Home | Classifieds | History | Technical | Links | Store | About Us | Email
Topics Topics Edit Profile Profile Help/Instructions Help Member List Register  
Search Last 1|3|7 Days Search Search Tree View Tree View  

Chrysler 318 Backfiring

Old Marine Engine » Multi Cylinder Gas Inboards » Chrysler 318 Backfiring « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

leebla
New member
Username: leebla

Post Number: 1
Registered: 07-2008
Posted on Wednesday, July 30, 2008 - 01:55 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I have a 1969 Chrysler Marine 318 with a Carter AFB carburetor in a '69 Correct Craft Barracuda.
The boat has developed a backfiring problem above 2600-2700 rpms. Idle is smooth and even, acceleration is good up to 2400-2500 rpms. Above that there is a constant "pop" and although acceleration is not great, the boat continues to accelerate. The carb has been adjusted at idle and the plugs seem to be burning acceptably (With the exception of # 6 which seems to be gettiong fuel, I can smell gas, but is perfectly clean. The points/condenser has been changed over to a Pertronix electronic ignition recently, the backfiring was worse prior. Plugs are new.
I have tried to power time under load to eliminate the backfiring to no avail. Any suggestions?
Any idea how the By-pass idle air adhustment screw is supposed to be adjusted?
Top of pagePrevious messageNext messageBottom of page Link to this message

mrpos
Member
Username: mrpos

Post Number: 12
Registered: 06-2006
Posted on Wednesday, July 30, 2008 - 03:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

You could be starving for fuel. The AFB's have a "piston" that gets pulled down under vacuum when the secondaries open up. This opens the needle valve more to let in additional fuel. They sometimes get stuck. You can check for freedom of movement by taking off the little covers at the top of the carb.
There are two of them. When you unscrew the retaining screw you will see an aluminum piston with a rod that bends over and points back down. Be careful removing the covers, the piston is spring loaded and will pop up.
Also you may try changing your spark plug wires.
Top of pagePrevious messageNext messageBottom of page Link to this message

richarddurgee
Senior Member
Username: richarddurgee

Post Number: 1751
Registered: 11-2001
Posted on Wednesday, July 30, 2008 - 05:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

*
Broken valve spring will pop like that ?

If you can hear it in the carb its an intake valve spring !

*
Top of pagePrevious messageNext messageBottom of page Link to this message

Rlfgc@aol.com
Visitor
Posted on Friday, July 29, 2011 - 10:34 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I have a 318 Chrysler and changed the points. Now my exhaust consistently spews water and I can not get my rpms over 1200. Did I install points
Properly
Top of pagePrevious messageNext messageBottom of page Link to this message

tonyj1961
New member
Username: tonyj1961

Post Number: 3
Registered: 12-2010
Posted on Friday, July 29, 2011 - 10:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I would check your dwell angle. Your points may have gone out of adjustment after installation. It happens occasionally. Also, you might consider installing a Pertronix electronic ignition kit. I installed one on my M440B and eliminated my ignition problems.
Top of pagePrevious messageNext messageBottom of page Link to this message

hcc440
New member
Username: hcc440

Post Number: 1
Registered: 08-2011
Posted on Monday, August 15, 2011 - 10:39 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I have a 1970 Owens with a M440 running rough only under pressure around 2200 RPM when i got it about 4 months ago i change plugs/wires/coil/dist cap/rotor /fuel pump and i was still running rough back fire and all so i had the timing adjusted ones the timing got adjusted. now it bogs down after having it at 2200 rpm for about a minute i can keep it at 2000 and ill run perfect but anything over that it gives me problems any suggestions
Top of pagePrevious messageNext messageBottom of page Link to this message

fabbe
Member
Username: fabbe

Post Number: 10
Registered: 04-2009
Posted on Monday, August 15, 2011 - 10:35 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

I have discovered the best first step diagnostic tool for situations like these. Put gas in a small squirt bottle, one that has a 1/16" to 1/8" hole and with the engine under load at max. RPM spritz gas directly into the carb. and if the engine picks up RPM you know you have a gas problem and not an ignition or valve problem. Maybe it's as simple as a clogged gas filter. But it is crucial to find the right type of bottle. DO NOT POUR GAS OUT OF A COKE BOTTLE for this test! Hope you find it is just a clogged filter.
Top of pagePrevious messageNext messageBottom of page Link to this message

charles mitchell
Visitor
Posted on Saturday, July 14, 2012 - 10:50 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

my 318 chysler turns over but wont start.
Top of pagePrevious messageNext messageBottom of page Link to this message

eddie
Senior Member
Username: eddie

Post Number: 299
Registered: 04-2003
Posted on Saturday, July 14, 2012 - 12:43 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only)

Did you have any symptoms before this ? Have you done any work to the engine recently ?

Add Your Message Here
Post:
Bold text Italics Underline Create a hyperlink Insert a clipart image

Username: Posting Information:
This is a public posting area. Enter your username and password if you have an account. Otherwise, enter your full name as your username and leave the password blank. Your e-mail address is optional.
Password:
E-mail:
Options: Automatically activate URLs in message
Action:

Administration Administration Log Out Log Out   Previous Page Previous Page Next Page Next Page

Home | Classifieds | History | Technical | Links | Store | About Us | Email
&copy 2005 OldMarineEngine.com, P.O. Box 188, Forest Dale, VT 05745-0188 • Phone: 802-247-4864 • All rights reserved.
   Marine Engine Seloc Repair Manual Lookup Tool

marine gas engine repair and restoration