[CantedValve]

Okay. I want to tune my carb. I need to do it in this order:

1) Idle
2) Primaries
3) Secondaries

Does this sound right? If so, should I try to completely isolate the primaries from the secondaries? It would make sense. It seems to me that Pat (camachinist) once said that a properly tuned carburetor should be able to lock-out the secondaries and run just fine.

Toss yer ideas in. I am game. I know this is the right carburetor. I am confident it will run. I just need a logical approach to tuning it. I know the beast is in there, I just gotta find it.

 

[veronica]

Hello.The way that I always did it was to get the idle circuit right first,then the transition circuit so that it didn't bog or stumble on accelleration,then get the jets,booster venturis and emulsion tubes for the primaries right,then set where the secondaries kick in,then just jet them like the primaries on a square bore or a few thousandths bigger on a spread bore.Hope that helps.

 

[66emberglow]

You just can't leave em alone can you?

 

[Jay]

I thought carbs ran best right out of the box? You mean there's no way for a factory to tune and optimize carbs for every single engine setup a customer could have? Huh? A big name company like Edelbrock would not lie to people would they?

:: :: :: :: :: :: ::

Your approach sounds fine. I'll tell you something weird though on my Demon. It's like some gremlins went in and totally messed up the adjustment of mine overnight. Out of nowhere it was running super rich and the idle was way up to compensate for it. I had to use the water down the carb trick to burn the carbon out and then reset everything yesterday.

Also used Bishir's homemade Octane boost using Xylene and it appears to be good so far.

 

[CantedValve]

Here is what I did last night. I wadded up some paper yesterday really tight, and shoved it in the vacuum pod to "lock-out" the secondaries. The "smoothness" was much improved. I did notice the engine start running dirty after the pump shot wore off. It appears to be lean on the primaries. I am gonna bump it up a bit to see where that gets me.

On setting idle. I have been taught to set idle to the point of greatest vacuum. I can do that. Should I do it differently?

I need to find a better way to lock the secondaries, cause I think they were allowed to flutter a bit. This might be the "dirty" running I felt after 3000.

So you would jet the secondaries equal to the primaries? That is something new to me. I dont think a single FACTORY carb is jetted that way. OH well, I will try anything at this point.

 

[CantedValve]

My sense of sarcasm is on vacation... I never said that it should run out of the box did I? It ran well outta the box... before I changed transmissions. Now its all wrong for some reason. It could have something to do with the 9-11 pieces of LOOSE metal I have pulled out of the metering blocks... naw

 

[sharkmouth]

What I do for idle mixture;


1. temporarily lean the motor with a small vacuum connection on the carb disconnected (optional...more for concern the engine has loaded up before I attempt idle adjustments)

2. make sure the idle speed screw isnt so far out the ported vacuum connection has vacuum (not getting into transition circuit).

3. lean both idle mix screws until the idle speed drops, then richen both screws until the rpm increase stops.

4. reset the idle speed where I want it.


I also ensure the idle mixture screws are turned out close to the same amount.