[OMC-Boats] Spark plug wire order for odd-fire V-6

From: Ethan Brodsky <brodskye@...>
Date: Sun, 9 Jun 2013 20:31:09 -0500 (CDT)

This question is directed to anybody who has an odd-fire 225 in^3 V-6. I'm
trying to trouble-shoot some ignition problems and it'd be nice to talk to
somebody who a similar engine. I noticed that Dave Rusilas discussed
having this engine in a post ~5 years ago (and again in 2010), so I'm
hoping he's still got his and is reading the list.

My points started sticking over the winter, so I opened up the distributor
(first time since I bought the boat in '04) to clean them. After that the
engine would start and idle just fine, but is popping (misfiring) under
load. I think that may just be due to the points still being dirty and
I've got some new ones coming (thought about doing Pertronix, but decided
to replace the points instead) but that's not my main concern.

The distributor is just as described by Dave below - a Delco Remy unit with
mechanical advance, a screen on the distributor cap (which has evenly
spaced contacts, both inside and out), and an elongated rotor.

While I had it apart, I noticed that the order of the plug wires makes no
sense. My OMC dealer service manual (for the exact make, model, and year
of my boat) says that the contact on the distributor just to the "right" of
the screen is #1, and that they increase in a clockwise order (looking from
the top). But when I look at my distributor cap, the one marked #1 is
exactly aligned with the screen and they increase counter-clockwise.

My understanding is that the portside cylinders are 135 (front to rear) and
the starboard cylinder are 246. The firing order marked on the valve cover
is 165432, so I would assume that cylinder 1 should go to contact 1 on the
distributor cap, cylinder 6 to 2, cylinder 5 to 3, cylinder 4 to 4, cyl 3
to 5, and cyl 2 to 6.

This isn't how it was wired though, either in the anti-clockwise order
marked on the cap or the clockwise order specified in the manual.

Unless my notes were wrong, they were wired as follows:
cylinder numbered contact on distributor
1 2
2 1
3 3
4 4
5 5
6 6

I can't come up with any rotation or reversal of this pattern that would
yield the pattern I'm supposed to get. I'm wonder if I wrote down the
ordering incorrectly? It seems unlikely, as I marked the wires one at a
time in order as I removed them and it idles fine with the current
configuration, but who knows? If my notes are correct, it's probably been
that way for years.

I am pretty sure that my engine is the odd-fire - the casting number on the
block is 991503, which is supposed to be "V6, Odd-Fire, Kaiser Jeep
Corp/AMC". I didn't look at the cam in the distributor, but the rotor has
the elongated arm described by Jeff.

To determine if your engine is an odd-fire, look at the casting number
(visible on the top of the engine, at the back where it bolts onto the
intermediate housing) and match it up with this list:

If anybody has an odd-fire V-6, is there any chance you could look at the
distributor and tell me:
   a. Which port is #1? (relative to the screen and the front of the engine)
   b. Do the ports increase clockwise or counter-clockwise?
   c. What is the part number on your distributor cap?
   d. What order are the cylinders wired to the distributor?



On Wed, 30 Jul 2008, drusilas@... wrote:

> Jeff,
> My boat is a 1969 Sportsman with an odd fire 155. It doesn't have the original block but I'm pretty sure that
> the distributor is original. It's a Delco Remy w/ centrifugal advance only. I'll try to get a distributor
> number off it later. The cap is held down by 2 screw latches and there is no gasket. It has a spark arresting
> screen breather on the side where the point's adjustment port would be on the auto version of the cap. The
> contacts are spaced evenly, 60 degrees apart from each other. The difference is in the rotor. Its contact is
> elongated by 15 degrees of arc to allow it to fire at both 45 and 75 degree intervals. The cam on the
> distributor shaft may have 45 - 75 spaced lobes. I'll look at it when it gets light outside and get back to
> you.
> I think that the irregular spaced cap contacts that Lee is talking about are on the Delco HEI distributors. I
> tried to install one once but it wouldn't fit because the diameter of the cap is so large that it interfered
> with the thermostat housing. I opted for a Pertronix Igniter system instead and it works great. It uses a Hall
> Effect trigger set off by magnets on a ring which mounts below the rotor. Magnets are spaced around the ring at
> alternating 45 and 75 degree intervals. The part number is 1165 if you're interested.
> Dave Rusilas
> -----Original Message-----
> From: JEFF DOOD <jdood@...>
> To: Evinrude & Johnson Boats of the 1960's and 70's <omc-boats@...>
> Sent: Tue, 29 Jul 2008 10:54 pm
> Subject: Re: [OMC-Boats] timing/carb adjustment
> awesome! i think i need to check out the underside of all my
> collection of caps and see what's up. then make sure i try this
> whole thing over with the odd fire distributer in there instead and
> see what happens. esp if it would start, but not have power past 10
> mph otherwise. sounds just like what my prob might be. plus i am
> armed with more info to quiz my mechanic about.
> on the car vs marine distributor topic though - i need some solid
> info. i have heard car distributors are illegal and get you big
> fines if discovered by the coast guard. also heard the reason is
> due to the seal around the cap. marines are screwed down, cars
> are not. spark can get out without screwed down seal. escaping
> spark can blow things up. fine or no fine, not interested in the
> blowing up part. so are the delco's just behind the times and
> everything since has been brought up to more stringent safety
> standards? and if the delco ends up working best with my engine,
> should i be concerned about it not being a marine distributor?
> On Jul 29, 2008, at 4:34 PM, Lee Shuster wrote:
> > 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.

<a href="http://homepages.cae.wisc.edu/~brodskye/"> Ethan Brodsky </a>
Received on Sunday, 9 June 2013

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