Re: Compression problem

Thu Dec 15, 2011 11:06 pm

Rudi wrote:Eugene:

Is the the right one from Sears? Craftsman Valve Spring Compressor - Model# 47627

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Yes. And that is a great price. I paid right at $30- for it.

When using on a Cub engine you need to put a piece of 2 x 4 on top of the head because the height adjustment will not reach the block without the 2 x 4.

Edit: 2 x 4 goes on top of the block not the head.
Last edited by Eugene on Thu Dec 15, 2011 11:14 pm, edited 1 time in total.

Re: Compression problem

Thu Dec 15, 2011 11:11 pm

ShineRunner wrote:Can't get the cub to run smooth. It will run fairly good at below half throttle and will not adjust. Above half it sputters and blows black smoke.
Start again at the beginning. Compression checks, dry then wet. Double and tripple check the ignition timing and system. Then move on to the fuel system.

Black smoke. As in fuel related black or oil pumping/burning black?

Re: Compression problem

Thu Dec 15, 2011 11:37 pm

Eugene wrote:Black smoke. As in fuel related black or oil pumping/burning black?


More like fuel related black. The guy that had the tractor before I got it had done a lot of stuff to it trying to get it running. He put a carb kit in, points, plugs, distributor cap. I have since taken the carb apart and soaked it in carb cleaner for a few hours and reasembled it. I made a template to set the float and cleaned all the jets and made sure all the gaskets and seals where installed. It has a cork gasket, do they give any problems?

The spring compressor from sears worked great. I didn't need to put anything on top, I adjusted the top pin down and it would center on the valve and when I had the valve spring where I wanted it I set the compressor. It then worked on all of them without any other changes. Great tool. I coulda used it on a golf cart project I did a little while back.

Re: Compression problem

Fri Dec 16, 2011 1:03 am

ShineRunner wrote:More like fuel related black.
I agree you have a carburation related problem.
ShineRunner wrote: The guy that had the tractor put a carb kit in, points, plugs, distributor cap.
Recheck everything the previous owner accomplished (?). Set engine on TDC and see where the rotor is pointing. Points gap, mechanical advance, - everything. Lub the wick under the rotor. Most folks remove the distributor to change points. Could be the distributor is a tooth off.

When you said that the engine ran for 90 seconds, flooded out, then wouldn't restart - my first thought was that the distributor was not bolted down tight and had rotated.

Re: Compression problem

Fri Dec 16, 2011 5:56 am

You don't recon the PO oversized the hole in the main jet while trying to clean it out do you? Or did you put in a new main jet?

Re: Compression problem

Fri Dec 16, 2011 6:33 am

randallc wrote:You don't recon the PO oversized the hole in the main jet while trying to clean it out do you? Or did you put in a new main jet?


Soaked all parts in carb cleaner tank and used very small wire and air to gently clean all orifice's. I may have to get a good complete carb kit and start over. Thanks

Re: Compression problem

Fri Dec 16, 2011 6:29 pm

I was just thinking (don't let that scare anyone) if the guy I bought the Cub from had the distributor off and maybe he got the distributor drive shaft off a tooth, could that cause my problem? If so what do I need to look for to fix this problem?

Re: Compression problem

Fri Dec 16, 2011 7:41 pm

ShineRunner wrote:the distributor drive shaft off a tooth, could that cause my problem? If so what do I need to look for to fix this problem?

No. From your descriptions so far, your timing is right or at least close enough to not be the problem. If it is off a tooth, you may want to change it eventually. But leave it as is until you have the tractor running OK.

Re: Compression problem

Fri Dec 16, 2011 7:47 pm

Looked around today locally for a complete carb kit and only found the basic. Looks like I will need to order one. I am also in the process of replacing my old timing light and dwell meter. Waiting on those. While I am waiting I will start over and check the compression timing and anything else that I can do while I get the carb kit, timing light and dwell meter. :)

Re: Compression problem

Fri Dec 16, 2011 7:49 pm

ShineRunner wrote:I was just thinking (don't let that scare anyone) if the guy I bought the Cub from had the distributor off and maybe he got the distributor drive shaft off a tooth, could that cause my problem? If so what do I need to look for to fix this problem?
Running rough at mid to high idle. Might be part of the problem. Could also be that the mechanical advance is not working.

Set engine to TDC #1 cylinder. Mark the distributor base directly below the #1 spark plug tower. Remove distributor cap. Check to see if the rotor is pointing to (centered on ) the #1 spark plug tower location mark.

Grab the rotor and gently twist in each direction. Rotor should turn about 7 degrees in one direction and none in the other (mechanical advance). Check the bottom of the rotor where it mounts - checking to see if it's still in good condition. Oil the wick under the rotor - see lubrication guide.

The distributor should be mounted near the center of it's adjustment area.

Remove the rotor and dust cap. The points gap should be slightly open and slightly front of the point of the cam lobe (counter clock wise as you are looking at the distributor).

I have purchased machinery that wasn't running well - that others had worked on before. First thing I do is a complete tune up and fluid change. I usually find 2 or 3 different problems that the previous owner(s) had overlooked. Speaking of which - did you set the tappet clearance when you installed the valves?

Check your choke operation - pull the choke lever on the dash - watch the small lever on the side of the carburetor. Horizontal - choke full open. Down - choke closed.

Re: Compression problem

Fri Dec 16, 2011 7:52 pm

ShineRunner wrote:I am also in the process of replacing my old timing light and dwell meter.
Skip purchasing the dwell meter if it's just for the Cub. Just set the point gap at .020"

Re: Compression problem

Fri Dec 23, 2011 7:52 pm

Figured it out finally!!! I started from the compression test. Real close to 120 lb on each cylinder. Rechecked carb. Then went to the distributor. Put in a another new set of points and replaced the old condenser with and another old condenser. (I didn't like the way the condenser was burning the points) The points dwell was at about 72 degrees so I opened them up a little and they are now at 66 degrees. I set the static timing and she cranked and ran good but wanted to kick back when starting. Grabbed the distributor and retarded a little and the kickback stopped she is running good now. I will take her out of the shop tomorrow and hook to my 4' x 8' trailer and haul a load of wood to see what she can do. :{_}: :{_}: :{_}: :D

Thanks guy's for all the great help :big smile: :applause: