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Idle speed Question

Started by Cudajason, August 08, 2017, 06:36:25 PM

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Cudajason

I do this every year, I guess I am just in search of the optimal tune on my car.

My 360 currently idles at about 650 rpm in Drive.  The AFR shows low to mid 13s.

I have no real issues with the idle, other then its a bit stinky and the idle just feels low, nit sluggish off the line, just seems like its too low a number.

I try not to get caught up on the RPM, but focus on the AFR and performance.

So what do you guys think, is that too low.

Here are the specs on my 360:

74 Cuda with a 360,
Eddy Performer RPM intake,
Eddy torker Plus cam,
The specs are as follows:
@050 Int dur. 222 , Ex dur. 234
Lift Int .447 Ex .450
Intake Centre line 107 Ex centerline 116.
About 9:1 compression (I may be exaggerating that).
Holley 750 vac secondary carb.
Dizzy has been recurved, running 22 initial, 38 total all in before 3000.
727 with stock converter
8-3/4 with 3.22s

1974 Cuda. 360 / A500 OD.  Yes its pink, no its not my wife's car!  Yes I drive it.


Chryco Psycho

Well you can try to lean the mixture screws or twea the idle circuit bleeds to clean the idle up ,
The accelerator pump should be tunable using either different cams or squirters to get more response off idle , is it going rich or lean off idle ? , the cam profile can be changed so you get more or less pump shot with 5 or 10 * throttle shaft movement .
float level can also affect response , if the level is too low it can delay pulling fuel into the air stream / lean , if it is high it can pull fuel in too easily /rich

Cudajason

Quote from: Chryco Psycho on August 08, 2017, 06:49:01 PM
Well you can try to lean the mixture screws or twea the idle circuit bleeds to clean the idle up ,
The accelerator pump should be tunable using either different cams or squirters to get more response off idle , is it going rich or lean off idle ? , the cam profile can be changed so you get more or less pump shot with 5 or 10 * throttle shaft movement .
float level can also affect response , if the level is too low it can delay pulling fuel into the air stream / lean , if it is high it can pull fuel in too easily /rich

Oh yeah tried all of those.

The car works fine off idle no stumble, no lean spots through out the RPM range.  I spent a lot of time tweaking that last year.

I just think the idle is low and a bit stinky, and wonder if I should just crank the idle speed screw to 750 and see what happens.  I guess I can always go back if it does not work.

Jason
 
1974 Cuda. 360 / A500 OD.  Yes its pink, no its not my wife's car!  Yes I drive it.



Cuda Cody

Quote from: Cudajason on August 08, 2017, 07:05:30 PM
should just crank the idle speed screw to 750 and see what happens. 

:iagree:  Give it a try.

Shane Kelley

#4
Does your carb have changeable idle air bleed jets? Also there is a small slot on the throttle base that the blades need to be partially over on the primaries. If the blades are to high it bypasses the idle circuit and will cause a rich idle. It should be set before carb is installed so you can see it. Then use secondary blades for idle adjustment if needed. You want to see a small rectangle exposed. The blade sitting almost perfect in the slot. This is a Quick fuel carb and has a longer slot than most Holley brand carbs.
I have a similier built 340 but manual trans. I like mine idling at 1000rpm. Might be hard to do with automatic.