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Wisconsin VF4 Rebuild

ceg

Registered
Hello I'm new to this site. I'm hoping to get some good info. 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.
 

K-Tron

Registered
Re: VF4 rebuild

Welcome to smokstak! You certainly can install the pistons with their rings and rod installed into the cylinder jug before bolting the jug down to the crankcase. You need to make sure that the pistons and rods are oriented correctly before you drop the assembly in place.

Chris
 

ceg

Registered
Maybe I didn’t make that clear. The cylinder jugs will be lowered over pistons with rings attached. The rods will not be removed from crank. If so I’m not aware of a ring compressor that will allow the tool to be removed so to allow cylinder jugs to seat against case.
 

K-Tron

Registered
That would be awfully difficult to juggle the ~30lb cylinder jug while trying to install the loaded pistons into the cylinders. If you have several people to help, you may be able to use a piston ring compressor plier to do one piston at a time. You would have to load the piston and rings up with assembly lube. I have never loaded a Wisconsin piston this way. It is simple enough to remove the oil pan, unbolt the connecting rod caps and assemble the engine normally.

https://www.matcotools.com/catalog/product/MST75A/piston-ring-compressor-set/

If all you have to do is cut the valve seats, you can use a Neway piloted valve seat cutter. That is what I use. Pack the flutes with grease, and put some grease over the valve guide to prevent chips from getting anywhere critical. Then obviously clean everything as best as possible before re-assembly. I hope this helps

Chris
 

ceg

Registered
Yes I thought about valve cutter before. What angle of cutter for a 1950 VF4 and what do I use for pilot guide. All this assuming my valve guides are good. Removing pan from bottom is not easy as it sits in a frame. I should post a photo of why I’m trying to save it.
 

K-Tron

Registered
The Neway valve seat cutters usually come with several size arbors. I made the one I use for Wisconsin engines on my lathe. Your VF4 will have a 45* seat. If your engine is original and from 1950 it will not have removable valve guides. You would have to either ream the cast in place guide and run the 0.004" oversize stem valves Wisconsin offers, or machine the block to accept replaceable type valve guides. If none of this is possible, I know that some people put a little bit of sandpaper between the valve and seat and swirl the valve around until the seat cleans up. Not the best method, but since your engine most likely did not have stellite seats in it in 1950 it should work. These engines are pretty forgiving, they will keep running and running even when they shouldnt.

Chris
 

ceg

Registered
I’ve never cut seats before. Valve lapping yes. Since I’m not familiar with proper use of a valve cutter. In my mind I’m thinking if valve guides are egged out then an arbor made myself or bought will not give the results I need, maybe worse. I’ll post photo later. The engine misses when warm up. It’s been a problem last few years. I need to do a leak down test. Dad always claimed bad gas. Not old but 21st century gas. New plugs fixes the problem but only for while. I should also try new condenser. Stay tuned in as this problem needs fixed. Thanks.
 

Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
The fact that new plugs fix the problem (albiet temporarily), points to an ignition problem. Poor coil. bad condenser, crud on points, ETC. i would do a compression test. You want at least 6 compression strokes if electric start, with all plugs out. 10 if hand cranked. All cylinders need to be within 10% of each other. That means if you have 60 PSI, all cylinders should be within 6 PSI maximum spread. Add 2 tablespoons of SAE 30 to each cylinder and spin engine for 30 seconds and re-test. No cylinder should show a rise of more than 10 PSI. if they do, you are lookng at rings, pistona and maybe cylinders, depending on wear. For a leakdown, you need at least 80 PSI. Set cylinder to be tested at TDC Compression and apply presure to plug hole and listen for air. Out carb - bad intake valve seal. Out exhaust, bad exhaust valve seal. Out tengine breather - ring/piston fit. NOTE - KEEP YOUR HANDS AWAY FROM ANY MOVING PARTS - THE ENGINE MAY TURN SUDDENLY!:eek: :rant:

Crap E-10 gas will behave erraticly if more than 30 days old. it WILL mess up the pot metal carb!
 

ceg

Registered
Thank you for advise. Yes very well aware on checking compression, leak down. Electrical is a possibility. I’ve cleaned cap, rotor, points and checked plug wires. I have all basics covered. Fresh gas. I even tried 110 leaded octane race fuel. Dad would always use lead substitute at twice the recommended rate. The plugs would glaze over as he called it with out it. This motor has been used quite a bit since 1983. It was rebuilt new at that time. The engine is a few hours away so I have limited time to work on it. I’m asking for advise here so to be prepared next time I can work on it. Thanks again, pic coming. You’ll like what u c.
 

ceg

Registered
yep. The Lawnmower was built in 1983. Mom is in photo just after completion. Now 36 years later. Engine was used to cut 2 1/2 acres all summer for those 36 years. I start the thread as VF4 rebuild because I believe shes a bit worm out. Yes the engine sits under hood. A screen cut out was soon after on top for more heat to escape. Keep in mind this engine performed well for more than 30 years. It was used to power the elevator during harvest. A buzz saw was used as an attachment in front. The drive train is an oil clutch to a 3 speed Studebaker tranny then to a High Low F20 gear box then to a 20-1 gear reduction box to reverse the PTO to a 3 on the tree Ford tranny finally to the Studebaker rear end. Electric start with generator. Yes it ran hot but 90 deg heat and 2 1/2 acres it worked well. Dad set the intake and exhaust valve gap to more than .020" I've tried Autolite and Champion plugs. The glaze he got I think may be due to exhaust valve leaking putting a crust on IMO. Thanks for looking and any advise.
 

K-Tron

Registered
That is a really cool mower! What is the 0 to 60 time on it :D Intake valve clearance is 0.008" and exhaust valve clearance is 0.016". 0.020" on the intake will prevent the engine from breathing properly, which may be a source of the problems that you are having. I have never had to run any form of lead additive in the fuel of any of my Wisconsin engines. I would definitely perform a compression test. Your engine should have about 70psi compression on all cylinders. On top of what Andy mentioned, pull all four plugs and crank the engine over. Observe the spark at each plug to be sure that the magneto is working well. Champion D16 plugs will be just fine gapped at 0.030". It looks like there is enough room to pull the cylinder shrouds and remove the heads should your compression numbers be all over the place. You would be surprised at how much a simple valve lapping and valve lash adjustment will do on these engines. You are correct that a worn valve guide will give less than desirable results with a guide piloted valve seat cutter, however there is usually a 0.003" valve to valve guide clearance which gives the valve a little bit of wiggle room to seat with the pull of the valve spring. I cut valve seats very lightly. After a pass I mark the seat with sharpie and spin the valve and take note of where the valve rubs the sharpie off. Then push a little harder on the side that the sharpie hasnt worn off on, with the next round of seat cutting. Usually only requires a turn or two to make a significant change. Once the seat is cleaned up, lap until the valve margin is acceptable, about 1/32" to 1/16" wide. Once compression is restored it will run great. Just make sure to blow out any debris in the cylinder fins, and change the oil out with some fresh SAE30 and you will be good to go for another 32 years.

Chris
 

ceg

Registered
Once I do a leak down test I’ll know more. You’ve given me confidence in cutting seats. I recently replaced all mani gaskets as a bad exhaust leak was present. Carb was cleaned also. I’m still loooking for a throttle shaft bushing someone sells as it could be tighten up a bit. It idles ok as is though. I need a small washer shim plus gasket ring yet because one exhaust port hole is rusted on cylinder. I’ve read about cutting slit in intake mani to reduce vapor lock but I don’t think after so many years that was a problem. Besides I have found no good instructions on exactly how much and where to cut. The gap is large because of concern of overheating I believe. I’m aware intake should be .008” and that seems too low for an air cooled motor anyway. The mag was taken off years ago and replaced with an M farmall distributor. A common practice he did on other old tractor motors he used in the 60’s. One might think timing is the problem but again this motor started and ran fine nearly half of its life in the mower with the M distributor mod. I have so many more questions but I have a lot to think about for now.
 

ceg

Registered
The manifold cut appears to be cut clear through. Your mani is different. Mine is an updraft carb. Unfortunately the mani is not with me to look at but is there a place to cut completely through that makes an air gap. Obviously not cutting into intake tract. Good photo on the valve and seat. I’ve used markers on constant velocity clutches but never thought to do it on valves, good point.
 

Zira

Moderator
Staff member
Last Subscription Date
03/21/2020
Oh...my...God. Not sure I'd let my mom drive that. Or my wife. Or me.
 

ceg

Registered
I now have it running with out it missing but it lacks power. I changed out coil, points, rotor, cap and condenser. The leak down test was done so the rotor was inline with dist cap terminal to be sure I was at or very near TDC. To be sure I rotated crank a few degrees each way but I was not able to get any cylinders to hold pressure for even a second or two. I could hear air escaping out of oil filler neck cap. I added oil to cylinder and turned engine over a few times and retested but same results. The compression test was done with hot engine and throttle wide open and showed 65 psi with 70 psi on number 2 cylinder. The oil level is good on dip stick but i have a LOT of smoke coming from vent cap when motor is under load.
 

DCAmp

Subscriber
Last Subscription Date
02/17/2020
Re: VF4 rebuild

I place the pistons in the the jugs with the inner wristpin snaprings in place just below the jug. Then push the pins in and install out snaprings. Drop the jug into place.
 

K-Tron

Registered
Re: VF4 rebuild

ceg, how was the compression on the other three cylinders? A VF4 with 60-70psi compression on all cylinders should run okay. 80 would be better. If it is not too difficult, pulling one of the cylinder heads will tell the whole story. The head gaskets are reusable. If your engine is hissing when stopped at TDC, the valves are leaking.

Chris
 

ceg

Registered
All but one cylinder was 65 psi compression. Number 2 cylinder was 70 psi. I’m not sure I have a trained eye to see if valve is not seating if I pull head. When I say I have a LOT of smoke from vent cap that’s an understatement. A cloud of smoke appears when motor is under load. I’m worried something is on fire under hood it is that bad. I would think I have ring blow by if crank case is smoking that bad. 65 psi seems low to me as a healthy motor imo should be 90 or above.
 
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