Re: [OMC-Boats] timing/carb adjustment

Jeff,

Sorry if I confused you with a little too much info. I'll make it a
little easier to understand:

Since the distributor is gear driven off the camshaft, and the camshaft
is driven by a 2:1 gear off the crankshaft, I could have explained the
odd-fire timing interval in DISTRIBUTOR CAP DEGREES not relative
CRANKSHAFT DEGREES. It's very helpful if you view
http://home.off-road.com/~merls_garage/oddfire.html

Let's look at your Mallory cap and assume for a minute that it is for a
EVEN FIRE ENGINE: You are correct 360 / 6 (evenly spaced distributor
posts is 60 degrees apart on the INSIDE of the distributor cap. I was
correct in saving 120-120-120-120-120-120 of crankshaft rotation for
each firing point because the crankshaft turns two revs for each rev of
the distributor.

If you examine in the INSIDE of a DELCO REMY ODD-FIRE Distributor you
will notice UNEVEN spacing of the contact traces. BUICK engineers
altered the contact area to match a 45-75-45-75-45-75 degree pattern.
The external wire sockets are NOT altered, the still are in the classic
60-degree spread. Pretty trick, eh?

So as they say, your mileage my vary, but I suspect a +/- 15 degree
isn't enough to keep the engine from starting with the wrong distributor
cap. But I can well imagine, it doesn't idle very well and doesn't want
to run more than 10 mph.
So is it a case of mis-matched distributors?

How do you solve this mystery? One certain way is to pull off a cylinder
head and observe the piston timing. Another way might be to start
looking for GM casting numbers or OMC serial number plate on the block
and try and determine if you have an odd-fire 225 or an odd-fire 231, or
an even fire 231 or even fire 252. I guess another method is trial and
error substitution. And don't forget -- firing order matters, as well,
as you have noted.

It's too bad the mechanic didn't take notes or write what he did. It
would be nice to get back to a known starting point, in figuring out
where you are and where you are going. If your Buick came out of a
dual-engine boat it is probably an odd-fire 225, but you can't be
positive someone didn't change them out.

It still sounds to me like you did get into an even-fire distributor
with the Mallory. Don't worry about the vacuum advance that's the least
of your problems. And I don't believe that OMC used marine-grade DELCO
REMY distributors, but I could be wrong on that on the V6 Buicks.

Lee

-----Original Message-----
From: omc-boats-bounces@...
[mailto:omc-boats-bounces@...] On Behalf Of JEFF DOOD
Sent: Tuesday, July 29, 2008 3:31 PM
To: Evinrude & Johnson Boats of the 1960's and 70's
Subject: Re: [OMC-Boats] timing/carb adjustment

thanks lee, you might be on to something here. perfect timing too
because i'm geared up to have to tow my boat back over to the mechanic
again tomorrow. i replied to specific parts of your email in caps:

On Jul 29, 2008, at 10:43 AM, Lee Shuster wrote:

> Hi Jeff,
>
> I'd like to ask a couple of "dumb" questions:
>
> >> So a short history on my boat: had "different" Buick 155 put in
> my boat last winter.
>
> Do you know the history or source of your "different" Buick V6? Is
> it a 225 Cu in or 231 Cu in?
>
NOT SURE - BOUGHT FROM A GUY WHO HAD TWO IN SOME SORT OF DUAL ENGINE
BOAT (NEVER SAW WHICH BOAT)
>
> It's a long shot but --- You could have a even-fire crankshaft
> (231) engine which requires a different distributor. Stay with me:
>
> The original OMC Buick V6's were all odd-fire and were 225 cu in.
> They used Delco-Remy distributors designed specifically for the odd-
> fire 225 cu in. Buick engineers first introduced the 90-degree
> "Fireball" 198 CID V6 for the Buick Special & Skylark in 1961. In
> 1964 Buick bumped the V6's displacement to 225 CID. The 90-degree
> 225 CID V6 engine was essentially the 300 CID V8 with two cylinders
> removed. Odd-fire V6 firing intervals were staggered at 90 and 150
> degrees so the tooling could be shared with the V8. A 231 CID odd-
> fire V6 was offered from '76 - '78.
>
> For smoother idling, Buick switched to a (weaker) split-pin
> crankshaft, resulting in an even-firing V6 with the 231 & 252 CID
> V6's midway through the 1977 model year and later. Even firing 6's
> use 120 degree intervals. Hard for the average car mechanic to tell
> the difference from external appearances.
>
> (Look at the distributor cap and you'll see the rather "odd" odd-
> fire spacing, 90-150-90-150-90-150.) See my website for more details
> on the odd-fire/even-fire Buick V6:
http://hhscott.com/evinrude/buick_v6.htm
>
> If you want a more detailed explanation on the odd-fire oddities
> see: http://home.off-road.com/~merls_garage/oddfire.html
>

WELL, CHECKED BOTH SITES - I'M GETTING LOST ON THE FIRE SPACING
STUFF. REGARDLESS, PART OF THIS COULD HAVE TO DO WITH THAT I HAD TO
SORT OF GUESS AT WHICH WIRES WENT WHERE ON THE NEW DISTRIBUTOR'S
CAP. I'M PRETTY CONFIDENT ABOUT WHICH CYLINDERS ARE #1, #2 ETC.
THE PREVIOUS CAP WAS MARKED WITH NUMBERS AND BEFORE TAKING OFF IT OFF
I MARKED THE PLUG WIRES. [THE #1 IS FRONT RIGHT SIDE WHEN VIEWING
FROM THE FRONT. ALL THE ODD'S ARE ON THE PORT, EVENS ON THE SB. ]
BUT THE NEW CAP DOESN'T EVEN HAVE #1 MARKED ANYWHERE LIKE THE
OTHERS. BUT ACCORDING TO THE MANUAL THE ROTOR POINTS TO THE FRONT
WHEN #1 PISTON IS AT TOP DEAD CENTER. AND THE ORDER OF THE WIRES
ON THE PREVIOUS CAP WAS COUNTER CLOCKWISE STARTING WITH #1. AND THE
NEW CAP (AND PREVIOUS) HAVE A PIN TO ALIGN THEM WITH THE
DISTRIBUTOR. SO I GOT THE #1 PISTON AT TDC, ROTOR POINTING TOWARDS
FRONT, AND SINCE THE CAP ONLY GOES ON ONE WAY, MADE THE ASSUMPTION
THAT #1 MUST BE RIGHT WHERE THE ROTOR WAS POINTING (WHICH MATCHED WHAT
THE MANUAL SAID). THEN I PLUG IN THE WIRES IN SEQUENCE GOING CCW
AROUND THE CAP. DID I DO THAT RIGHT?

TO ADD TO THE MIX HERE, YOU MENTIONED DELCO REMY DISTRIBUTORS. THE
"ORIGINAL" DISTRUBUTER THAT WAS ON THE ENGINE WHEN I BOUGHT IT (BEFORE
THE CAR DISTRIBUTER THE MECHANIC PUT ON) SAID DELCO - REMY ON THE
TOP. IT'S A BIG CAP, ABOUT TWICE THE SIZE OF THE MALLORY. AND IT
DOESN'T LOOK LIKE A TYPICAL DIST CAP. SO IF THE ODD FIRES CAME WITH
THOSE DISTRIBUTERS, PERHAPS THAT MIGHT INDICATE I HAVE AN ODD FIRE.
HOWEVER, THERE'S NO GUARANTEE THOSE WERE NECESSARILY "ORIGINAL"
EITHER. BUT MY GUESS WOULD BE THEY WERE.

I STILL AM NOT SURE WHY THE MECHANIC TOOK THAT DELCO REMY OFF AND PUT
ON THE OTHER "CAR" DIST.

AND JUST TO ADD EVEN MORE CONFUSION IN HERE, THE "CAR" DISTRIBUTOR
PUT ON BY THE MECHANIC HAD THAT SAME VACUUM TUBE THING STICKING OFF
THE FRONT LEFT SIDE, JUST LIKE THE "CORRECT" DISTRIBUTER SHOWN ON THE
ENGINE IN YOUR PHOTO AT YOUR SITE. BUT THAT'S THE SPECIFIC PART
THE GUY AT THE DOCK POINTED TO AND SAID "THERE'S YOUR PROBLEM, YOU
HAVE A CAR DISTRIBUTOR ON THERE, SEE THAT VACUUM THING ON THE
FRONT?" SHEESH. AND WHEN I MENTIONED THE PREVIOUS
DISTRIBUTER THAT HE FOR SOME REASON REMOVED SAYING "DELCO REMY" ON IT,
HE SAID "OH YEAH, THAT'S A CAR DISTRIBUTOR" - (HEARING ME SAY
"DELCO"). PART OF THE PROB IS HE'S THE SHOP OWNER WITH THE SUPPOSED
OMC EXPERIENCE, YET HIS UNDERLING HAS BEEN DOING ALL THE WORK ON THE
ENGINE. SO HE DIDN'T KNOW WHY THE GUY TOOK IT OFF EITHER, AND
MENTIONED MAYBE CLEARANCE WITH THE COWLING ISSUES (I LATER TESTED AND
IT CLEARED.) AND NEITHER THE DELCO REMY'S OR THE MALLORY THAT I
HAVE ON THERE NOW HAVE THAT LITTLE VACUUM THING ON THE FRONT LIKE
YOUR PHOTO. THOROUGHLY CONFUSED YET?

TO CUT TO THE CHASE, I STILL HAVE THE DELCO REMY. IN FACT TWO OF
THEM. HOW COMPLETE THEY ARE I DON'T KNOW, BUT ASSUMABLY I COULD
ROUND UP POINTS, ROTOR, CONDENSER.

BUT THIS ALL BEGS THE QUESTION(S) - IF I HAVE AN EVEN FIRE DISTRIBUTOR
ON AN ODD FIRE ENGINE, AND/OR HAVE MY PLUG WIRES IN THE WRONG ORDER
ON THE CAP, WOULDN'T ALL THAT PREVENT THE ENGINE FROM STARTING AT ALL?

IS MISSING THAT VACUUM THING PART OF THIS? THERE DOES NOT APPEAR TO
BE A PLACE TO CONNECT UP THE OTHER END OF A TUBE ON MY CARB ANYWAY.

>
>
> Was your "mechanic" a car guy or an experienced OMC marine guy?
>
SO HE SAYS.
>
>
> Your used Mallory Marine distributor? Is it possible you got an even-
> fire V6 distributor and stuck it into your odd-fire? Check the
> inside of the distributor cap: Evenly spaced 6's are
> 120-120-120-120-120-120 degrees apart.
>
CONFUSED ABOUT THIS. HOW CAN I TELL THE DEGREES? THERE'S SIX PORTS
ALL EVENLY ARRAYED AROUND THE 360 DEGREES OF THE CAP (60 d APART?).
WHERE'S THE 120 ?

> I have never heard of a Mallory distributor being used on an odd-
> fire Buick, but I suppose anything is possible. Also, re-check the
> firing order: The odd-fire firing order is 1-6-5-4-3-2.
>
> The even-numbered cylinders are starboard, while the odd-numbered
> cylinders are port-side.
>

MY ODDS ARE ON PORT SIDE.
> The heads feature an unusual valve arrangement: E-I-E-I-I-E (port
> bank, stated from front to rear, or starboard bank, stated from rear
> to front.) (Where Even-fire Firing Order is: 1-6-3-5-2-4)
>
> There's some very strange possibilities going on here -- This thread
> is beginning to remind we of Click & Clack!
>
> Hang in there -- I'm just trying to help out by figuring out exactly
> what you have. Do you have a SELOC or OMC shop manual? that would
> be helpful.
>

I DO HAVE BOTH ACTUALLY. BUT THE SELOC I THINK IS FROM THE MID 70'S ON.
>
>
> Oh yeah, what carb do you have? OMC used both 1-barrel (1964-65)
> and 2-barrels (1966 - 1970). I think the 1-barrel's were Carter's
> and the 2-barrels were Rochester's.
>

AH YES, THE CARB. IT'S A ROCHESTER 2 BARREL.

AND ON A SIDE NOTE- AFTER GLANCING OVER THE AFTERMARKET "BEEF UP
YOUR ENGINE" STUFF YOU MENTION AT YOUR SITE, I AM ABOUT READY TO SAY
TO HELL WITH MY POSSIBLY MIS-MATCHED WHO KNOWS WHAT CARB AND
DISTRIBUTOR AND GO FOR NICE NEW BEEFIER STUFF. I PLAN ON KEEPING
THIS BOAT FOR A LONG TIME. JUST BOUGHT NEW SEATS FOR IT. I WANT
AN ENGINE THAT STARTS AND RUNS AS RELIABLY AS IT POSSIBLY CAN. I'M
SITTING HERE TRYING TO LEARN HOW TO SET THE TIMING, KNOWING THAT IF I
DON'T IT MEANS WEEKS AT THE MECHANIC AND $$ EVERY YEAR. BUT IF
THERE'S SOME SORT OF UPGRADE THAT WOULD GET ME A NO TUNING NEEDED
ELECTRONIC IGNITION, I AM ALL FOR IT.

>
>
> Lee Shuster
> Salt City
>
>
> -----Original Message-----
> From: omc-boats-bounces@...
[mailto:omc-boats-bounces@...
> ] On Behalf Of JEFF DOOD
> Sent: Tuesday, July 29, 2008 10:00 AM
> To: Evinrude & Johnson Boats of the 1960's and 70's
> Subject: Re: [OMC-Boats] timing/carb adjustment
>
> .....so many applicable topics on this list to what i'm going through
> with my boat right now. first off, i have a mechanic, but i dread
> having to leave my boat with him because i usually don't see it for
> another month. So i have been crash coursing myself to try learn
> about my engine and work on it myself as much as possible. i am
> good with cars, great with electrical stuff. boat engine stuff - so
> so. and when it gets into timing and carb adjustment i am really
> feeling my way through it. i haven't even done that on a car yet.
>
>
> So a short history on my boat: had "different" Buick 155 put in my
> boat last winter. mechanic got it running, starting, but never water
> tested. a few weeks back took it out for test, started fine, ran
> ok at low speed, but lost all power at about 10mph. He thought
> carb rebuild needed. i rebuilt carb that weekend. test ran and
> still had same problem. Although adjusting it was kind of a guessing
> game. My mechanic said to screw the two adjustment screws in all the
> way until the engine almost stalls, then back them out about a turn
> and a half. he also said to do this while boat was underway, not
> idling in neutral. Well i did this, and had the screws in about
> every conceivable position and always the same thing - no power at
> about 10 mph.
>
> So back to the dock i slowly went. Random guy at the dock
> suggested it might be a bad distributer. (mechanic didn't bother
> telling me i had a car distributer on there). So i got a used but
> good condition, SUPPOSEDLY original Mallory distributer. replaced
> points, condenser, installed this past weekend. Went to dock to for
> timing last night. (First time i have ever timed anything). Got
> it started, idled alittle rough but nothing major. Twisted the
> distributer and got the white mark to mostly line up with the "5" as
> spec'd in the manual. Seemed to smooth out idle at first. Then i
> played with carb screws again. Double checked timing, etc etc.
> End result is same thing, except maybe a little worse. now idles a
> little rough and stalls out at about 10 mph.
>
> Any suggestions?
>
> When setting the timing, is the white mark that is to be line up
> with the "5" supposed to bounce all over making it really difficult
> to line up exactly?
>
> how important is the tach in this process? i have no working
> tach. But in theory, shouldn't i be able to get things get pretty
> close by just listening to the engine?
>
> am i adjusting the carb correctly? is there a sequence to
> adjusting all this stuff - carb then timing? timing then carb?
>
> if i end up having to replace the carb altogether, is there an source
> for those out there? new? used?
>
>
> would sure love to use my boat this summer!
>
> thanks, jeff
>
>
>
>
>
> On Jul 28, 2008, at 1:58 PM, Don Mandelas wrote:
>
> > Ethan, I undertsand what your saying. I'll recheck the RPMs with
> the
> > timing light again and double check the settings. (I'll re-do the
> test
> > so that I'm confident with the results). Maybe I'll even get the
> > tinytach you were talking about.
> >
> > Don.
> >
> >
> > > Date: Mon, 28 Jul 2008 13:42:35 -0500
> > > From: brodskye@...
> > > To: omc-boats@...
> > > Subject: Re: [OMC-Boats] Engine RPM and Boat Speed
> > >
> > > On Sun, 27 Jul 2008, Don Mandelas wrote:
> > > > This weekend I was able to obtained a timing light and digitally
> > measure
> > > > the revalutions per minute of my V-6 155 hp boat engine.
> > > > I discovered that when the timing light indicated 1,100 RPM's my
> > boat
> > > > tachometer was reading 1,000 RPM's. And, when the timing light
> > indicated
> > > > 4,000 RPM's my boat tachometer was reading 3,000 RPM's. This
> > means my
> > > > tachometer is reading a full 1,000 rpms below what it should be
> > on the
> > > > higher end of the scale and is probably the primary reason why I
> > am going
> > > > slower than normal. I'll replace the tachometer and try the boat
> > again.
> > >
> > > This sounds a little strange - you say that the tach is reading
> > low, so the
> > > engine is actually spinning faster (and making more power) than
> > believed.
> > >
> > > I found the opposite on mine - when I measure the RPM (using a
> > TinyTach
> > > inductive pick-up on a spark wire), I see that the tach is reading
> > > substantially high (1000-1500 rpm). My understanding is that older
> > tachs
> > > tend to read high due to weakening of the return spring with age.
> > >
> > > Are you sure you had the timing light set properly (some can be
> > switched
> > > between various combinations of two-stroke/four-stroke, single/
> multi
> > > cylinder, and wasted-spark modes) and it wasn't reading high by a
> > factor of
> > > two? I'm not sure how it works with older distributors, whether
> > each spark
> > > plug fires once for every revolution or just every second time. I
> > think
> > > it's the latter.
> > >
> > > Tinytachs are a fairly cheap way to have a more accurate RPM
> > reading, as
> > > well as an hour-meter. Unfortunately I don't remember whether the
> > 4C or
> > > the 2C should be used.
> > > http://www.tinytach.com/tinytach/gasoline.php
> > >
> > > If anyone has figured out a way to adjust the factory OMC facts,
> > I'd like
> > > to fix mine. I haven't figured out how to do that yet.
> > >
> > > Ethan
> > >
> > > --
> > > Ethan Brodsky
> > > _______________________________________________
> > > OMC-Boats mailing list
> > > OMC-Boats@...
> > > http://lists.ultimate.com/mailman/listinfo/omc-boats
> >
> >
> > Keep your kids safer online with Windows Live Family Safety. Help
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Received on Tuesday, 29 July 2008