72 HEI Conversion now Misfire

[Shtudwn]

Hello,

I have a 1972 K10 Cheyenne Super with the original 350 V8 that I just converted to HEI.

I have replaced the resister wire in the harness to a 12gauge for the HEI power. Starts OK but has a horrible miss.

I am in the process of rerouting the new 8mm wires, as I stuck with the original stock positions on the distributor caps posts. I have the back two wire crossing against the firewall not my favorite layout..... so I am rerouting.

Anyway, can anyone suggest what to look for on the misfire? I am frustrated. NEW Summit HEI distributor complete and NEW 8mm Summit wires. NEW plugs gaped to .045. Runs smooth other than that misfire.

I have pulled all the plugs and checked to see if any were cracked. Nope.

Any ideas helpful as I need to get this truck in for repaint soon.....before the weather gets too bad.

Thanks.

[AussieinNC]

Your comment re wires at back suggests the dist is not installed correctly...

Did the engine have a misfire before the HEI conversion?

Pull No 1 plug and put your finger over the hole and have an assistant bump the ign switch to slowly bring motor onto compression stroke for Cyl 1.
Align the timing marks on balancer and timing tab.
Replace Cyl 1 spark plug
Look at the rotor tip position is relative to the cap.
It should be pointing directly at the #1 cylinder but in reality so long as you can identify which cap contact is #1.
The cap position lining up with where the rotor is pointing is Cyl 1 fire position,
Starting with that position, go clockwise inserting plug leads in firing order 1,8,4,3,6,5,7,2...

Firing order for 350 is 1,8,4,3,6,5,7,2
Cylinders on drivers side front to back are 1,3,5,7,
Cylinders on passenger side front to back are 2,4,6,8
Rotation is clockwise looking down at top of distributor

Make sure leads are not touching any exhaust manifolds

Start the engine and set timing...

If it still misfires after that, suspect a bad HEI dist....there are posts on here about failure on newly installed or recently installed HEI units...

Let us know what the results are...

[Shtudwn]

Thank you.

I have a council meeting tonight but will get that done tomorrow night and report back.

Dan

[68bbc/20]

changing the resister wire with a 12 gauge wire won't help anything, it needs to be removed and a new power source run that is full battery voltage not reduced liked the resister wire supplied to the old distributer.

[Shtudwn]

I removed the resister wire, as well as the yellow wires to the starter. Replaced all of that with a new connector and plugged in where the resister wire entered the dash. Also bypassed all of this and went directly to the battery. Misfire still there.

[68 P.O.S.]

Aussie is right on. Have you inspected under the cap?

[Shtudwn]

I will check out thoroughly tomorrow.

Truck ran fine with points but the upgrade seemed like a better solution as the truck is new to me and I needed points, cap, wires, plugs anyway.

Thank you.

Dan