misfire that won't quit

[wolfie]

Ron, Run a bottle of techron through it now. If its crud or a carbon blockage somewhere techron will clear it up. Make sure you have a good filter in line before the pump as this stuff will also clear any rust and most debris in the tank and lines. I dont usually reccomend snake oil treatments but I have seen this stuff work firsthand and I am amazed by with the results. Good Luck, Steve

[wolfie]

I'm experiencing similar misfiring... but without the blue flame backfiring.

62 GT Hawk, 289 idles ok but engine doesn't rev properly. Miss lightly fires and stutters, power loss.

Discovered the condenser was the problem before. The wire was blown out of the condenser.

Replaced the condenser and new points (gap is match cover or .17 is my guess) and things seemed to work. Rebuilt the carb due to a worn excelerator pump. I see gas is barely seeping out of the front. Can only tighten screws so much! One screw on side is not able to tighten well.

Removed Autolight plugs (less than 5000 miles on them but 5 years old) they and the .35 gaps look good. Lightly sanded and cleaned them up. One plug on passenger side #3?? or #5?? had a light tan color on the electrode ceramic.

Should I replace the distributor rotor next? The brass has a slight play in it, a wiggle.

The distributor cap may need to be replaced too?

The distributor was changed out 5 years ago by trusted Studebaker mechanic. Vaccum seems strong but not sure if the advance mechanism is responding, don't know how to check.

Any suggestions out there?

See response 23 in this thread for instructions on checking your advance mechanism. Steve

[Ron Dame]

All better!

OK you electrical gremlin posters, guess what...it was the CARB! After the third or fourth time into the carb, I remembered I set the float 1/8" low to compnsate for ethanol's density. I decided to set it back to spec. I also read somewhere later that the adjustment was more like 1/32", not 1/8" .

Between that and maybe a piece of crud I hadn't got before (never saw it, I'm just guessing) the truck FINALLY is running right again! I still need to make some final tweaks to the idle and re-check the timing after all of that, but I think it is finally cured!

Thanks for all the help, everyone, even those who just knew it was electrical ;-)

[jclary]

Not so fast with the proclimation...it may be the carb, but it turns into an electrical problem when the timing changes as the engine anticipates a larger dose of gas and gets less. When this happens, the intake valve is still open while expecting more gas as the ignition system goes ahead and fires off the spark plug! In this case, the mechanical problem (incorrect float setting) results in an electrical ignition timing malfunction. Regardless, it has been a great exercise in troubleshooting and another bit of information for the rest of us. Thank you for sharing your frustrations. I am certain it has been much more fun for us than for you.

[Ron Dame]

Not so fast with the proclimation...it may be the carb, but it turns into an electrical problem when the timing changes as the engine anticipates a larger dose of gas and gets less. When this happens, the intake valve is still open while expecting more gas as the ignition system goes ahead and fires off the spark plug! In this case, the mechanical problem (incorrect float setting) results in an electrical ignition timing malfunction. Regardless, it has been a great exercise in troubleshooting and another bit of information for the rest of us. Thank you for sharing your frustrations. I am certain it has been much more fun for us than for you.

I'll give you part credit..that's an electrical misfire....but no amount of fooling with teh ignition system would ever fix it ;-)

I'll also state that despite being rebuilt, I've found the vacuum advance is stuck, so that's a new project now that the carb is back to rights. Maybe a backfire jammed the advance? We'll see.

[jnormanh]

I'm glad you found the problem. Too bad you have to denigrate those who tried to help you with suggestions about electrical problems. They are, after all, miles away while you are on the scene, as it were.

Looks like it took you many, many hours to diagnose a simple problem which your own incompetent monkey-rigging caused, and which a marginally competent person would not have created in the first place.

Next time have your car repaired by a competent mechanic. The kid at the local Jiffy Lube would have found the problem more quickly than you did.

[Ron Dame]

If you will notice, my reply was with ;-) That means it is in jest. Sorry you are so thin skinned, and had no help to offer. What a jerk.

[jnormanh]

Actually, Ron, a review of the posts shows that I did offer a suggestion as best I could without knowing that you had monkey-rigged the carb. As did many others.

The "jerk" here, sir, is you.

You should take this as a lesson to stay away from that for which you have no talent. As they say -

"A Stradivarius is worthless if you cannot play the fiddle."

You, sir, have a tin ear when it comes to car repair.

[Ron Dame]

Actually, Ron, a review of the posts shows that I did offer a suggestion as best I could without knowing that you had monkey-rigged the carb. As did many others.

The "jerk" here, sir, is you.

You should take this as a lesson to stay away from that for which you have no talent. As they say -

"A Stradivarius is worthless if you cannot play the fiddle."

You, sir, have a tin ear when it comes to car repair.

I'll let your post speak for itself. I'm ending that HERE.

For anyone else who may have been offended by my friendly, sarcastic response, please know it was all in fun, and no offense was ever intended. I appreciated all suggestions, even when it was to repeat all that I had already tried. There were many posts, many suggestions. Again if anyone else was offended, sorry.

[Jim B PEI]

If it were a new vehicle, I'd guess a failing but still operating fuel pump. I diagnosed it on my 88 Jeep 4.0, and it had same problems as your Stude. Still putting out 27 PSI, but needed 75 to work properly. Idled fine, horrendous backfiring at anything much above idle. But, yours is a carburetor, and you've covered a lot of ground. Since your pump has good pressure, I wonder it it a hidden restriction--one of those little hidden filters at the carb inlet, maybe? If not that, I'd change the plugs just to see.

[Ron Dame]

If it were a new vehicle, I'd guess a failing but still operating fuel pump. I diagnosed it on my 88 Jeep 4.0, and it had same problems as your Stude. Still putting out 27 PSI, but needed 75 to work properly. Idled fine, horrendous backfiring at anything much above idle. But, yours is a carburetor, and you've covered a lot of ground. Since your pump has good pressure, I wonder it it a hidden restriction--one of those little hidden filters at the carb inlet, maybe? If not that, I'd change the plugs just to see.

I dunno Jim, Autolites, Champions, no change. I'm guessing following advice for a Stromberg WW and doing that improperly messed me up. Now that the float level is to spec, it is running great. I just need to figure why the vacuum advance is stuck, and all should be perfect again.

[Dan Timberlake]

I suspect the recommendation to raise the float setting is intended to compensate for density differences in fuels containing ethanol, and keep the operating fuel level in the carb bowl the same asitt was for gasoline. Fuel level is important since it effects how much fuel flows thru the various jets in response to carb venturi vacuum caused by air flow. A lower level in the bowl would result in generally less fuel flow for a given air flow, or leaner mixture. Fuel level in the bowl tends to change the delivered mixture across most of the carb circuits, unlike jet changes or mixture screw adjustments that tend to effect only certain operating conditions.

Ethanol is a little more dense ( heavier) than gasoline.
".765 Kg/l was used for the density of gasoline and .79 was used for the density of ethanol."

http://www.ethanol.org/pdf/contentmgmt/E30_Final_Report.pdf

Note density of .79 is for pure ethanol

Other sources say things like the specific gravity of gasoline can vary quite widely (from 0.69 to 0.79), but is usually near 0.73.

So the carb float tends to rise higher in the denser E10 than gasoline, which would shut the fuel off at a lower fuel level in the bowl. But some gasoline could be just as dense as E10.

Much Too high an operating fuel level could even make fuel flow out of the jets with no air flow (engine off) and promote extreme idle richness that would not respond to adjustment.

On the other hand, gasoline blended with 10% alcohol has about 3% lower heat energy ( fewer BTUs per gallon), and thus a "perfect" air fuel ratio richer than gasoline. If a carbureted engine (that never have real uniform cylinder-to-cylinder air fuel ratios) was adjusted so it idled and ran smooth, it still could have a few cylinders running near the lean misfire limit on gasoline. But if the tank was then filled with E10 (10% Ethanol) gasoline, the lower BTU would result in a few percent leaner mixture, and lean misfire could begin on the borderline cylnders.

My conclusion is the "leaning" effect of E10's low BTUs tends to compensate for the "richening" from higher operating fuel level of the denser E10 fuel, which may not be that different than some gasolines anyway.
I'd leave the float setting the same for E10 if it runs smooth.

Dan T

[Ron Dame]

I suspect the recommendation to raise the float setting is intended to compensate for density differences in fuels containing ethanol, and keep the operating fuel level in the carb bowl the same asitt was for gasoline. Fuel level is important since it effects how much fuel flows thru the various jets in response to carb venturi vacuum caused by air flow. A lower level in the bowl would result in generally less fuel flow for a given air flow, or leaner mixture. Fuel level in the bowl tends to change the delivered mixture across most of the carb circuits, unlike jet changes or mixture screw adjustments that tend to effect only certain operating conditions.

Ethanol is a little more dense ( heavier) than gasoline.
".765 Kg/l was used for the density of gasoline and .79 was used for the density of ethanol."

http://www.ethanol.org/pdf/contentmgmt/E30_Final_Report.pdf

Note density of .79 is for pure ethanol

Other sources say things like the specific gravity of gasoline can vary quite widely (from 0.69 to 0.79), but is usually near 0.73.

So the carb float tends to rise higher in the denser E10 than gasoline, which would shut the fuel off at a lower fuel level in the bowl. But some gasoline could be just as dense as E10.

Much Too high an operating fuel level could even make fuel flow out of the jets with no air flow (engine off) and promote extreme idle richness that would not respond to adjustment.

On the other hand, gasoline blended with 10% alcohol has about 3% lower heat energy ( fewer BTUs per gallon), and thus a "perfect" air fuel ratio richer than gasoline. If a carbureted engine (that never have real uniform cylinder-to-cylinder air fuel ratios) was adjusted so it idled and ran smooth, it still could have a few cylinders running near the lean misfire limit on gasoline. But if the tank was then filled with E10 (10% Ethanol) gasoline, the lower BTU would result in a few percent leaner mixture, and lean misfire could begin on the borderline cylnders.

My conclusion is the "leaning" effect of E10's low BTUs tends to compensate for the "richening" from higher operating fuel level of the denser E10 fuel, which may not be that different than some gasolines anyway.
I'd leave the float setting the same for E10 if it runs smooth.

Dan T

Thanks for the dissertation, I better understand the density issue. I did not know 'pure' gasoline's density was that variable. The float level at spec seems to have cured it all, but apparently some have found with a WW, dropping the float slightly cures some ills blamed on ethanol

[DEEPNHOCK]

Forums are strange places.
Ask a basic question, and the answers/suggestions/swags/recipies pour in.
Answers that include everything from soup to nuts.
Then have an emoticon set someone off? Too funny.
We have the weekly wheel fit question, the monthly zddp question, ad nauseum.
But have a guy get stuck and come here to search for answers, and then get derided because of a comment?
Lighten up.
Betcha Ron said a whole bunch of words under that hood that were not fit to print.
And besides... It's the process.
At least he was pretty methodical about it.
We have seen people junk whole engines because they never bothered to learn how to adjust points to get a specific dwell.
We are here for a quest.
A passion for Studebakers.
To make them run, and keep them running.
Petty forum squabbles and personal swipes denigrate the Studebaker effort.
Take those directly to the person in question, especially if they hide behind a crappy profile that doesn't even show their name and contact info.
I'm just glad to see the simple mystery solved.
And I thank Ron for making it go on for two seasons and into reruns
Jeff

[DEEPNHOCK]

Add that earlier comment I tossed out about elevation in Asheville to exacerbate the density question.
Toss in some CASO diesel fuel to stabilize it a bit
Jeff

Thanks for the dissertation, I better understand the density issue. I did not know 'pure' gasoline's density was that variable. The float level at spec seems to have cured it all, but apparently some have found with a WW, dropping the float slightly cures some ills blamed on ethanol