Calling the carb guru's, question

ronmc1954

ronmc1954

Member
On my 74 Scout II I have a 345 with an edelbrock 1406 4 barrl. With electric choke. Now that is has gotten colder I have an issue with losing rpm's when the engine is about 1/2 way to operating temp.
To start I set the choke and it starts just fine with fast idle set, being in a hurry I start to drive it and the choke kicks off but it will idle down so far it starts to die and eventually will die. It starts right back up again but not with nomal idle speeds. Once warmed up to operating temp everything is fine.
I have had this happen on both my scouts, different carbs, just that loss of rpm's at low operating temps, after the choke has released the fast idle.
What do I need to adjust or check to keep the old girl running at lower operating temps? A stick on the accel pedal? (I have done that before) lol

ron
 
Thanks ice, the idle screws are set right, both of them, this problem happens when the engine is warm enough to dis-engage the fast idle but not warm enough to run normal. Setting the choke to stay on longer actually causes it to run to Rich.
Thanks
ron
 
Page 14 and 15 of the manual at this link http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1404_manual.pdf

The only suggestion I can come up with (other than fly me out there to help) is to start at the beginning and do a complete carb tuning from start to end to eliminate anything missed

I am cheating by posting links (actually to lazy to type). But I bet the choke valve adjustment is off causing the fast idle to come "off cam" to early
 
Ron you should be able to bump the fast idle or alter the fast idle cam relative to the choke butterfly by bending the connecting link. Basically you will want a deeper cam engagement on the fast idle screw when cold. The idle will stay on the cam longer so it won't die. I had to do this on the dual afb's on my 409. The big cam needed more fast idle time.
 
Thanks Robert, the thing that confuses me is when the electric choke warms up to release the choke and the fast idle cam there is no relationship to the engine temp. I can turn the key on for a little while without starting the engine and the choke will release the fast idle cam.
But you think I should be able to get it closer than what it is now?
When the engine is cold I have full choke with a high fast idle and when the electric choke warms up so the is no choke the fast idle cam is no longer in play, so to speak, but the engine is not up to temp yet.
Not to question your advice just trying to understand the relationship better. Actually I wish I could slow down the heat in the electric chock, like a resistor to lower the voltage.
Thanks
ron
 
It is possible that the heater is killing the choke to fast. Easiest thing to do is give yourself more cam time. I assume the hot air tube is connected and the air door is working? It needs the hot air in your cold climant.
 
Robert kenney said:
it is possible that the heater is killing the choke to fast. Easiest thing to do is give yourself more cam time. I assume the hot air tube is connected and the air door is working? It needs the hot air in your cold climant.
Click to expand...

You know Robert I can't answer your question air door and hot air tube. I will look into that, I installed the carb over a year ago I just don't remember.
Ron
 
Adding some resistance won't hurt ultimatly if you decide it is the only option. You would need to measure the elements hot resistance and chose a resistor/ ballast that would take the wattage power dissipation and drop the proper amount to time things right.
 
Robert, I have slept on it and wondering, are you talking about the hot air tube and air door in the oem air breather/filter housing? If you are, no it is not I am running an edelbrock air filter.

Ron
 
Alright, thanks for hashing this out with me. The more I think about it my theory is not going to work like I thought.
Dropping the voltage means the choke will stay on longer or run richer. But I can do the same thing by adjusting the choke to run richer, duh!
Sometimes I just need someone with brains to help this old fart remember what I already know, or in this case forgot!:icon_redface:

thanks guys for your help.
Ron
 
Earlier on in this thread you said it ran to Rich when you increased the choke close position. Guess that was a misunderstanding.
 
Robert kenney said:
earlier on in this thread you said it ran to Rich when you increased the choke close position. Guess that was a misunderstanding.
Click to expand...
No your right I did say that, maybe my adjustment was either to much or the weather was warmer. I am going to try it tonight, temp is in the mid 20's today.
But you see my point? If I lower the voltage it will do the same as if I turn the choke adjustment to run richer. Both will move the choke plate and the fast idle cam.
I am just way over thinking it.

Ron
 
It is crystal clear... :yesnod:
that carb has a choke pull off piston in the round choke housing so moving the choke more towards Rich should allow a reasonably normal cold idle mixture but delay the total choke end cycle..... If that is still to Rich try altering the fast idle cam link....
 
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