Motor Veiws

[Morgan1339]

Well my cub is running good as possible now. I got the carb rebuilt and the governor is working great. BUT---i'm afraid my motor is wore out. I just changed oil and filter bout a month ago, put some lucas in the oil and is has not used any oil at all. BUT---it has as scotty would say "I got no power" Also i can turn the crank with my hand How big of a rebuild job do you think this would be Opinions wanted please One man said he would rebuild it for $600.00(sounds Cheap) Let me hear some suggestions cubbers

[Bigdog]

I guess it kind of depends on what kind of oil pressure you have. If the bearings are good and the oil pressure is decent you might get away with a re-bore and a set of over-size pistons and rings. If it's really that worn you might as well do the whole thing. You'll save time and money in the long run.

[Morgan1339]

The oil pressure has always pegged the needle and i've had this cub for bout 25 years

[Lurker Carl]

Worn rings or maybe you need a valve job.

[cowboy]

Hi Morgan

If its not burning oil or having a lot of blow by coming out the dipstick. I would check the valve lash.

Billy

[Cecil]

A valve jog is real easy to do. I had never done one and had no problem. It scared the daylights out of me when I started reaming on the seats but what a difference in performance. I had a friend who had a valve grinder and he did the valves. I used the reseating tool from work. It is the same one they use on small lawn mower engines. The hardest part was getting the valve retainers back on.

[Charles (49) Mo]

Get a screw in compression tester with the flexible hose and the air chuck connector for the gauge Remove the check valve on the bottom ( tire valve core).Run your engine till its warm. Turn it off and remove the valve cover on the side. Rotate engine till you see both lifters on a cylinder completely down. Screw in tester base into cylinder that has completely closed valves. Connect air supply ( 90 PSI ) to hose and listen for air noise. If noise is at air cleaner or exhaust pipe its the valves, If its at the oil fill port on the engine its the rings. All will leak a little, but you can hear where the major leak is originating.

[WKPoor]

Unless your gauge has been checked against a master for accuracy I would consider it an idiot light. A couple of yrs ago Earl made up a gauge block where up to 4 gauges could be screwed in on top and checked against a certified one screwed in the side. I don't think we ever found one to read correctly. Some close, some way off. Ever since then the value means little to me. Either it has pressure or it doesn't, thats about all you can say.
I agree totally with Cecil, air check your cylinders first. I recommended the very same thing in another post regarding power problem. You won't make good power if you have leaky cylinders. My own experience has been that worn rings effect oil consumption but don't have a drastic effect on compression. Valves are more critical there.

[Morgan1339]

I just thought of something last night. A few years back the weather got cold and it cracked the head. I had it welded back. The crack was visible and was leaking water. Could this explain my loss of power Also how could a motor that uses no oil have bad rings I tend to go along with the valve problem

[Clark Thompson]

I doubt a cracked water jacket in the head would cause less power. I have been restoring cubs for a long time now. Every cub seems to run well when first started. After runing a belley mower or working the cub the engine starts to show its problems. I have had cub engines that I would swear needed nothing . when i took it apart it was a reality check. I would sudjest you take the engine apart. do some measuring. In most cases the cylinders will need bored. the crank will need turned. a proper valve job is a must. also replace the cracked head. It will eventually give you problems. a proper rebuild will cost around $1000.00 if you do the mechanical work yourself. it is money well spent.

[Rich Walker]

Hi Morgan,
I finished a rebuild on my '51 Cub last week. First engine I ever did myself. Bought the book and followed it. Total cost was $779. Pistons, crank, cam and bores were fine so I was able to use standard bearings and rings. My local shop charged $400 to clean block, head and all other parts, including regrinding the valves and installing with new springs. The balance of $379 was for parts. I did the rest of the assembly myself with minimal tools. When I got it all back together I did not get oil pressure so I shut it down, came to this forum and learned how to prime the oil pump properly. The satisfaction I got was priceless and it was the most rewarding project I've done in a long time. Good luck!