Running lean, suggestions

[Tigger72]

Here's the problem im trying to work on my '72. Running lean i believe. Tell me if im off and push me in a direction based on my notes below. To start, i believe my timing to be set well based on vacuum, yet the timing light says 15deg at 5700ft elevation with that dizzy setting. Ive set the idle mixture best i can and idles good. And I've done vacuum tests at the riser and also vacuum measure is fine at idle :

• Hard to start cold even in warm weather
• Runs "good" when up to temp BUT poorly till warm
• Exaust smells
• Lost power under load even when warm (this is a recent change for the discussion) but no jerking or stalling under load

What i see:
I rebuilt the carb myself and used a sonic parts cleaner to clean it with a rebuild kit. Mistakes could of been made as its my first time through it. Same jets it has always had and ran well for 50+ years at the same elivation. Adjusted the float so when parked and turned off after running, fuel level in the window is just above half. But at idle, the fuel level is well under half in the window. When parked over night, fuel level drains to low in the window. It has a new fuel filter. But the original fuel pump. No fuel leaks that I can see.

Suggestion i was given was a weak fuel pump. Or a weak hose connection causing a poor vacuum to pull fuel.

Is there another suggestion out there based on experience where I should isolate or start my search in another direction.

Thank you!

 

[Paul_A]

Will it run better with the choke partially closed?

 

[wimberosa]

I'm having hard start issues on a '79 but I've convinced myself that my igniter is weak. Consider making sure the electrical passes the FSM spec procedures.

 

[cruisermatt]

Why do you think it is running lean?
Why do you have your timing set at 15-degrees?
What is your actual idle RPM?
What is your actual vacuum measurement at idle? (“Fine” is not a measurement)

 

[samatulich]

What do the spark plugs suggest? They'll let you know a lot about your fuel mixture.
Have you tested for intake leaks? Base of the carb may not be air tight.
Backfiring at all? Lean would Backfire through the carb, rich through the exhaust.

 

[Tigger72]

Will it run better with the choke partially closed?

When warming up even on hot days, but not when idling warm. I havnt tried it under load though. Ill try that when I get it back out.

 

[Tigger72]

I'm having hard start issues on a '79 but I've convinced myself that my igniter is weak. Consider making sure the electrical passes the FSM spec procedures.

That was last summers adventure! Ha new dizzy, e points, and all else met spec. Im hoping thats all cured now!

 

[Tigger72]

Why do you think it is running lean?
Why do you have your timing set at 15-degrees?
What is your actual idle RPM?
What is your actual vacuum measurement at idle? (“Fine” is not a measurement)

I dont know for sure if its lean, but a guess based on symptoms. If im off, im game for more suggestions! Lags and weak at take off and on hills, was told the exaust smells like its running lean, and the tough cold running but runs better warm because of fuel needs.

I most recently set timing by max vacuum and backed off slightly till smooth. To see where it landed, I puth the light on it and advanced till BB was at the needle and 15deg was where it was happy. It is weird for sure and the flywheel could be off but in the history of the vehicle, its never been torn down that far to be reinstalled wrong far as we remember. Could be part of the problem wanting to run more advanced?

Idle RPM is set at 665-670. Thats as low as I can get it right now before the adjuster screw backs off the scallop after my last idle mixture adjustment. Also weird.

Vacuum measures at 16.5in at almost 6000ft elevation which i read is well in the window. True?

 

[Tigger72]

... I puth the light on it and advanced till BB was at the needle and 15deg was where it was happy... by this i mean, I advanced the light setting to see where the vacuum set landed, to be clear.