My question is about the idle air adjustments on each side of the carb. If I turn the screws on each side inward I am closing off the air mixture and getting a richer mixture, right? Backing them out would increase the air and lean out the air fuel mixtue, right? The carb I have is a 670 holley street avenger.
670 holley avenger idle air adjustments?????
- Thread starter duster360
- Start date
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805moparkid
Slant and AFX Guy
umm... i thought all holleys use a fuel mix screw, out is fat, in is lean...
easy to tell... go in on a screw and if it dies right out then its fuel...
easy to tell... go in on a screw and if it dies right out then its fuel...
805moparkid
Slant and AFX Guy
then they are fuel adjustments
lightly set them both (not running) and back them out about 2 turns...
805moparkid
Slant and AFX Guy
not if it likes it...
I will try the 2 turns out tomorrow and see what happens. I am trying to get better at tuning. I degreed the cam and now I have put a timing light on it and got the timing set at 34* total and 14 initial. It seems to be a little more peppy than it was. Now if I can just get this carb tuning stuff worked out.
805moparkid
Slant and AFX Guy
805moparkid
Slant and AFX Guy
then 1.5 should be ok...
805moparkid
Slant and AFX Guy
np... get a vacuum gauge to really dial it in...
LXguy
Well-Known Member
I highly recommend a wideband 02. They're not that expensive and they really simplify the process. The AEM is the way to go.
I am about at the same altitude as you are and my 5.9 liked between 1 and 1.25 turns out from closed.
Did your street avenger come with an instruction manual? It has some tuning guidance. Holley also has a DVD that can be helpful - it was included with the last street avenger I bought but you can find most of it on Youtube.
Good luck
Steve
I am about at the same altitude as you are and my 5.9 liked between 1 and 1.25 turns out from closed.
Did your street avenger come with an instruction manual? It has some tuning guidance. Holley also has a DVD that can be helpful - it was included with the last street avenger I bought but you can find most of it on Youtube.
Good luck
Steve
I bought it used. I did get the manual but not a DVD.
dgc333
Well-Known Member
duster360 said:
You should only make adjustments in 1/8 of a turn increments. You should also be using a vacuum gauge or tach when doing this. You want the highest vacuum or Tom reading.
67Dart273
Well-Known Member
Forget this nonsense about "how many turns" except in extreme cases
How far in/out the screws end up depends on a LOT of things, including what sort of cam you are running.
Start with them anywhere from 1 1/2 -2. Get the engine fully warmed, and use either a tach, vac gauge, or "good ears."
Back them out until the engine speeds up, alternate sides
When the engine stops running faster, slowly, and alternate, turn them in a little at a time until the speed / vacuum JUST drops noticabley, then right back left "just a touch."
I always just "rough them in, recheck idle speed and timing, make sure it's warm, then reset them again.
IF they "want" to be way far out or way far in, this can indicate a carb problem or big mismatch to the cam and build.
If one doesn't do the same as the other, you have something plugged on one side.
If you have a fairly large thumper cam, often you have to crank in a LOT of idle speed screw, which draws the primary butterflies out of the "idle transition." Not good
Years ago, many people advocated drilling holes in the front butterflies, but this has proven unnecessary in most cases. Often, you can "crack" the seconary bores open a tiny bit (there's a screw!!) and this will allow the front idle speed screw to be dropped back.
Run as much initial timing as the thing will handle. My 360, which is pretty mild, runs 15* initial
How far in/out the screws end up depends on a LOT of things, including what sort of cam you are running.
Start with them anywhere from 1 1/2 -2. Get the engine fully warmed, and use either a tach, vac gauge, or "good ears."
Back them out until the engine speeds up, alternate sides
When the engine stops running faster, slowly, and alternate, turn them in a little at a time until the speed / vacuum JUST drops noticabley, then right back left "just a touch."
I always just "rough them in, recheck idle speed and timing, make sure it's warm, then reset them again.
IF they "want" to be way far out or way far in, this can indicate a carb problem or big mismatch to the cam and build.
If one doesn't do the same as the other, you have something plugged on one side.
If you have a fairly large thumper cam, often you have to crank in a LOT of idle speed screw, which draws the primary butterflies out of the "idle transition." Not good
Years ago, many people advocated drilling holes in the front butterflies, but this has proven unnecessary in most cases. Often, you can "crack" the seconary bores open a tiny bit (there's a screw!!) and this will allow the front idle speed screw to be dropped back.
Run as much initial timing as the thing will handle. My 360, which is pretty mild, runs 15* initial
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