Popular Mechanics 1962 PM38 Build [SPLASHED 2017]

[gm280]

I think I'm using incorrect terminology. The motor looks like it sits nicely on the transom I think. The cavitation plate is probably half an inch or so below the bottom. I don't think I need to raise it up higher on the transom. What I was trying to describe was how I changed the location of the trim pin that adjusts the angle of the motor to the transom. I guess I should say I adjusted it out from the transom a bit so the angle between it and the transom changed. Not sure how to describe it. :lol:

Oh you did describe the tilt of the engine to the transom with setting out a couple holes. I totally understand that. I was merely stating that if you raise the engine on the transom itself you will gain top end speed and even more stability and handling the boat. And since you stated that the cavitation plate is sitting lower then the bottom of the hull, you really could raise it up some. JMHO

 

[pekstrom]

Oh you did describe the tilt of the engine to the transom with setting out a couple holes. I totally understand that. I was merely stating that if you raise the engine on the transom itself you will gain top end speed and even more stability and handling the boat. And since you stated that the cavitation plate is sitting lower then the bottom of the hull, you really could raise it up some. JMHO

Ah, I see what you are saying. Hmm, I'll have to ponder that.

 

[SGoergen]

Thank you Scott! I was quite surprised myself. I wasn't expecting such speed with all that weight. The throttle handle does have the power trim buttons built in, but the motor doesn't have any so manual trim it is. At first I had it trimmed all the way down which I believe would have dipped the bow a bit too much. So I trimmed it out a few steps so the prop points slightly upwards. I think I may have to lower it a step or though. It seemed to raise the bow a bit during planing. I'll have to experiment a bit. Power trim sure would have been nice! :lol:

How is yours coming along? Are you getting close to the splash as well? Oh, have you solved the problem of those bolts in the transom clamp? I haven't looked to closely at it yet on mine, but you are absolutely right. Those holes are just below the transom beam so it will take some work. I was pondering something like inserting the bolts from the outside and make some indentations in the beam for a washer and a nut for each. May be easier than to try and get the bolts through from the inside. Just a thought I'm having... Could be totally wrong. :lol:

I am making progress now that the new barn/shop is done! All the welding is finished on the trailer and it's now painted, still need to wire lights and add bunks. I just finished painting the bottom of the boat last night, going to give it a few nights before I flip it back over to finish off the topside. (Going to update my thread in the next day or so) I still have floor panels to make but all the major parts are ready for final assembly. Still working on the motor, but there really isn't too much left there. I haven't looked at a fix for the bolts yet, once the motor is on the transom I'll get a better look at it. Your idea of indentations in the beam might work.

Really glad to see yours on the water, gives me a little extra push to get mine finished!

Scott

 

[pekstrom]

This evening we went out on the lake for about an hour or so. And the motor definitely doesn't run well. Once she gets up planing it does good. But idle is terrible and it keeps stalling on me. When I give it a little gas it runs "unclean". Not sure how to explain it. It is almost as if one cylinder isn't working, or missing. It runs a bit rough I guess. So I'm wondering if it has anything to do with timing and ignition? It seems like it would. I know archbuilder mentioned the switchbox had to be replaced on the tower of power. I need to look again but I believe mine has a switchbox as well...

 

[thomas15]

In general most (not always) of the time 2 cycle engine issues are due to problems with the carbs. I'm sure you know about the Mercury sub-forum here on iboats they can be very helpful.

First thing to do is find the serial number for your motor and get your hands on the Mercury service manual for that particular motor. Good to have on hand. The generic manuals can be a bit vague and confusing.

Next check compression on all of the cylinders. They should be within 10% of each other. Then check spark with an air-gap spark tester. If you have good strong spark and compression then it's probably fuel. If you haven't already done so replace every single bit of fuel line, the hose and primer bulb, fuel filter and rebuild the fuel pump. Also make sure the vent on the fuel tank is open. You cannot have any air leaks in the system. When you squeeze the primer bulb, the bulb should get hard. Also, make sure the choke opens and closes properly and that the throttle butterflies open and close in sync. Then you should have a low speed mixture screw on each carb that needs to be adjusted. If when the motor is running poorly and you reach back and squeeze the primer bulb and the problem then the problem goes away for a brief amount of time then you have a fuel problem.

If none of this corrects the problem then you will probably need to rebuild the carbs. You must soak the carbs and blow out the solvent, spraying cleaner into the throat will not clean them. I hope this is helpful and not what you already know. If you haven't already replaced the water pump impeller now is a good time. Also drain and replace the gear oil in the lower unit.

One last thing. You could have several issues (spark and fuel). It may take a while to figure this out. Don't give up.

 

[Patfromny]

Definitely diagnose the problem, don't just start changing parts. Have you done a compression test? Have you tuned the carbs? This sounds like it could be a problem in your idle circuit. Have you checked the plugs? If one is wet and the other is dry it could mean ignition. Have you done a spark check on each wire? Turn the engine over with the plug wire close to a ground and look for a spark. When the motor is running rough, pull each plug wire and see if it changes the idle or remains the same. If it stalls on each plug, I'd suspect it's fuel. If nothing changes when you pull a wire. That cylinder is your problem. There are lots of parts you can change chasing a problem and this can get super pricey. Try and figure out which system is at fault before changing parts bud.

 

[archbuilder]

I would for sure do what Pat and Thomas are recommending. The switch boxes are expensive, so if that isn't it it would be a waste of a lot of money. In the end I rebuilt the carbs, rebuilt the fuel pump and replaced the switch boxes. It was just a combination of things, that is what happens when a motor sits for a long time!

 

[pekstrom]

Thank you thomas15, Patfromny and archbuilder. This has given me a lot of good things to look at. I totally agree that I don't just want to swap parts. Might as well buy a new engine instead. These tips and ideas give me a good place to start. I used to lean on my dad who was pretty good at this stuff but with his passing a couple of years ago, that's unfortunately not an option any more. I'll have some time this weekend to tinker so I'll look at some of this and see what I can figure out.

While we were out last night it did ok as long as I gave it a little gas. If I tried to idle it would stall. It cranked right back up as long as I gave it a little gas. It would run a bit rough at first when I increased the throttle and at one point it cleaned up and took off. When I went to take her out of the water the idle issue became a problem. I did notice that if I turned the choke all the way up it would idle better so I could get her onto the trailer.

 

[gm280]

pek, carbs first! Then tune and see. If the engine runs good at higher speeds I would think that would eliminate the switchbox. But then not being there and doing my testing, that is merely a wild guess on my part.

 

[pekstrom]

pek, carbs first! Then tune and see. If the engine runs good at higher speeds I would think that would eliminate the switchbox. But then not being there and doing my testing, that is merely a wild guess on my part.

I was pondering that very thing myself... It seems to run well and have good power at high speeds so would that also make compression problems less likely? I have the service manual so I'll take a look at the carb section and see. I have never had a carburetor apart so this should be interesting.

 

[pekstrom]

A friend of mine suggested I use something like Deep Creep Decarb to run through the engine and see if that helps. Is that something that's worth a try? What do y'all think? I guess it can't hurt?

 

[archbuilder]

I am betting cleaning up the carb will do wonders! You might check to see if this guy has a video on your carb, seems like he has one on every carb made! If so, he pretty much gives you a step by step.

https://www.youtube.com/user/MikesCarburetor/videos

On mine the switch box helped to clear up over all roughness and coming out of the hole. The fuel pump of course would cause it to bog when it would start to wind up out of the hole, basically fuel starving after what was in the bowls was eaten up.

Take a lot of pics of the carb and the manual never hurts! And don't loose ANYTHING! I would get a carb kit, doesn't cost much and it never hurts to replace the float, gaskets etc while you are in there. The only thing that sucks is they are usually for half a dozen carbs, so you finish up the project wondering if any of the left over parts should really be in the carb lol!

 

[Patfromny]

A carb isn't something to be taken lightly but it is by no means rocket science. I think creating a boat from nothing is a bit harder. What you're basically doing is taking it apart, cleaning all the parts, and replacing the gaskets and maybe the float if needed. I take my carbs to the local lawnmower repair guy after they are apart and he sonic cleans them for me before I reassemble. Charges me something like 7 dollars. Take your time, make sure everything is clean, and you will have nothing to worry about. It sure sounds like fuel to me. Right down to the choke helping matters. Good luck.

 

[pekstrom]

I am betting cleaning up the carb will do wonders! You might check to see if this guy has a video on your carb, seems like he has one on every carb made! If so, he pretty much gives you a step by step.

https://www.youtube.com/user/MikesCarburetor/videos

On mine the switch box helped to clear up over all roughness and coming out of the hole. The fuel pump of course would cause it to bog when it would start to wind up out of the hole, basically fuel starving after what was in the bowls was eaten up.

Take a lot of pics of the carb and the manual never hurts! And don't loose ANYTHING! I would get a carb kit, doesn't cost much and it never hurts to replace the float, gaskets etc while you are in there. The only thing that sucks is they are usually for half a dozen carbs, so you finish up the project wondering if any of the left over parts should really be in the carb lol!

I'm hoping cleaning the carb will help too. Thanks for that link. I did look through the list and didn't find the one for mine. It is supposed to be a Tillotson BC1B or BC1C. I'll have to look at it tonight. Didn't have time yesterday. That's an impressive list of videos that guy has though! I did see some comments while googling around that the Tillotson carbs weren't very good... Don't know how much of that is true. But hey, it said so on the internet so it must be true, right? :lol::facepalm:

For being such a small component on the motor it sure seems to have quite a few parts in it! Having parts left over is always a bit unsettling. :lol:

A carb isn't something to be taken lightly but it is by no means rocket science. I think creating a boat from nothing is a bit harder. What you're basically doing is taking it apart, cleaning all the parts, and replacing the gaskets and maybe the float if needed. I take my carbs to the local lawnmower repair guy after they are apart and he sonic cleans them for me before I reassemble. Charges me something like 7 dollars. Take your time, make sure everything is clean, and you will have nothing to worry about. It sure sounds like fuel to me. Right down to the choke helping matters. Good luck.

Doing something for the first time is always a scary proposition. Just like the boat project. But I pulled through so as long as I get my hands on the right parts I am pretty sure I will be able to rebuild the carb if I need to. But seeing all those parts in the diagram does sure make it seem a bit overwhelming. :lol: I'll have to do a bit more research so I'll know I am getting the parts I need and then dive in. Like you said, since the choke helped, it would seem like the carb could be the issue. I know the gas tank had some old gas in it when I got it. It wasn't much. I think around half a gallon. So I filled it up with new gas and oil thinking it would get diluted enough. It is entirely possible that caused the problems. :facepalm: I think it sat for about a year after I ran it on that mix.

 

[gm280]

pek, I have no concerns with you rebuilding a mere carb. You have the ability, but you have to convince yourself you do yet. If you are at all worried, take tons of picture in every step of the way as you disassembly it. But honestly, carbs are really not ever difficult to rebuild. If I can do it, anybody can. JMHO

 

[archbuilder]

Pek, you might watch one of those videos that is similar to your carb. You should get the basics after watching it, they are all really similar.

 

[Woodonglass]

refresh this Old dumb Okies memory. What Make and Model of motor are you using??

 

[pekstrom]

refresh this Old dumb Okies memory. What Make and Model of motor are you using??

Hi Wood, I have a 1980 Mercury 25 HP outboard. And I just noticed something today when I checked the spark plugs. It has two BU8H plugs. When I look at the parts diagram, Mercury lists Champion L77J4 plugs. And it doesn't look like BU8H are replacements for L77J4. My dad replaced the plugs on our old Chrysler 15HP we had when I was a kid and it gave us all kinds of fits. Similar to the problems I have. He got the NGK plugs from a friend of his who swore they were great. We swapped them out with Bosch plugs and it ran great. So now I am wondering if I simply have the wrong plugs in it?

 

[pekstrom]

Hi Wood, I have a 1980 Mercury 25 HP outboard. And I just noticed something today when I checked the spark plugs. It has two BU8H plugs. When I look at the parts diagram, Mercury lists Champion L77J4 plugs. And it doesn't look like BU8H are replacements for L77J4. My dad replaced the plugs on our old Chrysler 15HP we had when I was a kid and it gave us all kinds of fits. Similar to the problems I have. He got the NGK plugs from a friend of his who swore they were great. We swapped them out with Bosch plugs and it ran great. So now I am wondering if I simply have the wrong plugs in it?

Let me rephrase that... I wonder if the plugs may be part of my problem? I did try some of the other items mentioned like squeezing the fuel bulb, which didn't seem to make any difference. I don't have a compression gauge so I haven't looked at that yet. I have seen they aren't expensive so I will probably pick one up and check it out. Seems like something that may be good to have in the toolbox if I'm going to be tinkering with this stuff... The fuel line is brand new but the tank is an old metal tank. I'm thinking of getting one of those nice plastic ones for when I want to put a sender in it for the gauge on the dash. Turning the choke up does definitely help the idle problem. It still runs a bit rough and when I give it gas it sounds like a cylinder is missing until I get up in the higher RPMs.

 

[thomas15]

If you decide to take your carbs apart take a lot of pictures and label the carbs so that you don't get them mixed up. Sometimes on multi carb motors the carbs are slightly different from each other so don't mix them up. Take pics of the float before you remove it because you don't want to reinstall it upside down. Also take pics of the linkage so that your not scratching your head trying to figure out what goes where on re-assembly.

I'm not trying to sell anything but Chem-Dip (available at walmart) is an easy to use deep carb cleaner and effective but a bit pricy. But there are others that work also. Also of all things a compression tester is most useful to have but maybe perhaps you can borrow one from a friend. I'm not a carb nut and will do everything to avoid taking one apart but sometimes you have no choice.

Also I mentioned replacement of all fuel lines. Older fuel lines degrade from the ethanol now in gasoline. If your not using ethanol free fuel put some kind of treatment into the fuel such as Sea Foam or the Mercury Quicksilver gas treatment. I try to keep my fuel for my boat as fresh as possible, treated or not.

As implied by others, with motor problem troubleshooting, start simple and inexpensive, work up to complex (and expensive). Really love your boat pek and I hope to build one myself in about a year or two.