Stumped . . .

[Jon S]

I was helping a friend with his 1958 Cadillac.  I rebuilt his Rochester 4GC, changed the fuel filter and adjusted the timing.  The car still has a strange flat spot when first accelerating and intermittently stalls when coming to a stop.  It immediately starts right up.

If I put it in drive and hold the brake while giving it gas, it feels very strong and no flat spot.  However if placed in drive with foot off the brake, the flat spot re-appears.  (vacuum problem?). 

At first I thought accelerator pump, but at a steady 55 MPH cruising, it intermittently stalls and re-starts itself so have ruled out the accelerator pump for now.  Advancing the timing a few degrees seems to have helped the stalling problem, but the initial flat spot is still present, and as noted the steady 55  MPH intermittent stall is also still present.

It feels like a fuel problem, but am not ruling out ignition.  Thoughts???

[Jeff Rosansky CLC #28373]

Replace the condenser.  I had a problem that everyone thought was fuel, and it turned out to be the condenser.
Update us,
Jeff

[Scot Minesinger]

Yes, it sounds like ignition, fuel issues don't seem to fail like that.  This type of thing happened to me too only around 25 mph when coasting, at that speed on low throttle it kept stopping, restarting, over and over - press on the gas or brake and it went away.  After replacing the condenser as Jeff suggested because it is so easy and inexpensive, check the centrifugal timing weights.  My ignition assembly had worn ovals where the round holes used to be, and the ignition had to be replaced.  If the holes that hold in the weights are oval, that is the likely problem.  Remove rotor to see them.

[Jon S]

Jeff, Scot - Thanks!  Will have him pick up a Blue Streak condenser and I'll put it in soon and see if that solves the problem.  Never would have thought of that being the issue!  Will also check the weight when I have his distributor open.

[D.Yaros]

Do let us all know if the condenser resolves the issue.  Another item to consider would be the distributor vacuum advance.  I had a similar problem and a rebuild of the the distributor vacuum advance corrected it.

[Scot Minesinger]

Yes the holes becoming oval is what I mean by having to rebuild/replace distributor vacuum advance, only more to do with centrifugal weights.  When my car was traveling about 25 mph and under no load the car would shut off, then restart, then shut off, then restart...

You could hit the gas and brake, gas or brake any of the three possibilities and it would run fine except at that speed and no load.

I never did figure it out.  However, took the car in for some exhaust work and the mechanic who also does engine work was baffled when the car would not start.  He went thru either fuel or spark, no spark...hence the distributor was examined - problem discovered and quickly cured.  Now I know.  The great thing about this is that I took it to a repair place several years ago and that was the only time car would not start, and it happened to the mechanic instead of me.

[Jon S]

Well, I haven't fixed my friend's car yet, but my car experienced the stalling at stop signs problem. I limped home and replaced the ignition condenser. I took it for a short ride and it seems fine. Will take it for a more extensive test/ride tomorrow.

[Jeff Rosansky CLC #28373]

It's funny you posted this. I am having that issue too.  Couldn't figure out if it was the choke or not.  I admit my carb needs adjusting.  When cold, it cuts out but keeps going.  Yesterday it even died.  I had driven it less than a mile.  Pulled into a parking lot and let it just run at 1500 or so for a couple of minutes..... Smooth.  Then it seems to have warmed up and drove just fine.  Got gas and went for a short drive with no problems. 
This morning, I started it and let it run for a couple of minutes.  My kid was not ready to go so I shut it down.  Came out, started it, (it was slightly warm) and she didn't miss a beat.

I already have a new condenser--but that doesn't mean anything.  From what I remember, it will cut out at various RPM's and not run smoothly if it is the condenser. I am hoping it is a choke issue.
Any ideas??
Jeff

[Jon S]

Well, I haven't fixed my friend's car yet, but my car experienced the stalling at stop signs problem. I limped home and replaced the ignition condenser. I took it for a short ride and it seems fine. Will take it for a more extensive test/ride tomorrow.

Checked the dwell and timing yesterday.  Dwell was 27 degrees . . . I re-set it to 30.  Timing was on the 5 degree advanced mark with vacuum advance disconnected after I re-set dwell.  I upped it to 10 degrees advanced.

A little hard starting today, so I re-set timing to approximately 6 degrees advanced.  As I remember, it had a slight hesitation at 5 degrees which I fixed last year by advancing it a few degrees.  Will see how it starts cold tomorrow.

Glad I painted the timing mark bright white a few years back - much easier to read than chalk!