forged flathead pistons (Ross) ain't that much higher in price than good cast one's. My Pinto engine, the forged slugs are circa £1000!! For four!!
Sorry for long post,
But feel it's warranted here.
Martin.

[Bored&Stroked]

Originally Posted by 3twinridges

I talked to both Ross and Arias. Ross has a 3.2475 and arias has a 3.248 3 ring on the shelf for my stroke. How much more power am I likely to see (ballpark) in using one of those vs a cast 4 ring?

It is unlikely that you'll see any real performance difference - especially if your engine is primarily a stock setup. If you find a good set of 4 ring pistons that are the correct bore/stroke and dome profile - and the price is right - no problem running them.

You may find that buying a set of 'stocking pistons' from ROSS isn't much more money than buying a cast set from somebody else (especially if they have domes that don't match your heads - and you need to machine them).

What heads are you running?

D

[Ol' Ron]

Another factor to consider is the Piston to cylinder wall clearance. I run Egges at .002 and Ross at .005. I also like to run these engines Hot use 180 stats. This especially helps the Ross pistons expand. The fan comes on at 200. So Far the 294 is preforming quite well, it's very hard to keep your foot out of it.

[GOSFAST]

Originally Posted by 3twinridges

I talked to both Ross and Arias. Ross has a 3.2475 and arias has a 3.248 3 ring on the shelf for my stroke. How much more power am I likely to see (ballpark) in using one of those vs a cast 4 ring?

The straight answer is it depends on the ring pack they use. Any "moly" 3-ring pack will yield more power than any conventional "cast" 3-ring pack. Any "metric" 3-ring pack (1.5, 1.5, 3.0/4.0) is our choice here. We rarely use "cast" 4-ring packs any longer unless it's a customer choice and we absolutely don't care about the end HP numbers!

The bore finish also comes into play, "moly" rings need a much smoother finish allowing them to seat quicker, and we also use a block-plate on every build nowadays.

Personally speaking I would suspect a 15-20 HP gain with the lightweight pistons/rings and the correct bore finishes, maybe even slightly more!

Thanks, Gary in N.Y.

P.S. If you're "chasing HP" at all now is the time to do an upgrade!

[3twinridges]

I am going to use stock EAB heads, stock 1CM cam, 4" crank, stock 94. Difference in price is not that much when compared to what I have in the whole thing so I am thinking I am going to splurge on the Ross. I just don't want it to smoke or burn a lot of oil, would/could that happen with just three rings?

[flatheadmurre]

Forged pistons if you don´t need them...just more noise to me.

All theese upgrades coated pistons/molly rings/file fit/Gapless rings/torqueplate honing/hot honing they all give you a couple of percents more power each.

In a 800Hp natural aspirated racemotor it does matter...in a stock one...

Raising compression is the main thing gives you about 4% for each point you raise it.

[3twinridges]

Thanks for all the advice guys, sorry to be a nag on the questions. I usually just read on here but the rubber is hitting the road on this build and I want the best and most powerful stocker I can build. I am starting with a great block (thank you Ross).

[40 Deluxe]

Originally Posted by 3twinridges

I am going to use stock EAB heads, stock 1CM cam, 4" crank, stock 94. I just don't want it to smoke or burn a lot of oil, would/could that happen with just three rings?

Won't smoke/burn oil. Look at modern cars using these 'metric' rings: 10,000 miles between oil changes and they don't even burn one quart of oil!