Ok, I went back in, shortened the dizzy weight springs, put on the lighter Mr. Gasket weights with bushings. Put a new spring on the vac can and ensured that I got full movement by 9". Reinstalled everything, started, verified initial timing at 16*, mechanical comes in right at 36*. Getting about 15" at idle at this point. Hooked up vac line to dizzy (tried ported first), rpms shot right up, checked timing. Getting way too much vac advance, coming all in around 56*, but I leave it for a minute. Adjust idle down to 1k rpm, pulling around 12" vac. Get in the car, put it in gear. Dies. Tried again with manifold vacuum, same result. Seriously, WTF? I understand that this is a process, but I'm getting no significant change. Admittedly, the idle is better and much leaner, but none of that matters if the car dies once you put it in gear. So, what next?

Thanks,
Bryan

 

I'm beginning to think your problem doesn't have anything to do with ignition timing. Actually, I've been thinking that for awhile now.

Scott

 

I don't necessarily disagree with you, but what could it be? When I put the car in gear, I can feel the transmission engage, then it dies. It really feels like the torque converter is locking up but I just don't know what would cause it. If you have any ideas, I am all ears.

Thanks,
Bryan

 

OK, so let's back up and take another run at it. When was the last time the car ran normally, and what has changed since then?

Scott

 

Scott,

The simple answer is, I don't know and everything. I bought the car back in late 09. It ran then but very roughly and the transmission was shot, wouldn't engage 2nd or 3rd gear. I have been working on it slowly and have had the transmission rebuilt, new torque converter, the engine rebuilt with the components discussed at the beginning of this thread, new dual exhaust, no cat, removed egr, and carb rebuilt. Have also replaced or repaired a lot of suspension and drive line, but that doesn't seem relevant here. Also, replaced all vacuum lines, installed new radiator and the work performed in response to suggestions in this thread. That's about all I can think of.

Thanks,
Bryan

 

OK, so it has the original transmission, that means it's not a lock-up converter, so we can rule that out. When it stalls, how does it stall? Does it cough and sputter and puke and then die? Or does it just shut off with no drama? What happens if you just pull it straight back into neutral? What if you give it some gas and then try to put it in gear?

Scott

 

When it stalls, you can feel the trans engage, the rear end squats a little when put in gear, then it just dies. No drama, just dies.

I haven't tried pulling it straight back into neutral.

Giving it some gas and putting it in gear gets the same result. Dies.

Bryan

 

So no matter what you do it dies once in gear. No amount of throttle keeps it running?
Given that you get 15" on manifold vac I would leave it there for when we get this thing figured out.
When it dies and you try to keep it running does it seem to flood out or is it like someone turned off the ignition?
Have you left the vacuum gauge on (taped to the windshield or something) while putting it in gear to see what happens to the vac just after putting it in gear and before it dies?

Staring to think vacuum leak at the transmission modulator...maybe. I'm not completly sure what happens with the modulator is different in gear vs out of gear. If significant vacuum is being lost when it's put in gear two things for sure are gonna happen. One is the vac advance will be lost. The other is the APT in the carb will go full rich and might flood out the engine.
Try disconnecting your accel pump on the carb and then see if you can keep the engine running when you put it in gear.
Like scotty say it looks like this is more than simple timing issue, although it's all intertwined, Vac, timing, and carburation, so once we figure out the root cause other things may fall into place.

 

I won't say that no amount of throttle keeps it running. I mean, I have tried giving it light pedal with left foot on the brake when putting it in gear in an effort to keep it running but I haven't really juiced it. I don't know that I could tell the difference between flooding out and turning off the key, but this I can say, when it dies, I put it in gear and within 1-2 seconds, it dies, no coughing or anything, just shuts down. Vacuum gauge on the windshiled? No, I hadn't thought of doing that but that is a good idea. I will do that today when I get home.

I thought about vacuum modulator as well but I thought that just controlled shifts, but I recognize that I very well may be wrong. What is the APT? Also, can you tell me what the Accel pump is on the carb?

Thanks,
Bryan

 

Your right the modulator controls part throttle shifts by sensing vacuum. There is a steel line that should run from the tranny to a port on the intake manifold just behind the brake booster port on the carb base. Like I said though I'm not sure if it's function changes immediately once put in gear. I guess you could just pull that line off and plug the port on the manifold (just that line's port) and try putting it in gear. that would tell you if it makes any difference.

When you press the brake pedal is there a large fluctuation in rpms at idle before you put it in gear? Try observing the vacuum while depressing the brake as well to eliminate the booster a source of a leak.

The accelerator pump is the green lever in this picture. It can be removed by pushing/tapping out the roll pin at it's hinge point. A finishing nail works good or a small drill bit. It should come out easily. Don't push it all the way out.Push it towards the horn or inward, but not too far you want to be able to get a screw driver behind it to push it back in.
My thinking here is if you are experiencing a large loss of vacuum and the APT goes full rich then you push the accelerator you are now adding even more fuel with the accelerator pump. So you can eliminate that and see if you can keep the engine running after putting it in gear.
However this is not necessary if you can witness a large loss of vacuum when it goes into gear or when you push the brake pedal. Then we have the problem. It would just be a way to see if it's flooding out and that's why you can't keep it running.
[IMG][/IMG]
The APT is Automatic Part Throttle inside the carb. As near as I can figure it was introduced in 75 so yours should have it. It is a vacuum actuated fuel metering system for the main fuel rods on the primary side of the carb. It keeps the rods pushed into the main jets a certain amount to meter fuel through the main jets. When vacuum to this system is lost(ie full throttle) then the needles are retracted from the main jets by spring pressure to enrichen the mixture on the primary side.
So if the vacuum drops below a certain level ( the springs are changeable and the level of drop out can be changed) for any reason they will go full rich. The idle circuit on your carb pulls fuel through the main jets and thus the mains have some effect on the idle circuit. In addition you may have the primary blades open a little to get your idle so you may be operating partially on the main side instead of fully on the idle circuit.

On a forum trouble shooting can be a long process and some things may not occur to me until later since I'm not there to hear and see what's happening. Eventually though we can eliminate several suspects and hopefully find the issue. Maybe others can come up with stuff I may be missing as well.

 

Ok, so let's address some questions first. 1. No drop in vacuum with brake depressed. 2. Disconnecting vacuum line to transmission modulator has zero affect. 3. I cleared a path through the garage door and put the car in R while giving the pedal some gas, lurches in reverse then dies. 4. Tried taking it straight through to N. Died on the way there. 5. Disconnected accel pump, and besides having a difficult time keeping it running, no affect.

Finally, I took a short video of the drop off in vacuum when the car is placed in gear. Let's see if I can get it uploaded.

 

Wow, just like you described it doesn't even try to run. It's like the ignition is shut off. I guess we eliminated the modulator and the APT as possibilities.
It's almost as it the torque converter is not allowing any slip what so ever.
What I would do next is jack up the rear wheels and block it securely then run it and put it in gear. If it's a not some ignition or vac problem then the engine should keep running and turn the rear wheels since now there is no resistance for them to rotate. If it does keep running then slowly apply the brakes to force the torque converter to slip. See if you can keep it running.

Another thought is maybe there is some weird ignition thing going on. Hook up the timing light face it towards you through the windshield. Start the car put it in gear which happens first, light stops flashing or engine dies. This may give us some clues.
Hope we find out soon I'm getting to the bottom of my idea pile here.

 

I agree, that is what I meant in a previous post when I said it seems like the TC is just locking up, understanding of course that there is no lock up on a 75. I will try what you suggest. One question though. When I jack up the rear end and run it, do I need to put jack stands under the trailing arms to raise them up some? Doesn't seem like it would be good for the wheels to be turning when they are hanging like that. I will try the timing light test as well.

Thanks,
Bryan

 

Went outside and tried your timing light test. The light flashed until the motor died. They definitely stopped together. So I guess we have eliminated ignition.

 

Reminds me of when the misadjusted linkage on my manual transmission engaged two gears at once. That locks thing up pretty well. I assume you can turn the wheels by hand or push the car around?

 

Good, one more possibility down.
I have jacked mine just on the frame and let the wheels hang. No issues. You'll only be rotating at low rpms in any case. If it makes you more confortable remove the tires. I personally like having the tires on just incase it fell off the stands. Block the appropriate side of the front tires with a piece of wood or something also.
After the engine dies have you ever taken off the air cleaner and actuated the throttle while looking in the primaries and observed a good stream from the accel pump squirters? Yep, I'm sneekin up on fuel now.

 

Yeah, no issues there. When in neutral I can roll the car.

 

Taken it off? Hell, I don't remember the last time the damn thing was on. But more to your question, no, I haven't looked. I will try getting the rear end up in the air tomorrow and will also look at the primaries after it inevitably dies.

 

Check that there is voltage present at the dist / coil when you drop it in gear.

 

I hear ya. Mine's off more than on right now too.