will not fire on number 7

[beach57]

SBC
Changed plug ,lead,checked dizzy,compression 125-130psi,checked timing,reset valve lash,changed valve stem seals,carb flooded fixed,any more ideas before i smash it to bit

[ifan.miller]

inlet valve stuck closed?

[uber cool]

is No7 plug wet or dry?

[Darren West]

but would he not have ****e compression with no air going in

[ifan.miller]

nope you'd still have good compression

[rodster]

So when you say its not firing the exhaust branch is clap cold? Have you checked the compression on all the cyls for comparison because them figures seem a bit low, would still run ok but maybe its blown head gasket between cyls, whats the dizzy cap like maybe try another one, air /vac leaks, cam lobes for wear.

[prostreet70gto]

Inlet manifold gasket leaking into the oil valley side, creating a vacuum/air leak. try reseating the inlet manifold. an oily plug is usually mis diagnosed as valve stem seals for this reason. it sucks the oil vapour from inside the lifter area where it is not quite sealed and this then creates a full compression, perfect ignition/fuel system misfire....so quite baffling when everything seems ok.

[mygasser]

fit a new dizzy cap and rotor arm, may look ok but wouldn't be the first time they were faulty.

[Billy 4spd]

Put a plug on no 7 lead and make sure its got a spark, run it with cover off to make sure valves are opening and closing. sorry if done this already.
Billy

[Adam Sayers]

New engine or new cam? It could have a 4/7 swap in the vavle timing on the cam. That means a 4/7 swap at the dizzy. Probably the least plausible reason it's not firing but width mentioning.