mystery of no fire at plugs.

[thunderroze]

Looking for repair ideas. 57 312 4 barrel D code

Carb was leaking gas and had it rebuilt...
During rebuild I removed the manifold to clean up the top end, paint the manifold and polish the valve covers... reinstalled covers and manifold
Got carb back, installed and it ran very rough for no more than 5 minutes.

Now I have fuel but no spark. Cranks fine. Fuel in carb but no spark.

Checked and/or replaced points, rotor, cap, plugs, resistor, coil, battery. Plug wires less than 1000 miles.

Gotta be something simple I'm missing...

 

[Yadkin]

I've never had a 312 but the same principles still apply...

The first thing that I would check is your grounding circuit. Old Ford distributors get their ground from the engine through the tightening clap and bolt. Rust or ant-seize compound can increase electrical resistance.

Use a VOM and check resistance between your battery negative and block, block to distributor. Both should be zero. In some cases I've installed a #10 wire from the battery to the block, manifold, heads to get this down to zero.

 

[Dave747]

Points condenser problems are extremely difficult to diagnose you mentioned points but not condenser. It's worth a try for $20.
Good luck.

 

[paul2748]

If you changed the condenser before you started it up after the carb rebuild, then I would put back the old one. There are lots of bad (chinese) condensers out there. Double check the points as they may have closed up.

 

[Dave747]

:agreehttps://www.tbirdforum.com/forums/images/smilies/iagree.gif