TOPIC: Timing for my old merc1000

Some guys have suggested I need to check the timing on my motor, but also say I should check with folks that know how the change in fuels between 1963 and today (dreaded ethanol) might change that timing.

My manual says it should be 32 1/2 degrees BTDC. What does BTDC mean? I know it refers to "below top dead center" but what does that mean? How do I get there?

I have an old timing light I bought years ago and never used. I have never checked timing on any vehicle I've ever owned. I have friends who would do it for me. But this shouldn't be too hard right?

Any thoughts, suggestions, help, etc. greatly appreciated!

Frank

I've been told by someone I trust that 28 degrees Before Top Dead Center is plenty for these older motors, to be safe and increase the longevity. BTDC means the spark plug fires before the piston reaches the top of it's compression stroke, as the explosion that forces the piston down takes a milisecond to occur. Ideally, you want this to happen just as the piston hits the top, too soon is called "detonation" and can damage the piston, among other things.

This reading is at the proper WOT, and must be done in the water I believe. (Unless you have a test wheel to replace the prop, and a BIG test tank, and then I'm not sure you could get away with it!) There should be graduated timing marks on your flywheel, and if there isn't a pointer you'll have to make one up. I believe the Merc manual covers this, but don't remember for sure. (I let my manual go when I sold the 700FGS.)

I'd love to check this on my motor, but I go by myself most of the time and don't have anybody to drive the boat while I check the timing. Even if I did, the vision of trying to balance myself over a spinning flywheel while speeding across the lake scares the crap out of me! Maybe one of the Merc guru's up there can help you out here, F.

Clams (Wayne) Canino recommends the following procedure. Works for me.

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Topic: Timing and Sync of Merc Inlines (to 1988)
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Manual specs are different for each, but this is close enough to get them
all REAL close. This assumes nothing is broken or "wrong" with it. This also
assumes that the timing pointer is properly adjusted (if adjustable) to
accurately read TDC of the #1 piston.

This basic procedure will work for all the 2/3/4/6 cylinder inlines from
1960 to 1988. It's not for the newer 3 and 4 cylinder loopers.

Engine off

Disconnect throttle cable

Pull throttle arm to full throttle and verify carbs open fully. Adjust main
throttle stop so that the carbs are JUST hitting thier own little throttle
stops. The idea here is that you want the screw stop and NOT the carbs
acting as the "final stop" for your throttle lever.

Return the throttle to idle, carbs should be closed. Set all idle screws to
2 turns out from lightly seated.

Remove all plugs except #1, hook a timing light to #1. Then follow the
narritive.

When the throttle is in the idle position the carbs should be fully closed
and the ignition retarded. It is the amount of retardation that determines
your idle speed and is set later with the idle stop screw.

Timing Event One - throttle pickup.
As the throttle is advanced, the spark timing advances toward TDC and then
to before TDC. As the timing is just passing TDC the 1st (minor)throttle
pickup should hit and start to open the carbs. Use the timing light. Adjust
the tang or trigger screw to make this a reality. All of them are spec'd
different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win.
Use the timing light with a friend cranking it to complete this setting.

Timing Event Two - max advance.
As you continue to advance the throttle the timing will advance while the
carbs slowly open a bit more. The next adjustment is max advance, this is
the point where the distibutor (or trigger) can advance no more. Set the
max-advance stop to 21 degrees for "direct charge" inlines and 34 degrees
for the older crossflows. Use the light, - err to the side of caution.

Right after max advance, further throttle motion should cause the second
throttle pickup to hit and open the carbs to full. You already set that -now
verify it.

Leave the throttle cable disconnected and go to the water. Leave the boat
strapped to the trailer and back it in so it's deep enought to run. Have a
friend crank it while you operate the choke and throttle. Warm it up at 1500
rpms's.

When "warm" adjust the idle stop screw for about 800 rpm and then ajust your
idle needle(s) in (one at a time) till the motor stumbles. Quickly backing
it out 1/2 turn from "stumble" will usually save it from needing a re-start.
Do that for all the idle screws. Re-set idle stop for 800.

Now have your friend put it in gear (make SURE you are on the transom NOT in
the water) and reset your idle stop for as low as you can get it. 500-600rpm
is great if your old reeds will let it idle that low in gear. Now, re-adjust
the idle screws, in to stumble, then 1/2 turn out. When you've gone back and
forth with that a few times and have it "perfect" - adjust each one out 1/4
turn.

Reset the idle stop so that it's about 700-800 out of gear and 500-600 in
gear. Sometimes bad reeds won't let you get that low, you've GOT to get it
under 1000 in neutral (worst case) to avoid beating up your lower unit when
you shift into gear, even 1000 is "bad" but like I said "worst case".

Now adjust (and hook up)the throttle cable so that with the shifter in
neutral, there is light to moderate pressure holding the throttle arm
against the idle stop.

Take the boat off the trailer and go out in the water. Try the hole shot. If
it falls on it's face try adjusting the idle screws out 1/4 turn at a time
(all of them together) till you can get a hole shot. You can kind of do this
on the trailer at the ramp, but it's not really safe for you, the boat, or
the tow vehicle.

You're done.

-W

Okay, I just found out my old '63 does not use a timing light, no marks for it. There is a different procedure described in my manual, but of course it's in Greek ( ), but I'll keep at it.

Thanks guys.

Frank

Yes there is a special tool that is used to time that motor.

You thred it the top spark plug hole. It then finds TopDeadCenter then you find your correct .222 inches BeforeTopDeadCenter with it. or 32.5 deg.

Older motors like yours used inches, the later used degrees and markers to do this.

I made a tool with a dial indicator from Harbor Freight.

no this is not found on the water at WOT. It is done with the motor not running. Kinda hard to run the motor with this tool in place of the spark plug. It would be the last time the motor ran.


From what I have learned from the many knowlageable Inline 6 gurus is that the early design non Direct Charge motors did not suffer as much problems with todays gasolines and timing does not need to be reduced.(even tho I did a pinch on my 900)

The later High Dome Direct Charge Pistons had more compression and different piston design that today's fuels have problems with. These motors made from 1973 on (99cui) had the high dome pistons until the late70's/early 80's when they went back to low dome pistons.

These motors with the HDDC pistons with today's gas have had the timing reduced to save them on pump gas.

hope this helps.

Conrad

Top Dead Center is the point when the piston is at it highest (closest to the spark plug)

Before Top Dead Center is measured in inches or degress.

This is the distance you run the piston down to set the timing. The

WHen the engine is running the spark needs to happen before the piston reaches the top to create proper power.

The spark plug fires .222 inches before the piston reaches TDC to let the fuel come on combustion. (combustion is fast but it still takes time to happen) If the spark plug fired right when the piston reached the top it would be too late and not build power correctly.

Conrad

I know how to find tdc Conrad, it's getting it backed out .222" to do the btdc. I may have a way of doing that.

Thanks for the suggestion on advance for modern fuels. That's what I intend to do too, once I figure this stuff out!

Thanks for the suggestions, they are very helpful.

Frank

My apologies Frank, I had forgotten about the procedure being different on the older Mercs.

Oh yeah, and thanks Conrad.

milkdud wrote:

Top Dead Center is the point when the piston is at it highest (closest to the spark plug)

Before Top Dead Center is measured in inches or degress.

This is the distance you run the piston down to set the timing. The

WHen the engine is running the spark needs to happen before the piston reaches the top to create proper power.

The spark plug fires .222 inches before the piston reaches TDC to let the fuel come on combustion. (combustion is fast but it still takes time to happen) If the spark plug fired right when the piston reached the top it would be too late and not build power correctly.

Conrad

Conrad, so if I wanted to do the timing at 30 degrees (instead of 32.5) I'd do .205 for BTDC?

I'm trying to figure this out, and sure do appreciate everybody's help!

Frank

Frank

Frank do you have a dial indicator? You can use it to locate the T.D.C. and set the timing. By having the dial plunger set on top of #1 piston. Used this on the race motorcycles.

No I don't, but I have a good digital caliper that I can use with a homemade spark plug timing gauge to get whatever I need for BTDC. What I'm trying to figure out is what TBDC I should use. .222 (32 1/2 degrees) as the manual suggests or .205 for 30 degrees?

Again, I always run 93 octane with synthetic tcw3 oil.

Frank

Frank my 2 cents. I would set it at the factory setting for a base line and mark the distributor (very fine scribe line) Then take the boat out if it "pings" back it off just a little. Every engine has its "own timing" due to the wear on all the parts. I hope I don't get shot down to bad for this suggestion.
Pete

I can do that Pete, but I don't understand this stuff real well until I get into it step-by-step according to the merc manual. So for now my question is mark the distributor? Where?

Thanks again!

Frank

Maybe where the dist mounts to the bracket that holds it? I really don't know how your distributor is held in place. At the base where it mounts?

Thanks Mark.
Conrad

Yes .205 will give you 30 degrees. I would think that would be very safe there. But I think I am running my 1965 900 very close to .222 which is the same as your 1963 1000.

good luck hope it works

Conrad

AS allways I refer to the factory manaul.
Being a marine tech for the last 30 yrs
I have found that the older motors can be
picky but you should have no proble running
the new enhanced fules. As far as setting
the timing mark .222 btdc is correct. A in-
enxpensive dial indacator can be used, secure
it to the head w/the tip in to the spark plug
hole set the #1 piston to tdc then back off
.222 from there. then do the sync and link
set the idle and your set. I suggust you
find a old mecr service manaul (ebay?)or
try one of the aftermarket manual. Be adviced
these dont allways cover thing well.

hope some of this helped, Smoke

Smoke wrote:

AS allways I refer to the factory manaul.
Being a marine tech for the last 30 yrs
I have found that the older motors can be
picky but you should have no proble running
the new enhanced fules. As far as setting
the timing mark .222 btdc is correct. A
enxpensive dial indacator can be used, secure
it to the head w/the tip in to the spark plug
hole set the #1 piston to tdc then back off
.222 from there. then do the sync and link
set the idle and your set. I suggust you
find a old mecr service manaul (ebay?)or
try one of the aftermarket manual. Be adviced
these dont allways cover thing well.

hope some of this helped, Smoke

Smoke, I got both Glenn's manual and the factory one. One looks fairly simple, says to use a timing lamp (Glenn), the other reads like Greek (the merc manual). Never having watched anybody do this, I have less than the right amount of confidence.

Busy today, trying to get the hot rod ready for the cruise-in tonight, no time for the outboard other than gathering info.

Thanks for the suggestions!

Frank

These pix will give u an idea