Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

Nandy

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Apr 10, 2004
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2,145
Model 70573-b, serial J0001631

I bought this motor in october and got it running. It sounded well on the muffs but did not do a seatrial as I was working some trailer and boat title paperwork issues. Anyway, I decided to get the kits for the carbs and get them installed while waiting.
I'm installing the carbs back but the book mention synchronizing these carbs to the ignition. I am at a lost at what is that they are trying to accomplish. I can just do what the books says but I always like to understand what it is. Is by synchronizing the carbs to the ignition they mean that the carb has to be this much open when the ignition is these many degrees accelerated? Is that what it is?

Secondly, generally I take photos from the motors before I take them apart just so I can check where everything is. In this case since I had the parts before starting and I "KNEW" I will finish the job in a couple of days I left the picture part out. Here I am 7 months since I started working in the motor and I need to put the carbs back but I am having a few issues with some of the springs. I cannot for the love of God figure out how they were. So if anyone can take a photo of their carb linkage that will be great. If no I can take a picture and post it here and you guys can tell me what y'all think.

Thanks for your help!
 

Dhadley

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Feb 4, 2001
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16,978
Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

When you get the carbs back on go to the "Sync & Link" section in the (hopefully OE) manual. It'll walk you right thru it, no big deal.
 

Nandy

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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

I read the section. It just did not make any sense, at least not to me at the time.
 

Dhadley

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Messages
16,978
Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

Once you get the carbs on loosen all the linkage adjustment screws. Make sure the roller is not touching the cam follower. Snug up each linkage adjustment screw making sure the throttle butterfly stays completely seated. Then adjust the roller so it picks up the cam follower at the line.
 

Nandy

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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

Thank you!
 

Nandy

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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

Anyone with photos?
 

serge88

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Oct 31, 2009
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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

hey mate I will help you out, I'm also struggling with carby issues on the same engine in a different post :), I'm in Australia... maybe you could help me out in return. Do the high and low speed needles on the carby need adjustment after re installation back on motor? I thought they just need to be screwed in fully as they are fixed jets? At the moment its night time and rainy. I will see if I can get a few snaps now, if not first thing in the morning, Hope to hear from you soon. Serge.
 

serge88

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Oct 31, 2009
Messages
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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

Nothing an umbrella and a torch can't fix, please excuse **** photography, bit hard to hold torch, umbrella and camera at the same time :) I have the original OEM OMC manual, if there is anything else you need let me know. Serge.
 

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JB

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Re: Evinrude 70hp 1975 Carb synchronization and need photos of carbs.

This thread is 2 years old, Serge.
 
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