IH H4 Magneto spring replacement

Hi all,

My dad and I are working on the Farmalls he recently bought; a Super A and two Hs. The Super A and the '40 H have the H4 magneto. The '47 H has a distributor but the engine is still stuck. We can get around 3/8s of an inch of movement on the flywheel now. Hopefully we will get it unstuck soon. The other H and the Super A turn over good but no fire. We are experiencing a steep learning curve on the magnetos as we have never really delt with them before. He bought two Ford N Series tractors at the same time and we already have them running as we are much more familiar with them. All these tractors have been sitting out in the weather for quite a while. We were only able to get a small intermitant spark on the '40 H after cleaning up the contacts. (It took us a while to actually find the contacts!) My dad had another magneto from a previous purchace and we took it and the mag from the '40 H to a friend of my dad's that has a tractor repair shop. He told us that the mag spring from the H is weak but the other one seems good. We bought a set of contacts and condenser and will replace them the next time we work on it. The guy said both coils seemed Ok as we could get some spark from both. Hopefully when we replace the contacts and condenser on the one with the good spring and reinstall it we can get that H running. My dad has already been through the fuel system. The carb was totally plugged up as was the fuel bowl. My question is how difficult is it to replace/repair the spring on the H4 magneto? We still have to check the magneto on the Super A but expect to at least have to replace the contacts and condenser on it. Thanks in advance for any help.

Just get the impulse apart. The spring is easy to replace. No need to wind it like on some mags.

Put the drive end in some solvent of something to clean out the grime mite be all you need to do to get good impulse. You get your starter redone and with good cables and battery it will start just fine. Replacing the spring isnt hard but getting the drive apart mite be.

The spring is easy to replace. Just hold one of the lugs on the impulse with an adjustable wrench and use a socket to remove the nut. Right hand threads like a regular nut and bolt. Then just pull coupler off and clean it good before putting it back on. Make sure the spring you put in the drive cup has the little pins back in both ends of the spring. Wipe a little oil on it and reassemble.

(quoted from post at 08:55:31 12/02/10) Then just pull coupler off . . .

Click to expand...

That step is usually the trick. There is a puller for that task. Be careful doing it without a puller as it can easily be damaged.

http://www.cleancomputes.com/Cub/Bl...s/GSS-5035 Service Manual Magnetos/index.html

You don't need the special puller just to change the impulse spring on a H4 mag.