More 20HP Questions

[i386]

Model: 202HD<br />S/N: 2143<br /><br />My Seloc manual finally arrived today and I still have unanswered questions, regarding syncing the carb with the timing advance.<br /><br />First thing -------<br /><br />For those familliar with the Seloc manual, I have the C type carb.<br /><br />I am concerned that the throttle is not opening up wide enough. This may turn out false, but I want to be sure.<br /><br />On page 6-10 (carb. Type B Instructions)under the heading "Special Words For 20HP Model" it states that the throttle link must be connected to the inner hole. Mine is connected to the outer hole.<br /><br />In the Type C instructions there is no mention of this even though I have an inner and outer hole. The linkage is currently connected to the outer hole. There is also no information that I've found that describes the throttle plate position at WOT. <br /><br />I can say for certain that a true horizontal position is not possible. And a near horizontal position cannot be obtained with the cam on my motor.<br /><br />------<br /><br />Second thing:<br /><br />The Type C carb is equipped with a high speed adjusting screw. The problem is there's no instructions in the Type C section describing how to set it. One might say just leave it alone then but since the motor is used I have no way of knowing if the previous owners left it alone.<br /><br />To make matters even more confusing to me, I found this on page 6-12 (Type B instructions). "High Speed Adjustment Model 20HP: The carburetor adjustment used on the 20hp model has a fixed high speed jet in place of an adjustable screw. Just incase you missed the discrepancy, the Type C instructions state that I have a adjustable screw.<br /><br /><br />Somebody throw me a clue. Could I have a motor with parts off another motor that just don't jive with the manual?

 

[rbruce63]

Re: More 20HP Questions

Man! I never knew there was a different type of carburetor in these old dogs! But yes, there is a different carburetor for the 1976-1979 Chrysler 20's.<br /><br />This is what my Clymer's has to say: "Throttle Pick-up Adjustment". 1-Remove engine cover.<br />2-Disconnect the throttle cam rod at the magneto control lever. 3-Loosen the locknut on the eccentric screw (the one without the spring) holding the nylon roller to the throttle shaft arm (on the starboard side of the motor).<br />4-Set the throttle cam mark at the point close to where it will touch the nylon roller.<br />5-Turn the eccentric screw until the roller is at the maximum distance from the cam mark, then turn the screw counterclockwise until the roller barely touches the cam mark.<br />6-Tighten eccentric screw locknut, taking care not to turn the screw.<br />7-Tear a small strip from a sheet of writing paper (bond 20#) and insert it between the cam and roller from the top, then from the bottom. Note the gap between the cam mark and paper edge. If both gaps are equal, the cam mark is at the centr of the contact with the roller. if not repeat the eccentric screw adjustment.<br />8-Reconnect throttle cam rod to magneto control lever. Rotate magneto until the nylon throttle stop on the stator ring rests against the cylidner. Wide open throttle mark on cam should intersect the roller.<br />9-If cam mark does not intersect roller in Step 8, disconnect the throttle cam rod from the magneto control lever. Loosen the jam nuts and rotate the rod to lenghten or shorten it as required. Reconnect rod and recheck cam mark/roller intersection. Repeat this step until the mark intersects the roller with the rod is installed, then tighten jam nuts.<br />10-Check the throttle shutter postiion with the magneto at wide open throttle position and the wide open throttle mark on the cam intersecting the roller. if the shutter is not horizontal, repeat Steps 1-9." Clymer Chrysler Outboard Shop Manual.<br /><br />These explanation without the illustrations for the terminology could be tricky. But there is another thing:<br /><br />"Throttle Stop Adjustment (Manual Start Models)<br />The setscrew should touch the steering handle wall when the wide-open throttle mark on the cam intersects the roller. If it does not, adjust the screw in the throttle stop.<br /><br />I guess you should be able to make the throttle plate be horizontal at wide open throttle.

 

[i386]

Re: More 20HP Questions

I'll add some pics if it helps:<br /><br /> First Picture<br /><br />The arrow points to the lock screw. There's no eccentric adjustment (wouldn't that be nice). Instead, you loosen this screw which lets the cam follower flop around freely. You set everything into place and then tighten the screw back. Then you check it. If it's not right, you do it over.<br /><br /> Second Picture<br /><br />This shows the WOT position of the cam. In this position, the cam has pushed the cam follower out as far as it can. I use the term WOT loosely as the throttle plate is not horizontal.<br /><br /> Third Picture<br /><br />In this picture I have taken my finger and actuated the cam follower out to a position that is WAY past that which the cam could do. In this position the throttle plate is nearly horizontal. I could extend the follower even further but anything past this point and the throttle plate actually starts to move back toward the vertical.<br /><br /> Nope. I'm not confusing the choke plate with the throttle plate. <br /><br /> Fourth Picture<br /><br />This is a closeup of where the throttle linkage connects the throttle shaft to the follower assembly. Note the "inside and outside" holes.<br /><br /> Fifth Picture<br /><br />This is a closeup of inside the carb at WOT. This shows how fat my throttle actually opens. As you can see, it's not very far at all.

 

[rbruce63]

Re: More 20HP Questions

I posted the wrong instructions. You have a similar carburetor to mine. Try to follow the following adjustments as quoted from my Clymer's:<br /><br />1. Close the throttle until the throttle cam mark is on the starboard side of the carburettor follower roller. Pic 1<br /><br />2. Advance throttle control until throttle cam just contacts follower roller. Then slowly advance the throttle cam until the throttle shaft arm just starts to move.<br /><br />3. Check throttle cam mark and roller alignment. Roller should be at or within 1/32" of the mark. If not, loosen screw on carburettor follower, adjust follower arm postiion until alignment is correct and retighten screw.<br /><br />4. Repeat Steps 2-4 to recheck pickup point.<br /><br />I hope this helps! Your motor has an excess oil recirculation system and setting the idle could be tricky...good luck!<br /><br />Robert

 

[i386]

Re: More 20HP Questions

That's pretty much how I set it. At lowest throttle it's now set like it should be. I just question how little the throttle plate is open at WOT. <br /><br />I'm thinking it might open more if the linkage was set to the inside hole, but that's not in my instructions to it is mentioned in the "Type B" instructions.

 

[rbruce63]

Re: More 20HP Questions

Now it's the time for the tiller arm adjustment as posted in my latter response. The tiller has to push the stator plate all the way to the max.

 

[rbruce63]

Re: More 20HP Questions

Or perhaps your motor has a different stator-carburetor-tiller arm linkage that you have to study and find why will your motor not run at WOT.<br /><br />Good luck!<br /><br />Robert

 

[i386]

Re: More 20HP Questions

It pushes all the way till the rubber bumper on the stator plate hits the block on the port side. At this point there is no more slope left in the cam to force the cam follower to travel anymore distance.

 

[rbruce63]

Re: More 20HP Questions

Were you able to synch the carb with the stator plate?

 

[i386]

Re: More 20HP Questions

I've been able to do that from the get go....<br /><br />When the cam mark on the cam is aligned with the throttle cam follower the throttle plate is closed as per the instructions.<br /><br />It's the WOT position im concerned about. I guess what I need to know is if someone with a 20HP 1972 motor like mine with a Type C (MD) carb has a horizontal throttle plate at WOT (tiller).<br /><br />The only reference I saw in my manual as to the position of the throttle plate at WOT was the 55HP model.<br /><br />Attaching the throttle link to the inner hole as per the Type B instructions might make the throttle plate open wider but like I stated before, those instructions do not apply to my carb.<br /><br />If I only had a tach I'd know if she was running at high enough RPMS. If she was making 5000-5500 RPM with the plate opened just a little I'd say it's right and just forget it. Without a tach, just having the information about another person's motor would be helpful.

 

[i386]

Re: More 20HP Questions

To complicate matters even more, the diagram of the Type C (Tillotson MD) in the Seloc manual does not look exactly like mine. It's significantly different in several aspects.<br /><br />I could provide scans of each.<br /><br />The diagram in my Chrysler parts manual looks exactly like mine. In my parts manual it says I have a MD-148-A carb. <br /><br />Maybe they made more than one type of Tillotson MD carb.

 

[rbruce63]

Re: More 20HP Questions

Get the shop manual for your specific model at hurrikain.com<br /><br />I will tach mine soon. I haven't done it. I don't think yours came with the newer carburetor.

 

[i386]

Re: More 20HP Questions

I'll do that.<br /><br />What are you going to tach it with? I looked over the tiny tachs but I'be darned if I could tell which one to get for my motor. Actually, something handheld I could hook up just for testing would be nice, but those I've found cost more than the tiny tach.

 

[rbruce63]

Re: More 20HP Questions

I have an automotive type engine analyzer from Craftsman with DIS setting for two stroke motors where the spark fires twice as much as in a four stroke.<br /><br />Could it be possible that you have the "old" carburettor with a motor that came with the new carburettor and the oil recirculation system?

 

[rbruce63]

Re: More 20HP Questions

Another thing. When your'e running this motor wide open it really screams, to the point that after 5 hours of running your ears get numb. This might be a good ballpark measurement to where the rpms are relative to the sound of the motor.<br /><br />What propeller diameter and pitch do you have? Mine was the standard at 8 1/2" diameter X 8 1/2" pitch.

 

[i386]

Re: More 20HP Questions

I'll check the prop tomorrow. I'm pretty sure it's the same one that came on it. I also have a spare (it ain't pretty) and it looks the same.<br /><br />I attached the throttle linkage to the inner hole today as per the Type B instructions. With the throttle cam on the mark, the throttle is in the ready to open position as the manual states. <br />With the throttle in the fast position the throttle plate is nearly horizontal. I think I may have solved it. Tomorrow, I'm going to try it out. My guess is it's either going to die at WOT because of too much/rich fuel or either run like a scalded dog. We'll see.<br /><br />I'm going to have to watch it real closely because <br />I noticed a little fuel/oil on the block. I believe it's coming from the upper crankshaft seal. I don't know for sure, but it looks like it's easy to replace. I have one on order along with a spare cam key.

 

[i386]

Re: More 20HP Questions

Just a followup...<br /><br />The motor ran much better with the throttle linkage in the inner hole. The motor was definately turning more rpms than before, though how many exactly I don't know. It got up and planed out much quicker also. The top speed didn't change much but it was really windy and choppy where I tested it. Looking at the rooster tail while underway I could tell she was pushing a lot harder than before.<br /><br />The prop is the standard 8 1/2 but I don't know how to measure the pitch. Maybe I can find some numbers on it if I take it off.

 

[i386]

Re: More 20HP Questions

Another weird thig about this motor...<br /><br />The Seloc manual shows how to dissasemble and service 4 types of lower units. None of them are the same as mine. No telling what else different I'll find.

 

[rbruce63]

Re: More 20HP Questions

I386:<br /><br />You solved a tough problem and now your'e ready for more. Congratulations! Do remember that these Seloc's and Clymer's are one size fit's alls however they could point you in the right direction then you could get the original servicel and parts manual for your motor and you will see how specific they are.<br /><br />Good luck and keep us posted for the progress on your motor. Do check RPM's and remember that these 2 stroke motors love the high end of the range to keep carbon away. Do use an OEM motor oil and enjoy boating!<br /><br />Robert