557ha

bigrand

Recruit
Joined
Jan 16, 2025
Messages
3
I have a 1970 Chrysler 55 HP. Can not seem to get it to fire up. I t does fire for about one second. Then die off. One I try to start it again it back fires. Anyone have any ideas. I have cleaned carb. Replaced head gasket,checked point gap. It's at .020. spark is at both plugs. I'm not sure what's original or been modified. Their are tool markers all threw it so it's been worked on.
 

Nordin

Commander
Joined
Jun 12, 2010
Messages
2,573
Do you have spark at both plugs?
Does the spark jump 3/8 in or more with a spark tester?
Back fire sounds like the HT wires are connected to wrong plug or the flywheel key is shared.
 

bigrand

Recruit
Joined
Jan 16, 2025
Messages
3
Great spark. I reversed wired and back fire extremely loud. I will look at flywheel again and see if it slipped off when putting on. How many turned for the carb adjustment?
 

Nordin

Commander
Joined
Jun 12, 2010
Messages
2,573
Is it back fire or sneezing?
Generally setting for the air/fuel mixture screw is 1 1/4 turn out from seated.
It should run with this setting but it can be set in a range of 1- 2,5 turn out.
Most Chryslers will run desent with the screw set 1-1,5 turn out from seated.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,052
Backfire or sneeze can be it's sucking air someplace?
You say it runs for a second? does it run good for that second or just barely runs.
I'd check the fuel pump diaphragm. #5 should be a solid sheet of rubber. Any tears or holes will make it run like crap.

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