Thread: [57 Thunderbird] Running Rough

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Originally Posted by rspears

. Running out of gas generally doesn't result in a bunch of other problems. Chase one gremlin at a time would be my recommendation.

You should have seen the crud and corruption that came out the fuel line and tank of my 76 Vette after it had set for a couple of years. The fuel filter was almost totally plugged and the inside of the Q-jet was one of the worst I've seen coming off a running vehicle.

Originally Posted by NTFDAY

You should have seen the crud and corruption that came out the fuel line and tank of my 76 Vette after it had set for a couple of years. The fuel filter was almost totally plugged and the inside of the Q-jet was one of the worst I've seen coming off a running vehicle.

Ken, I agree 100%, and that's part a part of chasing the initial problem like you and I both said at the start of this thread. If it were mine I'd focus on the fuel system, tank through carbs, and be sure that was all cleaned up before I started worrying with any other possible gremlins. Just my $0.02, based on my life experiences.

I would imagine that the sock in the fuel tank if not plugged is close to being plugged and that's why I recommended dropping the tank and cleaning it out along with blowing out the fuel line.

Fords have always used venturi vacume source for dist advance and they didn't start mech advance until 1957-it also entailed a new design on the contact and condenser---the poit set was more of a curve shape base and the condenser also had a curved tab kinda off the end instead of the previous straight tab from the middle. The mech advance stuff was below the breaker plate and had 2 different advance slots and you could oil it via a felt tab under the rotor unlike the GM version that you couldn't lube.


In those years there was a tap for manifold vac for the wipers with an section (double diaphragm) on the fuel pump to boost the suck so wipers would work when you were on the gas--
No PCV until later-had a mount on the lower left side of block forward of oil filter for the road draft tube which is how crankcase was vented-------

Thanks Jerry, I was unaware of Ford using venturi vacuum advance after 1957, my bad.

While I have no doubt the fuel system needs attention, these are the clues that led me to think there may also be other issues and some further testing may be in order;

“605Scorpion; I made it to work, and after coming back out to drive home (12hrs later), it wouldn't start.”

Usually, when the gas runs out the motor stops on its own (this is not written in stone, just an observation). Many a time, a loose timing chain will skip on shut down and give trouble on re-start (a classic symptom). A timing light will show a worn chain by erratic movement of the timing. A simple test, just a thought to check.

“605Scorpion; I forgot about this, but yes, the vacuum is connected to the wipers. After the backfire, the wipers had trouble getting up, hence why the vacuum advance is drawing my suspicion so much.

Usually, when the fuel pump supplies vacuum (if indeed it has a vacuum boost fuel pump) and the vacuum decreases, the fuel pump diaphragm is usually compromised. A pressure gauge on the carburetor fuel line will show if there is low pressure from the pump. Keep in mind a clogged filter(s) can cause low pressure too and its a good idea to check the filters for flow restrictions if the pressure is low. A simple test, just a thought to check.

And, keep in mind that the OP said he had the carbs re-built, but is doing it again himself because he doesn’t trust the first job. Again, pointing to other possible problems that he may have already been warned. Rule of thumb, assume nothing, test everything.

My point is, the OP states he has owned the car for 2 years and driven it for 1 year. IMHO, he has jumped ahead of basic trouble shooting principles assuming the carbs are at fault, when there could be other issues. A few extra minutes of testing could have been better spent, i.e., compression test, fuel pressure, ignition. Granted the fuel filters probably need changing, as does the sock in the tank.

However, IMHO "Test, test, test, spend less, less, less".

Sorry for the rant.

In addition the "basic tests".. We haven't really heard much in regards to any basic maintenance.. was any performed?

Like 36 C-dan... I cannot say the carbs are the problem.. I think there are potentially other issues also.

Originally Posted by 34_40

In addition the "basic tests".. We haven't really heard much in regards to any basic maintenance.. was any performed?

Like 36 C-dan... I cannot say the carbs are the problem.. I think there are potentially other issues also.

I'm not saying that carbs are his only problem, but when you run an old car dry and then it acts up on restart chances are you've plugged up fuel filters, the sock in the tank, or pumped the carb(s) full of sediment, especially if there's no in-line filter which would have been an aftermarket add on sometime in the past 58 years. It's always worked best for me to work one problem at a time before jumping in and starting to pull other things apart, especially considering that our poster said at the start he's looking for novice level advice and that he's in a high rise apartment building, working at 2am to hide the fact that he's working on the car in his parking spot against the rules. Seems to me that we can get him in over his head pretty quick here, but whatever's right......

I'm done, at least until he comes back with some feedback or asking another specific question, and he's five hours earlier than me here in the heartland, so it's a loooooooong time until 2am for him.

LOL! You're probably right.

Alright y'all. I'm back after quite an absence ready for more advice, lol.

I did the carb rebuild, and everything went smooth until I tried to crank it up. It was running to fast. (circa 2K) After some musing, asking my pops, etc. I tried adjusting the floats, it indeed had an effect, but way too low. It was idling at 450 and struggling to even sustain the combustion cycle. Plus I was hearing some pops. Misfires, clanging? I was out of time for the day, and had to call it quits. I was so dejected I kinda just gave up on it for awhile, but I back to solve it finally. I live in a barracks so I can't just leave a car that looks like it wont run lying around, so that was just an additional factor in me not wanting to work on it. Whatever. Moving on!

Any advice for float levels? The specs cited in manual are useless (since it's an aftermarket combo). The literature cited in my rebuild kits seem impossible.

PS: Thanks for all the replies earlier! I really appreciate everyone willing to throw in their two cents.

In my experience with carb kits the instructions for float level have been crystal clear, and for everything but the performance carbs that have a sight plug and screw adjustment it's generally to hang the float from the carb top, carefully invert the assembly and check the level between the highest point on the float and the carb top, now sitting beneath the high point. Adjustment to match the specs shown on the instruction sheet (usually a picture) is as simple as carefully bending the tab that pushes the needle into the seat. Often they give you a little cardboard go/no go gauge cut to the proper level setting. You don't want to adjust by pressing on the needle, as you can destroy the sealing surface on the needle/seat assembly and you'll be buying a new kit.

Are you seeing something different in the kit you used?

If I recall the info I had was for the bottom of the float, not the top. I'll be looking at it this weekend reguardless.