Idle Mixture

[GregH]

Quick Question to the brain trust.

I was looking on here about how much to adjust the idle mixture screw to lean it out. One person mentioned in a post, backing it off a 1/4 turn, then next day when the engine is cold again, start and see how long one needs to leave the choke on until you need to have it on for 45-60sec).

Are there other methods as well for me to consider?

Note: this aspect will be the last thing after I get the timing/dwell tuned in as best I can.

[roadnsky]

This is a quote I've saved from Dr Neptune regarding idle mixture adjusting...

"When adjusting back and fourth at such low speeds some of the fuel will puddle and condense on the intake runners and until the engine is run and restarted cold you don't really get a good idle set. A trick I have used for quite some time on these A-4's is to after adjusting I leave it alone and let it sit. The next time I start I give the adjuster a "tiny tweak" to lean (open) and then start and let it warm. I can sometimes do this 2~3 times before the idle actually starts to faulter~then I go back to the last tweaked position. As I say I don't move it much IE less than a 1/8 of a turn at a time"

[Dave Neptune]

Thanx Jerry. This works

[Dave Neptune]

Not to sure what happened, I was still typing and saw that I posted.

Anyway that practice has worked well on every updraft carb I have "played" with. And remember any updraft fed engine will be a bit slow to start when adjusted properly.. An updraft is only quick to start when the idle is set to rich.

Dave Neptune

[roadnsky]

One other tip could come from Ed. He uses an air-fuel ratio gauge.
Talks about it here...

[GregH]

Not to sure what happened, I was still typing and saw that I posted.

... An updraft is only quick to start when the idle is set to rich.

Dave Neptune

Which is exactly where I am at. Once I had pre-check done and she fired right up.. 2 seconds; and choke off right away. Same as last summer.

This weekend's plan is to work on the tuning with the dist twist and then once that's all done, start the process of backing off the idle mixture over time as above.

{sidebar} - as part of the precheck and chasing down why no spark, the coil I have measures at 2.4 Ohms.