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The elusive 224/3.7 MerCruiser banger

Discussion in 'The Hokey Ass Message Board' started by tjm73, Apr 9, 2008.

  1. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    That's a good price!
    I recently bought some Boss 429 heads that I think are made by Speedmaster, but not sure. The rockers are listed by them, but never found boss cylinder heads by them. The heads I got look to be good quality and are heavier than the Kaase heads I have. But they are not a cheap option either.
     
  2. Sean Lougheed
    Joined: Dec 26, 2021
    Posts: 40

    Sean Lougheed
    Member
    from Canada

    Greetings all, Proving the obvious for all the other nerds like me... that just got to know.
    I have done some simulations of our cylinder liners under pressure both as stock, and with a deck plate installed. These are simplified tests with a constant 1000 psi on the whole liner, so it is really only the top inch of stresses that are accurate as the pressures drop off quickly from the top. That is a fair pressure but it sure shows what is happening pretty clearly. An interesting thing is that the shape of the liner has stress points where it thins, it is probably at this transition that Dennis G's liner cracked. A round liner works better that way but I think they thickened the liner on the sides to take the piston force or to just add some rigidity. Unsupported, the big stress at the Siamese is caused by the liner flexing outward where it is thin on each side. The unsupported liner also moves side to side with high piston forces, I got up to 5/10,000 of an inch and that's not good as that could eventually wear the gasket and make it fail. Keep in mind though that is only at 5500 or more rpm and not happening all the time. At lower RPMs the liner doesn't sway like a tree in the breeze like that. Install a 3/8" or 1/2" deck support plate and things really calm down. The side to side movement virtually disappears and those nasty distortions at the thin thick transitions are pretty much gone in the high pressure area of the combustion zone.
    So, a tight fitting deck plate is probably a make or break issue on a high performance 470, but like I said - we already know that. Now we just can see why, something that Mercury never had the ability to do at the time.
    [​IMG][​IMG]
     

    Attached Files:

  3. arse_sidewards
    Joined: Oct 12, 2021
    Posts: 220

    arse_sidewards

    How'd it flex in the high 4s?

    That was what Mercury said they were good for continuous WOT operation at.
     
  4. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    So Sean, are you going to bore yours to 4.5 bore? I plan to bore mine to 4.5 and make a deck plate as well. I sent the crank out this morning to be stroked as much a possible using the other haft set of alum rods that I have. 2.2 journal.
     
  5. Sean Lougheed
    Joined: Dec 26, 2021
    Posts: 40

    Sean Lougheed
    Member
    from Canada

    My simulation showed up to 5k the freestanding liner was still stable, movement pretty much undetectable. But once movement became detectable it started to ramp up. At 5500 the forces are getting up there to where it was worth noting. So Mercury did it right, as even 4500 it would be fine (according to the simulation). I was using the mass of the stock piston and rod which as far as I can find it is a stock 429 (probably from a Lincoln). The book says it is about a 1000gram piston. Forged pistons are now 830 to 850 grams. That would make a huge difference because the forces square as RPM winds up, so a little less mass would push that flex farther up in RPM. My gut feeling is after plugging in all this stuff that it would be well past 6000 or 6500. ( oh no... I am going to have to sim it again to know for sure... ) One important thing is don't get worried you will break the liner even at or above 5500. It is no where near breaking it is just flexing, of course that is not desirable but it has more bounce to go. I think you could wind the (stock) engine past 5000-5500RPM a good number of times, then mysteriously have the head gasket fail when the movement takes its toll on it.

    On boring. This engine I am building right now I am going to keep close to stock (practice engine to learn on) speed-master head, some light mods. Mainly because the bottom end is in such good shape, no wear in the bores, lifters like new etc. The second engine is going to 4.5 bore. I am reasonably confident in that with a.500 deck plate installed to support the peak combustion pressures at the top of the bore it will be fine.
     
  6. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    You are correct the stock piston is right at 1000 grams and if you are using little end of the rod weight, that be about 225 grams as I remember.
    My first engine is running it has pistons right at 675 grams and I have aluminum rods. I have buzzed mine up to 7000 a couple times and everything is holding up fine with no deck plate. My second engine I am doing now will have the same rods but more stroke and 4.5 bore and a deck plate.
    Thank you for sharing your findings!
     
  7. Sean Lougheed
    Joined: Dec 26, 2021
    Posts: 40

    Sean Lougheed
    Member
    from Canada

    That end rod weight is about right too so what I programmed was really close. . Glad to do it for us all.
    Having a reciprocating top end mass with something like a 40% reduction, that would relieve that side force by a factor of wow and it makes sense to me you can do a run up to 7K (and good to know too). Good to be on the R&D team.
     
  8. Randy Dupre ran his Mercruiser engines to around 6500 rpm at Maxton. He experimented with both long stroke and short stroke engines.
    When my first engine broke, the crack was nearly the full length of the cylinder and yes, I'm sure it began at the top. Sean thanks for the stress analysis, it adds so much to our understanding of the engine. 1/2 inch is too thick for the laser cutting equipment here but it will cut 3/8" . Isn't there reduced cut accuracy at greater thicknesses? May not matter as our cylinders OD and shape varies enough that I decided to fill the last little bit of the gap to the "deck plate" ( which in my case was support blocks) with epoxy but I do not know if it can regain its thickness after being compressed and heated. The thinner (dimension) the epoxy, the less the dimension change matters. Epoxy can be flexible, especially when hot. Don't limit yourself to using epoxy as aluminum "solder" which is mostly tin is much stronger than epoxy. tin "cries" on bending I kept a foot of it at my desk just to hear that. It bent easily, perhaps even easier than lead which I never tried to bend.
    Aluminum is sensitive to fatiguing and stress risers so any bending matters. Aluminum sports cars commonly had "dead" aluminum, that you couldn't rework, in places that, I assume, the aluminum vibrated.
     
    Last edited: Dec 7, 2023
  9. AccurateMike
    Joined: Sep 14, 2020
    Posts: 689

    AccurateMike
    Member

  10. arse_sidewards
    Joined: Oct 12, 2021
    Posts: 220

    arse_sidewards

    His parkinsons must have flared up when he was typing in the price hence the extra zero.

    I have a "the bores are good-ish but you need to make a jig to push the pistons out because they're that f-ing stuck in there" core I'd part with for 1-fiddy. 2BBL intake, no head.
     
  11. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 3,549

    GearheadsQCE
    Alliance Vendor

    :D
    That does bring up an interesting question, though. Knowing very little about boats, do those twin screws have one engine that turns in the opposite direction?

    Might make a difference when shopping. A guy could build u whole car around one and get a real surprise when letting out the clutch for the first time!
     
  12. arse_sidewards
    Joined: Oct 12, 2021
    Posts: 220

    arse_sidewards

    It's only a thing on boats with twin inboards.

    The only thing that's guaranteed to be different is the cam. Older engines with knurling to help the rear main seals do their job will typically have said knurling reversed on the left hand engine. Sometimes the starter is reverse rotation. Sometimes the bellhousing has dual mounting provisions and they machine it to be a left or a right like you see on a brake caliper.

    Stern drive boats will have a different gear housing on the port side to accomplish reverse rotation. Both engines will be conventional RH rotation.
     
  13. I read that in restoring a single cylinder stationary engine with a stuck piston, one could braze a grease fitting into a spakplug and pump the piston down with pressure from a grease gun. I never had to do that but banged the pistons loose by hammering a wooden block down onto them to break them loose. I concentrated the force around the edge of the pistons. The engine was to be rebored so minor damage would not matter.
    had one engine with funny looking bore surfaces which ran well and had good compression. It was the one that hydrolocked and split so there are photos of it back in this thread.
     
    Last edited: Dec 30, 2023
  14. It happened to me when I put rack and pinion steering in upside down (on purpose) turning the steering wheel left and it went to the right, turn the steering wheel right and the car went left so at that point I made a gearbox to reverse the steering back to normal.
     
  15. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    The engine I am running now was stuck tighter then a knot! Knowing it was the rings that were stuck, I took a hole saw to the top of the piston. I cut down to the oil ring, then the piston just tapped out. I was worried I would crack a cylinder if I just got rough with it. I think it was a 4" hole saw I used.
     
  16. arse_sidewards
    Joined: Oct 12, 2021
    Posts: 220

    arse_sidewards

    I have a grease fitting in a spark plug adapter for exactly that purpose. I fill the cylinder with oil first to save pumping. This is beyond that. I've broken oak 2x2s pounding on the back of the piston with a sledge. I'm sure I'll get it done, it's just a question of where the collateral damage will be.

    I'll probably whip up something a little more specialized out of scrap metal so I can take a full swing at it.
     
  17. If the hole that you sawed simply released pressure on the rings, that is awesome cleverness.
    If I read it properly, does the piston then come out in one piece?
     
  18. Clever to use oil that way.
     
  19. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    Here is what is left of the piston with the hole saw method.
    piston.jpg
     
  20. what about the part of the piston outside of the hole saw cut? Did it have structural integrity so you could use a long punch to move it or alternatively, could it be broken apart? Or was it in fragments? It looks as though your cut was very close to the ring grooves.
     
  21. Flatrod17
    Joined: Apr 25, 2017
    Posts: 577

    Flatrod17
    Member

    What was left outside of the hole saw just fell apart. I lubed the skirts and drove the piston out from the bottom tapping on the pin part of the piston. The idea was to just cut the rings loose from the piston and bore. It worked well for me. Never touched the bore either with the hole saw.
    This was all two years ago, but as I remember it was easy till I got to the oil scraper rings. I first cut ok, but the last (bottom one) spun and caught.
     
  22. With the oil scraper loose enough to spin, perhaps the piston could be pushed out at that point but with rusted cylinder walls it might hang up.

    Since sodium hydroxide reacts with aluminum to form hydrogen and other compounds, one might be able to "dissolve" the pistons loose. I have not heard of anyone trying this.
     
  23. Sean Lougheed
    Joined: Dec 26, 2021
    Posts: 40

    Sean Lougheed
    Member
    from Canada

    The reverse rotation 470 is really quite a brilliant thing. As I understand them the only thing different is a cam gear drive and the reverse starter. Everything else is the same - including the cam. Unlike a V6 or V8 reversing the direction of the crank doesn't change its piston sequencing, so timing and firing order stay the same. Not only that but the cam, now driven the opposite direction than the crank by the gear drive actually spins in the same direction as the standard rotation engine, that way the cam and the distributor stay the same too.

    I think Mercury bean counters probably liked this engine as reversing a big cube 4 cylinder was cheap compared to 6's and 8's that take much more to convert.
     
  24. Scott Danforth
    Joined: Dec 13, 2008
    Posts: 261

    Scott Danforth
    Member

    you guys arent boat people are you. Merc had the reverse running drives in front of one of the motors in a twins installation.
     
    arse_sidewards likes this.
  25. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 3,549

    GearheadsQCE
    Alliance Vendor

    If you refer back to my original question (post 3341) I specifically said that I didn't know much about boats. From the responses, I gather that there are several possibilities.

    So, let me make this VERY CLEAR:

    WERE THERE EVER ANY REVERSE ROTATION MERCRUISER 224/3.7L ENGINES?
     
  26. That is impressive. well done
     
  27. Sean Lougheed
    Joined: Dec 26, 2021
    Posts: 40

    Sean Lougheed
    Member
    from Canada

    For cutting anything over .25 accurately I would recommend a water-jet. The lasers leave a pretty rough cut over 1/4 and look more like it is sawn. It is rare to find someone with a laser big enough to do anything over 3/8. (aluminum absorbs a lot of wattage.) A water jet when run by someone that knows how (important) can be both accurate and leave almost no kerf. Accuracy wise most water-jets have kerf width compensation so if the operator knows you need the accuracy he can dial that in by measuring a test cut on the blank you are cutting the deck plate out of then set the kerf width offset to match so it comes out accurate. This will make up for the condition of the tip which widens the cut as they wear.

    I plan to mill my deck plate and then run the same path on the top of the water jacket to make it match, I will probe the water jacket to get the right shape, and move that line into the block a little when I redraw it. Shifting the tool into liners and block enough to clean them up and create a little register that the deck plate will sit on.

    I am going to think out loud and comments are welcome.... You are correct in saying epoxy is flexible, it seems it has some rubbery-ness, it also doesn't seem to get pounded out so I think there would be a benefit to filling any gaps with it as it will distribute some of the force into the deck plate.

    The Issue of epoxy has bugged me for a while. I have looked at a bunch of these Honda guys that have poured in epoxy decks and many seem quite effective considering they are stressing the heck out of them. But by the numbers (numbers guy here) epoxy is just too weak and can't do what an actual deck does, It really doesn't jive with how much they are cranking up the HP. So is there something else going on? Could be that JB and epoxies dampen the forces, at the top of the liner, they are kind of like a dead blow hammer, that goes thud not ting. I have suspected for some time the stock 470 engine could have harmonic resonance in the liners (as well as the crank and cam), something that could be common to all 4 cyl engines with open decks, many of which have head gasket problems too. A reasonably weak but shock deadening poured in epoxy deck would dampen that out a harmonic and I am wondering if that settles the liners to move less enough and not resonate such as to not pick up a harmonic that would move them more.

    One issue the with the 470 is it has no harmonic dampener (harmonic balancer). The alternator (on both my engines) is a solid flywheel with magnets. This is just a bad idea, and putting a harmonic dampener on will do wonders to dampen out the crank harmonics, extending bearing life, plus it could calm things down throughout the rest of the engine.
     
    dennis g likes this.
  28. Sean, I agree with your thinking. I did not know the detail you provided about water jet cutting . thanks

    I wonder how much precision matters as the gap is going to be filled anyway and it will provide penetration,( hopefully not too much). Phil's photos show what appear to be tig welding.I bought a big tig welder 20 years ago and never plugged it in as it can draws more current than my service can supply. They can make pretty welds.

    The downside of epoxy is that it being plastic (adjective) is that softening begins at a low temperature and increases as temperature increases to the melting point.. A solder, call it whatever you like,( some call it brazing) by melting in a tin-zinc (or other metals) alloy is much stronger than glue and there is no risk of melting the aluminum. I have used brazing making fuel tanks from disposable gas bottles as the metal is so thin that I can't adequately control the heat when welding them. And a braze will not leak like a so so stick weld can.
    The heat of welding changes the properties of aluminum and less heat means less distortion...unless you can evenly warm the whole block up in an "oven" before welding. Stressed welds crack if in brittle metal.
    There are so many advantages of a closed deck, that it is a must do if possible.
    you will have a little step under it for support if you can detrmine the force there you can make it large enough to take the load without compressing and deforming. Anything there will reduce the shear load on the metal connecting the plate to the engine.

    I mentioned plasticity in epoxy. It also takes place in tin as the tin softens with heat. Controlling the melting and softening points can be done with material selection. Another concern is expansion and contraction and it being temperature dependent is different at the top of the cylinder than lower in the block where the support is.

    both epoxy and tin are soft enough to absorb some shock and dampen vibration, but I don't advocate using a really high % of tin as it begins softening below the operating temp of a warm engine.
     
    Last edited: Mar 3, 2024
  29. As dampening vibration was just mentioned (and I'm sensitive to it) i will add that it has never been a problem for me with these boat engines I have usually used dampeners and like the convenient timing marks they have. I ride motorcycles and some have horrible vibration. Clearly the worst was a Whizzer motorbike its handlebars buzzed strongly and made my hands numb in 20 minutes, it seat also vibrated and the condenser shook apart at 6oo miles the rear fender lasted 300 miles , its license plate broke and the crankshaft broke after 800 miles. Soft rubber mounting will stop the transmission of vibration it helps everything except things right on the engine.
     
    Last edited: Mar 3, 2024
    GuyW likes this.
  30. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 1,037

    CNC-Dude
    Member

    Devcon is a better epoxy product brand and it can be stiffened up even more by mixing/blending metal shavings into it as you mix the hardener in with it.
     
    arse_sidewards likes this.

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