Timing and carb questions

[Fishstick1962]

I have a 2004 4.3 2BB Mercruiser. I followed the procedures in the book and it ran like crap. So now I have a couple questions.
#1 Do I need to set my timing light for 10 deg as listed on the breather, when setting the timing ? ( I'm in base mode )
#Step #8 in the book ( Servive manual #25 ) says to adjust the idle mix. But in the carb section is says the carb ca not be adjusted. So how do I get it right?

 

[Don S]

Re: Timing and carb questions

One note a lot of people miss on that base timing, is the engine has to be off when putting it into and taking it off base timing mode.
The carb mixture screw has a seal on it for emissions. The mixture is factory set to keep the mixture lean so it will keep the air clean. Even though it's very hard on the engine.
Only thing you can do is cut off the cap and readjust the carb....... however, your engine will fail emissions testing if you do.

 

[Fishstick1962]

Re: Timing and carb questions

Thanks Don-S. I did connect the ground before starting the engine. But when
i set the timing with my light set on 0 deg. (after disconnecting) it ran like crap. But then I set my light at 10 deg. and followed the book and it runs better. But then the carb thing had me confused. I still get a small "Bog" when accelerating fast. It's not responding as quick and smooth as it should. and idles kinda rough at 650 RPM.
BTW: New plugs gapped correctly
Cap and rotor.
Plug wires in right firing order.

Any suggestions? Should I go ahead and adjust the carb? We have no emissions tests here.

Thanks for your help Don-S

 

[Bondo]

Re: Timing and carb questions

It doesn't Matter, or it Shouldn't Matter,........
Whether you set the light to 0*,+ set the motor at 10*BTC,........
Or set the light to 10*,+ set the motor to 0*,........
As long as the Motor is set to 10*BTC..........

Should I go ahead and adjust the carb? We have no emissions tests here.

I would,...... That's the Only Way it's going to Happen...........

Your Bog could be from the Acc. pump,...... The Arm on your's might have Adjusting holes on it,.....
If it Does,..... Try Richening it......

 

[Don S]

Re: Timing and carb questions

You don't have a timing tab on your timing chain cover, just a notch. Set your timing light at 10? and align the marks on the timing cover and the balancer, then adjust the carb........... Then shut it off and take it out of base timing.

 

[Fishstick1962]

Re: Timing and carb questions

Thanks Bond-O. You answered my question on the timing. As far as the idle mix adjustment... Mine is capped off. I didn't know if I should cut off the cap and adjust it or is this a bad idea.
Thanks Bond-o

 

[Fishstick1962]

Re: Timing and carb questions

Thanks Don-S, that is exactly the info I was looking for! Now about the Carb... My book doesn't give any instructions on adjusting the Idle Mixture. It just says it can't be adjusted. Can you point me in the right direction? I also noticed that I have a 3 position accelerator pump lever. Mine is in the middle hole. I'm assuming the "bog" is a "rich bog" as talked about in the manual.

 

[Bondo]

Re: Timing and carb questions

The Air Screw is moved in or out til the Best Possible Idle.......

If your Acc. Pump lever is in the Middle,.....
Ya only got 2 Choices,....... Try 'em Both........