Th350 behind 4.8ls

[bucket]

The 350 is a vacuum controlled transmission.

One of my vac hoses broke and the result was it wouldn't shift out of 1st gear.

Def make sure all your vacuum points are working right still.

With the vacuum line unhooked, it will still shift, you just have to wind it out for it to do so.

When I was young and wanted my car to sound and shift like a race car, I experimented with removing the vacuum supply to the modulator.

 

[Ricko1966]

With the vacuum line unhooked, it will still shift, you just have to wind it out for it to do so.

When I was young and wanted my car to sound and shift like a race car, I experimented with removing the vacuum supply to the modulator.

I've driven cars with no vacuum to the modulator out of shear laziness before,for long periods of time. Bad modulator,cap it plug the vacuum line manually upshift it. 700r4 to th350 swap. I'll run a vacuum line when I get to it.

 

[dirtscoots]

So I just drove the truck again I’ll try to explain the symptoms. Taking off forward and reverse isn’t bad. It will go. It doesn’t want to pull a small hill on my road. Power to the wheels seems very minimal for as light of a truck with such small tires. There is zero possible way it will spin a tire on pavement. As I drive it to get it to shift up I have to floor it then completely let off. I’m also having other suspension issues so driving is very minimal. The modulator looks like newer style for sure. My next step is to check vacuum. I appreciate all the input it’s coming into hunting season so this will probably be on back burner for a bit.

 

[bucket]

Many times I've seen a vehicle that the engine was lacking so much power that it caused the trans not to shift properly, because your foot was in the throttle hard which makes the trans hold a gear longer. But there was no power to accelerate through that gear.

 

[AuroraGirl]

Many times I've seen a vehicle that the engine was lacking so much power that it caused the trans not to shift properly, because your foot was in the throttle hard which makes the trans hold a gear longer. But there was no power to accelerate through that gear.

what carburetor are you using

So I just drove the truck again I’ll try to explain the symptoms. Taking off forward and reverse isn’t bad. It will go. It doesn’t want to pull a small hill on my road. Power to the wheels seems very minimal for as light of a truck with such small tires. There is zero possible way it will spin a tire on pavement. As I drive it to get it to shift up I have to floor it then completely let off. I’m also having other suspension issues so driving is very minimal. The modulator looks like newer style for sure. My next step is to check vacuum. I appreciate all the input it’s coming into hunting season so this will probably be on back burner for a bit.

if you have a 4 barrel , the linkage for the secondary may be too aggressive , or you have the kickdown cable wrong adjusted, there are 2 different th350 kickdowns btw

The other thing is what cable are you using

A 2 barrel carb bracket on a 4 barrel is going to mess with allowing the cable to relax properly and maybe even open all the way, the cables are the same i think tho

 

[Ricko1966]

It will drive with the kickdown disconnected at the carb. It just won't kick down.

 

[AuroraGirl]

It will drive with the kickdown disconnected at the carb. It just won't kick down.

yes, but im saying he may have issues with the operation if its kicking down at the wrong times, so when hes expecting it to be charging up a hill its falling flat on its face instead of dropping

Also how is the timing done on this thing with a carb and th350, is there something using a vacuum signal or is it done only on rpm... i guess i have more questions now lol

 

[Ricko1966]

yes, but im saying he may have issues with the operation if its kicking down at the wrong times, so when hes expecting it to be charging up a hill its falling flat on its face instead of dropping

Also how is the timing done on this thing with a carb and th350, is there something using a vacuum signal or is it done only on rpm... i guess i have more questions now lol

I just take it for granted,that everyone knows how and when to manually down shift. I threw out the fact it will drive without the cable,thinking if OP had a doubt he'd disconnect it and go for a drive.

 

[AuroraGirl]

I just take it for granted,that everyone knows how and when to manually down shift. I threw out the fact it will drive without the cable,thinking if OP had a doubt he'd disconnect it and go for a drive.

Some people tho lol. Not likely this guy however. I wish 70s and 80s columns had the feature of the 90s+ where you push the lever forward and you can move it one at a time based on detents

 

[Ricko1966]

Some people tho lol. Not likely this guy however. I wish 70s and 80s columns had the feature of the 90s+ where you push the lever forward and you can move it one at a time based on detents

I can feel the detents in everything I own or have owned.

 

[AuroraGirl]

I can feel the detents in everything I own or have owned.

no, you mis understand, the feeling of the detents isnt what i meant, its that the individual positions of the column would be evident even if you removed the shifter linkage or cable (depending on year)

if you undo the trucks shifter from the trans lever, when the key is out of lock the shifter will be loosy goosy and goes all over.
A certain year, you could go all the way down, push it forward, and then move it a single gear at a time, they did this for when they went electronic shifter positions i think, so that when the transmission cable was adjusted this would allow precise and specific positions so that the dash will be correct, and because the transmission has its own detents , matching them will create perfect harmony unless a cable stretches

which i am noticing in my 2005 , i did the push forward thing and it binds trying to get reverse and neutral (which is something thats more likely when the cable is getting stretched)
The reason I wish old trucks have it , is so that when the indicator isnt aligned or when the shifter isnt distinct when you move it (old/wear) , you could count up from the bottom and know youre in something, or avoid overshooting a single bump up or down

 

[Ricko1966]

no, you mis understand, the feeling of the detents isnt what i meant, its that the individual positions of the column would be evident even if you removed the shifter linkage or cable (depending on year)

if you undo the trucks shifter from the trans lever, when the key is out of lock the shifter will be loosy goosy and goes all over.
A certain year, you could go all the way down, push it forward, and then move it a single gear at a time, they did this for when they went electronic shifter positions i think, so that when the transmission cable was adjusted this would allow precise and specific positions so that the dash will be correct, and because the transmission has its own detents , matching them will create perfect harmony unless a cable stretches

which i am noticing in my 2005 , i did the push forward thing and it binds trying to get reverse and neutral (which is something thats more likely when the cable is getting stretched)
The reason I wish old trucks have it , is so that when the indicator isnt aligned or when the shifter isnt distinct when you move it (old/wear) , you could count up from the bottom and know youre in something, or avoid overshooting a single bump up or down

I can already count up or down to figure where I'm at. Not problem for me.

 

[AuroraGirl]

I can already count up or down to figure where I'm at. Not problem for me.

no one is doubting your ability , but im saying it would be a nice QOL feature to have because of nature of 4l80e and very early 4l60e to require specific voltages on the mode switch to work right , and gives an extra layer of diagnostic for stretched cables (probably doesnt affect the linkage years unless you had some kind of massive wear on the shifter shaft, or maybe the column side of that.)
And in old squares with the indicator not aligned it would be nice because sometimes the shifter feel between the positions isnt very distinct, so it would allow assured shifting despite the indicator

 

[bucket]

no one is doubting your ability , but im saying it would be a nice QOL feature to have because of nature of 4l80e and very early 4l60e to require specific voltages on the mode switch to work right , and gives an extra layer of diagnostic for stretched cables (probably doesnt affect the linkage years unless you had some kind of massive wear on the shifter shaft, or maybe the column side of that.)
And in old squares with the indicator not aligned it would be nice because sometimes the shifter feel between the positions isnt very distinct, so it would allow assured shifting despite the indicator

I rarely ever look at the indicator, I just go by feel. But I know some people hate when their indicator is broken.

 

[GXPWeasel]

I rarely ever look at the indicator, I just go by feel. But I know some people hate when their indicator is broken.

LOL.
Mine's been broken too since I've had the truck on the road. The worst part... I have the parts to fix it, but haven't. Other things take priority. The good part, I've taught my daugther to drive the truck by counting the gears down as well. Came in handy for her '97 a time or two.