'70 Nova LY6/TH400 6.0VVT
#1161
TECH Fanatic
iTrader: (30)
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Yeah, I know what you mean about all the extra plumbing, etc. My trans and water temp gauges in my 73 are both Autometer electric units but I run a mechanical oil pressure gauge. Same on the 99 TA......Autometer electric water temp and mechanical oil pressure.
Funny thing about the 99 Fbods. Apparently, in 98 GM had a lot of warranty complaints about customers water temp gauges "moving around too much" and couldn't convince folks that the temp was supposed to drop when the thermostat opens and fans kick on. So instead they "desensitized" the gauge in 99. I've seen temps anywhere from 20 degrees above to 20 degrees below 210 and the factory gauge still reads 210.....lol.
Funny thing about the 99 Fbods. Apparently, in 98 GM had a lot of warranty complaints about customers water temp gauges "moving around too much" and couldn't convince folks that the temp was supposed to drop when the thermostat opens and fans kick on. So instead they "desensitized" the gauge in 99. I've seen temps anywhere from 20 degrees above to 20 degrees below 210 and the factory gauge still reads 210.....lol.
#1162
12 Second Club
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![](https://cimg8.ibsrv.net/gimg/ls1tech.com-vbulletin/800x450/ly6swap935_9bbba45a872ad48d38dc9f4ce3c29c483d22ee48.jpg)
And I hear you on the little things you need to get done now that it's driveable. Window and exhaust rattles, brake calipers coming loose, windshield seal leaks, center vents not blowing, LEDs going out... I have a host of things to fix now that it's not just sitting.
#1164
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I love everything about this. An older pair of car seats haven't left my back seat for at least the past year, and I usually drop the boys off at school in the Nova. I'm strongly considering refitting the back with 3-point belts and a modern bucket-style seat (like what scherp69 did) for a little more room and the ability to use boosters.
And I hear you on the little things you need to get done now that it's driveable. Window and exhaust rattles, brake calipers coming loose, windshield seal leaks, center vents not blowing, LEDs going out... I have a host of things to fix now that it's not just sitting.
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#1165
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Glad too see the car is back on the road, I have been checking in every couple months since the beginning hoping to see the finish.
A TH400 is so cheap and easy to rebuild, I would pull it and drop it off at a tranny shop. For $600 (around here at least) you would have a fresh tranny. Not much external to cause shifting issues with a TH400.
A TH400 is so cheap and easy to rebuild, I would pull it and drop it off at a tranny shop. For $600 (around here at least) you would have a fresh tranny. Not much external to cause shifting issues with a TH400.
#1166
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Juist go 4L80E
#1167
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My garage is a 3 door 20x30. The 20ft depth does not leave much room in front of a car for a workbench and room to stand, so I need to pull the car in just far enough to close the door and no more. Instead of dangling a tennis ball, I picked up parking laser pointer that activates with motion. I have it pointing to the transition between the hood and cowl panel so all I have to do is watch it as I pull in. This gets the back of the car as close as possible to the roll-up door so I have a couple feet in front to work.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap942.jpg)
I've decided to take the car out at least once a week, weather permitting, when I take my son to baseball practice. I love that I can fire it up and drive off immediately, without waiting for things to warm up, and it runs without stumbling to wherever I need to go. Of course it runs better as it warms up, but the fact that I can get out of the driveway with it cold is a huge improvement over my old carbed setup, which had no choke/fast idle and needed to run a few minutes before throwing into gear.
Here's a photo of the car at the baseball fields a couple weeks ago.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap944.jpg)
It occurred to me that a long time ago during the swap I had found the vacuum modulator screw was adjusted all the way out loose and I had turned it in about 1.5 revolutions because I read somewhere that was a good base line. Since getting the swap running and having the transmission problems, I've tried disconnecting vacuum and adjusting the screw in tighter, but I hadn't tried backing the screw out to loose again. So before a drove to practice yesterday, I loosened the screw and what do you know, it now will shift into 3rd and usually hold it there under part throttle. Something tells me I'm back to where the transmission was before the swap. I'm wondering now if maybe the line pressure or governor pressure is too low, requiring a loose modulator screw plus vacuum to allow the governor pressure to overcome the modulator and cause a shift. Maybe that would explain why the transmission is acting oddly with engine load / vacuum. At any rate it does seem to at least shift more normally now.
On the way to practice, I stopped at the pharmacy to pick up some albuterol for my daughter. She has breathing problems when she gets sick, so we have to treat her with a nebulizer. It sucks when she's sick.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap945.jpg)
When I got to practice, I had to parallel park and the power steering was just awful. That's when I discovered the fluid level had dropped to just the tip of the dipstick. After topping it off it started working more like it should. I'm guessing the system previously had some air that wouldn't burp. Good news there!
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap946.jpg)
After practice, we drove over to one of our favorite sandwich shops where I took this framer photo of my boy. He always asks to take the Nova everywhere we go - I hate to turn him down.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap947.jpg)
Here is a picture of my happy place - "the office". I still have a few dangling wires that I need to do something with, but I just can't find time to get any real work done on the car right now. I've had a recently family loss, and I'm contending with my job, unexpected house repairs, and all the demands of parenting. Anyway, near the parking brake I have rolled up the tach wires that need to be connected still and all the gauge wiring under the dash needs to be tied up or replaced with mechanical gear.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap943.jpg)
I read the oil pressure after warmup with the OBD2 reader and found it was showing a hair over 20psi while the gauge read about 15psi. I trust the obd2 over the gauge, but I still want to confirm with a mechanical gauge.
Looking forward to a lot more driving and buttoning up some loose ends!
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap942.jpg)
I've decided to take the car out at least once a week, weather permitting, when I take my son to baseball practice. I love that I can fire it up and drive off immediately, without waiting for things to warm up, and it runs without stumbling to wherever I need to go. Of course it runs better as it warms up, but the fact that I can get out of the driveway with it cold is a huge improvement over my old carbed setup, which had no choke/fast idle and needed to run a few minutes before throwing into gear.
Here's a photo of the car at the baseball fields a couple weeks ago.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap944.jpg)
It occurred to me that a long time ago during the swap I had found the vacuum modulator screw was adjusted all the way out loose and I had turned it in about 1.5 revolutions because I read somewhere that was a good base line. Since getting the swap running and having the transmission problems, I've tried disconnecting vacuum and adjusting the screw in tighter, but I hadn't tried backing the screw out to loose again. So before a drove to practice yesterday, I loosened the screw and what do you know, it now will shift into 3rd and usually hold it there under part throttle. Something tells me I'm back to where the transmission was before the swap. I'm wondering now if maybe the line pressure or governor pressure is too low, requiring a loose modulator screw plus vacuum to allow the governor pressure to overcome the modulator and cause a shift. Maybe that would explain why the transmission is acting oddly with engine load / vacuum. At any rate it does seem to at least shift more normally now.
On the way to practice, I stopped at the pharmacy to pick up some albuterol for my daughter. She has breathing problems when she gets sick, so we have to treat her with a nebulizer. It sucks when she's sick.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap945.jpg)
When I got to practice, I had to parallel park and the power steering was just awful. That's when I discovered the fluid level had dropped to just the tip of the dipstick. After topping it off it started working more like it should. I'm guessing the system previously had some air that wouldn't burp. Good news there!
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap946.jpg)
After practice, we drove over to one of our favorite sandwich shops where I took this framer photo of my boy. He always asks to take the Nova everywhere we go - I hate to turn him down.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap947.jpg)
Here is a picture of my happy place - "the office". I still have a few dangling wires that I need to do something with, but I just can't find time to get any real work done on the car right now. I've had a recently family loss, and I'm contending with my job, unexpected house repairs, and all the demands of parenting. Anyway, near the parking brake I have rolled up the tach wires that need to be connected still and all the gauge wiring under the dash needs to be tied up or replaced with mechanical gear.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap943.jpg)
I read the oil pressure after warmup with the OBD2 reader and found it was showing a hair over 20psi while the gauge read about 15psi. I trust the obd2 over the gauge, but I still want to confirm with a mechanical gauge.
Looking forward to a lot more driving and buttoning up some loose ends!
#1170
12 Second Club
iTrader: (12)
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For what it's worth, my pressure is ~35 at idle, according to my gauge. I've seen it reported anywhere from 20-40 at idle, so while yours seems low, it is apparently not cause for concern.
Croup is the worst. Twins had it when they were younger.
On the way to practice, I stopped at the pharmacy to pick up some albuterol for my daughter. She has breathing problems when she gets sick, so we have to treat her with a nebulizer. It sucks when she's sick.
#1171
TECH Senior Member
iTrader: (12)
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15 to 20 psi seems a bit low at idle. but it is not uncommon and is within specs. It is possible that the O-Ring on the pick up is not sealing and causing the lost in pressure.
Both of my cars are +55psi at idle when warm. Did you replace the pump when you put it together ?...
Sorry to hear about your family lost.
BC
Both of my cars are +55psi at idle when warm. Did you replace the pump when you put it together ?...
Sorry to hear about your family lost.
BC
#1172
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I did not replace the oil pump. I probably should have and I'm not sure why I decided not to.
I took the Nova to work this morning and logged the drive w/ the OBD2/Torque App. The idle oil pressure started at 25psi cold and eventually settled to 17psi warm. The Speedhut CAN-bus gauge was reading a few PSI lower than what I pulled off OBD2; I trust the OBD2 over the gauge, but I need to add a mechanical gauge and see how it compares.
Unfortunately the transmission problem still isn't resolved. At freeway speeds it's still shuffling between 2nd and 3rd. Still odd that it never did this before the swap. I must be missing something.
I took the Nova to work this morning and logged the drive w/ the OBD2/Torque App. The idle oil pressure started at 25psi cold and eventually settled to 17psi warm. The Speedhut CAN-bus gauge was reading a few PSI lower than what I pulled off OBD2; I trust the OBD2 over the gauge, but I need to add a mechanical gauge and see how it compares.
Unfortunately the transmission problem still isn't resolved. At freeway speeds it's still shuffling between 2nd and 3rd. Still odd that it never did this before the swap. I must be missing something.
#1173
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Now is the time to go 4L80e
#1177
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Joe,
So what are you trying to say? LOL.
Clint,
At least you're running and driving your conversion. Enjoy it. It might we worth a visit to any local GOOD tranny shop to see what it might be/cost.
So what are you trying to say? LOL.
Clint,
At least you're running and driving your conversion. Enjoy it. It might we worth a visit to any local GOOD tranny shop to see what it might be/cost.
#1178
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I pulled the governor and it looked fine. The valve and weights moved freely. It appeared to be a stock/unmodified governor, although one of the two springs was much heavier than the other. Here is a video on Instagram of my governor functioning: I put the governor back in and took it for a spin confirming there was no change. It continued to shuffle between 2-3-2-3-2 when cruising at part throttle and downshifted when applying throttle/WOT.
Next I disconnected vacuum from the modulator, simulating WOT. I found a good straight on ramp to the highway to see where it would shift. 1-2 shift hit at about 10mph and soft. I ran second gear all the way to the rev limiter 6,250rpm and it never shifted 2-3. It just stayed in 2nd. I'm pretty sure that's not right!
So last night I got the car in the air, drained the transmission and dropped the pan.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap948.jpg)
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap949.jpg)
I didn't find any broken bits in the pan. The filter was still attached at the o-ring/pickup tube (obviously I took it off before taking the photo above). The detent solenoid was bolted down tight.
I decided to drop the valve body. This is the furthest I've ever explored the internals of an automatic transmission. I don't expect I'll be going any further than this.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap950.jpg)
I checked each valve and they all seemed to move freely with a flathead screwdriver. I was hoping to find something obviously wrong, but no dice.
So my plan now is to start fresh on a few parts. I ordered a Transgo 400-PRO reprogramming kit, which includes new shift valves and springs, pressure regulator spring, accumulator piston, separator plate that dual feeds the direct clutch, governor springs, gaskets etc. I figure rebuilding the valvebody with this stuff will establish a fresh a baseline. I also ordered a new vacuum modulator in case something is screwy there and got a switch for the gas pedal so I can get the kickdown/detent system working.
I am hoping this is the last $100 I throw at this automagic and if it doesn't shift properly after this, I am going to live with it until I can find a suitable 6spd.
Next I disconnected vacuum from the modulator, simulating WOT. I found a good straight on ramp to the highway to see where it would shift. 1-2 shift hit at about 10mph and soft. I ran second gear all the way to the rev limiter 6,250rpm and it never shifted 2-3. It just stayed in 2nd. I'm pretty sure that's not right!
So last night I got the car in the air, drained the transmission and dropped the pan.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap948.jpg)
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap949.jpg)
I didn't find any broken bits in the pan. The filter was still attached at the o-ring/pickup tube (obviously I took it off before taking the photo above). The detent solenoid was bolted down tight.
I decided to drop the valve body. This is the furthest I've ever explored the internals of an automatic transmission. I don't expect I'll be going any further than this.
![](http://cjnn.xtremefabricator.com/images/LY6swap/ly6swap950.jpg)
I checked each valve and they all seemed to move freely with a flathead screwdriver. I was hoping to find something obviously wrong, but no dice.
So my plan now is to start fresh on a few parts. I ordered a Transgo 400-PRO reprogramming kit, which includes new shift valves and springs, pressure regulator spring, accumulator piston, separator plate that dual feeds the direct clutch, governor springs, gaskets etc. I figure rebuilding the valvebody with this stuff will establish a fresh a baseline. I also ordered a new vacuum modulator in case something is screwy there and got a switch for the gas pedal so I can get the kickdown/detent system working.
I am hoping this is the last $100 I throw at this automagic and if it doesn't shift properly after this, I am going to live with it until I can find a suitable 6spd.
#1180
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Clint,
Sorry for the family loss. (finally fully read that post, Sorry) Now onto your car. On the semi bright side, The fuild looks good. LOL. Hopefully the shift kit does the trick. BOL
Sorry for the family loss. (finally fully read that post, Sorry) Now onto your car. On the semi bright side, The fuild looks good. LOL. Hopefully the shift kit does the trick. BOL