OuchMyToe
Junior Member
- Joined
- Apr 4, 2019
- Posts
- 13
- Reaction score
- 2
- Location
- Tooele, Utah
- First Name
- Kyle
- Truck Year
- 1985
- Truck Model
- C10
- Engine Size
- 400 CID
Background story:
I have a 1985 C10 Scottsdale P/U that I just finished equipping with a 400 SBC from a 1975 (or 76?) Caprice Classic Convertable. The original 305 hydro-locked after...yadda, yadda, yadda...long embarrassing story. Anyway, while putting in the 400 (it's a SBC; how hard could it be?) I discovered many things that had to be changed and replaced to match the new (i.e., old) engine. During that process, I decided to remove nearly all the emissions controls. I live in a county that has no emissions restrictions and, as I'm sure many of you know, the 1985 C10 had a veritable rat's nest of hoses and pipes under the hood. I took out the EGR, AIR pump, EFE (because I had to get new exhaust manifolds), canister, and the small components in the air cleaner (including that weird permanent air filter that lies inside the paper filter—what is that anyway?). I also removed the electronic spark control box and jumpered the ignition coil. All of this may not be important but who knows. I removed all the thermal vacuum switches and ran vacuum hoses straight from the carburetor—which I also rebuilt—or the manifold source behind the carburetor.
Current situation:
So after finishing the engine and going for a test drive, I noticed that the 1st-to-2nd shift was quite harsh. 2nd-to-3rd, not so much. I found that giving it more gas made the shift better. Anyway, I didn't have a chance to drive much, and even then, not above 45 MPH, until today. As I drove faster today, the shifting grew smoother. After that, it was smoother even when driving slowly. I cycled through all the gears manually and it seemed to respond well. Five minutes later, after getting up to speed and then slowing down for a turn, I noticed that there was hardly any power after turning and the engine was slowing way down. I thought it probably was not downshifting so I manually shifted from OD to D...still no power, D to 2...still no power with fast engine, and 2 to 1...racing engine and still no power. I came to a stop, tried to start again, and what do you know? Power!
Possibilities:
#1 Perhaps the TV cable needs to be adjusted? I didn't mess with it during the swap but who knows? I've heard that 700R4s can be super sensitive to a TV cable out of adjustment.
#2 When others have run the TCC vacuum straight from the carburetor, they have also installed a lower-pressure TCC switch. I remember something about the stock switch needing 7 PSI and caused lock-up problems. I can't remember exactly what the problem was but perhaps someone here is familiar with that modification.
#3 The transmission has one foot in the grave.
Has anyone experienced a problem like this and found the solution?
I have a 1985 C10 Scottsdale P/U that I just finished equipping with a 400 SBC from a 1975 (or 76?) Caprice Classic Convertable. The original 305 hydro-locked after...yadda, yadda, yadda...long embarrassing story. Anyway, while putting in the 400 (it's a SBC; how hard could it be?) I discovered many things that had to be changed and replaced to match the new (i.e., old) engine. During that process, I decided to remove nearly all the emissions controls. I live in a county that has no emissions restrictions and, as I'm sure many of you know, the 1985 C10 had a veritable rat's nest of hoses and pipes under the hood. I took out the EGR, AIR pump, EFE (because I had to get new exhaust manifolds), canister, and the small components in the air cleaner (including that weird permanent air filter that lies inside the paper filter—what is that anyway?). I also removed the electronic spark control box and jumpered the ignition coil. All of this may not be important but who knows. I removed all the thermal vacuum switches and ran vacuum hoses straight from the carburetor—which I also rebuilt—or the manifold source behind the carburetor.
Current situation:
So after finishing the engine and going for a test drive, I noticed that the 1st-to-2nd shift was quite harsh. 2nd-to-3rd, not so much. I found that giving it more gas made the shift better. Anyway, I didn't have a chance to drive much, and even then, not above 45 MPH, until today. As I drove faster today, the shifting grew smoother. After that, it was smoother even when driving slowly. I cycled through all the gears manually and it seemed to respond well. Five minutes later, after getting up to speed and then slowing down for a turn, I noticed that there was hardly any power after turning and the engine was slowing way down. I thought it probably was not downshifting so I manually shifted from OD to D...still no power, D to 2...still no power with fast engine, and 2 to 1...racing engine and still no power. I came to a stop, tried to start again, and what do you know? Power!
Possibilities:
#1 Perhaps the TV cable needs to be adjusted? I didn't mess with it during the swap but who knows? I've heard that 700R4s can be super sensitive to a TV cable out of adjustment.
#2 When others have run the TCC vacuum straight from the carburetor, they have also installed a lower-pressure TCC switch. I remember something about the stock switch needing 7 PSI and caused lock-up problems. I can't remember exactly what the problem was but perhaps someone here is familiar with that modification.
#3 The transmission has one foot in the grave.
Has anyone experienced a problem like this and found the solution?
