New overhaul won't start

[ckraker]

I have a 1989 4.3 mercruiser. Just did a complete overhaul. I Cannot get this thing to fire up. I know i have fuel to the carb. I have the timing set at 8 btdc (that is only at cranking rpm). It will backfire through the carb and sometimes even likes to start little fires in my intake. I don't dare keep trying or I'll probably blow a gasket.... Literally. I have checked the firing order and cylinder numbers 1000 times. Everything seems fine.... I'm beginning to think the timing chain was off by a tooth. But that seems highly unlikely to me, pretty sure i quadruple checked that as well.
I'm leaning towards an ignition failure somewhere, only because my timing lights seem to be firing sporadically as well. What could i be missing? Please help me brainstorm....i don't like seeing my carb act as a geyser.
Thanks

 

[QBhoy]

Thinking simple...how is that fuel supply ? Other than timing being out, most other reason for popping is bad fuel with water in it. If there is any doubt...run it off a Jerry can of known fresh fuel.

 

[ckraker]

I'll give that a try. The fuel was definitely yellow. I hope it's that simple but i have my doubts.
Thanks

 

[alldodge]

Backfiring and little fires, my guess is your 180 out of time

 

[ckraker]

Backfiring and little fires, my guess is your 180 out of time

That is what i was thinking... But would my timing light still flash at 8 btdc 180 degrees off?

 

[ckraker]

I'm almost sure your right... Dang i hope i didn't break anything

 

[Lou C]

Or your hydraulic valve adjustment is too tight and holding a few intake valves open; this can cause a backfire in the intake manifold.

 

[ckraker]

Alldodge.... You were right 180 off. :facepalm: This isn't my first rodeo, can't believe i did that. I know what everyone is thinking..... "This schlub just rebuilt an entire engine and can't set a distributor correctly..... This engine doesn't have a chance."
Thank you guys for the help. Sometime i just need a friend!
Hope i didn't destroy any gaskets.

 

[alldodge]

I'm sure your good, we all make mistakes (me so many I stop counting :facepalm: )