Snowblower Forum banner
281 - 298 of 298 Posts

·
Registered
Joined
·
1,273 Posts
Discussion Starter · #281 ·
ok, consulting the aforementioned site:

Fuel Mix Ratio : Printed somewhere was found info stating prior to 1951 Sears recommended 3/4 pint of SAE 30 or 40 weight motor oil per gallon of gasoline (24-1) for all of these old water cooled motors. On motors after that, a decal placed on the RH side of the carburetor cover (shown in the photo below) is the inscription "For normal operation, mix 3/4 PT. of SAE # 30 oil with each gallon of gasoline. For trolling use 1/2 pint per gallon of gasoline" which would be (32-1). It is not known why the modification in the fuel mixture unless there were complaints of the spark plugs fouling a lot when trolling, which these motors were probably used mostly for.

You will also be reminded that the fuel in those days was leaded. Take my word for it that the regular automotive motor oil used in those days did not mix as well with the gasoline as the 2 cycle oil that is currently available does. Today, modern 2-stroke oil with the TCW-3 designation should be used on all water cooled motors. What this TWC-3 designates is that it is designed for Two cycle, Water, Cooled & is version #3, with the #3 being specially designed for use with non-leaded gasoline.

I would also recommended that the use of FULL synthetic TCW-3 oil be used for these motors as it gives better lubrication for the bronze bearings, burns cleaner leaving less oil on the water and will extend spark plug life, especially for these motors that will be used mostly for trolling. All of these 1946 - 1951 motors should run better than originally designed on 1/2 pint per gallon (32-1) of this FULL synthetic TCW-3 outboard oil. Note that NOT ALL TCW-3 oil is FULL-synthetic or blended, (it however will be priced considerably higher than the regular TCW-3) so look carefully before you buy. Now I will stick my neck out, and say that I use 50-1 ratio on my motor, BUT use FULL synthetic TCW-3 oil IF USED FOR TROLLING.

Gasoline of an 87 octane is recommended and that it NOT BE an Ethanol blend if at all possible. If you have to use Ethanol E-10, then I would recommend that you drain the fuel tank after usage if you are going to let the motor set for a over a couple of weeks.

FUEL MIXING TABLE
Gallons of Gasoline
Gasoline to Oil Ratio
Ounces of Oil to be Added
16:1
24:1​
32:1
50:1
100:1
1​
8​
5​
4​
3​
2​
2​
16​
11​
8​
5​
3​
3​
24​
16​
12​
8​
4​
4​
32​
21​
16​
11​
6​
5​
40​
27​
20​
13​
7​
6​
48​
32​
24​
16​
8​
 

·
Registered
Joined
·
1,273 Posts
Discussion Starter · #286 ·
i am a little confused. is it being suggested to use or not use the TCW-3 two stroke oil?

Prior to 1951 Sears recommended 3/4 pints of SAE 30 or 40 weight motor oil per gallon of gasoline for all motors. Starting in 1951, the specified mix was changed to 1/2 pint per gallon in all motors. Today, modern 2-stroke oil with the TCW-3 designation should be used on all water cooled motors. Air cooled outboards should use 2-stroke oils with the TC designation such as used by weed whackers and chain saws. Modern automotive oils should be avoided at all costs. All of the 1946 - 1954 motors should run fine on 1/2 pint per gallon.
 

·
Registered
Joined
·
1,273 Posts
Discussion Starter · #288 · (Edited)
All the reading aside, I guess the cheapest and fastest path is to use some 30 oil, as was originally called for. Grab a new plug. Have to study the tillotson carb to locate the various adjustment screws.
 

·
Registered
Joined
·
1,273 Posts
Discussion Starter · #290 · (Edited)
Grabbed this today. Stihl fs76. I have lots of trimmers now. Should I keep it? Obviously missing it’s shroud. Needs a fuel line kit. Tried a little fuel in plug hole, fired right up.
 

Attachments

·
Registered
Joined
·
1,273 Posts
Discussion Starter · #291 ·
On this trimmer carb, which is the fuel inlet and outlet. Been trying to get fuel flow, put on new fuel lines and filter, and bulb. Has a vented cap. Can’t get any flow. Getting bubbles in tank, but no fuel in the line. First assumed the upper nipple is the fuel filter input line. And return was lower.
 

Attachments

·
Somebody
Joined
·
3,949 Posts
On this trimmer carb, which is the fuel inlet and outlet. Been trying to get fuel flow, put on new fuel lines and filter, and bulb. Has a vented cap. Can’t get any flow. Getting bubbles in tank, but no fuel in the line. First assumed the upper nipple is the fuel filter input line. And return was lower.
I think the black nipple is the input... can't hurt to swap 'em and see. 👍
 

·
Registered
Joined
·
4,213 Posts
I vote the bubble pump is the inlet because you are sucking gas from the tank to go in to the carb.
 

·
Registered
Joined
·
5,477 Posts
On this trimmer carb, which is the fuel inlet and outlet.
The inlet is the one away from the priming bulb and should be connected to the line with the fuel pickup screen. The fuel return is the one connected to the primer base.
 

·
Registered
Joined
·
4,230 Posts
The black fitting is the inlet. Have you replaced the metering diapgram? The priming system will just pump air into the tank if there is no fuel in the fuel bowl because the metering diaphram is not pushing the needle to let the fuel in.
 

·
Registered
Joined
·
4,230 Posts
If your going to be working on small carbs like this it may be worth ordering some. I believe there is 3 very common metering diaphrams. There is the Zama ones and then there is the long and short pin metering diaphrams for walbro carbs. You can usually get these pretty cheap by themselves. These and fuel line are best to buy in bulk since almost every machine I have found has shrunk fuel lines that need go be replaced there is 2-3 common fuel lines sizes but I don't know them off the top of my head. 2 of them have the same outside diameter but inner diameter is different and the other size is smaller them these
 
281 - 298 of 298 Posts
Top