The V8 Owners Forum -

Currently I am building an AC Cobra and have fitted a Chevy small block v8. Just function tested the motor and it is only running on back 4 cylinders only. I have double checked and confirmed that the HT leads are all ok and distributor is good. Anyone suggest what could be cause of this?

Hi

Have you double checked that you have all plug leads in the right place?

Are you running efi or carb?

carb and manifold details ?

And as Rossco says, plug wires all in the correct order etc ? And is there any spark on where you think are the dead cylinders ?

How are you determining which cylinders are dead ?

All plug leads are on correctly, determined that cylinders not firing by touching (very carefully) the outlet manifold. Got Edelbrock “performer” manifold and carb.

On the Performer manifold, each side of the carb feeds 4 cylinders. Middle tow on one side paired to outside two on other cylinder bank.

Do the dead cylinders match one side? In which case I would think a big air leak or carb bolted to the carb in the incorrect orientation.

Ian

Try new spark plugs in dead cylinders. I have had a few new ones failing due to cold engine and rich mixture.

Ian Anderson wrote: ↑

Thu Jan 02, 2020 8:09 pm

On the Performer manifold, each side of the carb feeds 4 cylinders. Middle tow on one side paired to outside two on other cylinder bank.

Do the dead cylinders match one side? In which case I would think a big air leak or carb bolted to the carb in the incorrect orientation.

Ian

Or lack of fuel supply to one half of the carb maybe ?

And you have not confirmed then that there is actually a spark at all 8 cylinders ?

What do the plugs look like ?