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Wisconsin VF4 Rebuild

Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
Your compression is within the 10%, and pressure, so that should be OK. You may be overheating due to retarded timing though. That would also explain loss of power. Put the piston at about 1/8 to 3/16 before TDC compression and then turn distributer until points JUST open, then see how it runs. If you hear pinging (pre-ignition), turn the distributer to retard timing until knock goes away. A lot of smoke from the crankcase vent (fill tube) could be due to piston fit, glaze, engine overheating (blocked cooling fins or retarded timing) or just plain wear. Smoke from the exhaust - worn rings, valve guides. Make sure a mouse has not built a nest ubder the engine shrouds!

Here is another test for you - Set the engine at TDC compression on a cylinder and make a mark on the flywheel with a piece of chalk. Use a timing light on that same cylinder, to watch the spark. The chalk spot should remain relatively steady. if it wanders around, your distributer shaft or bushings are worn and timing will not be steady. If you have a Tach-Dwell meter, the needle should not wander in the dwell position. If it does, again a worn distributer shaft or bushings will affect timing. If you don't have a dwell meter, you can also grasp the rotor shaft and observe the points. Set them at maximum openning and pull the rotor shaft toward and away from the movable point arm rubbing block. The point gap should not change.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
I believe there was mention of it being allowed to get so hot that the valve lash was increased in an attempt to allow for it? Had I read that right? If it's been overheated, the temper may have been taken out of the rings.
 

ceg

Registered
All good feedback. Not uncommon for Dad to set valve lash large. This was done I believe as a cautionary step. Lesson learned from working a grain truck engine he had. How hot did the motor get hard to say. I’m positive the shroud was kept clean by Dad. I cleaned it out myself also. No doubt I’m dealing with multiple smaller problems that are adding up. Considering an M Farmall distributor was installed I suspect the timing might be retarted a bit again as it makes easier starting and risk of kick back on starter. I have a timing light so next visit I’ll check. I took plug out to locate timing mark that should be found on the mag gear but did not find an X or really anything that resembles a mark. I probably will pull head off and make my own mark. No degree wheel so establishing one could be done with a dial indicator but exactly how much I don’t t know. I believe someone mentioned 3/16” BTDC.
 

I like oldstuff

Registered
Last Subscription Date
11/09/2015
DC mark on the flywheel.
There is an x stamped on the edge of one tooth of the mag gear. Ya just have to look closer.
 

ceg

Registered
The plug near the mag closest to the flywheel is where I should find the X? If I need to pull flywheel housing shroud off to see anything that’s a problem. That hood must weigh as much as a Ford Pinto lol. I’ll do more research in manuals. Thanks again.
 

IndianaDundee

Registered
Is it possible to install cylinders onto crank case with pistons and rings attached to rod? I would like to do a valve job. ie. grind seats. Two stroke motors are done this way but they have fewer rings to compress in cylinder wall.
Short answer to the first question is yes. But to do a valve job you have to pull the head anyway, so it may be better to a full tear down.

I have just pulled a jug to replace a piston ring before on my VH4D. As long as the jug is not frozen to the block (my first one was) this is how I did it:
First remove the manifold/carb/exhaust then the air ducks/sheilds from around the jug. Then remove the six nuts that hold the jug to the block. Lift the jug straight off. Leave the pistons and rods connected to the crank while you work on whatever you need to do with the head/jug/valve assembly. Then while replacing the jug to block gasket remove the pistons from the rods. Make sure you note which piston goes in which hole and the direction. To remove the piston first remove the retainer clip from the wrist pin then slide the pin out. Once you have the pistons off the rods install them in the jugs from either the top or bottom with a normal piston ring compressor. Push the pistons down the jugs enough to insert the wrist pins but not so far that the oil ring comes out. Rotate your crank so that one rod is up and the other down. Install the outside wrist pin retainer clip in both pistons. For this part you will need a helper. I used my 11 year old son. While one of you holds the jug assembly over the higher rod the other person lines up an installs the wrist pin and inner retainer clip. Then push the block down to the lower rod and do the same for the other piston. Reassemble the rest as usual.
 

ceg

Registered
I’ve been away awhile. I used it to mow recently but it sure lacks power. Hoping to pick up this project again this fall. The description of pulling jugs seems reasonable. I just didn’t know how much room I would have to install wrist pins or squeeze in rings. If an 11 year old can hold jugs then I’m good to go. Good Wright up. Thanks.
 
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