Super six stalling

[Michael Joseph Moynihan]

Just had my BBD 8137S rebuilt and I installed it after sitting for 6 months in storage. It was leaking and would stall at every light. After rebuild same thing not a good idle shaking badly. Has a new recurved distributor, cap, rotor, plugs and wires. Do I need to adjust idle mixture or am I missing something else. Thanks

 

[BudW]

Did you get your existing carburetor rebuilt or did you get a carburetor from a box from a parts store (and yes, it makes a big difference).
Was the original carburetor leaking fuel externally or internally (into the engine)?
If externally, where about was it leaking from?

Anytime a carburetor is replaced, rebuilt or repaired, one always needs to adjust the idle mixture, idle speeds and so on.

Also check all vacuum hoses (for disconnection and for cracks). Many times I have seen a seemingly good appearing vacuum hose, split on bottom side close to its fitting. Also, check the brake booster for leaks (it should have enough vacuum inside of it for one and one half power assisted stops with engine off - after engine has been off for a good length of time).

The intake gasket can be checked for leaks by spraying canned parts cleaner around the intake to cyl head with engine running. If engine speeds up (or slows down) just after spraying an area - usually is a good sign of a gasket leak.

A hand held vacuum pump can check for leaks at the distributor vacuum advance or carburetor choke pull off. If you don't have one, sometimes one can be rented from your local parts store.

BudW

 

[Michael Joseph Moynihan]

Carb is the original was leaking around the bowl gasket, pull off is new as is the intake/exhaust manifolds. I will check the vacuum lines for leaks. Thanks

 

[BudW]

If the external fuel leak is coming from here (black arrow):

Then either the internal float is leaking (filled with fuel, and no longer floating) OR their is contamination at the needle and seat (red arrow), which is more likely. Either way too much fuel will make a car run bad, if at all. Another possibility is fuel pressure is too high, but I don't see that being an issue if using factory or decent replacement parts.

. . . is new as is the intake/exhaust manifolds.

You have new intake and exhaust manifolds OR the manifold gaskets? A new intake gasket doesn't mean it is not leaking at the gasket. There is a certain procedure to install a replacement intake (or exhaust) manifold on a /6, and if not done correctly, it has no choice but to leak at the cylinder head. I am not trying to be mean - but only saying I have been there and done that (and re-done it) many a time back in the day.

Would you mind giving a list of exactly what you have done to your car and how long ago, so far (please)?
BudW

 

[Michael Joseph Moynihan]

purchased in 2017 with 75K original miles. Exhaust manifold gasket leaking at back #6 port. Had it replaced by a friend who is a Mopar Man and no leaks when done but did not idle well. 2018 original distributor complete rebuild and recurved, new cap, rotor, plugs, wires and belts. Still not a good idle but drivable. Stored in 2020 and carb removed and complete rebuild to original carb.

 

[AJ/FormS]

I would start with a compression test which is back to basics, and a valve adjustment if it has solids.

 

[BudW]

I agree with @AJ/FormS. Adjust the valves (not sure what year you are working on, but most likely it will be solid lifters). The valves need to be adjusted every 30k miles and is not a difficult job (for the most part). Make sure the adjustment is done with engine is warm/hot - for it can make a difference. If not done it before, there are plenty of video's online to watch.
After valves are adjusted, then check compression. Your local parts store might even have a compression gauge to rent, possibly (mine does).

I would also get a can of spray parts cleaner (just pick one). When engine is running spray some cleaner at the intake gasket port (at cylinder head) as well as at the gasket between the intake/exhaust (under carburetor) and the carburetor to intake gasket. When performing this test, any rise or drop in RPM's indicate a leak.

If compression test results are within specifications (Specs for a '77 225 is: 100 psi (min) and max difference between cylinders is 25 psi. This is with all 6 spark plugs removed and with throttle open) and no leaks found when using spray parts cleaner, then we have to move to problem being ignition system, inside carburetor or possibly a really loose timing chain). We have to start with the basics first then work outward.
BudW

 

[FredMcJoe]

My Super Six Carter just did the same thing, spilling gas out of the top. I found the float bowls were full of fuel. I noted a difference in float bowl sealing when I shopped for a new float. The failed unit had a cement type of bonding of the float bowl halves while floats for sale were solder sealed. I found an old float, cement sealed, and I resealed it with thin layers of JB Weld along the old cement ridge. It has held tight. I also bought a soldered float as a backup. I have a hunch alcohol gasoline seeps past the cement. This cured a "long crank when hot" restart problem, too.

 

[BudW]

Brass floats work great - but I do run across a failed one every so often.
The plastic floats have a built in life expectancy - for the plastic will absorb gasoline over time and alcohol has a tendency to desolve the plastic over time.

A brass float that has a leak, you can shake it and can hear the gasoline inside sloshing around.
You can feel a plastic float, that has absorbed gasoline, when you have a new one in your other hand for a side by side comparison (noticeably heavier).

The problem with adding weight onto the float (via epoxy) is it will not float as well now (but makes for a good temporary fix). Solder is the best method.

If you are not sure about a carburetor float working or not, is to take the "removed" float and place a finger under the pivot. place the other end, the"floating part", in a cup of water. Water is heaver than gasoline, but will work in a pinch. Just don't put dirty parts into anything going back into your kitchen or your life expectancy might become shorter. Most carburetor floats will have about 1/2 of its body above the water level (when in water). if it is lower than that, then find another float.

I don't mind rebuilding carburetors, but if working on one with a plastic float, i generally plan on replacing it at same time as a rebuild just because plastic floats are problematic.
I'm now trail off mumbling something incoherent, about plastic being made from petroleum . . .
BudW

 

[Aspen500]

purchased in 2017 with 75K original miles. Exhaust manifold gasket leaking at back #6 port. Had it replaced by a friend who is a Mopar Man and no leaks when done but did not idle well. 2018 original distributor complete rebuild and recurved, new cap, rotor, plugs, wires and belts. Still not a good idle but drivable. Stored in 2020 and carb removed and complete rebuild to original carb.

I just noticed this post. Do you mean it idled good BEFORE the manifold gaskets were replaced but not after? If so, I would highly suspect an intake gasket leak. An air leak (or "vacuum leak") will cause a rough, uneven idle but the engine will run fine otherwise, unless the leak is really big that is.

I know, I get too picky sometimes. Technically it's an unmetered/unregulated air leak since a vacuum can't leak but air can leak into the vacuum. 38 years of being an auto tech will do that to a guy, lol.

 

[Michael Joseph Moynihan]

It never idled good before or after the gaskets were replaced. Has the same after the carb rebuild and all the other items done. I think that it in ignition wiring from the module to the distributor. It just acts like a something is arcing across to a ground.

 

[BudW]

IF you have an ignition module, on passenger side inner fender (yellow arrow), you might want to unbolt it (you can leave the wire plugged in).

Once unbolted, take some sandpaper and clean under the two screws (both sides) and the same to the fender. Then take a wire brush and clean the bottom of the two screws.

If the ignition module doesn't have a good ground to the frame - it could be a possible issue or concern.

The ignition module (itself) is either good or bad, so if car is running, you have a good module - BUT, if the module has a poor ground, that can be a possible issue.
BudW

 

[Michael Joseph Moynihan]

Thanks I will give it a try