Wide throttle stumble F-Ball 8

[Hans3]

My late 40s 248ci Eight stumbles and "misses" at wide throttle but performs and accelerates adequately after backing-off some.  Does it in all 3 manual gears.  New wires, plugs, condenser, and coil with timing set to 4 BTDC at low idle.  Vac adv holds vacuum and moves the plate.  I'm thinking perhaps sticking dist. weights or insufficient fuel pressure to match the WOT air stream.  Curious as to others' thoughts.

[Daves1940Buick56S]

Carter or Stromberg? If Stromberg could be clogged power valve.

[Ben Bruce aka First Born]

For what ever reason, not enough gas for the air!

 

  Ben

[Wayne R]

Go back to ignition   first , as i notice you did not mention  new points, you may  think your points are fine and good ,or  you may have

fitted new ones  a while back, but they can  go  bad in about 500 miles or so, if you dont fit good quality brand and  condenser.

hope you find the problem.----take a look at these  photos.

[Hans3]

Carter carb, and true the points were not changed; thanks.

[NTX5467]

How long has this been going on?  If it bogs in every gear at the same general rpm, hot or cold, that might well be an ignition coil which will only produce so much output voltage to fire the plugs.  How long has it been since the air cleaner was serviced?

 

Might also get a wrench and tap the areas on the muffler listening for a loose or mis-placed internal baffle?

 

Just curious,

NTX5467

[Hans3]

Thanks ... new coil and same behavior as the old one.  It has one of those gauze (clean with kerosene) air filters that I can't figure out how to open.  But I tried it with the air snorkel disconnected and same symptom.

[60FlatTop]

On 9/24/2023 at 8:01 PM, Hans3 said:

New wires, plugs, condenser,

If it was running well before the replacement go back and find your old condenser. The quality of new ones is very low. I have gad problems at times over the past 25 years. So few are in used today the manufacturers don't know. They just keep sending them out.

 

It is kind of like the foil seal under the peanut butter jar lid. If the president of the peanut butter company had to peel those seals off a few times they might do something. But he don't know, neither does the condenser guy.

[NTX5467]

The peanut butter guy is trying to save .001 cent on every container they seal.  Makes him more money, plus the stockholders . . . none of which probably use that stuff.  Just gently slit it down the middle and peel to the sides.

 

Condensers seemto be failing a lot lately, by observation.  New Old Stock is better than New Replacement Stock.

 

NTX5467

[Hans3]

Car has always had this issue in limited ownership.  Experienced an actual bad condenser and that was different:  Random missing at all speeds and throttle loads, amplified when cold because of weak spark.  I'm now leaning more towards the points issue or weak fuel pressure.

[old-tank]

Fuel pressure is easy to test.

Check that there are no shorts inside the distributor is the breaker plate rotates.

[60FlatTop]

Check the action of your distributor breaker plate. Yours should have a thin cork pad that wicks the oil drops from the snap top lubricator. The pad could be all dried out or just the consistency of peanut butter and not responding to the WOT vacuum drop quickly.

I would take the pad out and work fresh oil into it with my fingers.

 

My though was that the symptom came up after the tune up.

 

Keep that old condenser unless it really failed. Ignition parts are really poor quality. If I need any new parts I only use Echlin brand from NAPA or old stock. And a new Echlin condenser would be a last resort.

 

A few years ago I remember a story about Mrs. Warner of the Borg-Warner family really disrupting a stock holders meeting over the junk they were putting her family name on. I wish I had saved it.

 

On the peanut butter, I take it out on the back porch under a full moon and say "Klaatu Barada Nikto". Gives me a feeling of power.

[Daves1940Buick56S]

Also do a fuel capacity check. Should do a pint plus in 30 sec of cranking. I got burned once (actually all my exhaust valves did) by only checking pressure and not capacity as well.