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Johnson 25 HP 1974 (25r74m) - Connecting Rod (Flat spot)

There is a flat side on the connecting rod that connects to the wrist pin. Does it matter which side of the block the flat side goes (intake or exhaust)?

I'm rebuilding my first outboard and didn't notice the flat spot on the connecting rod when I took the connecting rod off the piston.

Thank you.
 
What matters is that the oil hole on that connecting rod is facing "UP".... that will determine which side that flat spot faces.
 
Joe,

The Service manual I have does not refer to the hole and location of the rod connector so can't thank you enough for your reply (see pic)!!


When you say "UP" do you mean towards the fly wheel (top of CAM)?
 

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Joe, The Service manual I have does not refer to the hole and location of the rod connector so can't thank you enough for your reply (see pic)!! When you say "UP" do you mean towards the fly wheel (top of CAM)?

Yes, that's exactly what I mean. The point is... if you installed that rod upside down, having the oil hole facing downward toward the propeller, there is no way the oil within the fuel mixture could drip in the hole to lubricate the wrist pin or rod bearing. Guess how long those bearings would last! :cool:

Also, I assume you're aware but just in case..... those connecting rods are cast in one piece, then the cap is broken off (no, i have no idea how they do that). The result being that the connecting rod cap fits that one particular rod and no other, period!

Also the cap only goes on one way.... you'll feel it click into place I'm sure but if in doubt, look at the side of the cap and rod near the joining area. On each piece, you'll see a small reverse dimple (a bump)... those dimples must both be on the same side.
 
Thank you! Yes, I saw the specific alignment (bumps/dimples) was listed in the service manual. Luckily, I kept the caps to each connector rod separated so I know where they belong. One more question if you don't mind.... Can I use Vaseline instead of bearing grease to assemble the bearings?
 
Just use regular oil for the fuel mix is all you need to assemble. Assemble it and torque the screws first without putting in the seals and check end play on the crank and that it turns over nice and smooth then you can seal the case halves and install the seals.
 
We used Vaseline for years, before OMC came out with their needle bearing assembly grease. Then we used the OMC product because it came in a squeeze tube---easier to keep clean than that jar of Vaseline that always seemed to get left open. The grease is for sticking the needles in place during assembly. Once the motor is started, fuel mix washes it out.
 
Can I use Vaseline instead of bearing grease to assemble the bearings?

In a word... Yes. OMC's (Bombardier's) needle bearing grease looks just like Vaseline anyhow. I've even used the heavier anti corrosive grease (used on the engine's grease fittings) to hold those older sets in place (separate needles and cages) and never encountered problems as the fuel mixture dissolved it very quickly.
 
Everyone, I really appreciate the help!! Thank you so much. Joe - I went back and verified the end caps on the rod connectors and I did have them wrong. UG!!! I mixed them up somewhere. But they are matched now.

Could you please help with one more question? Can I just sent the points to .02 (when the knob on the CAM,Magneto is aligned to each point) or do I need to actually use a timing light?

If interested, below is the history on what I'm doing.
My dad bought 2 older engines (76 Evinrude and 74 Johnson). Somehow I got roped into combining the 2 engines into making 1 good one. The cylinders/pistons were damaged on both engines. I was able to find a block on the 74 Johnson so that is the engine I'm using. The boat that the engine will go on is called 50/50 so the engine will fit right in!
 
With the coils external on the block .022 is closer to correct but setting the points with a timing light is allways the best method for max performance. OEM points are also suggested they last longer than aftermarket.
 
Yea that is the driver coil for the ignition system. In 77-78 they changed over to CD ignition with a charging system not sure if you can add a lighting coil to that motor? Racer would know better on your options.
 
A different motor. Or a battery charger that you plug into a wall outlet. Seriously, you don't really need a charger on the motor. The battery is only used for starting. But of course if you were thinking of running a trolling motor or something, a motor's alternator can't produce that much juice anyway.
 
So in July I'm going on a fishing trip with my dad for 8 days. With no access to electricity, I won't be able to re-charge my fish locator battery. So my intent was to avoid buying a 2nd battery for the trip.
 
The 2nd battery is a route that many boaters take to avoid a ruined trip.

Setting points: Have the flywheel key aligned with the fiber rubbing portion of the points, then set that particular point so that a .020 gauge will go through BUT a .022 will not... then go to the next set of points. That'll put you so close to factory specifications that it would be hard to tell the difference.
 
Pertaining to installing that driver coil.............

(Magneto & Driver Coil Alignment)
(J. Reeves)

To align the coils properly, have the metal vertical portion of the coil yokes aligned with the inside edge of the bevel that exists on the top portion of the aluminum seat upon which the coils sit. This creates the proper distance between the coils and the flywheel magnets. Faulty alignment creates friction and the yokes of the coils heat up, turn blue and expand.
 
Good? I didn't realize there was an adjustment on the coil. I thought the bolts automatically aligned it (so thank you...!!!). I took multiple pictures of the location of the old one then took a sharpy to mark where the old one was at. hopefully it's accurate.

Coil.JPG
 
Good? I didn't realize there was an adjustment on the coil. I thought the bolts automatically aligned it (so thank you...!!!). I took multiple pictures of the location of the old one then took a sharpy to mark where the old one was at. hopefully it's accurate.

View attachment 13397

I can'r see the bevels in that photo, sorry. Someone may have installed that one incorrectly so don't make assumptions using other people's installation methods should this be the case. Use the bevels as a guide to avoid the Uh-Oh remark as the flywheel magnets tear the top of the engine off.
 
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