piston choice

[mercrazy]

1. what's the best piston for a hipo merc motor?
2. how much clearance do i need if using forged seizco's?
3. has seizco definitely fixed the pin problem?
4. what's the maximum safe rpm for the pro marine hyper... pistons?
5. what type rings should i use on nic plated cylinders?

how about it jay and john and greg?

[Jeff_G]

If you are talking about a Mercury I would stick with Mercury. I would use a "Persan" Sierra next. If Weisco's just follow their recommendations. For the PRO marine here I'll probably get some flack but it depends on where they get their pistons. Steel rings in a plated cylinder

[us1]

The Mercury piston is the best. The clearance depends on 2.4 or 2.5, steel or Nicasil, thermostats or not. If you are using Nicasil you don’t have a clearance choice unless you are replating. I don't know of any piston made that has a pin that doesn’t fall out, they must be modified like I do on my race motors before it is fool proof. I run Titanium rings in the Nicasil motors but steel will work if that is all you can get for your piston choice.

[mercrazy]

2.4 and 2.5 steel

[Jay Smith]

Mercrazy,
It's according to what cyclinder you are using. For the coated liners I like the Merc Hi Per piston with "gold" rings. For a steel bore with limited rpms 7500 and below I like and have used the Pro Marine slugs with the stock clearence. If you choose the steel bores with Hi Per Block there is two choices the Merc. Hi Per and against te grain I like the "gold" ring with them too but the steel must be set up with a micro slick hone job be done , I use Dave Hensley in Tenn for this service. If budget constraints are hitting you you can use the Wiesco production forged pieces but along with the Pro Marine the ports will need to be opened the match the sleeve. Put the extra .003 clearence on them and I HIGHLY suggest the Cryo freezing for all the pistons aboved mentioned.
I also have a trick with the Weisco production rings for those who have put motors together you have seen te very high outboard thrust pressures these rings produce against he bores VS the slight amount te Merc. and Pro Marine produce (7 lbs VS 2 1/2 lbs ) this can be reduced by enieling the rings . I have a friend in the ceramic business and they allow me to hang a set of rings in the kild tru the fireing stage and it will take 50% of the outboard thrust tention out of the ring and prevent the common scraping and gaulding that is seen on the steel bores , Weisco combo. The scraping is also reduced drasticly by adding the more clearence as the Wiesco has a BAD habit of swelling unevenly and unless clearence is alloted gaulding is likley. I have to say this again to use 32:1 ratios andafter break-in use a good grade of syn . oil ...

Good luck ad good boating,
Like I've said in the past this ain't the only way to skin a cat this has just worked for me !

Happy Turkey Day to everybody ,
Jay @ JSRE

[us1]

I like to run Wiscos at .007 in 2.4 steel and a loose .008 for 2.5 steel.

[Jay Smith]

Thanks John for clarifing for me sometimes I assum people know what I'm talking about. The 2.5 should be .008" total piston to cylinder wall clearance and the smaller bore 2.4 .001" less or .007"'
Have a Happy Thanksgiving John , after the holidays we need to discuss something I have in mind that I think will give you a little mid range and upper end power .

Jay @ JSRE

[us1]

You have a happy thanksgiving too Jay. I am still working on that Z port with the water leak. We found that the builder has ported right through into the water jacket right next to the sleeve in the exhaust port. It doesn’t look good for this one.

[Jay Smith]

As you and I discussed I have had those motor in the past and they would'nt run out of thier own way . The water leak thing seem to be the norm , mine looked like a water sprinkler and like yours blew up on the hose with the pistons gaulding with 3 bores full of water ( leaking sleeves ) ........ Give me a Drag or an S-3000 ANYTIME !!!!!!!!!!!!

See ya, don't eat toooo much turkey !!!

Jay @ JSRE

[RichS]

Hey John!
Ya mentioned above about fixing the ring pins. Are ya talkin about pining them so they stay put? I got a new set of side stakes I'm putin in a drag that I would like the pins to stay in:eek: :confused:

[us1]

Yes, I don't run any pistons Mercury or not with the stock ring locator pins in the stock locations.

[dennymac]

ok john, you're teasing us again...whadda ya mean stock locator pins in the stock locations....do you use a different pin and where do you move them if they're not in the stock location??...one more little secret, we won't tell.....thanks, dennis

[us1]

Its a bit more complicated than that but I use a high Carbon steel pin in the finger port area pressed in vertically and welded into the crown with a special alloy and welder. This causes no warpage to the piston if fact the piston never get over 100 degrees. The old pins are EDMed out and the rings are recut with a high speed diamond cutter. The pistons are indestructible when I am done, as far as locator pin failures anyway.

[Techno]

Would it do any good to cryo treat the rings? It seems that these things need all the help they can get.

[us1]

I have never had any problem with the rings coming apart on their own.

[FCnLa]

Hi John,

You mean you drill through the pistion's crown into the ring land? And then weld the hole up? If that's it, seems fool proof.

Do you run the ring end gap in the same location (as stock) and cut a slot in the ring to position itself correctly via the new locater pin?

And why Ti rings? Less ring flutter? Or is that a problem?

If you don't watch out the us OMC guys might learn something here!:)

[us1]

Yes that is basically it and I have never lost a ring or locator pin again. I like to put the pin in the boost port, some Wiscos are and some are not in that location from the factory. I usually rum Wisco pistons in my race motors. After proper boring, cooling system mods and the new pin configuration they are bullet proof. I will run Titanium or steel rings, the Titanium just last longer. With Wiscos I am stuck with steel though.

[Techno]

I thought the rings were the reason for the rebuild times. Not that they come apart but get worn out.

[dennymac]

hey john, do you do this service on customers pistons...and if so, how much do you charge....it seems to me that i read on this site a while back where a guy was doing something like this to pistons...think his name was pierson, can't remember....also interesting is that you reuse the same rings, just recut them...did i understand this right?...if so, this is different from the other guy because i remember that you had to buy 12 rings from the new single ring race pistons to fit his modification...kinda pricey...
this is a sensitive subject for me as i've had several pin failures cause major damage...one other thing, does having the ring gaps on top of each other cause any problems with compression or leakdown?...thanks, dennis

[us1]

Its cost $200 and if you want to have the old pins removed by EDM that costs $90. This sill costs way less than a stock mercury piston if you use a Wisco, yes it’s a lot of work but it is definetaly worth it. I have also brought back to life many good Mercury pistons with loose pins that otherwise were good pistons. Yes I recut the stock ring to work with the new pin. The joy of the whole thing is I never even think about the pin coming out any more. I used to sit at the races and wonder if the pins are coming out yet, with Wiscos that’s at about 4 hours of run time. The compression and leak down are the same; there is no power loose from lining up the gap.


Techno, I have never tried that to see if they last longer.

[Techno]

US1 It occurred to me that your engine requirements might be like some of the drag racers but may not for the lake racers.(time)
How long do you expect your engines to last without looking at them?
How high do you spin them?
And what is it that your fixing or changing when you do yank 'em apart.
Is there an RPM threshhold for the diffferent parts? I've seen it mentioned before but it was a flywheel here or a piston there kind of thing. What I'm wondering is are there key RPM points where more parts are involved which would lead someone to choose a limit. The point of dimininshing returns thing.

It would seem comparable that one race for you would be like several weeks of lake use for the average guy. Unless they run in a short river maybe.

[us1]

That is very true I do use them up much faster. But with the piston in mind at a constant 8500 to 9000 RPM a Wisco locator pin will last 3 or 4 hours in a race motor. On a lake boat I have had them start to come loose at 18 to 25 hours. They will almost always come loose by 30 to 40 hours. The longest lasting one for me was 70 hours. Through racing I am able to find out much faster which parts will fail. A Wisco piston on a lake boat will last 200 to 300 hours as far as ware, so you can see how the locator pins are really wasting a lot of good pistons. As far as what I do on a rebuild between races, I check the crank and rod to make sure they are straight, check the bearings and journals for ware, mic the bores and pistons, check the wrist pin clips for pounding, replace rings if needed and put it back together. The parts seem to last up to 8500 RPM, over that stuff starts to tweak. On a lake boat only getting 70 hours on a set of pistons is ridiculous. Stock Mercury pistons will last a little longer before the pin fall out but not a whole lot longer.

[racer]

John, have had good luck with a similar method but only on the top ring. The bottom pin has never been a problem for me and then the gaps are seperated. What alloy are you welding with.

[us1]

Hey Racer, Yes the top pin always falls out first but on Mercury the bottom pin will fall out also in time. That’s why I just pin them both and then I can forget about it. Why is it that people like us can properly pin a piston but multi million dollar manufactures have never been able to figure it out.:confused:

Hey US1

I just pined a # 3137 wiesco piston, a little clearance work on the cam grind a little ring work. The locating pin in from the top, both rings and intercept the pin and bend it on the piston tang, no welding. Now it's time for the ceramic top coat and we will see.

I'm having US crome nicom the steel boars for me, can you say guineapig................Uncle Tony:D

[us1]

I used to do it that way a long time ago but it caused detention and piston failure over 9000 RPM. Tell me how the Nicom steel combo works out.

John

I've run the Merc top ring locating pin without a piston failure do to the ring pin. I had polydine coat the top of the pistons, I think that's why I've had no pin problem.........Uncle Tony:D

[dennymac]

i talked to us chrome last week and they said they 'could not' coat a steel sleeve with nicom....part of their process involves dipping the block in some sort of acid solution....they said this would destroy the steel and they couldn't do it....they could only coat aluminum....did i get some bad information?...dennis

dennymac

If you don't know who to talk to at US crome who knows what you will hear. Did they tell you then have been doing it for NASCAR motors.

It is true they have not done it on a Merc motor with cast Iron boars but I talked to the head cheese and he told me it would be no problem. There are other companies other than US crome that are setting up to do this process. I'm using cast iron boars not the steel insert over aluminum. I'll let you know as soon as I can how it works...........Uncle Tony:D

[Tony Brucato]

Just got back a couple of Merc Hi-perf pistons from Jay Smith.
He was able to save them with his ring locating pin mod.

I had thought about just staking the pins myself. After all how tricky can it be? Glad I sent them to Jay. He's got a special tool that forms a concentric ring around the pin, reducing the diameter by 25%. Looks bullet proof, and it's done right.:)

It looks so logical that you wonder why it's not done like that from the factory.

[us1]

Tony, I can assure you that after running my boats to two National Championships all with locator pins done by my method that they are “done right”.

[Tony Brucato]

John,

I wasn't implying that your pistons are not done right. Your method seems VERY thorough and failsafe. Your success with your method is testimony to it being "done right".

Jay's modification is also "done right" and I like being able to use stock rings "as is", without grinding another locating notch.

I know that you mostly use wiesco pistons with the stock locating pin further exposed into the ring land. Your modification does seem more appropriate in this case.

The Merc hi-perf piston has a smaller percentage of the pin diameter exposed into the ring land, and Jay's fix seems simple and effective.

The cat is skinned either way.

[Jay Smith]

As has been mentioned many times in the past and even in the above posts the locater pin problem CAN be delt with . We have had no failures with the Mercury Hi Per piston staking process with the pins coming out and destroying bores. The process is completed with no extra mod to rings and has a 1 day turnover time , the labor charge is $90.00 total +freight and stock OEM rings can be used.

I don't think Tony was implying one way is better or worse than the other methods used if they all have and do work the choice is the customers. He was stating that the "fix" I do was so simple and to him foolproof , and in his opinion , a way that this problem that has plagued us had been solved. Now that is the way I read it , others may have read it different.


Sorry John , I don't think it was ment to be taken that way.

I too have several High Points Championships and WORLD CHAMPIONSHIP titles, along with several people that are out of my shop with titles as we speak and they have been pleased with my process too.

Again sorry for any misunderstanding !

Jay @ JSRE

[us1]

It struck me as very odd that someone would make a post like that right after I get done answering someone’s question about how I pin I race pistons.

[us1]

I just talked to Jay and I am sorry if I miss interpreted your post. Please accept my apologies.

[dennymac]

look everyone...one thing to consider....jays method is great for preventing the pin from coming out....but does not prevent the pin from sinking in....i believe john's method would aleviate this concern.....jay's process is cheeper, john's is more expensive....
decide what your greater concern is and pick your poison.....

[Tony Brucato]

John,

Sorry for the misunderstanding. I was addressing the thread, not contradicting you.

The reference to being "done right" in my post is a comparison to;
Doing it myself versus having Jay do it. Not John versus Jay.

Your apology is not necessary. No hard feelings here.

[Techno]

Why does mercury make a componant that can't perform? I'm thinking for at least the drag engine if not the other Hi-Pos.
Is the wrist pin another weak spot?

[us1]

I would love to know the answer to that question. As long as the rods are straight the wrist pins seem to work ok.

[mercrazy]

will your technique work on the new wiseco's?

[Jay Smith]

Yes , the new Weisco's I've done ( OMC ) had to have a larger staking tool made by tool and die maker as the pin was larger in diameter and looked as if it was tapered.


Jay @ JSRE

[RichS]

John or Jay:....
John you talked about bent rods hurting the pins. I assume that if the rods are in service specs they are ok? do you press down on one end before you run the feeler under the other end. I had one that was ok for bent but had too much in the twist. I ran it and am about to tear it down so I'll see for myself but a second opinion never hurts. But these are the 2 ring top stakes so I hope that pin isn't loose:eek: :eek: :eek: :confused:

[us1]

A bent or twisted rod will pound the wrist pin clip out of the piston. A twisted rod seems to pound the clip out faster than a bent rod although that doesn’t seam to be logical. In a high RPM race motor I wont run a rod with any bend or twist at all, even if its with in factory suggested tolerance. You can get away with a little bend if you are running under 8000 RPM but .002 is pushing it, a twist is bad at any RPM. Yes I push down on the opposite end of the rod with rod cap off. Push in the center of the thrust area not where the rod it split. Same goes for the wrist pin end.

[Jay Smith]

I agree with John I force them down on a honing stone ( which is perfectly flat ) or a pain of glass will do in a pinch.

Jay @ JSRE

[Jay Smith]

If your at the races and want to check for straightness when youve had an oh oh use a deck height mic. as any reduction of clearences in reference to the deck height will point to a bent or twisted rod. When the rod is bent or twisted it will loose lenth !

Jay @ JSRE

[us1]

I left out the flat stone or honing stone, thanks Jay

[RichS]

Thanks for the help guys. I thought something was sounding funny. It's still healthy but its done till it gets checked. The water is gona start getting hard anyway:mad: :( Get'in the sleds ready:D

[espen]

John can you fix my early mahlie pistons with a vertical pin ?
Seems like all my pistons have 2 pins for each ring the biggest are pushed in. The piston ring gap dont line up on a bridge between the ports...is this common?
How much is it for 6 with new piston rings if you have.
If you want to ansvere offlist my email are [email protected]
Thanks

[us1]

Yes I can. I have emailed you with the details.