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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. It is not yet assembled as I think I'll take the block out Tuesday for a freshening of its top surface.
    So If you just want to see pictures of parts, ok: first the milled rear surface [5/8" removed]. Then block pix flywheel pix and modified intake manifold [needed as I'll be using a stock Ford head but not drilling for a water outlet in the front of the head]. cut block.jpg




    Then there are some carb options:

    Attached Files:

    Last edited: Jul 1, 2010
  2. FormerFueler
    Joined: Feb 3, 2009
    Posts: 410


  3. We can use smaller alternators from a geo metro etc. There is a Japanese alternator mounting bracket that I really like as it has a belt tensioning bolt as part of it. They sell for $30 and as on most alternators, the regulator is inside, so is all of its fan. In the photo of an alternator mounted on an allis chalmers engine, I mounted the alternator on the car frame and ran the tensioner to the engine.

    Attached Files:

    Last edited: Jul 1, 2010
  4. BigChief
    Joined: Jan 14, 2003
    Posts: 2,081


    Do you have more information on the application/part number for that bracket/alternator combo? My girlfriend wants to do an alternator swap on her NAA tractor and I'm still looking at options for my dad's '29 A coupe and my '48 Tudor.

  5. I went out to a wrecking yard and pulled the adjusting arm from a late model Japanese car. I think it was a Toyota made within the last 15 years. I don't even remember if it was on th alternator.
    It is distinctive, just look for the allen headed belt tensioning bolt at a right angle to the arm, no part number is therefore needed. It is easy to see. In my case I had to change to a slightly longer adjusting bolt.
    The adjustment is precise, easy and fast. Nicer than any other that I've seen.

    As to the alternator, mine was from a 1980's Suzuki Swift but a geo metro one would be equivalent. It looks a lot like the alternator on my wife's toyota echo.
    And even as small as it is, its output exceeded 50 amps on a test stand.
    Even smaller ones were on the 350cc Honda minicar.
    If you are looking for especially small alternators, some garden tractors have them.
  6. Do any of you know the thickness of a compressed merc 470 head gasket? I need an accurate figure to use to cut my block to adjust deck height(if needed).

    My new gasket measures .058 is labeled 1.2mm [50 th]
    Mercruiser could not come up with a thickness but warned against cutting more than 10 th of the top of the block. I've the feeling that they got the squish area wrong in the first place [73 th by my best estimate] and that much air over the piston would result in a detonation-prone engine. Could all that distance be something for valve clearance?
    As the engine comes up to temperature I'd expect the aluminum block to expand more than the steel conrod, thereby increasing the squish distance even more.
    in all fairness , I can't blame merc for the excess squish in my engine as it has hypereutectic pistons so I assume someone put aftermarket pistons in it.
    Last edited: Jul 3, 2010
  7. Do any of you have a figure for your deck height?

    I measured the distance from the block top to piston crown and got : .024", .022", .023" & .025" on $1,#2,#3 & #4 respectively. this coupled with a gasket .050" thick would give from .072" to .075" deck height, and that is too much.

    It looks like I should ask to get .030" milled off but Mercruiser said don't take more than .010" off.
    I don't know why they put that limit on it[ unless it is to keep it detonating :0) ]
  8. Warpspeed
    Joined: Nov 4, 2008
    Posts: 532


    I agree with you Dennis.
    Tighter squish, even with slightly more compression should improve the detonation resistance.
    I don't know the answer.
    The only wild off the wall theory I can think of right now, but how does the rocker arm geometry look ? Might there be a problem with excessive push rod length if you start cutting down either the block or head ???
  9. Possibly so, pushrods come in sets of different lengths to set up the valve train.
  10. dawford
    Joined: Apr 25, 2010
    Posts: 498


    Mercruiser engineers are some of the best in the world and even though this engine was engineered 34 years ago in approximatly 1976 I'm going with the engineers for reliability and torque HP.

    These engines were designed to pull all day long at 4500 to 4800 rpm against a wall of water.

    As I understand it when gasoline was reformulated people started having heating problems caused by pre detonation.

    The Mercruiser engineers then recommended that the timing be retarded about 5 degrees.

    We now have slightly better formulated gasoline than they had back then.

    We are also not taxing the engines with long time pulls against constant resistance as they did in boats.

    Our cars are light weight and will never offer the resistance that pulling 2 skiers and lifting the boat on plane nor will we be going up hill all day long in high gear.

    I believe that we can probably time the engines back to the original specs and maybe even advance the timing a couple of degrees without any trouble.

    If you want to increase the compression I would buy some Procomp aluminum heads with 84cc combustion chambers or even the Edelbrock heads with 75cc combustion chambers.

    On my first engine I will go with the stock 95cc size chambers on aluminum heads that are similar to Procomp but made by another supplier.

    If the first engine doesn't perform well enough to satisfy my needs then I might look at a turbo. In that case I won't want to high a compression ratio anyway and I will probably only want a low boost because I want bullet proof reliability.

    :) :) :) Dick :) :) :)
    Last edited: Jul 4, 2010
  11. You are right Dick.
    1. The cars run on the street offer little load on the engine which runs with its throttle closed and the cylinder is not filled so the effective compression ratio is much less.
    2. The alloy head with what is said to be a less detonation prone combustion chamber. would be a very good option.
    3. The engine should not be run retarded.
    4. higher octane premium fuel may be part of the solution to detonation.

    It does appear that the engine would benefit from tightening the squish a bit .075" does not squirt the air out from under the low part of the head as violently as .050". It would seem that the admonition to not remove more than .010" from the head or block is more about maintaining pushrod length so the lifters function, than anything else. Shims can be placed under the "saddles" on which the rockers pivot. This should preserve rocker arm geometry.
    Last edited: Feb 28, 2018
  12. dawford
    Joined: Apr 25, 2010
    Posts: 498


    The primary reasons that I am running the aluminum head doesn't have as much to do with pre detonation or squash as it does with bigger valves and ports providing better flow and with aluminum heads on an aluminum block.

    The intake valves are 2.19" and the exhaust valves are 1.76" and with the Mercruiser cam and the 1.72 rockers they provide about 1/2" of lift. The ports are large and smooth enough that I don't think I will have to port or polish them to achieve a very satisfactory result.

    The aluminum heads not only cool more efficiently but they also expand at the same rate as the block.

    In the original Mercruiser application with the heat exchanger acts as the radiator. It uses lake or sea water to cool the closed loop cooling water that runs thru the block.

    That way the engine runs at a constant temperature (170-180 degrees) as long as the system is functioning correctly. That system functioned pretty secuessfully if it was properly maintained.

    In a car the system relies on a radiator that hopefully is sucessful at maintaining tempretures near that range.

    My concern is that if I decide to drive cross country thru the desert and up hill when it is 109 degrees and the engine temperature gets up to 212 or more will I risk blowing a head gasket.

    In years past when some cars had cast iron blocks with aluminum heads or when they had aluminum blocks with cast iron heads they sometimes had gasket failures due to unequal heat expansion of the 2 dissimilar metals.

    The pictures have a silver dollar for size reference. If the valves were removed I think you could drop a hard boiled egg in the port and it would drop into the cylinder.

    :) :) :) Dick :) :) :)

    Attached Files:

  13. A very nice head Dick. Very nice indeed. I'm envious.
    they don't cost too badly $500+ for the single head we need and as everything is new the springs are all the same the guides and seats are all perfect and the combustion chamber is better. Not to mention larger valves if they are desired.
    And what you say about thermal expansion is a good point.
    Last edited: Jul 6, 2010
  14. Yesterday I found that an AN4 thin washer is a fairly good fit under the rocker tower. It only took a slight grinding on two opposite edges to fit in the slot in a Ford head.
    AN washers are made to have consistent and accurate thickness [ aviation spec].

    my thin ones were 0.017" thick.
    In a rough measurement a single thin washer increased the valve stem clearance about 0.030.

    Thick AN washers are also available. Shims assortments are available $11 for 36.

    I would not use more than a few washers as the rocker toweer must fit down in the "slot" for alignment of the rocker arm.
    But it is an alternative to the better solution of a different length pushrod for adjusting [fully collapsed lifter] valvestem clearance to be within 0.110" to 0.210" [so the lifter is in its operating range].
    Last edited: Jul 7, 2010
  15. how much does a "cheap" head cost?:
    $75 core purchase at wrecking yard
    40 to replace two valve guides
    53 resurface head
    160 grind 8 valves

    $330 total and if you do the valves $168
    It is about $220 cheaper than a new aluminum head, not greatly different. Clearly, it would be unwise to buy a new iron head. A used one balances out the cost but the features of the alloy head tip the balance toward one of them.
    Last edited: Jul 16, 2010
  16. dawford
    Joined: Apr 25, 2010
    Posts: 498


    The last 470 I bought has no head and is .030 over with dished pistons.

    It was presented as a runner without the head, manifolds and cooling parts. The man that I bought it from had been a mechanic and seemed to know what he was talking about.

    I supose the dished pistons were in responce to the detonation problem caused by reformulated casoline.

    Anyway the reason that I bought the engine was for parts.

    Since buying that engine about 2 months ago I purchased a set of 460 cast iron heads at a garage sale for $10.00 one of which has a bent valve and a damaged combustion chamber. The other looks to be very fresh.

    I also have 2 heads out of a Pick-A-Part that came out of a Truck that looked like it was a failed or abandoned rebuild attempt. These heads look to be a freshly rebuilt.

    I think that I might slap one of these heads on the .030 over block and see if I can get fire.

    If the compression and oil pressure are ok I might use them for initial installation in my Model A Pickups.

    The only downside if I fail to achieve my goal is the loss of time and a head gasket.

    :) :) :) Dick :) :) :)
  17. I looked at clearance between the head & piston crown. .073" if my head gasket compresses to .050". However there is not much clearance between the exhaust valve and the bottom of the piston recess...I wonder if valve clearance is the limiting factor on removing material from the top of the block. Mercruiser said don't take off more than 0.010". I figured the clearance to be 0.010" if the exhaust valve is fully open when the piston is at t.d.c. [ I'm not sure the valve actually is fully open at t.d.c.]
  18. Ok, I bit the bullet and asked for my block to be zero decked. I see no alternative to doing it.
    The valves can be recessed in the head or the piston valve clearance recesses may possibly be deepened so I've an out if the valves interfere with the piston.
    I want .085" intake valve clearance and .125 exhaust clearance. and around .045 squish.
  19. Phil1934
    Joined: Jun 24, 2001
    Posts: 2,717


    If valve adjustment is a problem, I've still got a half set of Crane conversion studs and BBC Energizer roller rockers.
  20. Thanks Phil, I appreciate your offer. I'll know in a few days.
  21. a set of pistons and machining the block and head have brought the total I have spent to $1700. Although it is not cheap it is still within reason. post #76 has the cost in detail.

    Summit got them to me in 3 days.
    Last edited: Jul 23, 2010
  22. I measured my cam and found some lobes worn 0.135 and a couple worn only 0.014. This is why the previous owner said it never ran right. Mystery solved.
    Not having a spare I took my old camshaft to Redline Cams in Albany Oregon [they have given me excellent service, I'm a repeat customer and recommend them] and arranged for a regrind. I asked for a milder crower grind, one I liked very much in my chevy van.
    { lobe centers 14 degrees
    203 degrees intake duration and
    210 exhaust duration,
    lift 0.278 [in] and 0.283 [ex]. }
    My reasoning was that I could sacrifice some top end power for more mpg. He suggested 15 degrees separation for better gas mileage so I'll try it.
    They are also going to balance the engine from flywheel to alternator.
    Last edited: Jul 22, 2010
  23. Does anyone have a favorite cam profile for this engine? [for street use]

    My cam was worn out and I'm getting it reground tomorrow. For a chevy 350 I liked a Crower Baja Beast grind [ lobe centers 112 degrees, 50 th duration 202 degrees for intake and 210 degrees for exhaust]these are the specs for that cam profile set for a 460 ford .
    My van did not need high rpm power and it had lots of torque, it saved gasoline and it would even rev freely.
    For a low speed vehicle it seemed to involve no compromises. Vacuum was high[ 18 inches at idle].

    So anyway, I'd like to hear some opinions.
  24. dawford
    Joined: Apr 25, 2010
    Posts: 498



    When I first decided to use one of these engines I took the stock 470 Mergruiser cam over to Jim Brierley of Brierley Cams to have the cam checked over.

    Jim grinds cams for the salt flats and other earley ford aplications and is very sharp on 4 cylinder power.

    He checked the profiles and timing of the cam and said that I should run it as is because he said that it would work very well in the Model A that I was putting it in.

    He further stated that unless I intended to go all out race with the engine that it would be hard to improve on what the Mercruiser Engineers had come up with.

    I have purchased good original cams for $50.00.

    The 190 hp cams have a slightly more agressive grind but are hard to find and are not that much different.

    Most of the 20 HP gain between the 170 and the 190 was from the QuadraJet 4 barrel carb and 4 barrel manifold.

    I am sticking with the stock cams.

    I will get my extra HP from the improved Performance of the aluminum head with the bigger valves and better flow and the slight reduction of friction with the roller rocker arms.

    :) :) :) Dick :) :) :)
    Last edited: Jul 26, 2010
  25. As the cam I had was worn badly, I had it reground as in message 264 as I will not be in the mercruiser optimum rpm band very much and I'm trying to take advantage of what the motor has [ torque] and hope to get a little of what it often does not have,
    good fuel economy.
    It may work, or It may not, but it is an experiment.
    I do anticipate buying a used cam with good lobes as I doubt that the motor will putout much power with the much milder profile.
    My motor is now carefully balanced. Its alternator rotor spit out a magnet so I'll buy a damper this week. It seems that pickups had engines with heavier dampers. A ford 300 damper may be the way to go.

  26. here are some heavier ford harmonic dampers
    FORD 300:
    C8TE-C 13 LBS 65-68 3 BELTS
    E3TE-BA 12 LBS 65-81 3 belts
    C8TE-AB " " " " "
    C5TZ-J " " " " "
    FORD 351 :
    D1ZX-AA 13 LBS BOSS351

    NOTE : some ford truck dampers weigh up to 20 lbs
    Last edited: Jul 29, 2010
  27. dawford
    Joined: Apr 25, 2010
    Posts: 498



    I am going to try a Professional Products S/B ford balancer from Speedway $67.99.

    The one I got has a removable 50oz counterweight which I have removed.

    With the counterweight removed it is zero balance and weighs about 10lbs.

    It also has 3 sets of timing marks.

    If the engine has too much viberation when it is in the car I figure that I will get another 50oz counter weight and install 2 of them to add another 6 1/3 lbs or get 2 of the 28oz and add 3 1/2 lbs.

    If I add the 2 counterweights I will have it rebalanced before installation.

    Others who have used zero balance mustang clutch and flywheels with zero balance S/B balancers have not reported any balance problems.

    Remember that the crank has only single wide conrod throws and extra wide counter balance weights.

    The crank weighs about 66 lbs.

    Add 18 to 20 lbs of balancer, 40 lbs of flywheel and pressure plate and 4lbs of pulley and misc. bolts and you have 120 lbs of rotating weight.

    That is a lot of weight to counter and absorb the power pulses and reciprocating forces involved.

    :) :) :) Dick :) :) :)
    Last edited: Jul 29, 2010
  28. Dick, thanks for the weight info...I did not have it. And the price info also as that price competes even with JC Whitney. I'd say you are right about adding the second 50 oz wt. I'm going to balance my balancer in any case as It will be free for me.
    The weights go on the rim, where they would be most effective, don't they?
    As these dampers [or dampeners] are a frequency tuned device, do you have any info on what frequency or RPM they work best at? More weight = lower frequency. I wrote the company for that info and will post it unless you beat me to it.
    their phone number is 323-779-2020
  29. dawford
    Joined: Apr 25, 2010
    Posts: 498



    The weights go on the inside of the rim where they won't interfere with the pulley and centrifugal force will lock them to the rim at rpm.

    As you can see the 50 oz weights are 1/2 circles that would make them easy to double up by drilling and tapping additional mounting holes.

    The only problem might be with interference with the pulley mounting holes that are already in the balancer.

    Still I really don't think the extra weight will be necessary in our application where we won't have to run at any particular sustained speed.

    The T-5 transmission will allow a gear shift to another ratio should any harmonic develop at a specific speed.

    I have a weighted arm that was attached to the tail shaft of one of the T-5 transmissions. I suspect that I might try to use it to dampen any harmonic that might develop.

    Again I haven't heard anyone complain about any balance problems in a street vehicle.

    If you just want a big heavy balancer use an original Mercruiser balancer with the magnets in it. Just loose the coils and get a power steering pulley for an external alternator.

    I didn't want to use the original balancer because it sticks out so far that it would necessitate moving the engine back even farther into the firewall.

    :) :) :) Dick :) :) :)

    Attached Files:

    Last edited: Jul 29, 2010
  30. I bought the same dampener that you did. Thanks for your help in making the decision.
    Yes the original mercury alternator rotor is really big, and the magnets are brittle and only glued in. I was going to use it until one magnet fell out. I then decided that I had to get a dampener. Not only do they look much better they are also heavier and cost less than a rebuilt Ford dampener.
    As to the weight, I also asked for a 50 oz one. You don't want the weight sitting on the rim though as the weight seems to screw into the center part of the balancer. The rim must be rubber-isolated from the center for it to absorb vibration well.

    My alternator rotor has a pulley as part of it.
    And I also have engine length problems due to the big alternator rotor.
    I think there would also be some dampening effect from a belt driven alternator
    ps: I like the color of your carpet
    Last edited: Jul 30, 2010

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