Timing 180 out???

[greg1ontheedge]

I recently pulled the dist to change intake manifold. Put back after and timed everything to the mark. But engine won't start and backfires. Is it possible that I'm getting spark at the top of the exhaust stroke rather than the top of the intake stroke? Thought I'd ask before I go home from work and change everything 180 degrees.  Thanks..........

[My68SS]

It's certainly possible, lining up the balancer mark only gets you as far as No 1 firing or No 6 firing. You need to pull a rocker cover to watch the cam action on either 1 or 6 to know which is on the firing stroke. If 6's valve gear is rocking as the balancer mark comes into line, then 1 must be firing and vise versa.