What causes a motor to spit through the carb?

[team39763]

Truck won't start now, so I'm gonna try to figure something else out.  I wish I could trust the mechanics around here, I'd just drop it off with some cash and pick it up when it runs decent.

[VileZambonie]

The B+ wire needs to go to the alternator either off of your junction block or off of the B+ terminal on the starter. Either way make sure it's got a fusible link.

[VileZambonie]

why won't it start? What's it do? Crank no start or no crank no start?

[team39763]

It cranks but won't start.  It definately has fuel, but it doesn't seem to have spark.  I'm gonna try to rewire the MSD box and see if that helps.

[SUX2BU99]

Do you have a ground strap from the engine to the frame? The alternator case is grounded, but to the motor. The motor needs to have a ground strap to the frame. Mine comes from a bolt on the front of the head through a braided steel strap, to the frame. Pic
Wherever ground straps connect, you need to scrap the paint away where it touches to provide maximum current flow. Maybe you motor is relying on other connection points like motor mount bolts, tranny mount bolts, etc to get the grounding current through to the frame.

[team39763]

I had put 3 grounds on there - 1 from each head to the body, then one from the block to the frame.  I made sure to remove the paint and rust on each of the contacts.  It also looks like I wired the alternator backwards, so I fixed that today.

[team39763]

I got it started.  After fixing the alternator wires, it seemed to start just fine as if the battery was fully charged.  Now I'm ready to get back to tuning it.

[Pushrod]

Alright then. Get a vacume guage, figure what your vacume is at idle in drive. Get a power valve 2 pounds below that and your backfiring should disappear. It may still backfire through the carb occasionally when the engine is cold. Especially if your choke is wide open or you don't have one at all.