ForumsBasic TrainingOnline Maintenance ManualsThe M715 Zone Vin RegistryVPW's M715 Parts ListGalleriesLinks

Go Back   M715 Zone > General Tech > Stock Tech

Stock Tech Tech forums for Stock M715 series vehicles

Reply
 
Thread Tools Display Modes
  #1  
Old June 19th, 2019, 07:19 PM
randall555 randall555 is offline
Private
 
Join Date: Dec 2008
Location: cleveland ohio
Posts: 201
randall555 is a Soldier
Default timing a stock m715 engine ???

does any one know if there is any thing special to do when timing a stock m715 engine . and also what is the timing for it ??? where is the timing mark on the front of the engine . I need to know because my truck will idle just fine but when I give it fuel it dies or misses really bad . i put a new carb on it not rebuilt and its the correct one . and new plugs and wires and points . also a new fuel filter does anyone have any ideals why it wont take fuel ?? does anyone know of a good aftermarket plug not the oem kind but regular plug type that would be a good choice ???
Reply With Quote
  #2  
Old June 19th, 2019, 08:12 PM
brute4c's Avatar
brute4c brute4c is offline
Grand Poobah
 
Join Date: Sep 1998
Location: North Central Wisconsin
Posts: 11,416
brute4c is a Soldier
Default

Timing with the stock wires requires an adapter to hook a timing light to OR a modified spark plug wire to hold a standard style spark plug and then allow a standard timing light to connect to it...

I did it this way:
Get a length of standard plug wire...strip down to the inner wire on the NON spark plug end...take off the #1 shielded wire (thats the stock military wire) and put this wire you made above in its place with the stripped part shoved down the hole of the cap first...the bottom of the hole and only a little of the side is where contact needs to be made...use a boot like the coils used in the 60's and 70's to hold the wire down in the hole.

Use a conventional Autolite #275 spark plug and time with a normal timing light.

To see the timing mark location, scroll down the tuneup section from the manuals to Figure C-10 on this page:
http://www.m715zone.com/vb/view.php?pg=24_tuneup

Timimg spec is listed as 5 degrees before TDC.

Make sure your points are properly gapped OR use a dwell/tach for, in my opinion, an easier and more precise setting. The instructions are on that same page linked above.


If the fuel filter wont fill up with fuel, you may have a restriction in the fuel system. Sometimes there is crud in the tank that needs cleaned out or in the lines. There is also a "sock" type prefilter in the tank that is known to deteriorate with modern gas and can plug the line. In such cases, members have taken off the fuel line and blown compressed air back down the line into the tank to blow the "sock" off the line and stop that restriction. You could also have a weak fuel pump.
Can you verify that the pump is pushing fuel to the motor?
Do you have an electric fuel pump you could put in the line to see if it pumps fuel when the stock one doesnt?
__________________
Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

Pro-choice, that's a LIE, babies don't choose to die!!
Reply With Quote
  #3  
Old June 19th, 2019, 08:30 PM
brute4c's Avatar
brute4c brute4c is offline
Grand Poobah
 
Join Date: Sep 1998
Location: North Central Wisconsin
Posts: 11,416
brute4c is a Soldier
Default

Also check the float setting...the M715 uses a different float setting that civvy units with the same carb and these are often set for the civvy purposes.
Scroll the following page to Figure 4-11 and it has the dry float setting there:
http://www.m715zone.com/vb/view.php?pg=34chapter4

Another thing to check is the accelerator pump arm...the stock one is plastic and tends to break, which means the truck will stumble when one tries to accelerate from idle, here is an image that shows the part:


Look at the line for the #5 item in the image, follow it up to the arrow at the end. Now go a little left and down and you will see 3 small circles in an arc...this is one end of the accelerator pump arm...the rest of the arm runs from there to the left and has a metal "J" shaped rod through the hole in the left end.
__________________
Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

Pro-choice, that's a LIE, babies don't choose to die!!
Reply With Quote
  #4  
Old June 19th, 2019, 10:13 PM
jeepdan's Avatar
jeepdan jeepdan is offline
Sergeant
 
Join Date: Jul 2012
Location: Wheeling, WV
Posts: 1,395
jeepdan is a Soldier
Default

All great info above^^^^

Also check to make sure that the accelerator pump is actually squirting fuel out of it's jet, by looking down into the carb while opening the throttle.
The rubber diaphragm can go bad, especially with todays methanol laced fuel.

What kind of a new carb? An old New Old Stock carb?
If so, you will need to overhaul it with a new kit that is methanol compatible.

The harmonic damper is known to have the outer ring slip on the rubber part shifting the timing marks out of place.

My truck must be that way. If I time it by using a timing light, it doesn't run well.

I have to time it by ear

Last edited by jeepdan; June 19th, 2019 at 10:22 PM.
Reply With Quote
  #5  
Old June 20th, 2019, 09:56 AM
kwai's Avatar
kwai kwai is offline
Sergeant

 
Join Date: Dec 2006
Location: Houston, Tx
Posts: 3,087
kwai is a Soldier
Default

You misspelled ethanol. Gasoline has ethanol in it.

You can also set the timing using a vacuum gauge.

If you have an old military spark plug wire, you can remove the shielding to create a spot for the timing light to get a signal.

Your symptom sounds most like an incorrect float setting. Follow the TM procedures to set the proper float level. And check all the other areas mentioned as well.
Reply With Quote
  #6  
Old June 20th, 2019, 12:25 PM
Barrman's Avatar
Barrman Barrman is offline
Chief 9-flats

 
Join Date: Dec 2003
Location: Giddings, Texas
Posts: 7,716
Barrman is a Soldier
Default

There is a military kit out there for timing and rpm gathering. Here is a shot of the adaptor to get a tach signal and the manufactured lead splice to do as Jon described to get the timing light signal:





RRRR.... I thought I remembered the new way to post pictures here. If you want to look, click on my user name and go to my albums. Picture post is the album that has these to parts. Sorry.
__________________
Remember if you didn't build it you can't call it yours.

6.2 powered M715, 5 M1009's, M416, 2 M101's, 2 M105's, 3 M35's, M1007 6.5 turbo Suburban project called Cowdog.
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


All times are GMT -7. The time now is 08:07 PM.

 

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
1998 - 2019


This site is owned and operated by:
M715 Zone, LLC
President: Jon Schmidt, User ID=brute4c
If you have any suggestions, comments, problems or questions, contact:  brute4c@m715zone.com

Use of this site means you understand and agree to our TERMS OF USE

Copyright Notice:
This web site is subject to the protection of the copyright laws of the United States and other countries. Except for Personal Use Only, you may not modify, copy, distribute, transmit, display, perform, reproduce, publish, license, create derivative works from, transfer, or sell any information obtained from any part of the M715 Zone website without the prior written permission of M715 Zone, LLC.

Written permission can only be obtained by contacting
brute4c@m715zone.com

Copyright 1998-2019