Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Fuel System

Reply
 
Thread Tools Display Modes
  #1   IP: 12.250.5.246
Old 07-25-2017, 10:25 AM
Jim Booth Jim Booth is offline
Senior Member
 
Join Date: Jan 2005
Posts: 151
Thanks: 2
Thanked 5 Times in 5 Posts
Carb adjustment after changes

I rebuilt the carb and put an adjustable main jet in. Also added the quick connect throttle cable fitting. I think I got the cable length adjusted back to where it was so the control is about where it was before. Now comes getting the main and idle jets right. I started with the main opened 1 1/2 turns I thought it would idle as before since I didn't touch the idle screw but it dies. I'm still out of the water. What's the method to get these set up before I launch ?
Reply With Quote
  #2   IP: 71.118.13.238
Old 07-25-2017, 11:25 AM
Dave Neptune Dave Neptune is offline
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
How did you "rebuild the carb" without disassembling? You could of easily blown something through the main jet and it could of lodged in the idle passages which are much smaller.
Is the throttle arm against the "stop" IER the idle speed set screw?

Dave Neptune
Reply With Quote
  #3   IP: 207.118.20.35
Old 07-25-2017, 11:30 AM
capnward's Avatar
capnward capnward is offline
Afourian MVP
 
Join Date: Aug 2012
Location: Deer Harbor WA
Posts: 335
Thanks: 41
Thanked 147 Times in 107 Posts
1 and 1/2 turns out from the seat on the main jet is correct for an initial setting. Turn the idle screw in until it seats, then 1 turn out. Turning the main jet out makes it richer, turning the idle screw out makes it leaner. I would guess that if it dies, it is too lean. I may be wrong. It may be dying for other reasons. When you had the carb apart, did you run a thin wire around in the idle jet, and the idle ports?
Reply With Quote
  #4   IP: 108.86.240.22
Old 07-25-2017, 01:36 PM
Jim Booth Jim Booth is offline
Senior Member
 
Join Date: Jan 2005
Posts: 151
Thanks: 2
Thanked 5 Times in 5 Posts
I had the carb apart to flatten the halves because it was leaking gas last season. I sanded both sides with 600 grit on a sheet of plate glass and lots of lube. Along the way, I blasted carb cleaner through all the passages, so it wasn't a complete rebuild. But the engine ran and idled fine last season.

So I guess I should leave the main adjustment at 1 1/2 turns out, then work on the idle mixture screw as I reduce rpm.

When the throttle control is all the way back, the throttle arm is on the stop.
Attached Images
 
Reply With Quote
  #5   IP: 71.118.13.238
Old 07-25-2017, 06:11 PM
Dave Neptune Dave Neptune is offline
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Jim, the sanding dust could easily plug up an idle passage or an idle jet. If you do not get any response from the idle air adjusting screw, get the idle passages blown clear for sure. The idle jet is around .018", very small. You could of blown other KRUD into them by not removing them.

Dave Neptune
Reply With Quote
  #6   IP: 71.178.91.151
Old 07-25-2017, 10:02 PM
sastanley's Avatar
sastanley sastanley is offline
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 7,016
Thanks: 1,134
Thanked 600 Times in 442 Posts
Dave, is there any danger in removing the idle mixture adjustment screw completely for cleaning and blowing out that area? I guess the only issue is to mind the spring, as you unscrew it, but that is why I am asking?
__________________
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif
Reply With Quote
  #7   IP: 71.118.13.238
Old 07-26-2017, 01:26 PM
Dave Neptune Dave Neptune is offline
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Shawn, it's no problem. By the time your unscrewed there is no contact with the spring so no "sproing" resulting in verbal abuse practice while searching.
You can blow into it and have no issues unless you go nuts with the air. The screws passage is upstream of the jet and E-well that feeds it so it is possible to blow out the Idle Jet but not the idle ports as the Idle Jet restricts the flow in that direction.

Dave Neptune
Reply With Quote
  #8   IP: 45.148.7.2
Old 07-17-2021, 08:45 AM
campbdon campbdon is offline
Senior Member
 
Join Date: May 2021
Posts: 45
Thanks: 16
Thanked 6 Times in 5 Posts
Hi, I hope it is correct form to piggyback off this thread for a related question.
My symptom is dry sooty plugs (all 4). The engine idles reliably at min throttle at 800RPM (approx) without stalling, and accelerates "explosively" when throttled up sharply. From other threads I gather I should look at cruising at higher RPM than is customary for me (ie: 2000 rather than 1500 RPM), and/or the mix is too rich so should lean out a bit on the main jet (It's at 1.5 turns backed off I believe). I don't have the adjustable but can do that manually. Any other advice please and thanks?
DonC
Reply With Quote
  #9   IP: 155.186.122.195
Old 07-17-2021, 09:42 AM
Dave Neptune Dave Neptune is offline
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
More info

Don, on the stock late model carb there is only an "idle AIR adjustment needle" that adjusts the air flow to the jet for mixing. And unless you or someone has added the "adjustable main jet" there is no real adjustment available or necessary other than idle.
If your plugs are dry and sooty you are way to rich somewhere. Since you have good response when revving we can set the exhaust aside for now.

First be sure the choke is all the way backed off VIDSUALLY and remove the flame arrestor. Now start and look into the carb throat while running and see if you see any fuel puddling in the throat of the carb. If so it is probably something to do with the floats.

Did you do any carb work? If so what did you do? Is fuel leaking anywhere?

And yes it is usually better to start a new thread to avoid confusion on your part and for those trying to diagnose the problem at hand.

Dave Neptune
Reply With Quote
The Following User Says Thank You to Dave Neptune For This Useful Post:
campbdon (07-18-2021)
  #10   IP: 172.58.76.239
Old 07-17-2021, 10:35 AM
roadnsky's Avatar
roadnsky roadnsky is offline
Afourian MVP
 
Join Date: Dec 2008
Location: Lake Mead, NV
Posts: 3,104
Thanks: 24
Thanked 467 Times in 309 Posts
Quote:
Originally Posted by Jim Booth View Post
So I guess I should leave the main adjustment at 1 1/2 turns out, then work on the idle mixture screw as I reduce rpm.
Jim-
Attached are the instructions that come with the Adj jet.
I assume you followed them?

Note in the instructions the caution about the internal washer. (2nd paragraph)
Could that be your issue?
Attached Images
File Type: pdf Adjustable Main Jet.pdf (33.1 KB, 270 views)
__________________
-Jerry

'Lone Ranger'

1978 RANGER 30
Reply With Quote
  #11   IP: 47.142.134.34
Old 07-17-2021, 10:48 AM
JOHN COOKSON JOHN COOKSON is offline
Afourian MVP, Professor Emeritus
 
Join Date: Nov 2008
Posts: 3,500
Thanks: 54
Thanked 855 Times in 629 Posts
TO START A NEW THREAD

Scroll down while on the forum home page to "Discussion Topics". Click on the most appropriate topic. The "start a new thread" button is on the upper left.

ex TRUE GRIT
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Carb Adjustment Tool gs11gk Fuel System 8 02-06-2016 09:15 AM
oops ,, idle hands cause much trouble BadaBing Fuel System 28 01-20-2016 03:40 PM
Carb adjustment after rebuild mrhoneydew Fuel System 18 05-06-2015 10:19 AM
Carb For Palmer P60 - Same as Atomic 4? bpowdrell Fuel System 3 08-29-2012 08:58 AM
Puzzling behavior after carb adjustment Baltimore Sailor Fuel System 22 06-11-2009 10:44 AM


All times are GMT -4. The time now is 07:52 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved