Torque Converter Shopping...Yay !

Tynan918

Royal Smart Person
Aug 2, 2021
1,120
63
I have a huge rpm drop (400) from Park to Drive, and a off idle bog, stumble, and stall that I can't get rid of now matter how much I adjust the carburetor and timing...those things are not causing my issue...and plenty are calling out this 1397 stall converter being the cause... it's either wrong or it's failing.



Need to find another converter with the correct range to replace it.

I need to know what stall speed range that I need for my car. (240 ft-lbs of torque at 3,200 rpm)
Screenshot_20221102-195527-613.png


Car and Weight: 1984 Monte Carlo, weighs 2987 lbs.

Engine: 83-84 305 H.O. L69, de-smogged, 600cfm Holley Street Avenger, Edelbrock Performer EPS intake.

Cam: 1982 -'86 L69 - Duration @ .050": 202/206
Max Lift: .403/.415 - 115
Idle: 650 rpm

Compression ratio: 9.5:1 (flat piston)

Torque rating: 240 ft-lbs of torque at 3,200 rpm.

Transmission: TH350C (lock up disconnected).

Tire Diameter: not sure about the tire diameter, but the rim size is 14".

What is the formula that I need to calculate in order to get the right stall speed for my build ?
 
Oct 14, 2008
8,310
113
Melville,Saskatchewan
If you aren't using the lock up, get a non lock up TH350. The lock up TH350 uses a unique and more expensive converter.
 
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ELCAM

G-Body Guru
Jun 19, 2021
804
93
Take your car over a scale, it likely weighs 3400-3500 pounds.

Need the rear axle ratio to determine a stall speed and the actual tire height.

As stated above the lockup converter is more expensive and limits choices.

You can modify the 350c to a 350 by changing the pump to a non lock up one, drilling the pump for a drain back hole, modifying the add on valve body and removing a check ball from the main valve body. Can post the info if you need it.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,403
113
Galaxy far far away
In stock form the curb idle for most 305s is 600 rpm in drive and 1k in park. My 2008 police packge Crown Vic has similar idle rpms.

Off idle bog could be a bad accel pump, idle circuit issues, vacuum leaks, bad or misadjusted choke pulloff, etc.

Moreover, you posted in another thread that you have a single plane intake manifold which can cause tuning issues on an otherwise stock street engine. Who knows if its even installed correctly?
 
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Tynan918

Royal Smart Person
Thread starter
Aug 2, 2021
1,120
63
If you aren't using the lock up, get a non lock up TH350. The lock up TH350 uses a unique and more expensive converter.
I can barely afford a torque converter yet alone a transmission.

The transmission I have is a th350c, the lockup connector is disconnected from it... can I get a non lockup torque converter for it ?
 

Tynan918

Royal Smart Person
Thread starter
Aug 2, 2021
1,120
63
Take your car over a scale, it likely weighs 3400-3500 pounds.

Need the rear axle ratio to determine a stall speed and the actual tire height.

As stated above the lockup converter is more expensive and limits choices.

You can modify the 350c to a 350 by changing the pump to a non lock up one, drilling the pump for a drain back hole, modifying the add on valve body and removing a check ball from the main valve body. Can post the info if you need it.
I thought it was a simple as unplugging the lockup connector ?

Sure for future reference, you can go ahead and send me that info. I may just buy another transmission if that's the case.
 

Tynan918

Royal Smart Person
Thread starter
Aug 2, 2021
1,120
63
In stock form the curb idle for most 305s is 600 rpm in drive and 1k in park.
The l69305 had different heads and different camshaft from the other 305s... The factory and gear carb idle is 650 for the l69

From Park to drive RPM drop should only be 200... If the in gear is 650 then my curb idle is supposed to be 850.

It runs better at a thousand RPMs in park because I'm at 650 and drive... And anything higher than that, it diesels.

It just sounds like I have my foot on the pedal when it's in park...
 

Tynan918

Royal Smart Person
Thread starter
Aug 2, 2021
1,120
63
There are some videos I shot yesterday...

One is showing the off idle bog and stalling..

The other is showing you the 400 RPM drop from Park to drive...


 

SSMonteMan

Greasemonkey
Jun 12, 2015
110
43
There are some videos I shot yesterday...

One is showing the off idle bog and stalling..

The other is showing you the 400 RPM drop from Park to drive...


These look more like carb issues than tq converter issues to me.
 
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Oct 14, 2008
8,310
113
Melville,Saskatchewan
I can barely afford a torque converter yet alone a transmission.

The transmission I have is a th350c, the lockup connector is disconnected from it... can I get a non lockup torque converter for it ?
No, not without doing the modifications mentioned, as in swapping to non lock up pump assembly. It has a different spline count vs a non lock up TH350.
 
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