Mercruiser 7.4L MPI Horizon distributor timing

[Snapon24]

Im helping a friend put his engines back together after doing the heads but he never marked the distributors when he took them out. I have the engines at #1 TDC on compression stroke but there are no numbers on the distributor caps so I need to know what position the rotor should be pointing for #1 or which terminal is #1 on the cap. Thanks

 

[Bill Curtis]

With damper at 0 degrees and the #1 cyl at TDC and both valves closed (compression stroke), dist points to #1 plug wire.

Just follow the wire from #1 plug and you have it.

 

[Snapon24]

With damper at 0 degrees and the #1 cyl at TDC and both valves closed (compression stroke), dist points to #1 plug wire.

Just follow the wire from #1 plug and you have it.

Thanks. Yes I know that part but he doesnt have the old wires or dist cap so I need to know which post is #1 on the distributor cap.

 

[370Dancer]

The one just to the right of the lockdown screw on the port side (from the rear of the engine)
what we don't know is what engine you are putting back together. Model and serial number would clear that up in a heartbeat.

 

[Snapon24]

After talking to a few other people it seems it doesnt matter where #1 is. Just put the distributor in at #1 TDC compression and wherever the rotor points, make that #1 and continue wiring it clockwise in the firing order. Thanks

 

[techmitch]

After talking to a few other people it seems it doesnt matter where #1 is. Just put the distributor in at #1 TDC compression and wherever the rotor points, make that #1 and continue wiring it clockwise in the firing order. Thanks

That's great! Until you try to diag. a misfire.

 

[John E3]

When I rebuilt mine last winter, #1 was slightly clockwise from from centerline of the engine, viewed toward the timing belt end. 1 tooth either way made a large difference, counterclockwise from CL, or way further clockwise.
This corresponds with the diagram on page 4B-6 of the service manual. And, puts #2 offset about the same amount counterclockwise. That puts the CL of the engine between 1 & 2 and 3 & 6.

Edit: Position matters. Custom wires will not reach if you don't get it right. They have near zero slack. The electrical connectors face approximately the opposite of the "a" in the diagram, slightly offset to one side or the other IIRC (aligned with 3&6). They have near zero slack too.

 

[PlayDate]

Thanks. Yes I know that part but he doesnt have the old wires or dist cap so I need to know which post is #1 on the distributor cap.

My first response I was going to post was:

Pretty sure it doesn't matter which terminal it faces as long as the firing order is correct from that terminal.

But... @techmitch is right.....diagnostics or it you have a distributor that actually cares....that could pose a problem.

 

[Bill Curtis]

Thanks. Yes I know that part but he doesnt have the old wires or dist cap so I need to know which post is #1 on the distributor cap.

Actually, the one it's pointing to is now #1, but that may confuse someone down the road troubleshooting a problem, if it's not like the picture.

My OCD tells me to make it like the diagrams. If it doesn't match then the dizzy needs to be reset on the cam gear.

 

[Snapon24]

Engine didnt start with just picking a post to start and wiring it clockwise 18436572. Anybody know the correct procedure to static time a big block distributor if nothing was marked upon disassembly? Where does the rotor point when the engine is at TDC compression? Thanks

 

[John E3]

Engine didnt start with just picking a post to start and wiring it clockwise 18436572. Anybody know the correct procedure to static time a big block distributor if nothing was marked upon disassembly? Where does the rotor point when the engine is at TDC compression? Thanks

See my post above.

Are you sure it's TDC on the compression stroke and not a full turn off?

 

[Scott215]

Just put your wires from the rotor pointing towards the number one cylinder start with one and go 18436572 You should be fine

 

[Snapon24]

See my post above.

Are you sure it's TDC on the compression stroke and not a full turn off?

Yes its definitely on compression stroke. Ill try wiring it according to your last post. Thanks

 

[Scott215]

Also look at harmonic balancer ,make sure it's on tdc