New engine swap

[Chevyguy85]

I have just swapped the 305 out of my 85 Silverado with a 350, but when I try to crank I seem to not have any fire. I'm no expert at wiring and not really sure where to start, all ignition fuses are good but not really sure where to go from there.

[hotsam]

Should be a lot of info here, but I'll bite.... assuming it's HEI distributor you need 12 volts to the large (pink) wire running to the marked Batt. Terminal on the coil/cap of distributor. Needs to stay there in run/crank position. Also are you sure your on TDC on COMPRESSION stroke on #1 ? Both intake/exhaust valves will be closed ( movement or slack in rocker arms by hand) and will remain closed with slight crank movement.. if on TDC EXHAUST stroke , (no slack or clicking of rockers by hand) any movement of crank either way will move one of the rockers as the valves are in overlap so you would be on wrong stroke. The piston is at the top on both strokes... so make sure !! Sure you have fuel to carb ?? Same dist. And components as before that were working ?? Roter button and all intact ? Wired correctly ? (18436572)... Is initial static timing too advanced, retarded ? (Rotating dist. Base) This should get you on a good start... Good luck !!

[johnwaynejeep]

Chevy Guy,

There's not a lot of info to go on in here, but there are few simple tests and questions that will help steer you in the right direction.

Let's assume the 350 motor that you dropped in was running before you dropped it into your truck.

1) Does it crank
Yes: your starting system is good, move on
No: There should be 3 wires going to your starter. a small wire from your ignition that supplies 12 volts. A large red wire directly from the battery and a large black wire that grounds to the chassis or engine block. Make sure all these are there and that they are tight and corrosion free. It's surprising how a loose or corroded connection can lead to a no crank situation.


2) Spray starting fluid directly into your carb. Does it run for a few seconds
No: your issue is with timing or spark, move on
Yes: Your issue is with the fuel system. Some carbs require a fuel return line to maintain proper pressure. Check both the old and new carbs and make sure the same number of fuel inlet/outlet lines were in use on both carbs. If they're the same then rebuild your carb. If you have 2 lines on one of the carbs and 1 on the other then you need to figure out how to adapt the carb for use in your truck.

3) Spark, check all the wires coming off the distributor (electrical wires, not spark plug wires) Are any of them grounding to the block?
Yes: Wrap up the grounded wire and try again. You may have to track down where these wires go and what they do.
No: Remove one of the plug wires and the plug. insert the plug into the wire and use an insulated tool to hold the curved electrode of the plug against the block while someone cranks the engine. You should see the spark jump the gap.
CAUTION: make sure there are no gas fumes or pools of gas around. this will ignite the gas and burn your truck to the ground. Also, use an insulated tool to hold the plug and wire, cause that thing will shock the heck out of you.
Yes I see spark: your ignition system is ok. move on.

4) Timing, set your engine to #1 TDC. Is the distributor rotor pointing toward the number one plug wire?
No: reset your plug wires for the correct firing order. you can look up a SBC firing order on google.

Hopefully this will point you in the right direction. When it comes to spark and timing you may want to reference back to this site and talk to people with more experience on these engines.

Good luck