Engine rebuilt - won't start

[dougd59]

I bought a 91 Sunbird with a blown 4.3L OMC Cobra. I pulled the engine,replaced the block, crank and cam with a 95 version from an S-10. I had the machining and assembly done by a pro engine builder who knew marine engines. Everything is back together with an electric fuel pump added to feed the original carb. Carb has been rebuilt. I've checked the fuel delivery and ignition systems over and over. Can't find any problems. I have good spark at all plugs. Timing has been checked and rechecked - top dead center OK - timing gears aligned - all I get is backfiring, and only after pumping throttle while starting.
Anyone got any ideas? It's way too hot to sit in the driveway instead of the lake!!
THANKS!!!

 

[Bondo]

Re: Engine rebuilt - won't start

all I get is backfiring, and only after pumping throttle while starting.
Anyone got any ideas?

Ayuh,.... Sounds like the distributer is 180? Out,+ the carb needs Fuel....

 

[jtmarten]

Re: Engine rebuilt - won't start

+1
Remember there are 2 TDC's for #1, so you're likely 180* out.

If the electric fuel pump isn't marine rated, you'll burn it up in 1-2 outings unless you're able to get a good gravity feed from your tank, and also be taking a heck of a chance to go BOOM.

 

[dougd59]

Re: Engine rebuilt - won't start

So, what the best way to remedy/ check to see if I am 180* out? I tried pulling out the dist. and rotating it 180*. Same issue.
If I understand what you're saying, the #1 cylinder fires once every two revs, so it's firing on the exhaust stroke now??