70 hp Chrysler backfiring

[Don357]

I have a 70hp Chrysler model 707HF apparently built somewhere in the '70-'73 range. I had it running beautifully, but left the gas tank vent open because of the heat, and guess what, it rained! Water in the gas and carbs now. Drained the tank, cleaned the bowls, strainer, and line. Then lost fire. Cleaned the plugs, cap contacts, and points to no avail. Had to replace the power pack. Now it still won't start, but at least it will backfire now. I'm thinking there may be some gunk still in the carbs or the points are opening too far. What is the correct setting for the points gap? It's been so long since I had to set them, I forgot.

Any other help or suggestions will be appreciated. Thanks, Don.

 

[huskerdaninva]

Re: 70 hp Chrysler backfiring

Points should be gapped to .014". Double check that your compression is good, timing is set correctly, and that the carbs are opening fully at WOT. What exactly do you mean by "backfire" specifically? Good luck and "Welcome Aboard!"...

 

[Don357]

Re: 70 hp Chrysler backfiring

What it's doing is spinning over, not firing, then suddenly, a violent bang through the exhaust. Almost sounds like water in the gas again. I plan to disassemble the carbs and try that too. Thanks for the specs on the points.

 

[huskerdaninva]

Re: 70 hp Chrysler backfiring

You may want to replace the fuel pump diaphragm too. I've heard that a backfire can rupture the diaphragm and cause fuel flow problems. Something to think about...