From: hotrod@dixie.com (The Hotrod List)
Subject: Mercury Marine
Date: Wed, 18 Nov 92 22:54:11 GMT
Organization: Dixie Communications Public Access.  The Mouth of the South.
To: hotrod@dixie.com
Reply-To: hotrod@dixie.com
Posted-Date: Wednesday, Nov 18 17:54:07
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X-Gifs-To: met@sunset.cse.nau.edu
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 I recently acquired a Mercury Marine boat motor for dirt cheap.  It had
been sitting in a friend's shed for several years; I swapped him some
big block parts for it.  Tommy even threw in a pair of 461 head castings
from a 327.

 Basically, it's an '87 Chevy 350.  The original owner didn't drain the
water the first time winter came around, and it wound up with a cracked
block and head after the equivalent of 5000 miles.  The block is no
trouble to have fixed; I've had worse welded successfully before.  (stop
drill the ends, grind the correct V groove, and make a special run to
Little Rock to get the proper welding rods)

 The right head appears to be undamaged.  The left head split a flap
about 3x4 inches out between the front two cylinders' exhaust ports.
I tried calling around for another head, but late-style 350s aren't
common, at least around here.  No way.  Also, according to the Chevy
Power book the engine should have severely dished pistons and tiny 54cc
chambers.  This marine variant has near-flat-tops and big chambers.  It
wouldn't surprise me if it was a real oddball.

 After consultation with my welder, I disassembled, drilled, ground, and
cleaned the head and left it with him yesterday afternoon.  I'll have to
have the exhaust manifold face remachined, but it's no big deal.

 When I get the block and head back I'll have to have them miked, of
course.  Wouldn't surprise me if I had to have the cylinders honed back
round on a Sunnen machine or have the welded head shaved, but
considering it's a nearly-new motor it's a small price to pay.

 So far, so good.  I haven't worked on a small block Chevy in probably
thirteen years, so they all look strange to me to start with (Ford and
Buick, that's me!)  Anyway, it turns out the '87 is almost completely
weird-Alice.  Here's a brief list:

Short block:  one piece rear main seal.  Special gaskets and seals
              required.  Oil pan does not interchange with early models.
              Crank does not interchange.  Smaller flywheel bolt
              pattern.  Externally balanced (old motors were internally
              balanced).  Cam bolt pattern is different.  Cam is
              retained by a plate like a Ford (it's about time), but
              that makes cams non-interchangeable.  Deeper lifter bores
              and bosses for roller lifter retainer plate.  According
              to Chevrolet, the engine is supposed to have roller
              lifters; being a Mercury Marine, it has a flat tappet cam.
              Timing chain set is different to accomodate new cam bolt
              pattern.

Heads:        raised valve cover rail, machined gasket surface instead
              of the crummy casting Chevy used to expect to seal, rubber
              valve cover gaskets, Ford 292-style retainer bolts through
              the center of the valve cover, 5/8 hex tapered seat plugs,
              1.94/1.60 valves, rotators on exhaust valves,
              old-fashioned tin oil deflector cups on top of the spring
              retainers, valve guides already machined for Perfect
              Circle style seals, with standard crummy Chevy O-rings on
              all 16 valves, *plus* PC seals on the intakes only,
              center intake manifold bolts are angled more vertical,
              probably for clearance - this however makes early and late
              intake manifolds non-interchangeable, rocker arms are
              wider and "straddle" the valve tip, again like a Ford,
              intake and exhaust ports are totally different from any
              Chevy port I've ever seen and not bad IMHO - small guide
              bosses, big short-side radius on intake port, exhaust port
              is almost constant in cross-section with D-shaped floor.
              It's the "lightweight" casting though, scalloped and with
              the big coolant holes.


 Sooo..... there isn't a lot of interchangeability between this and the
earlier motors, and of course very little with the '92 GEN II motors.

 I'm going to reassemble the motor and keep it as a backup should the
six in my '60 Chev decide to die.  To earn its keep, the 350 will
probably be used as a mule for the upcoming Performance Engineering
homebuilt dyno project, assuming the project ever gets off the ground.
(right now, it keeps kinda falling outta the nest and going "SPLUD")
                                   

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Posted by: emory!chaos.lrk.ar.us!dave.williams (Dave Williams)
Newsgroups: alt.hotrod,wiz.hotrod