Base Timing Mode

[Kubaat3lover]

I have 4.3L Carb 2005 (ex TKS- now Mercarb) and Ive rebuilt Carb and want to adjust it, before that i want to check if the timing is correct.
I think its Thunderbolt IV or V my s/n 0w326935, according to manual #25 i need to enter the Base Timing Mode right?

Using a jumper wire, connect the ignition system
timing lead “13” (PUR/WHT wire) to a good engine
ground (–). This locks the ignition module
into the “Base Timing Mode”.

But wheres located that cable/wire? Can anyone help me locate it i can provide photo of my engine.
Its similar like this from the net

 

[alldodge]

Look by the distributor, or follow the harness from the module toward the distributor

 

[Scott06]

It will be on the front left hand side of the engine laying on the intake manifold I think in the photo it’s just to the left of the two wire connector that powers the fuel pump

it will have a black rubber plug in it . Ground it turn the engine on set your timing, turn it off then remove ground when u restart it will be in normal advancing mode

good also to check your total advance should be about 22 degrees at 3 k rpm

 

[nola mike]

I have 4.3L Carb 2005 (ex TKS- now Mercarb) and Ive rebuilt Carb and want to adjust it, before that i want to check if the timing is correct.
I think its Thunderbolt IV or V my s/n 0w326935, according to manual #25 i need to enter the Base Timing Mode right?

Tb iv doesn't use base timing mode. You probably have tb v given the year, but

 

[Scott06]

Tb iv doesn't use base timing mode. You probably have tb v given the year, but

the ignition module in the photo is a TB V

 

[Kubaat3lover]

My Mercarb has been rebulilt, Need the final adjustment on the boat.
Do I have to put the igniton ino the Base Timing Mode?
Because final mixture/idle speed adjustment has to be done on the Warm engine, can I warm it up, then put into Base Timing Mode and then start adjusting?

Thanks

 

[achris]

Tb iv doesn't use base timing mode. You probably have tb v given the year, but

Serial number says TB-V...

 

[alldodge]

My Mercarb has been rebulilt, Need the final adjustment on the boat.
Do I have to put the igniton ino the Base Timing Mode?
Because final mixture/idle speed adjustment has to be done on the Warm engine, can I warm it up, then put into Base Timing Mode and then start adjusting?

Thanks

Don't adjust the carb in base timing mode

 

[Kubaat3lover]

Ok, so im curious why in manual they say to put it for Base Timing mode for mixture and or idle cam adjustments... (??)

 

[Kubaat3lover]

Can anyone explaint it? Thanks!

 

[alldodge]

Ok, so im curious why in manual they say to put it for Base Timing mode for mixture and or idle cam adjustments... (??)

Have no idea other then to take timing out of the equation. There should be no timing advance at idle with a TB if rpms are correct

 

[Kubaat3lover]

Ok, I will not mess with my timing, just adjust rpms and idle.
Any recommendation? Will be doing this 1st time!
take care

 

[alldodge]

I have to apologize, I forgot you have a TKS carb. While I'm still not sure why it needs to be in base timing mode (most likely all EPA stuff), I would adjust in in that mode.

The TKS does need to be fully warmed up before adjusting idle. Basically until the TKS module extends and extends and shuts off the extra gas. Says run it at 1300 rpm until warm, then idle down and adjust.

Have you removed the cover over the idle screw, and have the special tool to get at the screw

 

[Kubaat3lover]

But its Mercarb, previous owner Or someone removed TKS and put Mercarb..
I’ve cleaned carb, new gaskets new brass float.

 

[achris]

Engine still needs to be at full operating temperature before adjusting mixture and idle speed. And I would recommend you do it with new spark plugs in. BTW, idle speed needs to be done on the water, in (forward) gear, 'untethered'.

 

[Kubaat3lover]

Ok, warm engine, new sparkplugs, engine in forward gear in the water,
do I have to disconnect the throttle cable? And how about this timing?

 

[achris]

As per manual #25, to adjust idle speed and mixture, the timing MUST be in base mode. (Reason: Within the module is a circuit for 'Idle speed control'. If you try to adjust the idle speed without that circuit disabled, by going into base mode, then you have no idea if the idle speed is being controlled by the carb or the spark timing.)

You can leave the throttle cable connected, but make sure it's not having any influence on the linkages. I would leave the throttle end on, but drop the adjustable barrel off its stud. You'll need to adjust the barrel anyway.

Chris......