Tuning New Out of the Box Edelbrock AVS2 650

[68FishNate]

I didn't think the job was over and complete just throwing the new carburetor on my 340..If it could be just as simple haha.

I purchased and used a vacuum gauge to set a point where my car is driveable and stops and idles correctly, however the tuning side of it needs to get done and after making a fair amount of phone calls, no one works on carburetors anymore or tell me they're 4 weeks out from being able to see me. I know that the new carb needs jets upgraded and my electric choke needs to be adjusted and i'm willing to take it on and learn more about it and my motor/air/fuel. You tube has been a friend and was wondering if i need to remove the top plate and check or adjust the floats as the video i watched advised seeing as the carb is brand new.

I'm sure there is no motor build alike, no combination of jets that could possibly work the same as another, but here's to hoping you've been there and do i just keep changing out the jets on a trial and error basis? I'm noticing before i make these changes in jets that my car is running on the warm side and my thought is that with speed and needing more fuel that at rpm's its running to lean and needs bigger jets. I've adjusted back and forth on timing to bring it down, however timing is set.

Here's some info on my 340.

Roller cam - Comp Cams Extreme Energy Retrofit Cam
CCA-20-811-9
Hydraulic Roller, retro-fit
.274/.282 duration
.538/.544 lift
110 lobe separation

10.5 : 1

Is there an advisement on jets or if you're in DFW metroplex that may advise someone who works on carburetors before i get to into the big, but small pieces.

Thank you

 

[65TerrorCuda]

My new 650 had one of the step up piston wells vacuum passage not punched out. Might want to check yours too.

 

[Bodyperson]

Yes first thing is float height. You should have checked it out of the box. They get jacked around in shipping.

 

[66fyssh]

Definitely pull the top off and check measurements of the floats.

 

[Bewy]

The most important thing has not been mentioned: TIMING AT IDLE. That cam in a 340 is probably going to want 25-30* of timing at idle. The carb is the LAST thing you adjust, not the first. A common way to get this much timing is to use vac adv connected to manifold vacuum [ MVA]. Dist will need an adj vac unit to do this. To see the effect of what MVA will do, move your dist to about 30* BTDC. Rpm & vac will increase, idle will be smoother.
All the improvements below came from MVA.

 

[Frank Mopar]

I can fix your choke adj. Tie it open, pump the gas, start the car and drive away.

 

[RustyRatRod]

Most carburetor problems are ignition or timing problems.

 

[junkyardhero]

Most carburetor problems are ignition or timing problems.

most ignition problems are vacuum leaks.

 

[remytherat]

Most carburetor problems are ignition or timing problems.

Especially with the most forgiving carburetor ever made

 

[Ottmundr]

Most carburetor problems are ignition or timing problems.

I always thought that most of the problems are caused by the nut behind the wheel.
I know mine are!

 

[gdonovan]

Carb tuning? I could write a small book on the subject. I'd start with installing a heated O2 sensor in the exhaust and an inexpensive O2 gauge. "experts" will tell you that you need a wide-band and this is simply not true unless you are pushing the ragged edge with forced induction and even then my Reliant which ran 35 psi of boost did not have wideband. Been running that O2 sensor and gauge since the early 90's, it's a K&N unit that is long out of production on my dual carb GTX. You simply watch the gauge and note the lean/rich spots and adjust the carb as needed, no guess work. The hardest part is when you can't "adjust" something out by throwing parts and may have to tweak air bleeds. Carters are very forgiving units and much better than Holleys from transition to transition. Holleys just throw fuel everywhere to cover lean spots, the gauge tells all.

 

[Kendog 170]

I always thought that most of the problems are caused by the nut behind the wheel.
I know mine are!

Bad connection between the gas pedal and the seat.
I'd check float level but check timing and ignition as Rusty suggested.