Getting started on the mods

[Converted]

Someone had to go and ask me if I was done yet so I guess it was a good time to get started :roll:

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=6

Its very important for a shade tree mechanic to have a proper shade tree. This one is excellent.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=7

This is the piece that I removed and picked up 100RPM in the water at WOT. It really restricts airflow into the stock carb.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=8

This is the casting that also looks like it would not flow air as well as the old style that is used on the canister air filter. I think anyone running a stock carb would be better off with this one with a K+N cone filter (#RC1200 + RC1200PK)

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=9

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=10

BTW here is the string attached to the governor linkage to see if I'm getting WOT in the water under load with the throttle lever pegged. (In my case I was). Please be careful if you do this. PFD, Kill switch, and a buddy watching.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=12

Front cover removed

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=11

Carb assembly removed

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=13

That is one rough casting. Generally you want some texture in the intake path on carburated motors to maintain enough turbulence to keep the fuel and air well mixed. This is excessive. The entire intake will be polished out. I will come back with a sand blaster and apply some light texture. In addition in phase 1A I'm adding a carb spacer on the stock carb. Pending the "wow" level I'll be may be adding the 45mm Mikumi kit from MB as phase 1B. In either case the material between the two intake runners will be knife edged to enhance flow.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=14

Now we're getting to the good stuff. This intake port is interesting and I can see how the modified heads are so beneficial. In this case we'll call these the LithFlow heads when they are done. 8) It's hard to see in the pic but ther are very sharp edges between the intake ports and the bowl behind the valves. These sharp edges will cause the air to lift away from the walls and not flow well around the valves. They are easily remoced and a radius added. The second arrow shows an excessive valve guide boss. Nearly all of that can go resulting in a much lower profile and more aerodynamic flow pattern. I had assumed that there would be some material to remove to enlarge the port and match the intake gasket. In this case the gasket is actually slightly smaller than the port. The new gasket will be shaved to match and the intake manifold has considerable material to remove. I can't do the intake until the heads are decked and re-installed. I'll transfer an image from the newly installed heads to the intake and make sure the transition has no ridge to deflect air.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=15

The exhaust port also has an excessive valve guide boss (not uncommon for production heads). It also has some extreme ridges between the bowl and the port. In this case there is an opportunity to enlarge the port to match the gasket opening. In addition the exhaust side will be highly polished to move as much air as quickly as possible.

[Converted]

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=16

Here's a good pic of the intake manifold with the gasket still attached. There is a considerable amount of material that can be removed to match up with the intake port on the head. As I mentioned this precise allignment cannot be determined until the heads are done and installed.

http://www.unitedwaterfowlersfl.org/forum/picture.php?albumid=3&pictureid=17

This was disappointing. I've only had this motor out in the salt a dozen times or so over 2 years. I think we have a little cleaning to do :roll:

That's it for now, I'll keep you posted

[duckbone]

Couldn't you use a small brake cyl hone instead of a sandblaster and cross hatch it.

[Kevin Hall]

David,

Those pictures prove the difference in HP rating between the horizontal shaft motors (35hp) and the vertical shaft motors (36). The vertical shaft motors do not have the "adapters" on either side of the carb. The aircleaner assembly bolts directly to the face of the carb ... and the carb bolts directly to the intake.

Some of the guys have eliminated the division in the intake ... they have an open plenum right behind the carb ... and the runners break off to the cylinders much deeper into the intake. Most have reported smoother idling at a lower RPM. :) Just FYI.

[Kevin Hall]

David,

Those pictures prove the difference in HP rating between the horizontal shaft motors (35hp) and the vertical shaft motors (36). The vertical shaft motors do not have the "adapters" on either side of the carb. On the vertical, the aircleaner assembly bolts directly to the face of the carb ... and the carb bolts directly to the intake.

Some of the guys have eliminated the division in the intake ... they have an open plenum right behind the carb ... and the runners break off to the cylinders much deeper into the intake. Most have reported smoother idling at a lower RPM. :) Just FYI.

[Converted]

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1437.jpg

Valve covers removed

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1439.jpg

Pulled Rockers and push rods

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1438.jpg

I like to put groups of parts in zip locks to keep everything straight.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1441.jpg

Pulled head

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1444.jpg

At this point you can start checking for problems and wear. In this case there is still a crisp cross hatch hone pattern in the #1 bore. There is some vertical scoring on the top and bottom (thrust surface) of the bores but it is not too bad.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1445.jpg

You'll want to look closely for head cracks. The thin spot between the valves is the most common spot followed by the areas between the valves and the spark plug hole. Check closely before decarbonizing. After you start with the power tools you will fill any fine cracks and then you can't see them.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1446.jpg

My digital camera could not pick it up but you could see light when looking in the intake port at the back side of the valve. A little trick to check for valve seal if you are not planning a valve job is to pour gas in the port and look for seepage around the valve. In my case the gas would not have stayed long. It was quite clear that my leakdown test was correct, the intakes were not sealing.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1467.jpg

This piston (#1) looks to me to be pretty healthy.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1468.jpg

#2 on the other hand appears to be running lean. Seeing this along with...

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1463.jpg

A very white plug that has about 1 hour of mostly wide open running. I'm wondering if I really want to mess with the stock carb.

[Converted]

Time to start head disassembly

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1447.jpg

My first step was to record the installed height of each valve spring. The valve job will add to this height and I will have to account for that amount in addition to the shim that I want to add to get more seat pressure.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1448.jpg

Now the valves can come out

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1449.jpg

Pulled the retainers

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1452.jpg

After pulling the springs and before removing the valves I like to check valve guide/stem wear. In this case I set up a dial guage against the end of the valve stem

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1450.jpg

Set at zero with pressure toward guage

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1451.jpg

Apply pressure away from guage and note movement. About .005-.006. Acceptable, but I'm pressing in new guides as a part of the port work so it really doesn't matter.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1453.jpg

With the intake out you can check the condition of the seat. No cracks, that's good. I can't believe how crappy these castings are between the bowl and the intake runner. It looks like someone took a whole 10 seconds with a wheel to cleanup casting flash.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1456.jpg

The valve shows a considerable "shoulder" that can be backcut to aid in flow. I decided to buy new valves because the are only $12.95 from Briggs and my machine shop would charge be more than that to face them. I'll get the new ones backcut.

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1465.jpg

It was unclear from the Briggs site and the parts manual exactly what gaskets you get in the full engine set. Here you go.

I'll start in on the heads and post more in a few days.

Any feedback on my diagnosis of a lean #2 jug would be appreciated

[Kevin Hall]

David,

Almost every engine/carb that I've seen has had different sized jets for the two cylinders. That's probably the case with yours, as well. Once you get done with the head work, you'll probably have to re-jet the stock carb anyway. ;)

[Randy Clark]

cool pics thanks for posting

[whistlingwings]

David, have you found the intake valve warped in the least bit ?

[Converted]

I haven't checked it over that close. I've got some prussian blue paste on the way from Goodsons.

[Converted]

Got the exhaust port pretty well done on #1

Before

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1453.jpg

After

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1483.jpg

Before

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1457.jpg

After

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1480.jpg

http://i158.photobucket.com/albums/t83/Converted_UWF/Mud%20Buddy/DSCN1482.jpg

There was quite a ridge between the bowl and the runner on both sides. Those ridges are now a pile of aluminum dust on my work bench. I didn't take all the Valve Guide Boss off but I did take most of it. I will be pressing in new guides when they arrive later this week. I'll try to remember to get a pic of the markup on head #2. I may get out the cc'ing stuff and check the volume increase on that head as well.

Now on to the intake side of things...

[Converted]

I'll pass along some good info so anyone else trying this doesn't make the same mistake...

I heated the heads to about 300 in the oven. The valve guides had been chilling in the deep freeze at -3 over night. I pulled head #1 from the oven and put it on the press. A quick spray of Goodson press fit lube to both parts and the guides slid nicely into place.

I pulled out head #2 and started to repeat the process. Dang if the guide didn't slide almost half way into the hole with very little pressure. Hmmm, that ain't right. "well maybe when everything gets back to room temp we'll be OK" Unfortunately not. I started the reaming process and when I was almost through the #2 Exhaust guide the guide started to spin in the head.

I was pretty pizzed for sure. I was thinking that I somehow trashed a $238.00 head and many hours of work. After calming down a bit I called the machine shop to see if anyone was there on Saturday. After a hearty laugh on the other end of the phone I was told that it was not that uncommon and there were two relatively simple fixes. I was told to order another set of guides. The process that is used most in this situation is to knurl the outside of the guide before pressing it in. That adds a thou or so and gives better grabbing action. If the bore in the head is too large for the knurl trick to work the other fix is to take a larger guide and turn it down on a lathe to the required interference fit.

As it turns out I should have heated the head before pressing out the old guides. They told me that even then on occasion you will remove some aluminum with the guide and have to turn to a remedy.

Live and learn

[David B]

Updates on your hard work?