Ignition Installation Questions TB V

[76SeaRay]

First issue is a confusing anomaly with the distributor. This is a new Mercruiser OEM distributor. From pictures I have seen on other engines, the area where the ICM mounts on the distributor is pointed towards the Port side and the wire terminals and optical "points" sensor are pointed to the Starboard side. I am used to GM engines with cylinder one oriented to the front. However when I mount the distributor cap that has nicely marked cylinder numbers, they show number 1 being to the back of the engine just opposite normal GM orientation. Pictures below. Am I missing something here? By the way, my TB V ICM will mount on the Port Exhaust Manifold and will not be attached to the distributor.

 

[Bt Doctur]

Rotate dist so the module wires are straight back.

 

[76SeaRay]

That's what I was thinking but didn't know if I was missing something.

Next question, I know the connector on the top is for the knock sensor connections and the lower left is for the distributor and coil. What is the missing connector on the lower right used for and is it required?

 

[Scott06]

If i recall the four pins on the right have a connector to shift interrupt, i tial timing set , and alarm system. maybe only three wires. Do you have alfa or bravo drive

 

[76SeaRay]

Alpha One Gen One

 

[Scott06]

This is a snip out of the 5.7 tbV alpha drive with knock sensor wiring digram shows icm on distributor but you can see wire colors .
shows wires for initial/base timing ground , alarm(tan/blue wire), shift interrupt

 

[achris]

The engine doesn't really care how the distributor is orientated, as long as the rotor is pointing to the plug wire that is at the top of the compression stroke at the right time. You don't even have to follow the cylinder numbering on the cap, as long as the sequence is correct. Here's how Merc have set it up from the factory (we like to follow the factory set up as that makes things 'standardized', and we all talk about the same thing), but there's no rule or reason you MUST follow the factory positions....

Chris.........

 

[76SeaRay]

Weird that Merc didn't follow the normal orientation for GM 350 engines that has been around since before the 60's. The firing order matches what is written on the cap which makes it easy when changing plug wires. That portion is pretty slick from Merc. They even numbered the cap for standard and reverse rotation firing order.

 

[achris]

Weird that Merc didn't follow the normal orientation for GM 350 engines that has been around since before the 60's.

Possibly something to do with the layout of the leads. A 'standard' SBC has the leads running over the top of the exhaust manifolds, a marine engine has the leads running under them...