Galloping Fastwin

[jerryswiss]

1958 Evinrude 18 hp Fastwin. Got it in an auction for $40.
Condition:
Compression: 110 psi each cylinder (this is at 5,000 feet elevation, probably equiv. to 120-125 at sea level.)
Ignition: Good coils and condensers from my parts box. Good bright blue spark. Synchronization of linkage done. Points set at .020 in.
Carb: Soaked, cleaned with Welch plug out. Looks clean and functional. No new parts.

Problem:
Trying to dial in the carb jets in my test tank. 3/4 out on both needles. Do not have a test prop. Engine “gallops” all the time no matter where I try to set the needles. I understand this “galloping” condition is a sign of running too rich. Cannot seem to lean this out, help.

[Buccaneer]

Is #58 gasket in place and in good condition?

Prepare to be boarded!

[billw]

Thoughts: Make sure the carb float is right side up. I believe it can be done wrong. I recently helped my neighbor with his two cylinder, two carb 40, which is like 50. I hadn’t done one of those carbs for years. I was in a hurry and put one float in upside down. Very, VERY rookie mistake but I made it. Engine had some unique running characteristics, needless to say. But before you check that, with the engine off, simply use the tank primer and prime the system HARD. Does the carb overflow? It shouldn’t. If converted to a fuel pump, pump the primer bulb. If it has a fuel pump conversion, be aware that the diaphragm can leak fuel into one cylinder.

I think the initial setting for the low speed needle is more like 1 1/2 turns out, isn’t it? Maybe 1 1/4.

Long live American manufacturing!

• This reply was modified 3 years, 9 months ago by billw.

[fleetwin]

Not sure I understand “galloping”….Perhaps you could post a video. It is very tough to get these engines “dialed in” in a test tank. You can get close, but the final adjustments have to be made on the boat in the water.
Like Bill says, the initial low speed adjustment is about 1.5 turns out from gently seated.
One issue comes to mind on this engine though. The low speed needle actually threads into a collar that fits loosely in the carb body….You have to tighten the packing nut enough to jam the collar/sleeve in place… So, you may be turning the needle valve, but nothing is happening because the collar/sleeve is just spinning inside the carb body.
The other thing to keep in mind is that the high speed needs to be dialed in before attempting to dial in the low speed needle. It is near impossible to dial in the high speed needle in most test tanks…So, you might want to put the engine on the boat in the water, then reattempt the adjustments….

[jerryswiss]

Thanks for all the info. 1 1/2 turns out Low Speed. Is that the same for the high speed? I should have mentioned it does have a fuel pump conversion and for test purposes I do not use a tank on the ground with a primer bulb, but a gravity feed tank set up high. Could that be part of the problem? I have done this with many motors.

[bobw]

High speed should start out at 1/2 to 3/4 turn open.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[need2fish]

Galloping is what we call surging. in my experience, is a symptom of high altitude fuel starvation. It’s also a symptom of running in a tank where the engine is inhaling its own exhaust.

First of all , any elevation over 1,000 feet is considered high altitude… which means you have to richen both low and high speed mixes. I’m at 1,200 ft and have to run my smaller motors just a touch rich.

I confirm better results are obtained by testing on the water. When you do, bring along a spritzer with premix in it to shoot down the carb throat when the surging starts. If the rpms even out for a few seconds, that is proof of fuel starvation.

[jerryswiss]

Success! The final settings were Low Speed needle 1 3/4 out, High Speed needle 3/4 out. Will further tune on the boat. need2fish mentioned that at high altitude you need to RICHEN both needles. This is in opposition to everything I have ever done in the past. I have always leaned. Why is that so?

[fleetwin]

jerryswiss wrote:

Success! The final settings were Low Speed needle 1 3/4 out, High Speed needle 3/4 out. Will further tune on the boat. need2fish mentioned that at high altitude you need to RICHEN both needles. This is in opposition to everything I have ever done in the past. I have always leaned. Why is that so?

I thought you had to lean the needles also at higher altitudes… Glad it is running OK now….

[need2fish]

I wasn’t articulate enough….perhaps need to review what I type before I hit submit… with the surging you should start by richening both high and low then back off on hi-speed untii running smoothly at ~ 3/4 throttle, then throttle down and back of until lo-speed running (1,000-2,000) is smooth.

• This reply was modified 3 years, 9 months ago by need2fish.

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