Phantom fluttering

[1969c10joe]

the spring has no affect on cruising when you gas it the vacuum drops rod stages rich giving you more gas i dont think its the springs do you still have the manual?

[1969c10joe]

i believe you need more fuel at cruising speed so maybe rod change maybe rod and jet but check usual stuff like timing vacuum advance idle mix etc

[demian5]

For sure its a carb issue and not a misfire??

[custom10nut]

To try to clarify.
This fluttering at hi way speeds is not a new issue. I first thought is was caused by plug wires: new wires, still there.
Maybe electronic control module, no. It won't run at all if faulty.
Maybe fuel pressure: I installed a new fuel pump and regulator. Still there
Maybe a lean condition: I changed the metering rods and springs. This helped with the hesitation at low rpm, but not the "at.speed" issue.
Do I look toward the transmission?

[1-PU70]

Is the gas filter new? Check the float.

[1969c10joe]

im sorry i feel i may have confused you you are right unless you have a big cam and low vacuum dont worry about springs

[demian5]

What carb?

[1-PU70]

If you had this problem before new carb i would rule it out. Go through the fuel system. Sock in carb, all rubber lines and steal lines. maby blowing out lines. Check for kinks or rust in lines. Did truck come with 307 or a 6 and you changed to a 350 or bigger your fuel lines could be to small.

[custom10nut]

Originally Posted by 1-PU70

Is the gas filter new? Check the float.

I put in a new inline filter when I put the regulator in.

The carb is an Edelbrock 1406

[1-PU70]

I meant sock in tank.

[1969c10joe]

good idea check float level check for any debris too then try abigger jet I have a 1405 i run a .100 i live at sea level whats your vacuum? no im no expert just have similar carb

[custom10nut]

Nope. It's a numbers matching truck I've cleaned out the whole system, and I had a clear filter before I put he present on on, and there was no contaminants. Much as I hate to say it, it may be an issue with the tranny as suggested before. Rats!

[geezer#99]

You guys hashing over the carb are certainly entertaining!
Did you ever hear the first rule!
It's always been 'Timing first, carb second'!!

So a few quick questions.

What's your timing curve like?
What's initial timing?
How much mechanical in the distributor?
All in by what rpm?

[1969c10joe]

i did say check timing but it flutters when cruising when he hits throttle it goes away and when he richened mixture it ran better or did those dam teenagers put something in my coffee again

[1969c10joe]

i also said check vacuum advance but didnt somebody say something about having an edelbrock 600cfm and living at the same altitude as this guy i bet they both have dual plane manifold on top of chevy 350

[1969c10joe]

besides this is the easiest thing to fix so check timing vacuum advance vacuum numbers tranny full of clean fluid dont worry yet!

[1969c10joe]

Originally Posted by demian5

For sure its a carb issue and not a misfire??

no honestly im not sure how about another definition of fluttering dont mean to be a smart ass

[custom10nut]

I call it flutter because I don't know how else to describe it. The tach doesn't move while its doing it. The timing is set where I've always had it, and all the vacuum lines are fairly new. With all the input on here I'm beginning to think it may be trans related.

[1969c10joe]

and when you gas it your vacuum drops below 10 in vacuum power valve stages into rich mode and the symptom disappears?

[1969c10joe]

hope its not trans good luck. if you decide to change jets you will need air horn gasket and cotter pin i needed HUGE magnifying glass to read numbers on rods. only take you 15 mins plus youll have more power

[1969c10joe]

if it doesnt work change it back

[1969c10joe]

if youve never done this before its really easy i dont mean to assume anything about your skill level as a mechanic

[geezer#99]

Originally Posted by custom10nut

. The timing is set where I've always had it, .

And one time more and only one time more, what is your timing set at?

[1969c10joe]

if you hear the fluttering itsnot carb if its a subtle feeling its most likely carb. I must have missed the post about the trans problems

[1969c10joe]

Originally Posted by 1969c10joe

and when you gas it your vacuum drops below 10 in vacuum power valve stages into rich mode and the symptom disappears?

oops i meant to say metering rod instead of power valve sorry