'63 running a bit rough on the freeway

[Adambravo]

So, long, horrible story...

1. Brought my '63 into the shop last July for some serious electrical issues. At the time, it was driving ok--mainly rather rough when cold.

2. Picked up the car a month later--it was barely driveable, stalling frequently. Had it towed back.

3. Carburetor needed to be rebuilt. Housing was warped, so we bought a matching-number unit on eBay (which turned out to be marginally functional, but not warped). Eventually sent both units to an expert in California to create one working carb.

4. Carb arrived in January (here in Michigan). Shop hung onto the car until the roads were clean enough to drive it, and changed the oil along the way.

5. Picked up the car this week, and, with the tank nearly empty, gave it a fresh tank of premium . Starts good, idles smooth, but, on the first trip on the highway, I noticed that at around 70mph indicated (63mph actual), it was running a bit rough. Didn't want to push it for fear of stalling. Once I got off the freeway below 60-65mph indicated it was once again running fine.

 

I'm hoping this is due to the car sitting for eight months (fortunately, a heated garage), but figured I'd solicit some input from the experts out there. Thanks in advance...

 

[lrlforfun]

OK AB:  Probably not what you want to hear.....Gotta first find out if it's a fuel delivery issue or an electrical issue...or something else.  Isolate each system and it's a process of elimination. Mitch

[Adambravo]

2 hours ago, lrlforfun said:

OK AB:  Probably not what you want to hear.....Gotta first find out if it's a fuel delivery issue or an electrical issue...or something else.  Isolate each system and it's a process of elimination. Mitch

Well, yes and no. Could you be a bit more specific on possible causes? A friend suggested a clogged fuel filter, or issues with the distributor and points, which would both affect the car at higher speeds but not at lower speeds.

[TexRiv_63]

29 minutes ago, Adambravo said:

Well, yes and no. Could you be a bit more specific on possible causes? A friend suggested a clogged fuel filter, or issues with the distributor and points, which would both affect the car at higher speeds but not at lower speeds.

All good possibilities. I would add sparkplugs and cables to that list, basically everything involved in a good tuneup unless you did all that as part of your electrical issues.

[Seafoam65]

               If what you are experiencing is the engine bogging down at 70 but not missing like a dead cylinder, still smooth but

goes slower the more gas you give the throttle, you have a bad fuel pump, stopped up sock in the tank or a clogged filter. Usually

if the problem is electrical like plugs, points and condensor, rotor plug wires etc. It will do it the worst when you are accelerating from a stop or accelerating at low speeds....not at 70 miles per hour, and it will run rough due to the fact it isn't running on all 8 cylinders. If your filter turns out to be clogged, you most likely have a gas tank full of rust and sludge that needs to be replaced or sent out to be restored.

[1965rivgs]

2 hours ago, Seafoam65 said:

               If what you are experiencing is the engine bogging down at 70 but not missing like a dead cylinder, still smooth but

goes slower the more gas you give the throttle, you have a bad fuel pump, stopped up sock in the tank or a clogged filter. Usually

if the problem is electrical like plugs, points and condensor, rotor plug wires etc. It will do it the worst when you are accelerating from a stop or accelerating at low speeds....not at 70 miles per hour, and it will run rough due to the fact it isn't running on all 8 cylinders. If your filter turns out to be clogged, you most likely have a gas tank full of rust and sludge that needs to be replaced or sent out to be restored.

This is good advice and good reasoning, thumbs up,

  Tom

[lrlforfun]

OK AB: Well, when I had the car lot and I isolated a system I would have a standard drill in the isolation process.  Say, you've eliminated the electrical .  Now, fuel delivery. The hose to the carb was the easiest to begin with then to the fuel pump.  Next, right to the tank and work forward. For some reason the tank was often the culprit.  Vandalism, busted-up locking gas caps and then, occasionally gook.  Today?  I think gook has inched it's way to the top of the list.  BTW, when things are apart many times it's a good idea to clean things up, replace the hoses and other items that fatigue and  could cause trouble down the road. New hoses, filters, gas caps are cheap and usually easy to replace.  A new fuel pump is cheap too but....not as easy to install.

 

What ever you do....isolate, diagnose, verify your diagnosis and ALWAYS.....why did the component fail?   NEVER randomly replace parts and guess.     Mitch

[petelempert]

I had a similar problem years back and the culprit was the fuel tank. It was the most bewitching car experience I've ever had. It was about one year of frustration. What looked like a relatively clean tank turned out to be a nightmare. The way it affected the car was crazy. Junk in carb, ruined the fuel pump etc. I dropped and steam cleaned the tank twice. Sometimes the thing ran great, sometimes totally inop, sometimes idled rough, sometimes wheezy at high speed. Finally got a scope up in the tank and it looked like a combination of a coral reef and the wreck of the Exxon Valdez. The gunksickles and slime was clinging to the corners with a death grip. It's not really a surprise, it's a 50 year old tank after all. PRL

[Adambravo]

1 hour ago, petelempert said:

I had a similar problem years back and the culprit was the fuel tank. It was the most bewitching car experience I've ever had. It was about one year of frustration. What looked like a relatively clean tank turned out to be a nightmare. The way it affected the car was crazy. Junk in carb, ruined the fuel pump etc. I dropped and steam cleaned the tank twice. Sometimes the thing ran great, sometimes totally inop, sometimes idled rough, sometimes wheezy at high speed. Finally got a scope up in the tank and it looked like a combination of a coral reef and the wreck of the Exxon Valdez. The gunksickles and slime was clinging to the corners with a death grip. It's not really a surprise, it's a 50 year old tank after all. PRL

 

Question: was this a problem that developed over time? Prior to the car going into the shop, I had no problems whatsoever getting up to 80+mph. And, in the past, the car has sat up to 5 months in a detached garage with no problems, so I figured 8 months in a heated garage wasn't that big of a change. Have taken the car around since the highway driving glitch and still no problem--and will try it again later today on the highway.

[petelempert]

It sort of came on slowly. I got the car running after it had been sitting for almost a decade. I knew enough to clean all the lines and clean the tank (or at least I thought I had) back then. It ran pretty good for about one year. But as I tuned it, adjusted stuff and drove it more it got worse. Then it became a major problem. My theory, which I can't prove, is that maybe all the driving and fresh gas might have dislodged stuff. PRL

[EmTee]

It's beginning to sound like time to try rigging a temporary fuel line.  A length of fuel hose could be inserted into the filler neck so that the end lies on the bottom of the tank.  The line can be temporarily secured along side the stock fuel line and routed to the carburetor.  Add a new in-line filter before attaching to the carb (preferably one with a clear plastic housing).  Drive the car as you have before when it acts up and see what happens.  In any case. when you're done driving the car remove the fuel filter, cut it open and inspect the filter paper to see whether there's evidence of any silt, scale, scum, etc.  If it looks dirty, it's time to drop the tank.  If it's clean and the car ran better, then either the fuel pickup in the tank is plugged, or there may be a pinhole leak in the line somewhere that is allowing air to enter.  Do you ever smell gas or see any wet spots on the lines after the car has been parked?  It sounds like the tank may be crusty inside...

[Adambravo]

Just a quick update...

Had a friend check vacuum (which was fine) and timing (which was just a hair advanced). Car is otherwise running fine (although city fuel economy, normally at around 11mpg, is now closer to 9mpg). I will be making arrangements to take the car to the shop in the near future, and will include all your notes here; fortunately, it's  still fine for driving around town and cruising for ice cream...

[lrlforfun]

OK Adam: Did you say ice cream?     Mitch

[Adambravo]

Mitch--yes, of course...

 

Everyone--problem (apparently resolved). Was talking to a friend who indicated that, at $50, I might as well get a new fuel pump, 'cause you never know. Got it, had it installed at a local shop, and went on an hour long cruise today, hitting up to about 72mph on the freeway without any stumbling.