1957, engine suddenly surging at idle | Ford Thunderbird forum club group 1955-2005 models

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1957, engine suddenly surging at idle

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vernz

vernz

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1957
My 1957, stock D code 312, came out of hibernation yesterday. It started and restarted perfectly and ran well for about 1.5 hours which included a couple of stops of 20 minutes to 1/2 hour. Then, at a stop sign it suddenly started surging from about 700 to 200 RPM. It did stall once, but that may be from my clumsy attempts at keeping it going. After that it did not stall, but I was running stop signs rather than giving it a chance to stall. The engine temperature was consistently in the normal range and the outside temperature was in the high 60's. I am running standard point ignition. I fueled it up with premium non-ethanol gas plus lead substitute just before starting the excursion. I fueled up another car at the same station with the same fuel and that car ran fine. After the surging problem at idle it seemed to run OK at speed. The next morning I started the car and it continues to surge at idle (at least it isn't an intermittent problem). The carburetor was professionally rebuilt about 2 years ago. Any thoughts on what I should check first? Thanks, Vern

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vernz said:
My 1957, stock D code 312, came out of hibernation yesterday. It started and restarted perfectly and ran well for about 1.5 hours which included a couple of stops of 20 minutes to 1/2 hour. Then, at a stop sign it suddenly started surging from about 700 to 200 RPM. It did stall once, but that may be from my clumsy attempts at keeping it going. After that it did not stall, but I was running stop signs rather than giving it a chance to stall. The engine temperature was consistently in the normal range and the outside temperature was in the high 60's. I am running standard point ignition. I fueled it up with premium non-ethanol gas plus lead substitute just before starting the excursion. I fueled up another car at the same station with the same fuel and that car ran fine. After the surging problem at idle it seemed to run OK at speed. The next morning I started the car and it continues to surge at idle (at least it isn't an intermittent problem). The carburetor was professionally rebuilt about 2 years ago. Any thoughts on what I should check first? Thanks, Vern
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I suspect the problem is in the carb or you developed a vacuum leak so check all vacuum lines. If the timing isn't stable that too can affect idle speed. If you have a timing light you can hook it up to see if the timing is jumping around while it's surging. Try it with and without the vacuum line connected to the distributor. If you have a vacuum leak that might also be affecting the vacuum advance up and down.
 
One day my '56 started running bad after fueling up. But it ran poorly at all RPM's, so I limped it home just a few blocks
It happened so immediately from the start where the new fuel couldn't have been the culprit.
Stalled at stops and when moving seemed to surge a lot like it wasn't running on all 8 cylinders
Neighbor mechanic guru asked what brand of plugs were in it, Autolites then he cringed
Several mechanics since have mentioned that cheap Autolites or Champion plugs aren't worth the trouble
and refuse to install them. I'm sure opinions differ

So a new set of quality NGK's and it's been good ever since. I've also since then changed out the plug wires
and added extra rubber sleeves to protect these going around the back corners of the block or where wires
might cross and touch each other. Rubber blocks and brackets hold these into place but OK I'm crazy.
As insulation breaks down from age and use this can cause shorts
Opening the hood while running at night without any light and looking around at the plugs and wires can show a lot of things

BTW, an old school mechanic guru told me to "NEVER NEVER EVER" leave that car idling in park and get out.
Proper adjustment of the shifter with the Fordomatic transmission is critical and they have been known to jump from park to reverse
from engine vibrations or shaking worn parts etc. thus sending the car into anything behind
Then he mentioned "Ask me how I know"!!
So I shift into neutral and chock the wheels whenever I can. "AND ALWAYS USE JACK STANDS!!!"

Just sharing again
All be well
Bobby
 
Thank you Bobby. I bought new wiring last year, but did not yet install it. I need to be able to get the car in the air for the wiring. I did replace the plugs, but with autolites. Since I want to replace the spark plug wires anyhow, I might as well do it before trying anything else about the surging. Also, as a career safety professional, I appreciate the safety warning. It is a good one!

Vern
 
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