1994 Mercrusier 5.7 timing

[Mullady76]

HI, I just replaced one of the 5.7 mercruiser engines on my boat and I’m getting conflicting information on the base timing for this engine. The original engine was a 1994 5.7 bluewater ( S/N F490119). I found one manual that said the base timing was 8 Degrees BTC and another that said 10 degrees BTC. This engine has the ThunderBolt IV ignition without a knock sensor. What is the correct timing?
Thanks, Sean

 

[alldodge]

Howdy
That serial number list a TB4 and carb so it would use manual 17 and timing would be 8* BTDC

 

[Mullady76]

That’s is the problem I’m having. The flex plate is stamped at 10 degrees, but everything I read says 8 degrees

 

[achris]

Flex plate? What flex plate?

 

[Mullady76]

The timing mark on the back of the motor. Flex plate or damper plate, what ever you want to call it, is marked at 10 degrees.

 

[alldodge]

Manual 17 list 8* for all MCM and MIE (yours being MIE)

That said, running at 10 BTDC and a TB4 should not be an issue. To make sure if it is done, check the plugs after some WOT runs. Don't let it idle much before pulling plugs are checking

 

[alldodge]

just replaced one of the 5.7 mercruiser engines

Using this statement let me add.
Starting in 1998 the carb 5.7 was a TB5 and used 10* and the MPI used 8*

 

[Scott Danforth]

96 and later had the vortec heads and could live with more initial advance as the combustion chamber would prevent detonation more than the pre-vortec SBC heads

 

[Mullady76]

This is a non vortec center bolt valve cover engine with tappet cam and a Quadrahet carb.