Thingamajig???

[Blinkin]

1977 Chrysler 75hp outboard motor (model: 757 HC).

I figured I would use the proper terminology this time. It is obviously not a whatchamacallit. Man I really need to order a good manual so I don't have to ask what something is every time, but until then...

On the starboard side of the engine there is some linkage that is connected to the carbs and runs down where it connects to another portion of linkage which runs back up and is somehow connected to the starter. Not sure what it does. I moved the throttle back and forth and it is not it, howver it does run close by the throttle linkage.

The reason I am asking about this is where the first piece of linkage runs down, it connects to the other portion on some sort of pivot before it runs back up towards the top of the starter. Well... where the other portion of linkage attaches it is connected by a black rubber/plastic joint which allows it to rotate on the pivot point. This piece is old and broke and the previous owner wrapped it with wire to hold it together. I don't like any kind of rigging like that because it could one day cause me to have to paddle my boat back to shore. Not my idea of fun when it could have been prevented by replacing what looks to be a cheap part.

This sounds confusing but if anybody has a clue what I am talking about I would appreciate some words from the wise.

Thanks

 

[Frank Acampora]

Re: Thingamajig???

Glad to see you are using proper marine terminology blinkin! LOL

Seriously though, you do have me confused so I will describe linkages on that engine and maybe by accident will have answered your question.

On the Starboard side of the engine there is a three piece aluminum bar that connects all theree carb butterflies. The lower carb has a black plastic roller that the throttle cam rides on and opens the butterflies. This cam is connected to the timing tower by a short aluminum bar about 2-3 inches long, threaded on both ends with black plastic ball joint fittings on each end.

The bottom of the timing tower rides in a black plastic sleeve. The top of the tower also rides in a black plastic sleeve. The top of the tower rod is connected to the distributor by a short threaded rod with two black plastic ends. The threaded rod is threaded opposite on both ends like a turnbuckle so turning it one way advances the timing and turning it the other way retards timing (This is only for initial timing setting when synchronizing).

Now we will go back down--As a 77 your engine should be new enough the have the neutral interlock switch below the carbs (brown plastic microswitch with two yellow wires attached.) Below the switch is the shift linkage. In neutral, a bent plate will contact the switch button, allow the start circuit to be made, and allow the key to energise the start solenoid. When the linkage is either moved forward or backward, the switch is open and the start circuit is disabled. (believe it or not moving the linkage forward is actually reverse gear.)

If the microswitch is by chance mounted on the distributor, It functions the same, except that advancing the distributor away from neutral setting will disable the start circuit. Only difference is that the throttle control cable now controls neutral interlock. It was initially Coast Guard approved but later, regs were changed to require the interlock on the shift linkage--considered to be safer.

That's it for the Starboard side. Port side only has choke linkage and nothing on either side connects to the starter (which is on port side).

Hope that helps. And when does your Clymers arrive?

BTW: The reason that all plastic fittings are usually black is that the black filler makes the plastic more ultraviolet resistant. Other than that, color does not matter.

 

[Blinkin]

Re: Thingamajig???

You're pretty good... Nailed it again. The part I was referring to was simply the black plastic ball joint end towards the front of the motor. It is obviously old and weathered and cracked. The guy has wrapped it with wire to keep it from coming apart and is holding for now. Is this an easy to replace part or would I have to buy the whole linkage setup and then play hell with keeping the timing set right?

I know when we had it in the water it had a little stutter when we would first take off, could a little play in that part cause a stutter? I was thinking it just needed a little tune-up, but... I'm no expert. What's your take on this?

I have another question for you as far as a tune-up goes. I noticed it had champion plugs. Do you have a preffered plug you use? I know Champion does most of the plugs for engines like that but I have never been a fan of them in the applications I usually run into. On one of my motorcycles I had an old NGK give out more spark than a brand new champion so I always preferred to go with another brand, I love NGK. But at the same time we are talking marine application here so it might not be a good idea to change. Opinions?

One more quick thing: is there a set torque for installing new plugs and would you by chance know what plug to use in this motor (or one to cross reference for an aftermarket replacement)?

Once again I appreciate your help and information. I have to get online and find a Clymer so I don't have to bug you so much.

Thanks,
Tommy

 

[Frank Acampora]

Re: Thingamajig???

The ball joints were almost never changed in design so you should be able to buy them through a Merc dealer--only, use a 1988 90 or 125 engine as reference--They don't know what to do with Chrysler engines any more. Better alternative would be to go to The Chrysler Crew and contact franzmarine.com Franz will have them--probably only a couple of bucks. When you replace it, try to keep the lock nut in its position for reference. This link does not change timing, it simply sets the throttle butterflies to horizontal when at wide open throttle. If you are off a small amount, the engine won't even notice it, unless it has also changed the cam position for idle.

As far as the stutter, a lot of Chryslers seem to do that. They are a little rough just above idle then clear themselves out and run smoothly. Sometimes it is carb adjustment BUT I CAUTION YOU NOT TO TRY TO ADJUST CARBS. Inadvertently setting the low speed needles too lean will almost always quickly melt pistons at or near full throttle. NEVER-Never-Never set the low speed needles leaner that 3/4 turn out from lightly seated. I prefer 7/8 turn even if the idle suffers a bit.

Plugs: surface gap Champion Possible new number 322 (old L20V) or NGK BUH. Torque to 10-15 ft pounds OR finger tight then 1/4 turn more--REMEMBER--this is an aluminum head. Do not try to use a bent electrode or multiple electrode plug (for example Split Fire) in an effort to get better performance. They are much hotter than the surface gap plugs I listed and will melt a nice little 1/4 inch hole in the piston crown.

Timing: 32 degrees before TDC at wide open throttle. this can be set without the engine running (static) top cylinder is #1 Remove #1 plug, ground agaibnst block. With ignition on and throttle in full forward slowly rotate flywheel until plug fires. Rock slightly back and forth to confirm setting. Remove and ground other two plugs to prevent damage to electronic unit and to prevent engine from starting.

 

[Blinkin]

Re: Thingamajig???

Well Franz had a whole bunch of the ball joints for about $10.00ea and O'Reilly's has the NGK spark plugs in stock for $1.99ea. That ought to put the old motor in pretty good shape. I appreciate you helping me out again. I guess I need to find a place that sells the Clymer manual for that motor and I could at least figure out what I am looking at. LOL

Do you know what would make the motor smoke a good bit when running? I know a lot of 2-stroke outboards smoke some, I guess because of the fuel/oil mixture, but this one appeared to smoke more than I would think normal. Maybe the new plugs would help this, but I was wondering if there is a fuel additive that could help or something of that nature. Any advice for a newbie?

Thanks again,
Tommy

 

[Frank Acampora]

Re: Thingamajig???

10 dollars each?--OUCH! Pricey. That's why I buy Junker engines and salvage anything I can.

Chryslers seem to smoke more because the exhaust relief is right out the back shroud well above the water line. So at idle, all the exhaust and smoke blows back into the boat. Proper fuel mix is 50 gas to 1 oil --or 1 pint to six gallons gas--(48-1). More makes them smoke even more. Proper oil is any OUTBOARD TCW-3 oil. Do not use automotive oils! The additives are harmfull to 2 cycle engines and can cause scoring of cylinder walls as well as carbon build-up in the exhaust ports. I personally don't believe in it but if you want to try decarboning the engine, do a search on the forum for "seafoam" A lot of guys use it and are happy with the results. But read the pros and cons and make up your own mind.

By the way: you can also use Champion UL18V plugs or NGK BUHX if the recommended are not available. They are actually for a different Chrysler but will do no harm in your 75. I think they are a resistor plug. Also Autolite 2852 replaces L20V.

Clymers sometimes comes up for sale on ebay. But I think you should also be able to get them here at iboats. Chrysler/Force 3.5-1140 HP 1966to 1988. B750. Runs around 36 bucks new.

 

[Blinkin]

Re: Thingamajig???

When he sent the invoice they turned out to be $5.85ea. Not bad considering that is the only thing wrong with the motor after all.

That makes sense about the smoking problem, I just wanted to make sure. I checked the NGK website and they referenced BUHW for that motor and o'reilly's has them in stock. If I can get a NGK plug for it at $1.99 I am going to give them a shot. If I don't like the performance I will try your other suggestions. I didn't realize they made surface gap plugs for those, I didn't know what a surface gap plug was actually. Funny looking things without the post on them, just flat. I have a lot to learn.

Looks like I will be heading over to the Marine store here to pick me up a Clymer's. I appreciate the info once again.