MIssing Cylinder

[Captain Spoons]

Have a 1700 XFlow Supersprint with a mysterious problem!!
Missing on Cylinder 3- but getting good spark from NEW plug, much head scratching going on!!!, any ideas in a "idiots guide" sense, gratefully recieved.
Cheers!!

[Captain Spoons]

Its missing from start up, plugs look ok to be honest

[Captain Spoons]

Fraid so, 4 new spark plugs from caterham and leads all ok- have been swapping between them all weekend- always #3 that is the problem.

[Captain Spoons]

car is on twin 40 DCOE webers, regarding peassure test- my tiny mechanical brain is working against me on this- how do i do that?
the coil is a single one- standard classic SE car with supersprint engine

[Captain Spoons]

car had new head gasket about 500 miles ago and had carbs balanced 50 miles ago approx- if that rules anything out?

[Captain Spoons]

thanks for the wise words, will limp to a garage as dont have a compression test thingy!!