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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. distributorguy
    Joined: Feb 15, 2013
    Posts: 45

    distributorguy
    Member
    from MN

    My stalling immediately follows a lean condition where I get a lean misfire, AFRs jump over 16. It happens slowly, but not slow enough that I have time to really watch the AFRs as its happening since it happens under heavy load, like when I was climbing the hill behind my house, still covered in deep snow. It almost feels like the pump slowly decreases pressure, everything is new so that could be the case, but that's not really how a float bowl works. The hill may be the issue, or the pump, or simply the boat carb. I can't even bring it back with the accelerator pump, which is working.
    Off with the intake today, then we'll see what appears. It got worse after snugging the intake bolts, which should never happen.
     
  2. gasket sealing [ updated 15 March 2021]:

    FAILED to seal the fiber mercruiser headgasket:
    ----- silver paint
    ----- permatex(unknown type)
    ----- hylomar
    ----- the slick transparent coating on the gasket

    SEALED the fiber headgasket:
    1 -----Permatex#2 on both sides of gasket plus "grey right stuff" at the lifter gallery(has not leaked after a short run)
    2-------Locktite 518 on both sides of gasket and block in critical areas (works so far low rpm low engine load for an hour this on a Sierra gasket with no sealant bead. this block has more aluminum added to the intake side)
    3 -----the factory sealant bead that came on the gaskets (it works for years)
    4 -----spray on copper seal seals copper headgaskets
    5 -----metal o rings in machined grooves seals copper headgaskets
    6 -----dry deck the engine with an aluminum plate to seal the fluid openings in the deck and head. run coolant tubes from block to head. This bypasses the problem
    --------------------------------------
    UNTESTED but promising ability to seal Mercruiser headgaskets:
    1. coolant additive
    ----- GM coolant suppliment #3634621 (was used on all open deck Cadillac engines)
    2. Aerobic sealants (require air to cure)
    -----Threebond#4 (also sold as Yamabond#4 and Hondabond#4) (a popular motorcycle case sealant)
    -----Hi Tack
    3. Anaerobic sealants: (require absense of air to cure)
    -----Locktite 518 (designed for aluminum and if made recently,does not need primer/activator)
    4. others
    ------One copper gasket appears to come with a properly placed sealant bead
     
    Last edited: Dec 13, 2021
  3. note: I have made changes to the sealants list.

    1. I removed Kuril from the list as I can't find it being sold. It was nasty to work with.

    2. Locktite 518 has been reformulated sothat it no longer needs a primer/activator. Most locktite needs an active metal Iron, copper, brass for it to thicken and cure. I used to use primer N routinely but quit when its price shot up. There is a locktite 4 oz red spray can of "cleaN prime" for $18 Locktite tech says it will work as it is relabled primer N. With primer/activator it sets up quickly and fills wider gaps, but is not as strong.
    Whenever you use locktite the surface must be quite clean, otherwise it is like trying to paint on a house in the rain.

    I still need your input on headgasket sealing success or failure.

    updated march 21 2021
     
    Last edited: Mar 21, 2021
  4. Just off the phone to locktite: Some oddities now explained about locktite 518 and primer.
    1. In the last two years 518 ( part number #2096059)has been reformulated so that it no longer needs primer.
    high strength 518 is the same. Its part number is 2096064.

    the old 518 needed a primer containing copper salts on some metals but most aluminum is alloyed with copper and is thus weakly active. Therefore will not require primer if at least one surface is active.

    2. as to the mystery of the primer price: I was told that primer N in the green areosol can ($48) is exactly the same material as kleen N prime # 37509 in a red aerosol can ($14) the difference being that the green can is sourced through a supply chain to manufacturers and the red can is sourced through a supply chain of automotive distributors. Any way for locktite 518 made in the last 2 years( #2096059)( $13 for 50 ml) Locktite tech service told me you don't need primer at all although the package states that you should prime with#37509. the old 518 (#51837) did need it on inert metals. It will cure faster with primer and that may be too fast I used to prime everything and their thread lockers sometimes set up faster than I could get the bolt screwed in.
     
    Last edited: Mar 17, 2021
  5. As automotive applications involve great differences in load and speed, the air to fuel ratio can be expected to vary. As you only have 4 cylinders to deal with, determine which one of them is running lean and jet it so that it stays below 14:1, the other cylinders will have to take what they get. You absolutely do not want to use your expensive hot aluminum as fuel for any excess oxygen to burn.
    In my experience, when a lean engine on the ragged edge is performing very very well, it only takes a few seconds to burn a hole in a piston.
     
  6. About air bubbles trapped in a cooling sysyem:

    1. the steam* holes in the head gasket are there to allow air bubbes in the coolant to leave the block and accumulate in the header tank.

    2. Air is dissolved in most water. Water holds less air in solution at higher temperatures so as the water's temperature rises air bubbles form. This happens at lower temperatures than boiling and is not boiling.

    3. Disolved air can be removed from water by boiling it before putting it in your cooling system. Bubbles seen on the side of a pot of hot water are dissolved air leaving the water.

    4. Normal coolant flow washes air along to the high spot in the cooling system, the header tank.

    *steam will only be in the cooling system if something is seriously wrong and the coolant is boiling.
     
    Last edited: May 15, 2021
  7. distributorguy
    Joined: Feb 15, 2013
    Posts: 45

    distributorguy
    Member
    from MN

    Well my stalling issue was actually from tight valve guides in the new aluminum head. #4 ended up eating a pushrod when the exhaust valve stuck. It also appears detonation in #4 damaged a ring land, as the 2nd ring was stuck compressed. The block is out for a bore job, crank is being ground, and the head has already received a valve job and cut the guides to proper clearances. Only 1 of the new valves was concentric. Unbelievable. So much for using a "pristine" low hour engine.
    Now I have to deal with pushrods. These are not hardened for use with guide plates. Has anyone used a longer pushrod or split length set to deal with the canted valves? I won't be able to work through the geometry for about a month when reassembly begins.
    BTW, I had used permatex #2 on the head gasket, with the grey Right Stuff around the lifter galley. it sealed beautifully given the poor conditions it suffered through. I think machining was the key, as the block and head were fresh and square. Cylinders were block-filled prior to machining the deck.
     
  8. beck
    Joined: Sep 20, 2008
    Posts: 272

    beck
    Member

    I had to order pushrods for proper length with my aftermarket aluminum head. Mine took 2 different lengths. I bought mine from Smith Bros. There is another "big name" company making pushrods also, but I cannot remember their name.

    Poor assembly isn't uncommon in aftermarket heads. Poor valve seats is a typical problem. Have you shared with us what brand you used?
     
  9. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 2,843

    GearheadsQCE
    Alliance Vendor

    'Trend' is the supplier for most of the high performance pushrods
     
  10. distributorguy
    Joined: Feb 15, 2013
    Posts: 45

    distributorguy
    Member
    from MN

    Manton makes good pushrods too.
    The head was a cheap 429/460 Ebay special. I already ditched the sloppy fitting guide plates and used Comp's cheaper steel roller tip rockers. There's a lot of side stress on the pushrods, so I think I need to go with hardened pushrods. The stock ones are getting pretty chewed up considering how little run time I had before the issues.
    Beck - what head did you use and do you have documentation of the pushrod lengths? I plan to go through the measuring process but it would be interesting to see if we get the same numbers.
     
  11. beck
    Joined: Sep 20, 2008
    Posts: 272

    beck
    Member

    Trend is the brand I couldn't remember.

    The pushrods shouldn't be pushing that hard on the guides.

    My head is a Trick Flow A460. It is taller than the stock ones, so I doubt the pushrod lengths would be the same.
     
  12. beck
    Joined: Sep 20, 2008
    Posts: 272

    beck
    Member

    Sometimes I have to wonder about myself. I have been building on my 470 for many years for competition use.

    I am finally to the point of getting it ready to run. I put the oil in and primed it with a hex shaft through the distributor hole. Everything seemed good. Later I was cleaning up under it and discovered an oil puddle. After some effort and removal of the transmission, bellhousing, clutch, etc. I found the problem. I probably should have put a rear main seal in it.

    Now for my question - Why was there oil pressure at the rear of the crank to push the oil out of the seal opening?
     
  13. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    Priming the engine you have oil leaking off through the rear main bearing. There is a drain hole in the cap so it don't over come the seal. With no seal it will just run out the back as well as run down the drain hole.
     
  14. distributorguy
    Joined: Feb 15, 2013
    Posts: 45

    distributorguy
    Member
    from MN

    What Flatrod said. If you remember what the rear main cap looks like, there's a slot cut just forward of the machined seal area to drain back into the pan, but whatever flows around that dumps on the ground. :-(
    Hopefully you did remember to install the two square seals at the rear main cap parting line? If not that'll require a little more effort than pulling the flywheel. I'm just assembling mine now after a crank grind and bore job. Only 125 hours on it from new.
     
  15. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    I am pretty close to putting mine together. I had a cam reground and am not happy with the specs. What is everybody here using? I am running a mechanical fuel injection, Boss head, 6 speed trans on the street. Hopefully a less then 2000 pound car. No pleasure driver, way more hot rod.
    So what are some specs you guys are using on a reground stock cam?
     
  16. my car weighs 1800 lbs wet with a 3 speed saganaw transmission and 3.07 rear end.
    It cruises at 2200 rpm on a 2 lane highway so that s where I want my torque.
    I liked a Crower torque profile (Bajha something with in Crower words "stump pulling torque" that I'd used 20 years earlier) and had a cam ground to approximate it. It came out very well.
    One of my lifters was not spinning and wore one lobe so I replaced the cam with a new "Mercruiser cam"from Elgin that was so bad it's only use was a cam blank. It caused the cranking compression to increse 40psi to 210 psi and it detonated and overheated no matter what I did. My favorite cam gave 165-170 psi cranking and that is about right with an iron head and the block zero decked. With tight piston clearance, quench is improved and the engine resists detonation. It runs smoothly, has abundant torque and gets good fuel economy (important if your gas tank is very small)
    I like to run a mild short duration high lift flat tappet cam. It is a supercharger profile but makes a nice cam without a supercharger running.

    lobe centers 115 degrees.
    Intake duration 203 degrees at 50 thousandths
    exhaust duration 210 degrees at 50 thousandths
    the lift is higher than stock as with this timing, the engine is valve lift limited.
     

    Attached Files:

    Last edited: Jun 10, 2021
  17. A volkswagen type 1 axle tilted forward so the tubes lay flat. Clever. Although they are heavy, they make a much more stable and adjustable suspension than my I beam axle. VW connecting rods can be used to mount the tubes And the little vw steering box is very light. I used headlights to hide my vw axle on one car.
     
    Last edited: Jun 15, 2021
  18. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    Dennis, How is your cam idle? I got a mound of paper work back with my cam. So what I can get out of it is I have .564 int and .561 exh lift with my 1.75 rocker and .022 lash. ( I had my cam ground to solid specs, not a hyd anymore) I think it has 206 duration at .050 on the intake and 219 at .050 on the exh. On 118 lobe center. I have had my pistons made with 11 to 1 compression, I guess that is static compression and will have anywhere from 7.8 to 8.3 depending on where I install the cam and how much lash I use. I was hoping for a little more lift and at least 10 to 15 degrees more duration.
    If your cam idles smooth with your specs, then I think this one would too. I wanted a little more rough idle. Is your engine stock stroke with just a .030 or .040 over bore? Mind is .030 on the bore but I did stroke it .250. so my bigger engine should eat up some of that duration.
     
  19. My idle is smooth as butter and slow 800 rpm . one engine is 30th over with flat pistons another is 40th overwith dished pistons both have the same cam grind (could even be the same cam, as I burst a cylinder on the first engine and saved the remaining good parts). Do you have cranking pressure we could compare ?
    Ignition timed 32 degrees advance at 2200 the cam I hated (literally true) made the 030 engine knock unless advance was less than 28 degrees at that rpm. My hated cam gave 210 psi cranking pressure and had lobe centers claimed at 116 degrees but measured at 115. and the favorite cam gave 165 to 170 psi at 115 degrees lobe center. I will try to scan my data ...several pages including cam profiles but my scanner faled to work last time I tried it. I may have to buy another.
    I will post the above for now.
     
  20. blue screen on scanner I must buy another

    meanwhile here is my cam card data:
    hydraulic lifters
    valve lift 0.456 intake 0.492 exhaust with 1.73 stock rockers
    overlap 27 degrees
    lobe seperation 115 degrees
    exhaust duration 210 degrees @050
    intake duration 203 degrees @050
    he ground 4 degrees advance into the cam & I put in in not changing anything
    ------------------------------------------------
    I measured all of both camshafts lobes between centers on my lathe but there are too many page of numbers to write down now
    dennis
     
    Last edited: Jun 15, 2021
  21. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    I am not assembled yet so no cranking compression. Thank you for your specs. If I can find another cam I may try to get another regrind, I think I want a little more.
     
  22. Look on ebay for a used cam, the lobes are big giving ample room for an easy regrind to a profile. One is listed there today (June 12, 2021) for $45. That is a common ebay price. Don't pay more than $50 because they all have to be reground anyway(even new ones because you probably need a different profile).

    There was a change made in the nose of the cam where it fitted the impeller so if you use the merc. water pump be sure to get those parts to fit. It makes no difference to me as I cut that part of the cam off and plug the hole in the cover.
     
    Last edited: Jun 12, 2021
  23. We make design choices with specific purposes in mind. I wanted a lazy, comfortable driving experience so I chose to have broad torque in my cruising operating range. As the engine is large (3.8L) for a light (1800lb) car, a 3 speed transmission suits my needs as does a short duration camshaft and a 3.08 axle.

    My old truck needed its 24 forward speeds for its 32,000lb gross weight. Its design parameters were completely different from a light car. Both of them had engines similar in size and at one point each got 3mpg. 3 mpg for a road car is useless so I changed it's engine to a Mercruiser engine and its acceptable 20 mpg. The truck only had to haul fruit 5 miles and for that 3mpg did not matter.
     
  24. Perfect seal,which is specified for mercruiser 3.7 head bolt torque, is no longer available. Permatex($13) now comes inside Mercruiser Perfect Seal boxes for about $50.

    Cured perfect seal is a rubbery and bouncy material. Non-hardening permatex is suggested as a substitute, but removing old Permatex screw on lids makes me worry if headbolts put in with permatex will be removable. Permatex 1, 2 or 3 is not rubbery like perfect seal. There is, however, one permatex which claims to be rubber.
     
  25. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    You are using sealer on the head bolts? They don't go into water so I don't see a need for sealer. I plan to just use oil. I did clip the bottom of two head bolt holes when I drilled my block for oil returns. A wedge head oil flows to the push rod side sitting flat, so probably didn't need them. But a Boss head the whole exhaust side will fill with oil, so I drilled return holes on a tip from GearheadsQCE. It looks like Mercruiser had thought to put them in, as all the meat is there to do so.
     
  26. It is a rare headbolt that comes out of a block without some rust on it. One set was rusted so deeply that when I turned the shanks down below the rust some were 0.440 inch in diameter...They were not useable bolts so I had my fun turning their shanks down. One became a good thread chaser.

    My reason for using Perfect Seal was to get the torque right as that is how Mercury did it. (Sealant on the threads and sealant under the head). Water seeps into the block around the bolts. Sealant on the bolt where it contacts aluminum reduces electrolysis. Paaint on the bolt stops rusting. The holes the headbolts go into are all blind holes but the front and rear holes on the intake side can be expected to have some coolant in them. Protecting the threads and getting the torque to spec. are strong reasons for using perfect seal if you can get any.

    I painted the shanks of a bolt set I have but no paint where sealant is applied. They have light rust after being in the engine 2 months and I had polished them before use. they have black oxide finish which gives some protection, but paint is more effective anti-corosion. Acetone loosens Perfectseal I soaked the bolts, then wire brushed them and soaked them more.
    sealant from deep in the threads came loose during the second soaking and I pushed the old sealant out of the threads with a sharp scribe.
     
    Last edited: Jun 18, 2021
  27. Interesting about the oil drainage differences. If you race on an oval track the oil may drain while the car is in the corners.
    I had rockers hitting my valve cover so I put it up on double gaskets with aluminum between them to get clearance...this on a wedge head with the aluminum Mercruiser cover.
     
    Last edited: Jun 15, 2021
  28. Jegs has $90 stud sets for the 3.7 (stock Ford lengths). I assume they are from China. I ordered some yesterday with the intent of getting more accurate torque. They also have the sets of studs that cost much more than twice that.
    Jeggs studs come in set for a ford V8 so the cost per mercruiser engine is $50.

    My studs arrived and I can see that their shank diameter exceeds the shank diameter of headbolts. The maximum diameter of the shank is better to be no more than the minor diameterof the threaded ends. As there are fine threads on one end and coarse threads on the other use the minor diameter of the coarse threads for the maximum shank diameter. Studs will then appear as if the threaded end is larger (and it should be larger than the shank. )
    Changing the shank diameter for the inexpensive speedmaster studs is made easier as one end of the stud comes center drilled. As they are strong and hard I'd use a carbide cutting tool.

    Do not buy speedmaster studs mine were made wrong. The coarsely threaded end is too short and will pull out of the block. The fine threaded end is too long...they made them just backward from how they should have.
    Also, the shank is too fat so the stud will not flex but will instead break in its threaded area.
     
    Last edited: Jun 26, 2021
  29. Flatrod17
    Joined: Apr 25, 2017
    Posts: 167

    Flatrod17
    Member

    Studs or bolts, still have not decided which I will use. I have both. I have seen rusty head bolts, however this engine I took apart had no rusty bolts. I have seen the end bolts that have outside holes, end of the head holes, that let moisture in and they can get rusted really bad!
     
  30. This locktite product has not been around long but looks good for our headbolts.
     

    Attached Files:

    Last edited: Jun 18, 2021

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