Rookie question: The 1970 stock 350 engine has been running perfectly on test drives around the neighborhood....until today....now, when cranking the hot or cold engine...it starts great/hits on all cylinders.....but runs two seconds then dies as though key was turned off.............WHY ????.........................

check list below:

alternator working correctly
lots of spark at plugs

new gas in tank (no water/moisture in gas) added Lucas fuel treatment last week

new sock on tank sending unit
tank clean inside
new soft lines at tank
no smashed steel fuel lines along frame
good gravity feed when fuel line is removed from fuel pump inlet
new soft lines before/after fuel pump
new inline clear fuel filter before carb inlet
6 pounds fuel pressure when cranking with coil wire removed
good flow into gallon jug while cranking
Edelbrock carb recently installed by P.O
all linkage working properly
electric choke working properly
brass floats have no leaks
floats set correctly
accelerator pump works correctly
needles and seats sealing well/releasing correctly
bowls are clean
gaskets are good
carb/intake bolts tight/gaskets good
accelerator cable good & set correctly


The tank has 3 inches of gas left in it....the sock is one inch off the bottom of the tank (the sending unit assembly/suction line is in great shape).

After checking everything (I think).....I added 4 gallons of new gas...after a minute of 5 second at a time cranking....

The engine runs as great as before!

Is it "normal" for the carb to starve for fuel with 3 inches of new gas left in the tank?

If so, I need to adjust the sending unit float to allow for "running out".... I will set the float to show empty with 5 inches of gas (6 gallons) still in the tank.

ANYONE GOT AN IDEA OF WHAT COULD HAVE CAUSED THE DYING ENGINE AFTER 2 SECONDS OF RUNNING (other than "out of gas" with 3"/3 gallons still in the tank)???

 

Bad ballast resistor on the ignition

 

I'm betting it is electrical not fuel. Fuel would sputter out. Electrical just cuts out. Make sure you are getting power when in the run position of the key. You may be getting power to coil when cranking but when you let the key go the power may be cutting out. If it is happening in this sequence.

 

Thanks for reminding me about that...

I'll check it tomorrow by doing a wire jiggle test and by using with a voltmeter while cranking/after cranking when engine starts!

Right now it is starting/running great....but my '34 SBC/HEI street truck left me on the road a few time---- with a loose wire that failed only when the truck was driven for an hour or more-------( at the distributor connection)

 

That was my thought as I read your problem analysis. BTW, your list of steps taken was concise and complete. Well done.

If the '68 is like '69, there isn't a hard physical resistor. It is a resistance wire. When cranking, the resistance is bypassed so there is full battery power to the ignition circuit. When running, the direct connection is broken and the lower voltage/current supplied prevents the points from self destroying. If the resistance is open, no power to the distributor, hence starts and dies.


Pete

 

Curious to learn what the root problem turns out to be

 

You guys taught me to provide as much info as possible when asking you to solve a "long-distance" problem

I may have (probably) re-wired Bubba's HEI distributor incorrectly...I disconnected his OEM resistor wire that he connected to the HEI---then I ran a new hot-with-key-on fused wire to the HEI.

I remember reading something about needing to disconnect another wire in the harness when using an HEI distributor, but I can't remember which thread the info was in......

Anybody got an idea of what I'm referring to? (time to break-out pappawanna's wiring diagram again and double-check my A.D.D/P.T.S.D/W.X.Y.Z,..........wiring attempts!!!!!!

 

On the original set up, the solenoid bypasses 12V to the coil for cranking, then it drops off to the ballast for running. If the Voltage is lost on the ballast wire, it acts just as you describe.


If you are rewiring for an HEI, you only need 12V for run, so find a switchable 12V source from the key switch and get rid of all of the other stuff.

 

I'm sure that I ran a new dedicated 12V wire to the distributor.

I'll check to see if I have any "extra" wires going to the distributor from "other" sources tomorrow....Thanks.

 

I checked the distributor wiring with a voltmeter today with the key in the on position/the key in the crank position/the key in the run position.

Everything seemed good....13 volts at all times to the HEI distributor.

So I did the wire "jiggle" test on all the connections/harnesses.

When I got to the cockpit fuse block and touched the dedicated Hot-with-key-on fused wire that I ran to the distributor.....THE ENGINE STOPPED!

It seems that there is a gremlin in the brand new fuse block at the spare Hot-with-key-on terminal! I'll remove the fuse-side of the fuse block tomorrow and see what is causing the intermittent loss of voltage to the distributor.

(Gremlins....they got into everything in the Viet Nam War.....errr....Police Action!)