No spark

[Rich77]

Hello,
My truck is a ‘77 c10 with 400/th350.

The engine is rebuilt. Basically everything under the hood is brand new.
First time trying to fire up the engine-
Fill carb bowls, turn key, there was a “pop!” and just turn over without firing.
I thought that maybe the timing was off. Went through the whole process with the distributor again and made sure that it was correct.
I tried firing it up again, and it will only turn over but not fire.
I pulled number one spark plug and checked it on a valve cover, and it does not spark.
I’m using the Summit Racing Ready-to-Run Billet Distributors SUM-850205 with mds 8207 SS coil.
Do I need to jumper some ignition terminals?

Thanks!

 

[legopnuematic]

Have you checked for +12v at the coil+ wire and at the pigtail to the distributor? Both with key on and while cranking?

 

[Rich77]

I have not. I need to go buy a new meter today.

 

[Markmx6]

Definitely check power to the distributor first, but keep in mind the valve cover is usually a poor place to get ground, the exhaust manifold or cylinder head is a better location.

The pop is what is making me think... Was it like an ignition pop? or was it possibly a mechanical pop? If it was ignition then it seems you had power long enough for one fire. It just seems unusual for it to only fire once. I would pull the distributor cap and crank the engine over and make sure the rotor is turning. (Obviously if you have no power to the distributor then this isn't important yet)

 

[Rich77]

The rotor is turning.

Ok. I’m missing something here…
The distributor connects to the blaster ss coil via the distributor’s 3-wire connector (which becomes 2 wires at the coil) and the main center plug.

There’s nothing else connected to either.
How do they get their power?
Do I need to run a wire from the junction bar on the firewall over to the coil?

My battery positive is connected to the starter.
My wiring harness connects to the starter and the junction block on the fire wall (and the fuel sending unit, water temp sensor, etc)

 

[Bextreme04]

The rotor is turning.

Ok. I’m missing something here…
The distributor connects to the blaster ss coil via the distributor’s 3-wire connector (which becomes 2 wires at the coil) and the main center plug.

There’s nothing else connected to either.
How do they get their power?
Do I need to run a wire from the junction bar on the firewall over to the coil?

My battery positive is connected to the starter.
My wiring harness connects to the starter and the junction block on the fire wall (and the fuel sending unit, water temp sensor, etc)

Can't really tell anything from your pics. What happened to the factory wire harness IGN+ wire? A '77 model year would have been factory HEI, so you should have a solid 12v source wire right there to tie into the coil. According to the summit instructions you wire the distributor like this:

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My guess would be that the factory HEI 12v+ should run to the coil +, that will then power the coil and the ignition module in the distributor(through the red wire in the pigtail). The ignition module in the distributor will then fire the coil using the orange wire in the pigtail.

 

[Bextreme04]

My other thought(if all the wiring is correct), is that a pop but no start is exactly what you would get if you have the distributor installed 180 out. If you find that you have all the wiring correct and 12v at the coil+ with the ignition on, then you should turn the engine over until you have the timing mark at TDC, then look at where the rotor is pointing. If it is pointing at #1, remove the distributor and crank the engine over one turn, then put the distributor back in pointing at #1. If it is pointing at #6, just pull the distributor out and turn the rotor to #1 before sticking the distributor back in.

 

[Rich77]

When I got the truck it was in bad shape. It basically had the short block and trans.
I had to buy a new engine harness.

The distributor and coil are wired together correctly through the supplied pigtail and the center power wire.

With the key in “on” position there is 0v at the + on the coil.

I still don’t understand where the coil or dist. get their power.
They’re only wired to eachother.
I must need to run 12v from somewhere to the coil??

 

[legopnuematic]

You will need to locate the +12 IGN wire in your harness (should be a slightly thicker wire than most others) and it should have steady +12v with key on and while cranking. Connect that to the + side of the coil.

From what I can tell that Summit distributor is a pertronix type unit, basically a points style distributor converted over to a magnetic pickup. Reading the instructions it seems they have bad information saying to remove all old wiring from the coil and just connect the new harness to it.

 

[Rich77]

Should there be a dedicated +12v ign wire?
There is not.

Can I run a spade/wire from the ign on the board in the cab?
Or
Run a wire from the starter?

 

[Rich77]

I ran a wire from the ign on the board in the cab to the coil +.
I had 12v at the coil + when I used my meter on the coil + and the - distributor harness ground connected to the frame.
I pulled no1 spark plug. I turned it over and had spark on the head.

I reinstalled no1 spark plug.
I tried firing up the engine.
I was getting backfires out of the carb.
The distributor was 180 so I reinstalled.
I tried firing the engine again. It won’t fire but seems like it’s trying.

 

[squaredeal91]

Sounds like you're close. Can someone turn it over while you turn distributor to get it to fire?

 

[Rich77]

Sounds like you're close. Can someone turn it over while you turn distributor to get it to fire?

How do you do that?

 

[squaredeal91]

While someone is cranking you can turn distributor a little back and forth till it starts. Watch out for fireballs tho. Or find TDC compression stroke on #1 and see where rotor is pointing. Firing order is 18436572 check plug wires too.

 

[Rich77]

I will try that!