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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. I am very sorry to hear of your wife being ill, best wishes for her speedy recovery. Taking care of her, you are putting first things first.

    I looked up your gasket last week I think it was a Sierra gasket(check comments on that earlier in this thread). I bought my gasket online from Pat's Small engine Plus (www.psep.biz) It cost $40 plus shipping. Its part number is L710-27-13709 . Although I was worried, it has not blown out in the two years that I have had it in the engine so mine is working well.

    Dennis
     
  2. turboclubnorth
    Joined: Apr 7, 2010
    Posts: 28

    turboclubnorth
    Member
    from sweden

    Thank you Dennis for help and wishes, I talked to a local mercruiser dealer that I found, and he will order the original head gasket for me. I dont want to take chanses because of the boost from the turbo.

    Johan
     
  3. chowen
    Joined: Apr 22, 2011
    Posts: 3

    chowen
    Member

    I have a pair of these in a 28' Imperial. Run these engines by the book and they are great. 1300 hrs. on mine no problems. Change the coolant every year, use good oil, they like to rev so don't lug them. Most of the problems were from over propping and under 90 octane fuel. I cruise at 3600 and full throttle is about 5600. The marine mechanics hated them because they didn't know them and were too damn lazy to learn.
     
  4. I put a more conservative cam in mine and the power still comes on strongly at 4000 RPM
     
  5. I am about to change distributors. I am going to use a converted Vega* distributor. and Mercruiser engined car owners should consider doing this. It is only for cars driven on the street, not boats, not race cars.
    you will need some parts from a Mercruiser distributor:
    1.the aluminum adapter ring on the neck of the Mercruiser distributor body
    2. the drive gear and oil pump drive rod from the Mercruiser distributor

    * there are no more Chevy II distributors, they are all gone. Some Vega distributors are still available and they share the same body with the Chevy II and the Nova. The Mercruiser 470 uses this body but is drilled for ventilation and bushed out to fit the Mercruiser block and the vacuum advance was stripped off.

    The advantage of using a car distributor on a car is that it has a vacuum advance. I will explain why in the next post.
     
    Last edited: Jan 12, 2013
  6. I abbreviated this from a post on the Camaro board by a retired Chevrolet engineer:

    Why use a vacuum-centrifugal distributor?

    Lean mixtures at idle and steady highway cruise take longer to burn than rich mixtures.
    The mixture must be therefore ignited sooner. For full power less advance is needed.
    Idle mixture is especially lean due to exhaust gas dilution.

    Although vacuum advance is a relatively crude mechanical system, it does a relatively good job of optimizing engine efficiency, throttle response, fuel economy and idle cooling while having no effect whatsoever on wide open throttle. You may see as much as 50 degrees advance above 15 inches of vacuum, below that, the vacuum mechanism operates to remove about 15 degrees of the advance. This does not work with a "big" cam as there is much less vacuum to work the vacuum mechanism.. For those hotrod engines use an Echlin # VC1810 vacuum can (available at NAPA) it operates down at 8 inches of vacuum

    Using manifold vacuum versus ported vacuum. Ported vacuum is zero with the throttle closed at idle. The purpose of it was to increase exhaust temperatures to reduce emissions on the exhaust air injection pollution systems. Cylinder pressure dropped,the engine to ran hot at idle, combustion efficiency decreased, and fuel economy decreased. The engines with ported vacuum spark advance did not run well.
    He says to just use manifold vacuum instead.

    (the above is about 10% of what he wrote which was reposted to the Corvette Action center)

    www.corvetteactioncenter.com/forums...our browser for it to work due to its length.
     
    Last edited: Jan 12, 2013
  7. Vega and Mercruiser distributors compared.

    In a side by side comparison, there are differences, but not so big that they can not be overcome.

    The vega distributor has a different gear which is mounter higher on the distributor shaft.
    The vega shaft is 7mm longer.
    The vega shaft extends 2mm more into the cap than the Mercruiser shaft
    Expect the two rotors to fit but a Vega rotor can cause an erratic misfire in a Mercruiser which can be frustrating to find. (guess how I know this)

    The bodies appear to be the same casting with the mercriuser distributor body neck bushed longer and fatter.

    The mechanical and vacuum breaker plates interchange. A little slot needs to be filed out for the vacuum pot arm. And two holes drilled and tapped to mount the pot.
     
  8. Vega and Mercruiser distributors compared.

    In a side by side comparison, there are differences, but not so big that they can not be overcome.

    Differences:
    The gears do not interchange
    The shafts are different the (Vega shaft is 7 mm longer is drilled differently.)
    A Mercruiser distributor has a shaft oil seal
    The rotors are keyed differently to prevent accidental interchange.
    The bodies are close but different. the Mercriuser distributor body neck is longer and bushed to be fatter.


    The mechanical and vacuum breaker plates interchange. A little slot needs to be filed out for the vacuum pot arm. And two holes drilled and tapped to mount the pot.

    To make a vacuum conversion, you will need the parts from two distributors.
    Adapting the Mercruiser distributor body by drilling and filing is far easier than machining the Vega distributor body, making a bushing, putting a bearing (bushing) in its end and inventing a lubrication scheme. The Merc shaft is the one to use as it is drilled properly for the oil pump drive extension.
    The shaft can be shimmed up and down to fit the cap using washers under the advance mechanism. I measured end play on all three distributors at .035 thousandths. If it was shimmed to 10 thousandths end play timing would be more accurate.

    Merc parts to adapt a Vega distributor:
    distributor shaft (Merc)
    drive gear (Merc)
    delco lower bushing (Delco)
    adapting sleeve ( you make it from billet)
    rotor (merc)
    cap ( depends how you shim the shaft)

    Vega parts to adapt a Merc distributor:

    Delco advance plate with advance mechanism
    Delco vacuum pot
     
    Last edited: Jan 23, 2013
  9. aussie63
    Joined: Jan 28, 2013
    Posts: 13

    aussie63
    Member
    from australia

    hi im doing a engine for my boat and i read alot of the 51+ pages-my question is about harmonics from crankshaft and camshafht--My plan is to do away with the water pump in the timing cover and fit a electric one only because of the seal failure on them-now i may off changer my mind.do you think that merc put the water pump on the camshaft to help with harmonics because it seems like a implelor in water woul act like a dampener--do you also think thats why merc done it that way
     
  10. dawford
    Joined: Apr 25, 2010
    Posts: 499

    dawford
    Member

    aussie63,

    I think that the Mercury Marine Engineers put the water pump on the end of the cam and the alternator on the end of the crank because that is the way that they have always done it.

    The 470 is the only inboard engine that they have made for the Mercruiser application.

    They usually buy engines from ford or Chevrolet and convert them for marine use.

    The Mercury outboard engines have the components run directly from the engine without belts.

    Those that who have extensive knowledge of this engine being used in a cars have not complained about harmonics.

    The 470 being a large displacement 4 cylinder engine without counter rotating balancing shafts does have some vibrations however the weight of the huge crank, the flywheel and clutch or torque converter pretty well dampen those vibrations in an automotive application.

    I do not think that the absence of the water pump on the camshaft will be a problem. I would leave the heavy alternator balancer on even though I would run a standard marine alternator in a boat.

    Dick :) :) :)
     
  11. turboclubnorth
    Joined: Apr 7, 2010
    Posts: 28

    turboclubnorth
    Member
    from sweden

    Hi again from Sweden.
    Have anyone changed the timing chain and sprockets?
    I suppose the model is some kind of Ford smallblock, but is it really possible to change the parts. ( thinking of the length of timing chain and the mounting off the sprockets)
    If it´s possible what model should I use.

    Johan
     
  12. Hi johan,
    Ask Randy, he must have done it if anyone has. I just found nearly new but used Mercruiser sprockets, chain and tensioner and used them. It would be silly for Mercruiser to have special chain and sprockets, so they exist.
    dennis
     
  13. I agree with Dick on running the alternator/balancer. The weights fell out of mine while it was being balanced so I had to use an automotive dampener.
    My engine does not vibrate noticeably.
     
  14. It might dampen the cam a little, but I don't know if it amounts to anything. It is a good idea to get rid of the stock water pump as the cam wears badly at the seals. The electric pumps should work well and save some power which can be used to drive the car. I used a toyota corolla pump bolted onto the front of the engine and belt driven as it was less expensive.
     
  15. I have my engine running again and with a converted Vega distributor. After I finished I found that a 1969 Rambler American distributor was much closer to the Mercruiser distributor. Martin suggested converting a volkswagen distributor as they are so small.
    Good suggestion as there is only a few thousandths clearance between my distributor cap and the water neck I added at the front of the intake manifold. That was after serious grinding.
    Old 4 cylinder points distributors with vacuum advance are not common as they once were. So if you are thinking of using one, keep your eyes open.
     
  16. Firehawkslp
    Joined: Dec 7, 2009
    Posts: 2

    Firehawkslp
    Member

    from which eng the 6cyl or the v-8 amc? Thanks

    roger
     
  17. Fairlane Mike
    Joined: Sep 21, 2010
    Posts: 389

    Fairlane Mike
    Member

    Just ran across this thread, Dennis, you are very sharp, analytical type. I don't know if anybody answered your question, I am a FoMoCo guy through and through, but I like Q-Jets. I have ran them on almost six different Fords. Extremely tuneable, G.M. used them on 231 to 501 cubes. Your question, back in the eighties I was committed to improving mileage on 2 different vehicles. I don't think G.M. had a wet float value or measurement, float settings were one area I experimented with, I do remember setting the dry value and then trying to get a fuel heighth when I had the top off for a jet or rod change. The phenolic floats I consider a liability, I believe they were used for cost considerations only. Not sure what you want to do with it, you may have to create your own parameters. On a lighter side, I have only used the bath tub for cleaning SOME parts, usually just pistons I have soaked with oven cleaner to "scrub" out the under side!! Out of curiosity, what kind of a motor was it you had in the tub?? I use the kitchen floor to assemble engines, nothin' grimey, you could eat off my engines!! LOL!! Oven cleaner is one of my alternates to more costly stuff! Also your friend in Florida buying a lawn mower to "mow the lawn", LOL!! Imagine that!!
     
  18. The 6 cylinder engine in the late 60's Rambler American came with a delco vacuum/centrifugal advance distributor. the others may have also. It had a body which looks right and only needs to be "fattened" with a tube and of course you will need to add the lobes from a 4 cylinder delco distributor.
     
    Last edited: Feb 10, 2013
  19. Yamaha motorcycle engine in the tub, it was just stored there as that was the only part of my tiny student-days apartment (40 years ago) which was not in daily use.
    A carpeted area is nice for engine assembly, I just roll a heavy engine around to get it oeriented the way I want. I can sit right down near it to work. and not sit in dirt, oil or antifreeze. I'm no lawn lover, have a dinky lawn and mow it with an electric mower. Planted periwinkle around it and year by year there is less grass to mow.
     
  20. There is another distributor option. A mid 80's cavalier has a 4 cylinder HEI distributor which could be reworked if you wanted to use an engine with computer controls. If you went that way, you could use throttle body injection. As early 90's Lumina throttle bodies, sized for 125 hp, are nearly large enough.
    I use 2bbl motocraft carbs because of their simplicity ( and because I've run them without trouble for 48 years). So I'm not likely to go to HEI as a functioning coil and points ignition is as good (in my opinion) for a car which does not rack up miles.
     
  21. A side by side comparison of two distributors I used in a mercruiser distributor conversion. Easy even if they are not quite the same. M&v.jpg ........ merc vs vega top.jpg

    It was not too hard to make them the same length. The shorter one is a 1974 Vega distributor. They can still be found.

    Note that the Mercruiser distributor has a vacuum advance slot in its casting.
     
  22. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

  23. tjm73
    Joined: Feb 17, 2006
    Posts: 3,315

    tjm73
    Member

    I'm dreaming about this engine again. LOL!!

    If you didn't want to cut the bell housing area, could just bolt up an automatic trans? Like a 200R4 or a 700R4? I can't make sense about how the torque converter can mount to the flex plate and still interface the trans properly.
     
  24. Bad Zuk
    Joined: Mar 10, 2011
    Posts: 11

    Bad Zuk
    Member
    from US

    yes you can.

    I have a th350 bolted to the back of my 3.7. After much measuring and playing with flex plates and spacers and not having a solution I was comfortable with I simply made a bushing on a lath to hold the snout of the torque converter, and then drilled the stock flywheel with the correct bolt pattern for the converter.

    So far it has worked well, I was worried about the excess weight of the flywheel and torque converter together, but the engine still revs up well, and on the low rpm it lugs along like a tractor.

    I use this in my off road buggy, so it is not a screaming high performance drag machine, but it scoots along just fine.

    Total cost? = about 10 minutes of machine time from a friend, and a 2" long piece of scrap tubing.

    Having one of the best performing and most unique rigs on the trails...Priceless.
     
  25. Bad Zuk
    Joined: Mar 10, 2011
    Posts: 11

    Bad Zuk
    Member
    from US

  26. turboclubnorth
    Joined: Apr 7, 2010
    Posts: 28

    turboclubnorth
    Member
    from sweden

    Hi again I got my headgasket and I just wonder how did you seal the outer side of the lifter gallery. Why don´t the gasket go all the way on the outer side?

    // Johan
     
  27. moonlight graham
    Joined: Apr 17, 2007
    Posts: 155

    moonlight graham
    Member
    from wyo

    Any of you guys interested in a factory four barrel intake and carb? I have one i'm never likely to use.

    Thank you,

    geoffrey@bresnan.net
     
  28. As My block was milled I reduced the width of the lifter gallery cover so it would still fit. You might use rtv silicon to seal it.
     
  29. turboclubnorth
    Joined: Apr 7, 2010
    Posts: 28

    turboclubnorth
    Member
    from sweden

    I dont think you understand me right. I mean the surface between the block and the head. Why dont the headgasket go along the block side.

    / Johan
     
  30. The head to block joint you mention is not under pressure. Silicon seal is enough to plug it and block air and oil mist from going in and out there.
    The why is harder, perhaps the gasket was developed from a Ford 460 gasket. The main reason to use Mercruiser head gaskets is the better sealing properties they have.
    The Ford V8 may not have a sealing surface at the point which concerns you.
    Johan, your gasket is like all of those which I have seen, so don't worry about it.
     
    Last edited: Apr 15, 2013

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