Re: [OMC-Boats] delving into scaryland....

From: Lee Shuster <Lee.Shuster@...>
Date: Tue, 8 Sep 2009 12:05:59 -0600

Explaining what you have is relatively easy. Your Buick ENGINE (Block, Intake, Heads) can be positively identified by looking at it's CASTING NUMBERS.

Use this link for reference:

I'm picking up on a couple of items in you picture that tip me off as it being a 1971-72-ish unit.

The Dipstick tube has the threaded hose cap and the exhaust manifolds have the cast-in OMC logo.

Once you identify the casting numbers, you should be able to simply tell your parts man you want any and all items for a 1967 to 1971 CJ-5/6 Jeep (Kaiser or AMC) 225 Dauntless V6. Any OMC reference from 1967 to 1972 should also be good (for the engine). Or if you prefer tell them you have a 66-67 Buick Special/Skylark.

The OMC parts: the intermediate assembly and the stern leg could be identified separately, but aren't your major concern at the moment.

The engine and intermediate should come out together once you loosen the stainless steel ring that seals the boot and the sterndrive is removed. Of course you'll need to disconnect all electrical and fuel service lines, as well.

Spark plugs rarely get installed with ZERO gap (self-grounded). Something bent that probe over against the electrode. And it doesn't take much.

Shop around, there are probably several good machine shops in your area that could do a decent job on your heads and or your block.

Good luck.


-----Original Message-----
From: omc-boats-bounces@... [] On Behalf Of jd
Sent: Tuesday, September 08, 2009 10:14 AM
To: Evinrude & Johnson Boats of the 1960's and 70's
Subject: Re: [OMC-Boats] delving into scaryland....

On Sep 8, 2009, at 8:00 AM, Lee Shuster wrote:

> JD,
> One tool that you'll find invaluable is the illustrated OMC Parts
> Catalog. Available FREE online at BRP-OMC or CROWLEYMARINE.COM. OR you
> can but a REAL HARD COPY at BRP or look forever on eBay. I feel like a
> broken record, but I get the idea few of us have these, by the nature
> of a lot of the questions that crop up here.
> Careful study of this "EXPLODED" diagram will revel (4) bolts holding
> each cyl head to the block. It is a simple as your lawn mower, times 6
> cylinders. With the OMC PARTS CATALOG it's like you have X_RAY vision!

Yep! HAve em all already and refer to them all the time. However I couldn't quite decipher exactly how the head comes off from the
diagram I have (for a '68). From Bill's reply, sounds pretty easy.

> New Parts for the 3.7 Litre or 225 cu in ODD_FIRE BUICK V6 are
> relatively plentiful and easy to obtain including rebuilt short or
> long blocks. Even the OMC log-style. exhaust manifolds are still
> available, but they are expensive, see below) Nothing particularly
> expensive or specialized, as GM and Jeep built this engine for years.
> Just don't confuse it with it's 231 cu in
> (3.8L) even-fire sister. Anything you might need for this engine is
> available, if you carefully explain what you have and ask the right
> sources. This was probably the second most popular GM engine that OMC
> used after the 100-110-120-140 Chevy-II 4-banger.

The explaining what I have is gonna be the hard part. I can probably get them through NAPA, have had good luck with them for other
gaskets. But telling them year of my engine is the challenge.
Boat is apparantly '64, but I had engine swapped last summer for an
apparent '70. I'm about 85% confident that's the year, but the
mechanic who told me that was wrong about some other stuff. I would
like to know for sure. How do I find out for sure?

> If this were my project, I'd start by having getting help to remove
> the stern leg. Then I'd carefully determine if there's room on your
> boat to pull the engine and intermediate out as a unit to gain better
> working access in a clean shop environment.

I have room/shop/hoist. A little nervous about doing it, but it's
a road I need to go down at some point ("pulling the engine") and
would love to know how to do. But pull the intermediate and engine
as one unit? I know if I pull off the heads and no obvious loose
part drops out, I'm gonna have to go deeper into the engine.......which I'm guessing is't going to be possible w/o pulling it right? Gulp.

> easy to stress (causing cracks) in the head mating flanges by lifting
> on the manifolds, so DON'T DO iT!). This will cost you big money. If
> it were mine, I'd carefully remove the exhaust manifolds, before
> removing the heads, to reduce the weight and possibility of ruining
> the manifolds.

Makes complete sense, although for some reason my manual specifically says to leave them on when removing from engine and then take them off on the bench.
> And Bill's right, treat that motor to a nice valve job. They'll most
> likely install modern hardened valve seats (for lead free gas).

I am all for this - makes sense while things are torn apart.......but this is all first time territory for me. What exactly does this
entail? Where do I take them? I know my local NAPA had a sign about
some attached machine shop - will that work? How much should I
expect to pay? Will I notice it in the end?

> The timing is right to get started on good off-season project.
> Also, the fact that you mentioned a spark plug with NADA-gap is
> SIGNIFICANT. That plug most likely has encountered MECHANICAL
> interference and will PROBABLY be a clue as to where the SOURCE of
> your strange NOISE is.

I thought about that, then thought - "nah...couldn't be!" So by
mechanical interference are you suggesting something loose in the cylinder a hitting the end of the spark plug and bending the gap
closed? It seems like a stretch, but then again, I have a
mysterious rattling noise and a what looks to be bent tip spark plug -
so maybe. Not really sure how anything could be in a cylinder - and
the engine still be able to run so well for all this time.

> BTW, what year/model is you boat? From you pictures, your Buick V6
> appears to have been retrofitted from a 72-73 era OMC. Do you have a
> serial number or model number off the engine tag?

> It's not all that important, just curious.

haha - see above. yeah, need that. Where's the tag? Here's what
I "kinda" know from last summer's verbal stuff the mechanic was
telling me: '70 engine, attached somehow to original '64 outdrive
stuff. But then there was also a lot of the "I don't know man, you
got all kinds of stuff in there" comments being made. Get the

I know there's a plate on the flywheel housing. But that is
apparently the original part. Where on the engine itself can i find
a stamp or plate that might tell me the year?

> Lee
> On Sep 8, 2009, at 7:56 AM, BLDFW wrote:
>> I've pulled a couple of engines apart to do a rebuild. The tube or
>> bar is just holding the valve rocker arms in place. It rests on top
>> of the rods and the springs. The springs hold the actual valves and
>> are held in place by a snap ring that holds the little round 'cover'
>> you see. You are safe to remove the bar and the rocker arms. They
>> will either lift out with the bar or will just rest on the rods and
>> valves and you can pluck them off one at a time.
>> The heads, once unbolted, will have to be gently prided up to free
>> them from the block and yes, they will be trashed so you will need a
>> new gasket set. Since you have already gone this far, I would
>> seriously recommend considering going the next logical step and
>> sending the heads out for a valve job. Would be a shame to waste
>> breaking the engine down this far and not doing that but then again,
>> if it's not necessary, no sense in doing it either.
>> Good luck and keep us posted!
>> -Bill
>> Dallas, TX
>> 1970 Evinrude Explorer - 155 Buick V6 - OMC Sterndrive
>> --- On Tue, 9/8/09, jd <jdood@...> wrote:
>> From: jd <jdood@...>
>> Subject: [OMC-Boats] delving into scaryland....
>> To: "Evinrude & Johnson Boats of the 1960's and 70's"
>> <omc-boats@...
>> >
>> Date: Tuesday, September 8, 2009, 12:30 AM
>> right on the heels of getting my switch issue overwith, and having
>> a fabulously smooth 30 min test at WOT right after the other day,
>> I was ready for a real outing. but of course, not without a new
>> issue to solve springing up. and not a pretty one. I was at the
>> dock (fortunately) and had just got back from my test run. Was
>> playing with idle trying to get it to go down to where it's
>> supposed to (sticky cable issue i think). in the spirit of trying
>> to learn what does what, i pulled off the spark arrester and
>> started playing with the flapper inside the carb. a tiny little
>> brass screw that partially held the flapper together was barely
>> screwed in and sure enough dropped down into the black abyss of the
>> carb, never to be seen again. I put stuff back together,
>> started, no probs -smooth. started moving the red throttle lever
>> back and forth. all of the sudden a clanking noise. however,
>> coincidentally NOT the screw - a much bigger clanking noise, and
>> only at low idle - often causing stalls. And in fact, i had
>> heard this same noise 2-3 months ago during a start up.
>> immediately shut it down. it never came back, and i forgot about
>> it. so here it was again, this time a lot worse and causing
>> engine to stall. a car mechanic guy happened to be at the dock,
>> listened around the engine with me, sounded like it was coming
>> from the port side, deep within somewhere. It's definitely the
>> sound of a "metal piece" sort of bouncing and clanking around
>> inside the engine. It's not a rattle type sound, more of a
>> random clanking - like coins in a dryer. And it sounds big - not
>> like a tiny brass screw, but a nut or something bigger. ugh.
>> So long story short, he suggested i start with the valve covers
>> and see it anything is loose. the remove the intake manifold.
>> as you can see, have done both. jiggled a tiny little piece of
>> solder (from a previous owner's attempt at repairing carb flapper)
>> out of the IM, but no brass screw. So now I'm on to the only
>> next place I can go, the cylinders. Pulled the plugs out,
>> nothing unusual with them. One had NO gap whatsoever, but
>> probably unrelated. time for new plugs regardless.
>> So my questions are these: I'm about the pull off the cylinder
>> heads. have never gone this far into any engine. and am flying
>> somewhat blind. yes, i have all OMC 3 original manuals. yes,
>> i've read them. they aren't much help. So excuse my ignorance
>> beyond this point. But there's no way I am handing my boat off to
>> another mechanic for another year. Gotta go it alone.....
>> 1)As shown in the photo. there appear to be about 8 bolts holding
>> the heads on. 4 inside, 4 down by plugs. but unscrewing those
>> doesn't look like it will do much because all the valve stuff.
>> So if i undo the 3 bolts holding that bar of levers, will it just
>> come off easily and allow for the rest of the head to come off
>> somehow, or will springs go flying everywhere? I don't wanna mess
>> with valves if i can help it. just wanna get to the cylinders.
>> So much easier on a lawn mower. Manual says remove heads WITH
>> manifolds still attached. But can't get to a couple bolts cause
>> manifold gasket is in the way. So i guess I'll be taking those
>> off as part of this.
>> 2) Will the head gaskets be trashed after this, or salvagable?
>> Anyone know right off hang if they are they out there for sale, or
>> one of those impossible to find way overpriced no longer made
>> vintage parts? Yes I will poke around online, but just trying to
>> get an idea....
>> 3) After i get the heads off, I'm assuming I will be able to see
>> the tops of the pistons. I'm not expecting much, but perhaps
>> I'll find something obvious clanking around in one of the
>> cylinders. perhaps a coin, or a wedding ring, or maybe the top
>> half of a spark plug. probably not. So where is the next
>> place deeper within that something could be clanking around?
>> what's under the cylinders? Could the oil pump be making that
>> noise? It wouldn't cause the stalling though.
>> glad it's the end of the season.
>> thanks for any help, Jeff D
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