I just bought a 87 Silverado w a 700r4 the owner claims to have just freshened up. I see a new converter in there too. The problem is on the highway when it shifts to overdrive it acts like it is surging in between D and OD. it shifts firm all the rest of the time and doesn't always happen. Im not 100% sure its not in the top of #rd that the problem is as if I keep it in 3rd it almost feels like it wants to do it in the top of the gear. Anyone have any ideas? It will actually hunt between D and OD I guess you could say.
700r4?? not in my Buick
- Thread starter TWISTER
- Start date
- Joined
- May 28, 2001
OK. Now let others in on the "find"???nevermind i think i found the issue
It is a 87 chevy half ton 2wd truck w 305 TBI (170hp) at best. Previous owner added 3/4 ton axles and a transfer case and made it a 4x4. Along with heavy 35" tires. Need less to say the computer controls shifts and it doesn't have enough hp to sustain the OD so it bogs on the shift and starts to hunt..lol.. Easy fix is the Vortec 350 Carb conversion I have planned..lol The dipstick on the trans pushing out seems to be common but I need to look for a plugged vent. Now I just have to find the best Vortec route to go for a carb set up...lol
RmvBfrFlght
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- Joined
- Sep 28, 2007
The computer doesn't control the shifts with the 700R4. Shifting is hydro-mechanical via the TV cable position (line pressure) and governor RPM.
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That makes sense.. none the less the 305 will bog at the D, OD shift.. If I leave it in D I have no issue. I just hope its the weak 305 and not a trans issue. I will adjust the TV cable and go from there I guess. Funny you responded as I was just looking into the Dynamic EFI for this truck rather than a carb. But I didnt think I cound run it on a 450cfm TB that needs to support 300hp or so.
RmvBfrFlght
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- Sep 28, 2007
Can swap the small TBI unit from a BBC unit. Has 48mm bores for 670 CFM (4-bbl rating).
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