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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. Three Widow's Garage
    Joined: Jan 18, 2010
    Posts: 230

    Three Widow's Garage
    Member

    Thanks for the diagram, It looks like if you eliminate the intake heating, exhaust cooling and the raw water lines you end up with the coolant coming in the front of the block and exiting the front of the head just above where it entered doesn't seem like the back of the motor would receive much circulation. Would it matter if the flow was reversed? It seems to me that it would be better if the coolant could enter the front and exit in the rear somehow.
     
  2. tjm73
    Joined: Feb 17, 2006
    Posts: 3,484

    tjm73
    Member

    Looks like the head gasket restricts the coolant flow path to go around the cylinders and enter the head from the exhaust side only. Then it flow around and out the end of the head.
     
  3. Three Widow's Garage
    Joined: Jan 18, 2010
    Posts: 230

    Three Widow's Garage
    Member

    That would make sense, I 'll have to check out the head gasket wonder if the Mercruiser is different than a standard Ford. It could force most of the coolant around the cylinders then into the head at the back of the block and out at the front of the head. Still wondering if it would matter if the flow was reversed.
     
  4. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    Yes, it matters. The colder coolant enters the cylinder area soaks up some heat then goes into the head. If the cold coolant enters the head first you will crack the head.
     
  5. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    At first glance they look the same but the Mercruiser gasket is different from Ford because of sealant around cylinder bores. DO NOT USE FORD GASKET UNLESS you have closed the deck!
     
  6. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 3,375

    GearheadsQCE
    Alliance Vendor

    Since this thread is getting some renewed interest, can anyone take some measurements on a block and head?

    I'd like to know the length and width of the head at the block mating surface. Also, how big of a piece of aluminum plate would it take to make a plate to close in the deck.

    Also, what is the crank to cam center distance? A tape measure or scale would be close enough for now.

    I've had my eye on an engine here. The guy has been selling off all the boat pieces and I think I can pick up the short block fairly reasonably, soon.

    Thanx in advance,

    Bruce
     
  7. Three Widow's Garage
    Joined: Jan 18, 2010
    Posts: 230

    Three Widow's Garage
    Member

    I can get some measurements tomorrow P.M. Just a heads up if anyone is looking for engines keep an eye on e-bay for a seller boatangelministries, they get unwanted boats donated and run them with a $10.00 starting bid most of them go real cheap. I've seen 3 Mercruisers in the last few months you have to know what your looking at, the ones you want will have the intake and exhaust on opposite sides. Read the fine print the seller charges a 300 dollar paperwork fee on top of the sale price, pick up is on you - no delivery. Just checked and didn't see any right now but I'm sure they will have more. Scrap the boat sell the trailer get a almost free motor.
     
  8. Three Widow's Garage
    Joined: Jan 18, 2010
    Posts: 230

    Three Widow's Garage
    Member

    I finally got chance to get some measurements. The deck of the block is 21.5" X 7.75" the plate would be 2" narrower as it wouldn't cover the lifter / pushrod area. The crank & cam are still in my block so I measured the snout of them divided those in half and added the distance between and came up with 6.035" I'm going to guess the centerline distance is actually 6". Hope this helps.
     
  9. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 3,375

    GearheadsQCE
    Alliance Vendor

    Yes, thanks that helps a bunch.
     
  10. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    Going to clarify a few things.

    The block is 1 inch deeper could be 1.125 off my measurements. Or my 78 block us anyway.

    I know people who have 460 gaskets in there 4 cylinder and they run.

    That intake really needs water. Pontiac tech4 have water in the intake too.

    I'm starting my project back up. Going to weld some washers on a tall sbc throwout bearing. Notch the bellhousing. Drill the crankshaft. I had someone drill the flywheel for gm 10.4 diaphragm. It was right on the edge of the wheel. Let's hope the water pump seal doesn't go out when I get it going. And jegs sells inline thermostats. Oh! You can use liquid aluminum to close the deck. B20 honda guys use some chemical aluminum and pour it around the cylinders bake it and drill it. I'll post a link when I find it.
     
  11. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

  12. tjm73
    Joined: Feb 17, 2006
    Posts: 3,484

    tjm73
    Member

    I would question if the open deck is an issue at anything less than all out competition levels of power. I would also think that the biggest problem is the iron head/aluminum block configuration it left Mercruser with. Which any of the good BBF aluminum heads would correct. An aluminum BBF head should be performance change number one.

    Lately I've been thinking that a Holley throttle body EFI (looks like a carb) on any factory intake (Holley makes 2 and 4 barrel setups now) with an aluminum head, roller rockers and a block header would be a simple reliable and relatively powerful setup. The EFI is decidedly not HAMB friendly, but much of this thread is not exactly HAMB friendly as pretty much everything is outside the "guidelines". Thankfully the captain of this ship has let this one slide and there is now a wealth of useful info on this oddity in this thread.
     
  13.  
  14. I used a Mercruiser gasket ($64) on my first build. It had beads of sealant. Later I used another gasket with sealant beads ($38). Most recently I bought a Mahle gasket but it lacked sealant beads and that lack makes me uneasy as Randy Dupre wrote that only the Mercruiser gaskets could seal. Randy posted on this early in this thread.
    A Mahle tech told me they made the original Mercruiser gaskets.
     
    Last edited: Oct 29, 2018
  15. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    I got a cheap Chinese scj head and just going to slap it on with studs. I also got a set of eBay headers and the driver side worked fine just had to bash to clear the starter. I'm gonna keep mine carbed. It runs fine.
     
  16. Cheap does not tell me enough. Roughly what do they go for?
     
  17. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    I was thinking along the same lines, but also boring cam journals for regular cam bearings with an .05 offset to correct timing chain slop. Having a hydraulic roller cam ground and bush the lifter bores. There is a factory cast truck exhaust manifold with O2 bung available.
    MVC-615F.JPG.jpg
     
  18. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    The Holley Sniper EFI 2300 is a 2 barrel that supports up to 350 HP, that should be more than enough for a street engine. The other mods I mentioned should make a very long lasting reliable engine.
     
  19. iadr
    Joined: Apr 14, 2007
    Posts: 147

    iadr
    Member

    99% sure that manifold is for the late head from 89 or so up truck applications.
    On those, the exh ports are shrunk and moved upward relative to the line of studs. It's an application of what Ford A460 heads taught, applied to production.
    Result of putting that style manifold on to the engines we are speaking of, would probably be about a 5/8" (!) port mismatch relative to "OE Mercruiser (vintage Ford)" & most new aftermarket heads.
    Performance heads in the aftermarket are designed for compatibility to the earlier heads - which in this sense are the inferior heads... But they are what belongs to the muscle car era and is what headers and such are built up for, so that's how performance heads are cast.
    Some aftermarket heads have slightly raised ports but they raised the stud line with the port, so the misalignment problem remains.
     
  20. tjm73
    Joined: Feb 17, 2006
    Posts: 3,484

    tjm73
    Member

    That manifold is from a heavy truck.
     
  21. iadr
    Joined: Apr 14, 2007
    Posts: 147

    iadr
    Member

  22. drtrcrV-8
    Joined: Jan 6, 2013
    Posts: 1,707

    drtrcrV-8
    Member

    Dennis G: Which "cheap Chinese head" did you use, which vendor, & how much??? Inquiring minds want to know......
     
  23. I'm using iron ford and mercruiser heads Ivans572 has not replied to my cost question.
    Weight saving is important I run tube headers and would like aluminum heads .

    If you have to buy heads, old iron heads are no bargain. My advice is to buy a new head instead.. as to new heads new iron heads are not cheap and junk heads are expensive after fixing them. I bought a junkyard Ford head for $75 and after paying to do valve guides, valves and surface the head It was close enough to the cost of a new iron head that I'd say just get an aluminum head instead. If you do the machining an old Iron head is not so bad...except for its weight and poor combustion chamber.

    A friend suggested that I make a zero deck engine. My cranking compression was around 165 psi and it did not knock. A cam change and the cranking pressure became 210 psi and it knocked badly. Cam timing matters...a lot.
     
    Last edited: Nov 26, 2018
  24. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    Have a pic from earlier in this thread of someone using this manifold, can't remember who posted it. PICT3203 (Small).JPG.jpg
     
  25. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    Here are pics of a head from Summit Racing 429/460 head and the cast manifold. Looks to me as if they will match! BBF460Bare.jpg s-l400(2).jpg
     
  26. BIGDOG69
    Joined: Jul 6, 2018
    Posts: 21

    BIGDOG69
    Member

    Found heads on eBay, $1300 a pair for hydraulic flat tappet or $1350 for hydraulic roller.
    Item #202208972257
     
  27. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    I got my head for $300 used. Not that great but 325 cfm at .650 is great. Too bad my cam is only 220 degrees with 500 lift.
     
  28. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    When I am at school tomorrow I'll get a picture of my eBay header. Had to buy 2 for $100 but built well. But here is a v8 monza bellhousing. Really need a 4cyl housing since it makes use of one more bolt. But if it breaks I'm damn good at pulling motors. To take the chunk out I drilled holes and angled the drill in the hole and took out lots of material. But here is a picture of it. I know a lot, and know lots of people. So ask away. 20181126_121236.jpg 20181126_121243.jpg
     
  29. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    Also, I sold the 80 sunbird and bought a car 600 pounds lighter. A 71 vega! With this power to weight ratio I'll be in high 13 second power to weight ratio. Someday, I'll be in the 9's with no power adders and a 4.0 liter 4 cylinder. Can someone clarify the weakness with these motors other than the open deck? 20181120_080936.jpg
     
  30. ivans572
    Joined: Mar 10, 2016
    Posts: 30

    ivans572

    Here is the driver side ebay header. Going to work great. You can also buy conversion flanges to bbc style. 20181129_103619.jpg
     

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