tuning up a fat 50

[PmDavis300]

so im do some tuning on my fatty, and i plan on doing a link and sync and possibley setting the points. but i was wondering if i should even bother with the points unless they are causing problems? or is it good practice to adjust them anyway?

 

[tashasdaddy]

Re: tuning up a fat 50

good practice, also making sure the contacts are clean and shiney.

 

[PmDavis300]

Re: tuning up a fat 50

good practice, also making sure the contacts are clean and shiney.

ok will do, didn't want to go through the trouble of pulling that fly wheel off and retimeing if it wasn't necessary.

 

[R.Johnson]

Re: tuning up a fat 50

With that age engine, certainly start with a compression test, then check your spark, and fuel system. You are going to want a manual to guide you thru . I would at least cleen, and adjust the points. A word of caustion on this engine, especially if it is off of the boat. This engine has a tilt assist spring to help when tilting the engine on the boat. The spring is a square section spring, 1/4 thick, and it is hellishly strong. When off the boat,if you were to release the engine lock down lever, that transom clamp assembly will fly up with tremendous force, and I mean bone breaking force. I have'nt worked on one of these engines in years, but I think we can help you along as you go.

 

[R.Johnson]

Re: tuning up a fat 50

You don't pull the flywheel on this engine to deal with timing. It has a belt driven magneto. There is a timing mark on both the flywheel, and magneto pulley. You loosen the magneto bracket to slacken the belt to make this change if needed. You then bring the magneto, and throttle linkage into sync. Have you a manual for this engine?

 

[PmDavis300]

Re: tuning up a fat 50

You don't pull the flywheel on this engine to deal with timing. It has a belt driven magneto. There is a timing mark on both the flywheel, and magneto pulley. You loosen the magneto bracket to slacken the belt to make this change if needed. You then bring the magneto, and throttle linkage into sync. Have you a manual for this engine?

sorry, i meant the magneto pulley. yes i have a manual and have actually gotten it started and done some work on the lower unit. im just wating for some parts and thought id do some other things while i wait

 

[PmDavis300]

Re: tuning up a fat 50

oh one more thing, does this engine have a tell tale?

 

[Chris1956]

Re: tuning up a fat 50

No, The fatty does not have a real telltale. it has a spitter on the rear midsection. Sitck a meat thermometer into the spitter and it should read about 140 degrees.

On that motor, there are two sets of points. You can set them with a feeler gauge, or continuity meter. Look for the second timing mark on the dist. pulley base. It is 90 degrees away from the first mark.

 

[PmDavis300]

Re: tuning up a fat 50

No, The fatty does not have a real telltale. it has a spitter on the rear midsection. Sitck a meat thermometer into the spitter and it should read about 140 degrees.

On that motor, there are two sets of points. You can set them with a feeler gauge, or continuity meter. Look for the second timing mark on the dist. pulley base. It is 90 degrees away from the first mark.

ok well i have a question about each of the things you brought up. lol
first off, where is this spitter? is that the exhaust releif port??? also, is there some info somewhere about setting the points with a continuity meter, i would like to try that. also, what is the mark second mark your talking about for? syncing?

 

[R.Johnson]

Re: tuning up a fat 50

Hopefully, the manual you have will lead you thru how to set the fuel, ignition linkage, it is rather difficult to discribe here without the engine right in front of me. You can set the points with just a feeler guage, that will be fine, When this engine came out, you could buy a magneto pulley thru the special tools catalog. All it was, was a regular pulley with about a 90 degree section cut out of the side, and top. When the proper timing mark was in place for the point you were setting with a continuity meter, or light, you could reach thru the cut-out on the pulley to set the points. I still have one of these pulley's hanging above my bench. Needless to say, it has been hanging there awhile. If this engine is new to you, fuel consumption is going to be a surprize, a nasty surprize.

 

[PmDavis300]

Re: tuning up a fat 50

Hopefully, the manual you have will lead you thru how to set the fuel, ignition linkage, it is rather difficult to discribe here without the engine right in front of me. You can set the points with just a feeler guage, that will be fine, When this engine came out, you could buy a magneto pulley thru the special tools catalog. All it was, was a regular pulley with about a 90 degree section cut out of the side, and top. When the proper timing mark was in place for the point you were setting with a continuity meter, or light, you could reach thru the cut-out on the pulley to set the points. I still have one of these pulley's hanging above my bench. Needless to say, it has been hanging there awhile. If this engine is new to you, fuel consumption is going to be a surprize, a nasty surprize.

oh ok, ya i read about that method of setting the points. interesting, but i dont have that special pulley. guess ill just use a feeler gauge

 

[Chris1956]

Re: tuning up a fat 50

PM, I think all the fattys had the cutout pulleys. When you remove the three screws on top og the dist pulley, the cover will come off and expose the points. That motor has the two sets of points, one condenser, two magnets and a single coil. I owuld start by setting the points usintg a feeler gauge. A continuity meter is better, but more difficult.

The carb is synched to the timing like this. Turn the flywheel until the timing marks on the recoil starter flywheel and block line up. Now set the throttle until the timing mark on the base of the dist pully matches the notch in the black distributor bracket. The dist pully should have a timing mark that alines to the pully base and the bracket. If not adjust the dist pulley's position by pulling off the timing belt and rotating the dist pulley. Now the throttle cam should just touch the carb cam follower that opens the throttle. Adjust the set screw on the throttle arm to make it so. There is an adjustable link between the distributor and the throttle bellcrank on the starboard side of the motor, to help the dist. pulley base line up.

 

[PmDavis300]

Re: tuning up a fat 50

ok well i did something wrong.....
i removed the magneto last night and took it home and adjusted the points, then this morning i put it back on the engine and attempted to time the engine and sync it up. now heres the crazy part.. i started her up with the throttle in the start position and she revved up very high, so i shut it off immediatly. i then proceeded to screw around with the throttle thinking it was set to high, it tried to start a few times, but now the starter still turns it over but it doesnt sputter or anything. spark is still good, and theres plenty of fuel going to it. what did i do wrong?

 

[R.Johnson]

Re: tuning up a fat 50

The link% sync. has to be in proper order. I'm not going to try to discribe the whole procedure. With the trottle lever all the way back, the magneto must be againt it's stop, and the carb throttle plates must be completely closed. With the trottle lever all the way forward, the magneto must be at it's full advance stop, and the throttle plates wide open. If you push the throttle lever wide open, the magneto will be againt it's stop, while holding it there, loosen the screw at the carb linkage at set the throttle plates to wide open, lock the screw. This will put you close to where you want to be, not right on, but close. If every thing else is correct, the engine should start, and run. If set as I discribed, when you retard the throttle lever part way, the throttle plates will go partially closed, but the magneto will remain at full advance. That is the function of the mouse trap spring at the top of the throttle tower shaft. Keep in mind, I am going from memory here, I have'nt touched one of these engines in a good gone while.

 

[PmDavis300]

Re: tuning up a fat 50

ok well ill try and do it again and see what happens. for the timing, all i needed to do was align the flywheel marks and the distributer magneto pulley marks to their respective marks and put the timeing belt in place right?

 

[Chris1956]

Re: tuning up a fat 50

Not quite, Reread my last post. Set the flywheel timing mark to match the ones on the rear of the block and top of recoil starter. Set the timing mark on the pulley base to match the "dent" in the black dist. bracket. Set the dist pulley so the timing mark matched the pulley base. Now install the timing belt. Adjust the stainless arm that goes to the carb, so that the carb just starts to open at this spot. make sure both sets of points are set to .020 In clearance at their max opening.

 

[PmDavis300]

Re: tuning up a fat 50

should i be looking at the magneto pully and indent mark on the base from a 90 degree angle when lining them up? or should i be off to the side? in my book they show them lining up when looking at it from the side.

 

[Chris1956]

Re: tuning up a fat 50

The pully base and the bracket should align. I would think you would be standing sorta behind the port side cylinder head to see it line up.

There is also a timing mark on the vertical linkage from where the throttle cable attaches to the distributor. You should align the raised mark on the dist link arm, with the mark on the crankcase. Be sure those many linkage points have little or on "play" it, and your tuneup will be more precise.

 

[PmDavis300]

Re: tuning up a fat 50

ok thanks guys, i got it started again. i redid the timing and sync procedures and then adjusted the throttle cam, and she started up and ran at a normal idle speed. no clue how the throttle cam got out of whack.

ok next problem, which probably isnt a big deal. i installed the impeller but it really didnt want to go over the impeller key. i got it over it, but i dont think i shoved it down far enough and i believe the impeller is rubbing against the housing because its very hard to turn the propeller. is this normal for the impeller to fit very tightly?

 

[F_R]

Re: tuning up a fat 50

It will be difficult if it is dry. That's a honkin-big impeller in there.