1963 75hp Near Disaster with Rebuild

[yorab]

Long story but I need to vent and I'd like to have some confirmation on a couple of things.

Have you ever done something that you know you shouldn't be doing, but for some reason you do it anyway? That happened to me today--three times. After a complete rebuild, I was ready to run a compression test, then install plugs and plug wires and start it up. That's when I noticed that one of the Helicoils that the shop put in for me during head servicing was coming out of the hole. About half of a revolution of the thread insert had jumped out somehow. I tried to use needle nose pliers to twist it a bit and a screwdriver to push it back in, but the screwdriver kept slipping and I was afraid that I would mess up the aluminum threads that the inserts seat into. So, I went to the shop and talked to the guy. I asked if I could borrow his Helicoil kit so that I could replace the bad one at home without removing the head. He agreed. I took out the old one and installed a new one. When it came time for me to break off the tang, I used a crappy pair of needle nose that were very old and had no gripping ridges left. The gripping surfaces were smooth. This was mistake #1. Of course the tang broke off and slipped out of the grip of the pliers and into the cylinder it went. I tried to feel for it with some pick tools but I couldn't feel it. I thought that the piston was at TDC so it wouldn't hurt to back the piston up so that I could at least feel the tang and possible grip it somehow. Mistake #2. I know to never, ever move a piston with junk in the cylinder but I did it anyway. Turns out that the piston must have been a bit shy of TDC because when I turned the flywheel, it seemed smooth at first. Then it became tough to turn. I knew that the tang had got caught between the piston and cylinder wall. I panicked for a second and turned the flywheel the other way. Damn! Mistake #3. Now I'm not sure if the impeller vanes got bent backwards. At this point I knew I had to pull the head. I found the tang stuck between the piston and wall as I had suspected. After pulling it out, I saw a lovely gouge in the freshly bored cylinder wall. I believe that I may have been not only extremely stupid today, but also very lucky. The gouge is at the top of the cylinder next to the bevel. It seems to be above the highest point of piston ring travel. From what I know about internal combustion engines, the gouge should not be a problem if it is above the ring.

Questions:

1) If that gouge is above the ring travel, will it be a concern?
2) Is there any way to know if I boogered up the impeller vanes without dropping the lower unit? I can say that after I removed the tang from the cylinder, the engine seemed to spin quite normally just as it did before my major flub-ups.

 

[Will Bark]

Re: 1963 75hp Near Disaster with Rebuild

Don't know about your gouges; but I think I have seen Joe Reeves and Boobie both say that the impeller will straighten itself out when motor turns clockwise again. One of them will chime in I hope. Good luck.

 

[redfury]

Re: 1963 75hp Near Disaster with Rebuild

run a dry and wet compression test on the cylinder, that will tell you if the small gouge is going to affect anything. As far as the impeller goes, if it's new, the rubber should be supple enough to flex into the right direction. Chances are you didn't 'flip' the direction the vane was in anyway with such little movement. A simple run in the dunk tank when you have the motor all buttoned up will tell you if the impeller isn't operating properly.

Live and learn right? At least you were willing to share your story so someone in the future won't make the same or similar mistake.

 

[yorab]

Re: 1963 75hp Near Disaster with Rebuild

Thanks for the advice guys. Guess I just had one of those days.

The impeller is new and very flexible, so I'm guessing that it is okay. I just wanted to hear from somebody who may know from experience that it will right itself.

I'll try the dry and wet compression test once I get a new head gasket.

I've attached pics. The first is the Helicoil coming out of the hole. Sorry for the bluriness. The second shows the gouge. It is hard to see but it is the dark line that is about 1/8" long at the bottom center of the top cylinder. It starts at the edge of the bevel and moves directly down the cylinder.

 

[AlTn]

Re: 1963 75hp Near Disaster with Rebuild

On the brighter side...the gods may have smiled on you. Suppose you'd never noticed that insert, installed the spark plug, found that it wouldn't torque, nor could you back it out. Off the head has to come and back to the machine shop for a repair, or a new head. Possibly it could have held long enough for you to be going down the lake and then blown the insert and plug out. I wonder if the shop tried to insert a spark plug and torque it while they had it? In the auto world, with an aluminum head , I've seen my wife's uncle try to correct the threads with a thread chaser well greased on the end to keep the " cuttings" from dropping into the cylinder. However, this is after telling the owner that if it doesn't work the head will have to come off. He clamps the head down and puts the plug in and removes it several times before putting it back on the car as head removal isn't one of his favorite things. The impeller vanes I wouldn't be concerned about at all. The nick/gouge, as you stated, in that spot doesn't seem to be of much consequence. Maybe someone with a lot more experience and knowlege can lend an opinion. Don't ask about why it isn't a good idea to use a pencil to get close to determining tdc on a 1968 250 triumph tiger cub in an unheated out building at 1 a.m....and it's mid winter 20 degs. or so. This may turn out to be a very minor set back in your restoration... a cheap lesson in the education realm.

 

[Willyclay]

Re: 1963 75hp Near Disaster with Rebuild

Don't ask about why it isn't a good idea to use a pencil to get close to determining tdc on a 1968 250 triumph tiger cub in an unheated out building at 1 a.m....and it's mid winter 20 degs. or so.

It must be something about old Tiger Cubs. My 1959 model did not like the timing setting I had established after overhaul and blew the spark plug completely out of the head when I tried to roll-start it down a hill. My first intro to Heli-coils. Live and learn!