Mercruiser gm 2.5 cranks no start

[trikeman72]

ok have a 81 kayot with a gm Inline 4cyl I had running but needed carb rebuilt.
So rebuilt carb put new plugs wires cap rotor and pertronix module with flame thrower coil.
Changed head gasket coz it was bad also.
I reset valves then it would run but worse as we ran it. Was horrible inside carb so that helped. Then rechecked valves was ok. cranked but backfired out carb.
Checked firing order actually had 2 wires crossed. Figured yay but since I did that it cranks but don't start. Have spark at all plugs. Even poured gas in carb.
Has original mechanical fuel pump so I'm wondering if that's the problem??
not sure where to startlookin.

 

[Scott Danforth]

backfiring out the carb is either timing or other issues

what is your compression on all cylinders?
what is your timing set to?
will the spark jump a 1/4" gap?
did you fully rebuild the carb?

 

[trikeman72]

Never checked compression as it ran even tho badly with pop out carb
fully rebuilt carb
timing I'm not 100% on cos ya can't get to crank pulley as front mount obstructs view. I put finger in number 1 plug and bumped it around til it popped out my finger then took off cap to verify rotor was pointing just after number 1 wire.
I thought it may be 180 out but I wouldn't think it do anything that far off??
Im leaning to timing just not sure how Togo about setting it I guess

 

[Scott Danforth]

did you check timing?
by fully rebuilt carp, you chased every passage with a fine wire, correct?

 

[trikeman72]

Either fine wire or pipe cleaner.
I need to check timing but how can I when the crank pulley is covered by front engine mount??