All fine but a very weak spark, engine will not start.

[32chevy]

Hi,
The engine in the rod will not start. So far checked all of the below

Battery very good
Fuel pump very good
All lights and dash lights work
Starter cranks full bore
Petrol tank 3/4 full
Fuel squirts in the carburettor at crank

The thing will not start
Checked the spark with a spark plug removed and held against the engine
block cranked the engine and the spark is very weak.
I am at a loss what it could be.
Any pointers will be most welcome.

[hudson nut]

It sounds like the gap has closed up on your points.

Dany

[FRANK BASILE]

What engine, what ignition system ? This may help suggestions. Crook points will be a start if points type. Crook coil . Weak spark also if the bypass is not connected ,this gives full volts across coil when cranking . Points coils are 8volt running through a ballast on normal run ,when cranking the ballast is bypassed so voltage drop does not affect the coil supply adversely. I assume that the engine was normally starting beforehand anyway so this can be discounted. Or if electronic HEI system without points the module could be suspect.

[32chevy]

Thanks for the replies.
The engine is a SBC, with carby. Was running until a couple of weeks ago. Tried to start it a few days ago, and no go as described. I will go over the wiring in the coming week to make sure there is no short anywhere.
I will come back after that.

[FRANK BASILE]

Unlikely to be a short. Nothing at all would be the result. Does it have points? . Check that they are ok, and the small earth strap grounding the breaker plate to inside the distributor to the housing is ok.

[Thomobro]

Check points condenser
Faulty condenser will give weak spark

[Thomobro]

Check points condenser
Faulty condenser will give weak spark

[Greg N Smith]

Have ya tried a good squirt of Start Ya Bastard ?

[HOT ROD FRED]

Is your coil ballast resisted? Check that the resister hasn’t burnt out

[steve the ford guy]

Have ya tried a good squirt of Start Ya Bastard ?

Yes if there's no fuel in the cylinders or manifold from sitting a long time you'll need to try this first

[FRANK BASILE]

I should have asked, when it last run?.

[jeffa]

I should have asked, when it last run?.

Hi Frank.
As per OP's previous: "Was running until a couple of weeks ago."

He didn't say what sort of ignition though.

[FRANK BASILE]

I should have asked, when it last run?.

Hi Frank.
As per OP's previous: "Was running until a couple of weeks ago."

He didn't say what sort of ignition though.

Yes jeffa. Makes a difference to the fault finding . A crook module can also produce a weak spark. Had one do that in a VH Commodore HEI . Similar if the module is not earthed properly. That earth is via one of the Bosch module cover screws on the distributor clamping it..