How to unflood a 32 DMTRA carb for '74X

petex19

petex19

True Classic
My son's '74X won't start as is being discussed in a different thread but I thought that an instructional about flooded 32 DMTRA deserved its own thread.

The Good:

Cam and Crank timing marks lined up at TDC.
Rotor pointing to #4 contact in distributor cap.
Fully charged battery.
Cap and rotor look perfect.
New spark plugs properly gapped.


The Bad:

I checked this morning January 8 and I have NOOO spark at coil or at plugs so as well as a flooded carb I have no juice on what was an excellent running motor only days ago. GRRRRR!!!!!

The base plate of the Weber 32 DMTRA carb collects fuel on it when attempting to start the car. As was suggested by other Xmembers I believe the carb is badly flooded so how do I fix this?

I'm sure thier probably isn't a drain of sort because that would be too easy so what are my options?

Can I remove the carb off the manifold and let all the fuel out of it and then replace the base gasket and re-install and if so does it have to be a Weber base gasket or can I make one from gasket paper?

For the record the new spark plugs were just installed after setting everything else up so they haven't been fouled by the flooded carb yet.

'PeteX1/9
 
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If this is a chronic problem...

the most likely reason would be incorrectly set floats.

If it is something that has just occurred, try to start the car with the pedal to the floor. Yes the accelerator pump will put a little more fuel in while the pedal is in motion, but once the throttle plates are held wide open, you are letting in a lot more air to correct the mixture somewhat so it will start. Obviously if the car has a choke, it needs to be off (open).

Pete
 
I had this problem on my car and I had to take the carb apart and bend/adjust the float until I got it right. BTW this happened on the way home from work, and the repairs had to be made in the gas station at the pump and was a huge PITA as it took several attempts to get it adjusted properly and each time everything (hoses clamps carb etc..) had to be removed/reinstalled.:rolleyes: You might wanna check the needle as well as it my be worn out.
 
Unflooding is easy

You let the car sit overnight without touching it. The excess fuel evaporates.

When you try starting it next day, try cranking it without even touching the throttle, see what happens. Does it flood then? If not, try one pump of the pedal and see what happens in the carb barrel.

If it massively floods again as you soon as you try starting it next day, then it's time to worry about sunken floats and other carb problems. But I keep coming back to one thing: It ran well before you degreased it and accidentally moved the distributor... Maybe you got unlucky and the carb crapped out at the same time, but more likely it's some little thing connected to what you last changed that's making you crazy here.
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BTW, did you check the position of the cam lobes by looking into the oil filler cap when the motor was at TDC at the cam timing marks were aligned? That's a long shot, but there are ways that the PO could have put things together so that the cam is 180 degrees out and the motor wants to fire number #1 cylinder instead of #4.
 
pull the plugs too

and dry them out. Also check all the plugs to see if they spark. I've bought new plugs that were bad before. Plugging/stopping any new fuel from coming in and trying to get it to start/fire off with starting fluid would isolate the carb as the problem. Don't run it on the starting fluid, just get it to fire off. Starting fluid is hard on an engine.
 
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Not to insult your intelligence, but just to OVER explain things just to make sure all the bases are covered:

The carb itself doesn't flood. It will on occasion dump too much gas into the engine. The "flooding" is describing the top of the piston. If you pull a spark plug and it's wet with fuel, it's certainly flooded. Basically too much gas, not enough AIR.

If it's SUPER flooded, take out the spark plugs and let the cylinders dry. Air compressor? Blow air into the spark plug hole to speed the process. If it's cold, the gas can take forever to dry. Hair dryer? I've seen engines flooded SO BADLY that they begin to hydraulically lock and the engine can't turn over any more (can't compress a fluid).

SERIOUSLY - after drying the car really well, prepare for a restart by disconnecting the fuel pump, or at least pinching the fuel line to the carb with vise grips. Prevent any new fuel from entering the engine. Spray a couple of squirts of starting fluid (ether) down the throat of the carb and try to start the engine. Keep turning the engine until it fires but no longer than about 5 seconds. If it doesn't fire, something else is wrong.

It will fire, but you may see flames blowing back out of the carb or loud backfiring or just sense the engine "trying" to start but can't quit catch. All signs of bad ignition timing.

Next step: fill the float bowl of the carb with gas ONLY and restart. The engine should run fine then die after about 30 seconds maybe. Then reconnect the fuel source correctly and let-er-rip and see if it floods again. (Sounds like you have a sunk float or dirt in the float needle valve).
 
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You may have an intermittent spark. Sometimes it works, sometimes not. With no spark, the engine will flood. It doesn't burn the gas, so it just builds up in the cylinder.

NOT FUN!!! Check for moisture in the most unlikely places. My car wouldn't start after a wash, and water had gotten on top of the computer behind the spare tire. Check all the connectors. Pull the car into some place warm and blow a fan on it. open the doors and windows. This is a really frustrating thing to fix. But the only way is to check everything. It could fix itself given time!!
 
Does even the '74X have a computer? I never thought of removing the spare tire and checking in there. The car is indoors, a heated garage at that and it was washed inside this garage but although I covered everything electrical and the carb with plastic bags the access panel behind the distributor was not covered and did get spayed with water so moisture would have gotten into the spare tire well.

I will definetely check in there for sure.

'PeteX1/9
 
No, there's no computer in there on the '74, but it is very likely that moisture may have collected somewhere and is making life that much less fun for you and your son. Might even have something to do with your coil/ignition issue as well. Or that they're working hand in hand. How long has it been since you cleaned up the engine bay? I would think it would all be dried out by now...
 
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Right, as stated above you don't have a computer, but my point is that water can get into things you don't expect. Check every connector. and even a tiny amount of condensation inside the distributor cap will cause a problem.

Looking at ALL the problems you've had, I'm also drawn to wanting to check for a good GROUND between the engine and frame. You have had:
Flooding
Alternator light not working
Starter dragging
Intermittent spark

There are strong reasons to suspect a bad ground cable (common anyway). Also, check those big multi-wire connectors for corrosion or water.

Flooding and dead batteries usually go together. Things happen when you are grinding on the starter trying to get it to start. I'd say the place to start NOW would be in this order:

1. Ground wire from engine to frame then frame to battery.
2. Check the hot wire to the coil for current - (bad connections or ruined resistor or bad ignition switch).
3. Check continuity from the ground wire to the frame with points CLOSED (bad points or connections or capacitor)
4. If 1 thru 3 are OK, replace the coil, a common failure due to moisture ingress.

You will now have spark. At this point, things will start popping for better or worse. Get the static timing correct and control fuel flow to avoid reflooding.

Tips on engine cleaning: don't do it in the winter EVER. Warm garages and no air flow are the worst for condensing water in places that cause shorts (and rust!). Sometimes covering electronics can make the problem worse. CONDENSATION is the enemy in the winter. Get a fan blowing. Borrow an air compressor.

Report with your results.
 
My only caveat to your suggestions is...

USUALLY a poor ground does not allow the starter to crank. If the engine is cranking then the ground is usually pretty good.

BUT... a poor ground and a starter demanding MOST of the current because of it COULD be contributing to a WEAK spark.

One other suggestion... when checking for spark... I ALWAYS connect a lead to a removed spark plug and ground the negative electrode to the valve cover... so I can clearly see the spark jumping the GAP and not arcing to the side or anything less.
 
Thanks for the great tips. I will definately follow those steps for sure but I don't know what you mean by step #3 regarding the points?

3. Check continuity from the ground wire to the frame with points CLOSED (bad points or connections or capacitor)

I've already ordered a new coil and condensor. The ground from the frame to the battery has already been removed and cleaned up for good connections.

I'm going to replace the ground strap from engine to frame on Wednesday and check in the spare tire well at any wires that pass through there for any loose or coroded connections. I know I have ignition power to the positive side of the coil but how do you check for a ruined resistor or bad ignition switch?

2. Check the hot wire to the coil for current - (bad connections or ruined resistor or bad ignition switch).

'PeteX1/9
 
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