Rough idle on cold start ?

[hooverfish]

My 84 has orig stock 6 cylinder automatic, electric choke, fresh rebuilt 2 barrel carb. Engine is orig with 90k, still has smog pump. Also recent tune-up.

After it sits all night it runs terrible for 1 or two minutes, then smooths out and runs fine, runs fine on warm start.
Would like to get some ideas on what to fix.
If it's the choke, I dont know how to adjust electric choke so help with that would be great.
Or any other ideas on what to try ?

[geezer#99]

Could be your choke blade is not open enough on first start and it runs rich and rough.
The choke pull off should pull the blade open about 1/4 inch on start up.
Easy to check.
Just start it up with the air cleaner lid off and gently push on the choke blade opposite of the blades opening
and see how it reacts.
Usually only needs a tiny bit more opening.
What carb you got?
Can you take some pics of it.

[hooverfish]

Here's some pictures.
Started engine with lid off, choke only opens 1/16 to 1/8 inch.
I pulled it open a little farther and idle speed increased seemed to run better.
Carb is a Rochester 2SE

[geezer#99]

First thing I’d try is adjusting the black cap. It might have a lean/rich indicator on the cap.
Loosen the three screws holding it on and rotate the cap a bit towards the lean side. It might not take much.
If no marking on the cap then just hold the throttle open slightly and rotate the cap and watch the choke blade. It’ll be easy to see which way to turn it to make it leaner.
You won’t need to make much of an adjustment.

[Shugalou]

Have you tried the bolts that hold the carb down? Mine was running really ruff and it turned out they needed to be tightened down again...hopefully that helps as it is an easy fix

[hooverfish]

Originally Posted by geezer#99

First thing I’d try is adjusting the black cap. It might have a lean/rich indicator on the cap.
Loosen the three screws holding it on and rotate the cap a bit towards the lean side. It might not take much.
If no marking on the cap then just hold the throttle open slightly and rotate the cap and watch the choke blade. It’ll be easy to see which way to turn it to make it leaner.
You won’t need to make much of an adjustment.

I loosened the screws and turned the black cap about 3/16" to the right.
Let it sit overnight, started and it RAN MUCH BETTER, smooth fast idle.
I'm going to drive it like this for a week or two before anymore adjustments.
Think this has pretty much fixed my problem. Thank you very much !!

Originally Posted by Shugalou

Have you tried the bolts that hold the carb down? Mine was running really ruff and it turned out they needed to be tightened down again...hopefully that helps as it is an easy fix

I installed this carb last summer, then re-tightened the bolts in the fall. Thank you for your input, it's what makes this a great forum.

[geezer#99]

Did the choke adjustment continue to help?

[hooverfish]

Absolutely. I've moved it just a little more and it's perfect. So much better.
High speed idle before kick-down is nice and smooth.
Thanks again for your help.

[geezer#99]

You’ve made my day!
Keep on truckin’.