From: hotrod@dixie.com (The Hotrod List)
Subject: Re: Mercury Marine
Date: Mon, 23 Nov 92 17:38:47 GMT
Organization: Dixie Communications Public Access.  The Mouth of the South.
To: hotrod@dixie.com
Reply-To: hotrod@dixie.com
Posted-Date: Monday, Nov 23 12:38:41
X-Sequence: 2794
X-Gifs-To: met@sunset.cse.nau.edu
X-Gifs-From: ftp.nau.edu

> 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.

 I've built a 350 from a 1991 GMC truck and its engine was similar.
One piece rear main seal, different pan, different crank (I believe Chevy
does make a kit to use an old style crank in this block, tho).  Not
sure about balancing.  The cam bolt pattern was the "old" style though.
Factory cam was flat hydraulic.  No thrust plate, but block was machined
for the factory roller cam style thrust plate.  I had Crower grind a new
cam for it, and they used the GM rollercam style small bolt pattern.
Lifter bores were too short for GM's roller lifters.

> 
> 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.
> 
 Again, sounds very similar to my 91 truck engine.  Center intake bolts
are angled vertically on the 91, too.  A little work is required to use
an old style intake, but not too bad.  I don't remember what the ports
looked like.  Didn't use the heads for my project...  used Dart II
sportsman instead.


-- 
Jon Lusky
lusky@gnu.ai.mit.edu

 79 Rx-7 12A/Holley 4bbl
 67 Camaro/350/4spd (under construction)
 89 Jeep Wrangler/258 (currently self destructing)

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Posted by: emory!gnu.ai.mit.edu!lusky
Newsgroups: alt.hotrod,wiz.hotrod