I think i know the issue, but looking for help with bog down

[TexasVol]

Background:
I've had my 68 roadrunner for a few months now and I'm slowly tinkering with it working out bugs. It is an original numbers matching 383/727 car. It has had a trans leak since I bought it. At first I attributed it to seals leaking, thinking that it had sat for an extended time. (Don't have a ton of info on it.) I've driven it about once a week as I work through issues. Rebuilt the original Carter carb, new plugs, new tires, new rear shocks etc.

The issue:
Recently it has started to bog down to the point it almost stalls out when I put it in gear. It will idle all day without issue but put it in gear and it sounds like I'm choking the life out of it. I made the mix a little richer and that helped a little but still obviously bogging. I also looked for vacuum leaks and found none. This has lead me to believe it could be the torque converter? Would that not explain my bad trans leak too? I'm learning as I go so feel free to explain this like I'm 5.

Thanks for the help in advance.

 

[WileERobby]

What is your idle RPM ? What is your in gear RPM ? What are your readings on your vacuum gauge ?

 

[Curiousyellow71]

How is the timing set?

 

[TexasVol]

What is your idle RPM ? What is your in gear RPM ? What are your readings on your vacuum gauge ?

I'm not at home right now but I'll get a read for you this week. I just adjusted the carb by ear.

 

[TexasVol]

How is the timing set?

I haven't checked it either. I have a feeling it is a touch too advanced based on warm starts.

 

[Fran Blacker]

Where's the trans leak.

 

[TexasVol]

In short, everywhere lol. Definitely coming from the front of the bell housing, the pan gasket, around pretty much every gasket in the thing. That is part of what lead me to think that they needed to be replaced.

 

[Fran Blacker]

Sounds like you're pulling the trans, torque converter seal. While your shift lever seal and kickdown shaft seal etc.

 

[Lefty71]

Youd probably notice a lot of "hunting" and no smooth idle if there was any kind of vaccuum leak. Need to do some basic troubleshooting, including the carb. If you dont come up with anything before tearing into the trans, i agree with you, id probably pitch that converter and get a new one that matches your goals for the car.

 

[TexasVol]

Sounds like you're pulling the trans, torque converter seal. While your shift lever seal and kickdown shaft seal etc.

So a good freshening up might be the answer? Replace all the seals? What about the torque converter itself?

 

[TexasVol]

Youd probably notice a lot of "hunting" and no smooth idle if there was any kind of vaccuum leak. Need to do some basic troubleshooting, including the carb. If you dont come up with anything before tearing into the trans, i agree with you, id probably pitch that converter and get a new one that matches your goals for the car.

So the idle is solid. I replaced all the gaskets and cleaned the carb when I had it apart. That makes me think it isn't a carb problem. I'm no expert but I have to think I made it better with the tear down.

 

[Fran Blacker]

So a good freshening up might be the answer? Replace all the seals? What about the torque converter itself?

Think lefty71 advice was right. If you go to a high stall converter a trans cooler should probably be installed. Don't know your skill level but take converter off with trans, leave on engine can wreck pump bushing.

 

[BSB67]

Here is what I think.

1) Your posted “issue” has nothing to do with your torque converter. Nothing.
2) Your motor is not running correctly
3) It is either your carb, or your ignition.

Focus on the motor now, worry about the tranny leaks later.

My guess is that your motor is not really idling well in neutral either. The symptoms of the poor idle just don't present in neutral like they do when the motor is in gear under load.

Here is what I suggest you get:
1) Timing Light
2) Vacuum gauge
3) Service manual

Here is what I suggest you do:
1) Get the engine good and hot.
2) Record the idle rpm and vacuum in neutral and in gear
3) Record the ignition timing in neutral and in gear
4) Remove the new spark plugs and takes pictures. Take pictures of the old plugs if you still have them.
5) Take pictures of the carb and intake from a few angles
6) Maybe make a vid with it running in neutral and in gear.

Then report back to us and post the pictures.

 

[TexasVol]

Here is what I think.

1) Your posted “issue” has nothing to do with your torque converter. Nothing.
2) Your motor is not running correctly
3) It is either your carb, or your ignition.

Focus on the motor now, worry about the tranny leaks later.

My guess is that your motor is not really idling well in neutral. The the symptoms of the poor idle just don't present in neutral like they due when the motor is under load.

Here is what I suggest you get:
1) Timing Light
2) Vacuum gauge
3) Service manual

Here is what I suggest you do:
1) Get the engine good and hot.
2) Record the idle rpm and vacuum in neutral and in gear
3) Record the ignition timing in neutral and in gear
4) Remove the new spark plugs and takes pictures. Take pictures of the old plugs if you still have them.
5) Take pictures of the carb and intake from a few angles
6) Maybe make a vid with it running in neutral and in gear.

Then report back to us and post the pictures.

Will do

 

[lewtot184]

if you have the stock carb and automatic trans then the idle circuit (smog stuff) will be too lean. the manual trans carbs had a little richer circuit and there is a noticeable difference in tuning between the two. i went to the manual trans calibration along with backing the mixture screws out on my auto trans smog carb and it made a world of difference. hopefully you're not over cammed.

 

[BLK 68 R/T]

Don’t over look something as easy as the dipstick tube o-ring being the source of the leaks.

 

[Lefty71]

Here is what I think.

Then report back to us and post the pictures.

All solid info....can not disagree, except to say, If you do get the motor running well, and you have'nt touched the trans, don't forget to get a good stall test and actually rule out the converter before you decide it's Ok, or not.

 

[TexasVol]

Ok, so I just want to confirm that I am doing all of this right. To check the initial timing I should disconnect the port vacuum line running to the distributor. Put my gauge on there and check the timing on a fully warm engine correct?

 

[Lefty71]

Ok, so I just want to confirm that I am doing all of this right. To check the initial timing I should disconnect the port vacuum line running to the distributor. Put my gauge on there and check the timing on a fully warm engine correct?

Yes, and make sure the idle is at curb....not elevated or you can get a false reading since the mechanical advance could come into play.

 

[TexasVol]

Update: Just for good measure I replaced the vacuum lines on the carb. I have it idling around 1000 rpms and it looks like I'm at 24°btdc. I didn't mess with the A/F mix screw, it is at 2 turns out.

Since I first posted the other day I have retarded the timing a touch and been able to bring the idle down with it. That by itself seems to have helped. It was hard to start when warm before. It's firing right up now. It was idling around 1350 and has something like 32°

I just took it down the road and it seemed to act better than before.

Once again I don't have any info on what has been done to this motor although other than maybe a small cam I don't think much. Any recommendations on where I have things now? Does the idle need to come down some more?