Register now to get rid of these ads!

The elusive 224/3.7 MerCruiser banger

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

  1. calvinh
    Joined: Aug 31, 2009
    Posts: 176


    My parents had a 16 ft VIP with a Mercruiser and that thing would flat out run. Only problem was it blew a head gasket about twice a season.
  2. Dennis,
    I'm a big fan of the BMW mounts. Not sure why you found so many broken ones, but the V12s have a huge span from the left to right mounts, and over 300lb/ft of torque; so they are pretty stout... The nice thing about them is the mounting surfaces are parallel which makes fabricating brackets pretty easy. I've also hidden them on the bottom of aluminum motor plates for a drag race look with good vibration isolation. They're available new online for about $80 a pair. Top quality Beck/Arnley mounts are about $60 each.
  3. DeepSea Fish
    Joined: Sep 6, 2008
    Posts: 81

    DeepSea Fish

    We used to race against one of these monsters. If it lived.... We got beat, period. Seemed like they over revved it all the time.

    We since moved on to Asphalt Supers. The guys that raced that thing then have moved on to an aluminum headed half a super engine. Only thing is.... It's about 240 cubic inches, with a head that flows 300cfm. With a billet crank, rods and pistons, they turn it 9200rpms. So good luck with your 2300 Ford outrunning that beast.
  4. dawford
    Joined: Apr 25, 2010
    Posts: 498


    dennis g,

    Only a math major, an engineer or a retired scientist would calculate the forces on motor mounts, Just ribbing you :).

    In the 70's While on the Long Beach Police department I was driving a traffic car, I believe it was a Dodge, when a motor mount failed. It allowed the engine to lift up enough under torque to cause the throttle linkage or cable to jam wide open.

    What a thrill. Fortunatly brakes and turning off the ignition let the engine fall back into place.

    Low throttle allowed me to return the car to the City Garage for repair.

    This experience did have a marked impression on my thoughts about motor mounts.

    I always look for motor mounts that have a thru bolt or safty strap that keeps the engine from lifting if the mount fails.

    I would think that any mount for a modern american V8 would work fine if it had the safty feature and fit and looked ok.

    I plan to have the motor mounts just inside the frame (Model A Boxed and Gurdered). The Idea being that the further from the center of the engine the more the engine will be able to twist and jiggle at idle.

    I have 5 or 6 sets to choose from including the Hot rod standard round ones with a thru bolt that I think I will try first because they look so good and the engine, transmission combo is so light (about 365-375 lbs).

    Speedway has them for $19.99 a pair and a set of frame adapters to bolt the motor mounts to the inside of the frame is $24.99.

    If they fail to give the vibration damping I want then I will go to something else.

    I don't plan to go very to high RPM so I am more concerned with idle speed movement and vibration.

    I imagine that any High RPM vibration is more of an issue for the internal wear of the engine than something that I will feel in the car.

    With a T5 overdrive transmission cruising speed will be at low RPM and I will only run the engine at high RPM ocasionally for very brief intervals.

    Let me know if you have different thoughts on this.

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

    Attached Files:

    Last edited: Jun 19, 2010
  5. Dick, you've brought up a very important issue. The trough-bolt or safety strap is essential as its weight can not be depended on to keep the engine in place.
    The mounts you show are attractive, inexpensive and compact. Aside from friction, do they have anything to hold the engine in place horizontally? If the cone-shaped lower rubber fits into a tapered hole, it would locate the engine horizontally.

    Mounts tipped 45 degrees work well for lateral location but do nothing for longitudinal positioning. Perhaps the transmission mount would work for that?
  6. In 3or 4 BMWs I saw in a local junkyard, none of the engine mounts survived intact. They were in cars with smaller motors. I saw no through bolt or safety strap. I looked at so many cars there that I can not be sure, but I think that I saw a perforated disk down in the ripped up BMW mounts. {It looked exactly like the drain sieve in my bathroom sink}.
    The big ugly chevrolet mounts had captured rubber loaded only in compression. All of them survived.
    You are right about the mount spacing, even soft widely spaced mounts give much more resistance to torque and they can be left soft to absorb low frequency vibration.
  7. dawford
    Joined: Apr 25, 2010
    Posts: 498


    dennis g,

    If you go to Speedway Motors online you will find that the #7209314 motor mounts have a step in the hard rubber lower pad that keeps the mount from moving in both directions.

    That step fits into the frame adapters #1353274. These adapters are made to sit flat and they are found on many small block V8 hotrods that have much more power and weight than any thing that we are likely to get out of the 470.

    If you look at the picture you will note that the holes are slightly oblong allowing the engine to center its self.

    There is an engine mounting guide under Info that showes the setup with a V8 block.

    These motor mounts and adapters in addition to the third mount at the rear of the transmission should be perfect for the ideal 3 point system.

    :) :) :) Dick :) :) :)
  8. Warpspeed
    Joined: Nov 4, 2008
    Posts: 532


    Failure mode analysis is the sort of fancy highfalutin stuff engineers do, but most of us can just look at something and figure out what is probably going to happen if something important does let go.

    ANY suspension rubber parts must be designed to hold parts captive if the rubber tears.
    A through bolt, or safety loop, a giant washer on the end of a bolt, or even a short piece of chain may save you one day.
  9. agreed, it must have a backup. dg
  10. Thanks for the reference Dick, I will check the parts in a few minutes.

    I saw 1965 chevy v8 pickup mounts in a store today, they have a simple clean appearance and are of heavier metal than the Indian clones that were ordered for me. Aside from the base, attachment is by a single screw in bolt rather than a crossbolt.
    Last edited: Jun 19, 2010
  11. I looked up photos of the parts dick suggested. They look nice, are inexpensive and they should work well, locating the engine in 3 directions. my only concern is that the bottom rubber has the potential of getting chewed up by horizontal forces. [That happened to a similar mount I made last year, but the metal around it was thinner and sharp]
    A big washer of 3/16" or 1/4" plate at the bottom of the lower rubber should safety them.

    Attached Files:

    Last edited: Jun 19, 2010
  12. dawford
    Joined: Apr 25, 2010
    Posts: 498


    dennis g,

    Do you wear suspenders and a belt? :)

    Speedway has been in the hotrod parts business since 1952 and is probably the biggest in the business.

    I wouldn't worry about this setup because it has been sucessfully used in thousands of hot rods for many years.

    The mount in my previous thread that I bought at a parts swap isn't the Speedway part but is similar in apearance and I won't know for sure if it is identicle untill I get one from Speedway, but it has metal sleeves molded into the rubber that I am sure won't allow it to self distruct.

    I noticed that the one that I have has a metal cap that goes over the top of the rubber. I imagine that it is there to protect the rubber from oil and other contaminants that were a problem with older hot rods.

    I suspect that with newer cleaner hot rods they found them unnessary.

    I don't think that the 470 will have any problems in this area as I have seen many well used engines and haven't observed much in the way of stray fuel or oil around the engine compartment.

    :) :) :) Dick :) :) :)
    Last edited: Jun 20, 2010
  13. dawford
    Joined: Apr 25, 2010
    Posts: 498


    dennis g,

    After posting my last I thought of a solution for someone who wears suspenders and a belt. :)

    Cut a piece of 3" pipe about 1/2" long and weld it to the top of the frame bracket and slip the top mount into it to keep the mount centered for sure.

    It looks like from the picture of the speedway frame mount that it might necessitate enlarging the flange a little or welding the pipe piece to the large washer. Then welding the washer to the frame mount.

    I would think that the pipe flange should be a little larger than the rubber to allow some unobstructed side movement.

    As I am visualizing this I thought that this pipe piece might be a catch basin for forign matter so it might be a better idea to leave the bottom open if the pipe ring is larger than the frame mount. That would allow material to work it's way out the bottom.

    I might even do this on mine as it won't hurt anything and it might actually help.

    :) :) :) Dick :) :) :)
    Last edited: Jun 20, 2010
  14. three examples of captured rubber mounts:
    a 1980 Lincoln mount, (much like the chev mount)

    a 1995 econoline mount, simple, safe & $15

    and a 1972-2010 chevrolet v8 and v6 mount.
    Can't argue with 38 years of success.

    Attached Files:

    Last edited: Jun 20, 2010
  15. More noteworthy mounts of t he 60's:
    1962 nova
    1965 mustang [ which persists as a 1995 F150 mount
    1969 chevy pickup mount, used through 1972
    none are captured rubber so they could pull apart

    Attached Files:

    Last edited: Jun 20, 2010
  16. Buick was more adventurous in their mounts:
    [in order]
    1972-1990 Riveria mount [must have been a success] $18

    1972 Skylark mount

    1975 Skylark sort of a copy of the 69 vette mount. seriously ugly.

    1990 3.1L mount $28 (same as $5 1962 nova mount??)

    1990 v6 3.8L right rear mount, captured rubber and it does the angle, it might be very good. $27

    Attached Files:

    Last edited: Jun 20, 2010
  17. the 3" pipe ring would be good as long as it can not contact the washer or mount arm.
    It would locate more strongly than the smaller rubber could. I used a short length of fuel line for the small rubber and lacking metal protection, it was cut through.[not that it mattered a lot]
    First I did not need pants, later I needed pants but no belt, but now it is all essential and sometimes suspenders[and pants] would be better.
    Last edited: Jun 20, 2010
  18. The following mount is sold in speed shops, an import from India. It is a cheap[ the right word] copy of a 69 vette mount. As its metal is so thin, I calculated stress on it. The original must have been better.
    [and it is truly ugly]

    Attached Files:

  19. All mounts are not created equal.
    I found a 427 vette mount in a napa store and it looked Much stronger than the 427 mount that I bought earlier. [thicker metal, larger contact area with the rubber]. Not only stronger, but also 20% less expensive. It should be firm enough to keep the engine from bouncing around as there is a lot of rubber in compression.
  20. BigChief
    Joined: Jan 14, 2003
    Posts: 2,082


    Check the classifieds boys. A buddy of mine is selling his 224/3.7 stash. One complete motor and one short block. Rebuildable cores only, not ready to run.

  21. made in India VS made in USA,
    three sets of chevy mounts.
    The two left sets are made for the pre 1972 big block chevy in a vette. For comparison the set on the right is the captured rubber mount used since 1972 by chevrolet .
    Now for a second comparison, look at the difference in metal thickness in the two photos on the right. India [black] vs USA [NAPA][unpainted in part]. I returned the made in India mounts.

    Attached Files:

    Last edited: Jun 25, 2010
  22. Got my engine back from a shop today.
    $300 so by now it has cost more than what are claimed as good running 470 engines. But I know what the insides are like and that is an advantage.
    The others would probably take some work too.
  23. dawford
    Joined: Apr 25, 2010
    Posts: 498



    What did you have done to it?

    :) :) :) Dick :) :) :)
  24. Nothing really, it was to free up the crank :
    I began assembly but the crank locked up when the main cap bolts were snugged down... they:
    -polished the crankshaft $43
    -align honed the block $137
    -resized the connecting rod big ends $38
    -cleaned the block $36
    -checked bearing clearances $38
    it did not take a lot of time but the flat rate made it expensive. They said the crank now turns.

    I measured head and block flatness yesterday, and lapped the head to a 8x30" piece of plate glass. It cleaned the mating surface on the wrecking-yard-supplied used head. There were a couple of little high spots that became shiny but most was dull-looking. Then I used a 8"x 12" aluminum block and sandpaper to get a surface that at least looked polished.

    ----I think you are actually asking about new ideas.

    The only thing along that line is Dick Carrier's suggestion last night that I replace the head and main bolts with studs. I may wait on that one. Has anyone had a stud pull out?
    Last edited: Jun 30, 2010
  25. I read a wonderful article on bock and cylinder head surface smoothness. Dont know how to post a link andit is copyrighted so I can't reproduce it here
    however google on "cylinder head resurfacing" It is by Larry Carley and appeared in engine rebuilder mag.
  26. dawford
    Joined: Apr 25, 2010
    Posts: 498



    Are you using a cast iron head?

    :) :) :) Dick :) :) :)
  27. Yes I am. A different Dick said it would increase stability of the top of the engine.* I'm unsure of that, but it was $450 cheaper. It is said that the combustion chamber shape is better on the alloy heads and that the iron heads were not so good.
    Last edited: Jul 1, 2010
  28. Block filling has been mentioned earlier here.
    It may be the way to get some lateral support for the cylinders and water jacket.
    I could see laying wax rods or candles into the block filler beside the cylinders to form water passages in the block filler. There would have to be some sort of a wax dike ahead of and behind the filler.
  29. I talked with a shop that does mercruiser engines, he did not know there was a factory tool to align the water pump I was asking as the one I made was a few thousandths loose in the distributor body bore and the end moved around so much that it seemed I could do a better job of placing it by moving it right and left in its mounting holes and splitting the difference. Any ideas?
  30. tjm73
    Joined: Feb 17, 2006
    Posts: 3,382


    Any pics of the engine?

Share This Page

Register now to get rid of these ads!


Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.