Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Mf-7 Repower

h70 tecumsey mf-7 ohm90

  • Please log in to reply
24 replies to this topic

#16 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 14, 2012 - 10:58 PM

Well, I've pretty much got the repower done. I test mowed my lawn last night and it appeared to work fine, except the engine only runs at one speed, regardless of where I put the throttle lever. It's moving the lever on the engine, but the governor holds it in one place... I'll have to look into that a little more.

One picture I didn't show previously was the running of the extended oil drain lines.

2012-06-22_20-56-50_109.jpg

After I got it bolted down on the tractor I discovered I really didn't need the two elbows--I could have just run the 1/4" pipe straight from the engine to the front, then elbow it down and cap it.... oh well!!

Anyway. After I got the charging circuit hooked up, I went to work on mounting the fuel tank, battery, and air cleaner--pretty much in that order.

I decided to use the OEM tank but mount it up where the battery used to go. There's just enough room to clear the hood.

2012-07-28_10-42-11_321.jpg

I measured the from the inside of the grill to the front of the engine--enough room for a lawn and garden type battery with about 1 1/2 inches to spare. I figured if I made something to help isolate the battery from engine heat, I could probably use it there.

MF 7 Engine Space.JPG MF 7 Engine Space 2.jpg

So, I started in earnest on the fuel tank. I used the original straps, and the original shutoff valve. I bolted a couple pieces of 1 1/2 x 3/16" angle onto each side of the battery box for a "shelf" for the fuel tank. I used a piece of corrugated plastic from a yard sign as the shelf--it will also help insulate against heat. I had to notch out one shelf to allow for the shutoff valve.

2012-07-28_10-39-59_372.jpg 2012-08-13_18-54-18_328.jpg

I mounted the tank and hooked it up, then fired up the engine using the pull starter-- SUCCESS!!

On to the air cleaner assembly.

The original air cleaner was too big and interfered with the mounting of the grill--even with the POs butchering job...The muffler just barely fit under the hood, but the exhaust exited to the front of the engine--putting a lot of hot exhaust under the hood.

MF7 Engine Swap LH Frt.jpg

The hood also interfered with the engine shroud--fortunately the previous owner solved that problem for me by notching the hood.

For the air cleaner, I used 4 1/2" electrical cover plates to "sandwich" the air cleaner between them. The air cleaner is a 5" diameter unit I picked up from the local O'Reilly Auto Parts (Formerly Schucks/Kragen/Checker). I think it cost about $6.00. I found a 1" ID radiator hose with an elbow in it to make the bend from the horizontal inlet to the carb to the vertical inlet to the air cleaner.

2012-07-28_10-42-37_460.jpg

I measured for clearance for the sealing part of the air filter, and cut a hole in one of the plates, then welded a 1" diameter pipe onto it. I drilled two 1/4" holes in the plate just a little offset from the center of the air filter, and bolted two pieces of 1/4" all-thread to the plate.

I drilled two corresponding holes in the other plate for the top piece and my air filter assembly was complete.

I had intended to have the aircleaner sit horizontally and above the carburetor. However, the edge of the air cleaner interfered with the edge of the hood. I could have just tilted it over, but it looked real tacky, plus I didn't have something I could brace it with. I set it aside to work on something else while my mind ruminated on the problem...

Another problem I had is that the choke lever on the carb stuck way out to the left side of the engine.

2012-07-28_11-36-50_401.jpg

The previous owner had already butchered the left side of the grill to make room for the H80 engine he used to replace the original H70. I bought a longer cable to go from the dash lever to the choke, with the cable housing running along the left side of the engine, and shortened the lever and redrilled the hole two different times, but I still couldn't open the choke lever.

I finally re-routed the cable along the right side and front of the engine, and cut off the first bend of the choke lever and redrilled it. Now it works!!

I had to make a bracket to hold the clamp--fortunately there is a strategically-located bolt that held on the original muffler guard in just about the right place.

Now back to the air cleaner housing. I was concerned that the metal of the cover plates might be a little thin, so I bought two more plates and started looking for a spot welder to double them up on each side--thus making them stiffer.

I had seen the spot welders at Harbor Freight, but wasn't too impressed with them. The biggest problem I saw was that the tips were really sloppy and didn't line up with each other. However, I had read some good reviews on this forum and elsewhere, and they were on sale at HF so I decided to buy one. Just as I was about to leave for the store, something prompted me to look in the local online classified ads. Lo and behold!! Someone had a 110V version for sale in practically new condition for $60--about a third of the sale price at the store.

He was an hour away, but I jumped in the truck and beat feet to his home. Turns out he had a business building hydrogen generators and had bought the welder for some fixturing he had. He had some neat products, many of which were in production... for use in automotive and home generator applications... cool!! but I digress.

I got the welder home, and it had the same problem with the arms and tips having too much slop in them... I finally found a cheap solution for this, which I'll share in another post.

After welding the stiffener plates I felt much better about the air cleaner housing though it was a bit heavy.

I finally decided to mount it with the filter in a vertical position. This required finding yet another radiator hose with a right hand elbow and a "zag" in it to place it above the engine... for those of you that don't know, a "zag" is a technical term for the second half of a "zig-zag". ;o}

I still needed to brace it with something. I had some heavy gauge (16 ga or so) galvanized steel, so I sketched out a bracket that would attach the the side of the grill on one side, using two existing carriage bolts. The other side bolted to the bottom plate of the air cleaner.

2012-08-13_18-54-03_740.jpg

To bend the bracket, I used a nifty little tool that I bought at Harbor Freight years ago. It's like a press brake die, but has an angle bracket with magnets that attaches to a large vise. You position your part between the two dies and turn the vise handle in... Mine is 6" wide, and made from two 3" segments. I believe you can get wider units as well...

2012-08-11_19-32-06_174.jpg 2012-08-11_19-33-11_306.jpg

2012-08-11_19-35-41_836.jpg

An added benefit was that the bracket also acts as a heat shield for the air cleaner and the top of the battery.

2012-08-13_18-54-12_150.jpg

In mounting the battery, I used a piece of 1/2" CDX plywood and covered it with yet another piece of corrugated plastic. I ran two pieces of all-thread along each side, and secured the battery to the wood with a piece of angle under the wood. The wooden platform also bolts to the center bolt by the grill... it appears pretty sturdy--time will tell.

I bought a piece of 6 ga electrical wiring for the positive battery cable. I routed it to the battery terminal of the start solenoid--using plastic wire loom where it runs close to the engine block. A piece of corrugated plastic placed vertically between the battery and engine helps insulate the battery from engine heat.

I put the grill and hood on the frame--it fits close enough that the hood latch works...

Not especially pretty, but definitely functional...

2012-08-14_18-08-01_271.jpg 2012-08-14_18-08-41_24.jpg

I love the sharp turns and easy handling of these little machines... I only wish I had a hydrostatic drive rather than the manual transaxle, but it will do nicely just the same.

Regards,

Utah Smitty

#17 KennyP ONLINE  

KennyP

    FORDoholic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2253
  • 28,494 Thanks
  • 39,727 posts
  • Location: Collinsville, Oklahoma

Posted August 15, 2012 - 04:50 AM

Wow, US! A lot going on in that post! Glad you found the hose with the "zag", I usually find the "zig" and it won't work.
  • Utah Smitty said thank you

#18 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 15, 2012 - 04:56 AM

Wow, US! A lot going on in that post! Glad you found the hose with the "zag", I usually find the "zig" and it won't work.



LOL!!

Well, I'm glad it's done. Now mom can mow her lawn with it instead of the big Sear GT18 she has...

Thanks for you insights and help.


US

#19 KennyP ONLINE  

KennyP

    FORDoholic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2253
  • 28,494 Thanks
  • 39,727 posts
  • Location: Collinsville, Oklahoma

Posted August 15, 2012 - 05:17 AM

If Mom's happy, everybody's happy! Did you get the throttle figured out?

#20 HowardsMF155 OFFLINE  

HowardsMF155

    Tractorholic

  • Senior Member
  • Member No: 4243
  • 2,699 Thanks
  • 2,916 posts
  • Location: Central NC

Posted August 15, 2012 - 06:41 AM

Excellent! Those little tractors are great, very nimble as you say. My biggest problem is getting my long, heavy self folded up on the seat!

#21 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 15, 2012 - 12:27 PM

If Mom's happy, everybody's happy! Did you get the throttle figured out?


The throttle cable works okay... it just doesn't change RPMs much. I broke the engine in using the original aircleaner and muffler, so something I've done in those areas may have affected it. However, I ran it several times for short periods without the aircleaner-- just the elbow, and it behaved normally, so I'm not sure what is causing this.

The other thing I noticed was when I was working on it Saturday evening. I started the engine and let it run... The coffee can muffler and 1" pipe got very hot--started to glow red in fact... is that normal???

#22 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 15, 2012 - 12:29 PM

Excellent! Those little tractors are great, very nimble as you say. My biggest problem is getting my long, heavy self folded up on the seat!


Yeah, I suffer from the same problem, being 6'0" and 300+ lbs. However, they're easier to go onto than my Sears GT 18--no clearance to speak of between the steering wheel and the seat on the Sears.

#23 HowardsMF155 OFFLINE  

HowardsMF155

    Tractorholic

  • Senior Member
  • Member No: 4243
  • 2,699 Thanks
  • 2,916 posts
  • Location: Central NC

Posted August 15, 2012 - 03:20 PM

The throttle cable works okay... it just doesn't change RPMs much. I broke the engine in using the original aircleaner and muffler, so something I've done in those areas may have affected it. However, I ran it several times for short periods without the aircleaner-- just the elbow, and it behaved normally, so I'm not sure what is causing this.

The other thing I noticed was when I was working on it Saturday evening. I started the engine and let it run... The coffee can muffler and 1" pipe got very hot--started to glow red in fact... is that normal???

I went through this on a Tec 120 that ended up having a small valve gap and a delayed ignition timing. Generally, I think the concensus was that if you are working it hard and it is dark, there will probably be a dull cherry glow. High exhaust temps can be caused by running too lean, an exhaust valve that won't close, and late ignition timing. The engine also lacked power in my case.
  • Utah Smitty said thank you

#24 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 15, 2012 - 04:21 PM

I went through this on a Tec 120 that ended up having a small valve gap and a delayed ignition timing. Generally, I think the concensus was that if you are working it hard and it is dark, there will probably be a dull cherry glow. High exhaust temps can be caused by running too lean, an exhaust valve that won't close, and late ignition timing. The engine also lacked power in my case.


Thanks, Howard. This engine was just running on the service platform with no load... I thought it might be running lean, but am not sure where the problem would be... The carb is mostly plastic and doesn't look like you can do much to adjust the float, etc.


Regards,

#25 Utah Smitty OFFLINE  

Utah Smitty

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 5557
  • 1,643 Thanks
  • 1,746 posts
  • Location: Northern Utah

Posted August 16, 2012 - 09:16 PM

Here's a little better picture of the air filter set up. The "zag" is clearly visible where it goes into the air filter housing.

M-F Air Filter.jpg

I hooked the crankcase ventilation hose up to a piece of copper tubing that I soldered into the base of the housing.

I'm thinking I probably ought to put a pre filter on this thing as well...

Edited by Utah Smitty, August 16, 2012 - 09:17 PM.





Top