86K5toy

I have a '86 K5 that I have changed out the 305 for a 350. The 350 motor is made up of a '79 block with '69 fueler heads, Edelbrock preformer intake and cam and a 600 cfm carb. I have fuel to the carb and I have 12.5 volts going into the distributor but no spark at the plugs. I took the coil and ignition control module in and had them tested and they passed. The engine control module has been removed so there is a jumper on the 4 pin connector on the distributor. I have verified that the rotor turns when I crank the engine. I even replaced the car and rotor but still no luck. The blazer started and ran great before the 305 motor died so is it my dumb luck that the distributor when the motor died? What else can I try to get spark?

RPegram

Have you checked the pick-up inside the distributor? It's the one that if you need to replace the shaft has to come out and then put in new pick-up.

frickenbored

This prob wont help any but a while ago I changed most of my gauges to electric gagues, I mounted them in the stock places so it looked like they were supposed to be there, turns out that one of my negative wires from a gauge was touching the circuit board that fed power to the stock gauges and because of that I had no spark...i have no idea why this happened and it took forever to find that.

As for your problem, you say you had an ECM so i'm guessing your 305 was TBI, if so I thought you needed diffrent distributors for a TBI system and a carburated system. I did in my case.

86K5toy

RPegram,
thanks for the input. What is the best way to test the pick up coil? Is it a continuity test?

Frickenbored,
The 305 was not TBI. 1986 was the last year before they changed. Since the ECM has been removed the and the jumper installed the distributor should not know that it is in a 350 and not a 305. right? At the parts store they did list a different distributor for the 305 and 350 but I would think that is only if the ECM is hooked up. I would hate to install the new distributor and still have the same problem. Electrical parts and non-returnable.

frickenbored

My bad, I forgot that 87 was the year for TBI...You shouldn't need a new distributor then, a couple months ago my buddy swaped out his 350 for a 305 in his 85 chevy truck (he wanted better gas mileage) he took the HEI distributor out of the 350 and threw it in the 305 and it worked perfect, so your distributor should be fine. See what happens when you test the pickup coil.

RPegram

Honestly I've never tested one. If everything else checks good, I just throw one in there. Here are the directions on how to check though.
To test the pick-up coil, first disconnect the white and green module leads. Set the ohmmeter on the high scale and connect it between a ground and either the white or green lead. Any resistance measurement less than infinity requires replacement of the pick-up coil.
Pick-up coil continuity is tested by connecting the ohmmeter (on low range) between the white and green leads. Normal resistance is between 500 and 1500 ohms. Move the vacuum advance arm while performing this test. This will detect any break in coil continuity. Such a condition can cause intermittent misfiring. Replace the pick-up coil if the reading is outside the specified limits

86K5toy

Hey thanks for your help guys. I will try testing the pick up coil.

archebald23

sounds like another victim of the VATS anti theft system. Try to crank it and look at your instrument panel. See if the security light comes on. That would be the anti theft system. Those cars are pretty bad for the connections in the ignition cylinder wearing out after a lot of use. Basically the resistor value in the key has to match up with the value required by the system to start the car. Sometimes the contacts in the ignition cylinder become worn out and an incorrect reading of the resistance is sent. Incorrect resistance = no crank.