Compression problem

I am new to the Cub site and have just gotten a 1956 Cub. It had not been running for about 2 years. I got it to start and it had a miss. The more I tried to fine tune it the worse it has gotten. I pulled the plugs and checked the compression 1 and 4 had about 90 lb. 2 and 3 10 to 0. Does this sound like a head gasket to you? I ordered the set and will be taking it apart next week if all goes well. It has no water in the cylinder or oil pan that I can see. Thanks for your help in advance. This is a great site for the NEW Cub owner

Stuck valve

Test the compression again, do a wet test this time if it is still low, take off the valve cover and see if the valves are moving.
Go from there..........

Bruce T.

Agree with the others stuck valves.

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I will do the wet test and check the valves through the side plate before taking the head off. What is the best way to free up stuck valves? Having a great time working on this little red tractor. The engine sounds solid except for the miss. Thanks

ShineRunner":329kr7os said:

What is the best way to free up stuck valves?

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Use the search function at the top of the page. There are several recent discussions on freeing up stuck valves.

You may not need to remove the head. It all depends on how stuck the valve(s) are.

Stuck valves :!:

Why do I know this :?: Dealing with the exact same problem with my 47 - Granny - here is the thread - Stuck Valves. Pull the plugs on 2 and 3, pour in 1 tablespoon of oil, rotate engine by hand a couple times. Take the side valve cover off. Spray the valves/valve springs and tappets with your favourite penetrating oil. I like Nut Buster and Loctite's Solvo-Rust. Rotate the engine by hand with/without hand crank again but while watching the valves functioning. You should see whether it is exhaust or intake valves that are sticking. Take a standard screwdriver and very.. very gently tap the offending valves once or twice. I used a dead blow mallet to reduce the shock to the valves. Spray the valves in the spark plug holes with your favourite penetrating oil. Rotate the engine by hand a couple times hopefully twice each cycle. Continue to do this until the valves drop and drop they will. They are just stuck up because of carbon/oxidation.

After the valves have dropped, add another tablespoon of oil to each spark plug hole and hand crank the engine again. When you feel the valves are moving freely, add some SeaFoam to both the gas tank and the crankcase according to the directions on the label. This will help clean the valves/valve stems and guides. It may still take a bit to get the engine to fire up, but this is the first step.

Eugene":1mwbhcgr said:

ShineRunner":1mwbhcgr said:

What is the best way to free up stuck valves?

Click to expand...

Use the search function at the top of the page. There are several recent discussions on freeing up stuck valves.

You may not need to remove the head. It all depends on how stuck the valve(s) are.

Click to expand...

I agree, but if you are like me and have a new head gasket available, I would be just curious enough to want to see what things look like under that head on your new Cub. It makes getting to the valves much easier and you can clean all that carbon out of there. But that's just me. :roll:

Congrats on the new '56. :-:

i hope you are not planning on hauling shine with that cub, not very fast. :bellylaugh: :bellylaugh: welcome to the site. tomcat

tomcat":19fjw2mk said:

i hope you are not planning on hauling shine with that cub, not very fast. :bellylaugh: :bellylaugh: welcome to the site. tomcat

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Not a problem, The revenooers would NEVER suspect a slow vehicle! Ed

I live only a few miles N of Junior Johnson in Wilkes County NC. I am in the Real Estate business now and Charlie Felts Jr. is one of the guys that I deal with now in the real estate business. His dad was one of the main revenuers (with the same name) when the product was in demand.

I have been to Jr.s old shop. I think Flossie still lives there
Boss

Have also been by his small new house
Boss

Must take a small army to tend to the grounds there

I agree with Rudi's instructions. I freed the valves (2) using this method on a 1952 Cub engine that had sat more than 30 years without being rotated. It took about 2 weeks of random tries, plenty of patience and penetrating lubricant. I like PB Blaster and ATF. (Using a wooden hardwood dowel instead of a screwdriver might keep from niching the metal.) Stan

EDIT NOTE: I was able to lubricate and tap the top of the valves through the spark plug hole after removing the hood.

Pull the head, makes everything easier

As everyone has pointed out it is most likely a valve problem.
However, if you did your compression test with ALL the plugs out, you may want to take another compression test with the other plugs in. this test may show a head gasket failure or not. In my experience, if you have a cylinder with the same compression as its companion , install a plug on the companion and retest, if the cylinder pressure rises you most likely have a head gasket issue.

Thanks for all the information, I will redo the test with plugs installed and working on the valves this coming week. I have a product called KROIL that I will try on the valves to loosen them. Hopefully that is the problem not the head gasket. I have used this penetrating oil on a lot of old machinery. I have a 1946 Model FB 13-7 grain drill that I used three to make one that I use to plant wheat every year and it worked great on the old rusty bolts. The two donors had set in the weeds for years. I will try to get some pics and post up what I find. Thanks again :thumbsup:

Stan:

I never thought of using the dowel :idea: Now that makes sense and I think I will do that on the next valve I come across. I was constantly in fear of damaging the valve :!:

Worked on the little red tractor this week. It now has good compression in 1-2-3 but only about 50 lb on 4. It has a hiss through the carb when turning it over. I have worked the intake valve on #4 up and down for a while with no real change. Sprayed with Kroil and put Marvel Mystery oil in gas and in the cylinder. Have adjusted the valves and rechecked twice.

I don't have a timing light so I did the static setting. The setting was about 1/2" before the first mark. The crank pulley has two notches and I let it pass the first notch and set it on the second. Is this correct? When I go to town again I will see if the parts store has a timing light. The engine sounds solid if I can just get number 4 compression up. I try to fix one problem at a time but it seems that I have had more than one thing going on at a time. I ran the engine for about 15 minutes the other day and it died. It would try to start but die, maybe run 5 to 10 seconds, so today I pulled the distributor again, cleaned the points and reset checked with continuity meter and all worked fine. Put the distributor back on and she cranked. I let her run for 15-20 minutes not very smooth but ran.