I'm on the tail end of an engine rebuild and now we're trying to work out all the kinks that keep coming up. One of the issues is that my transmission will shift into drive, but after that won't shift up so I end up running around 3000 RPM only doing 30 or so mph. When we pulled the engine we just left the transmission in there, so I haven't done anything with it other than plug the engine back in. Any suggestions on why it might not be shifting? My timing is also apparently off, from what I've read it should be closer to 8 degrees before 0 (the engine is an 86-88 350, and according to haynes the timing should be anywhere from 4-8 degrees before 0)

 

Unhook the shifter linkage to see if it will shift in all gears without it running, and wheels blocked. If it does, then suspect shifter cable/linkage. Also could be the kick down cable/rod engaging it. Was it like this before?
It could be lack of vacuum to the modulator valve.

 

Ya gotta tell us what you are working on. Can't read your mind.

Allan

 

Sorry, I thought I included that. I am working on a chevy 350 ('86-'88 350 shortblock assmebly w/ 305 heads (installed by previous owner)) and I beleive the transmission is a 700R4.

kevinkpk, I'll try that and let you know what happens. No it wasn't like this before, but the transmission has had some rough times, I got some gaskets replaced and the shop didn't refill the fluid so drove for almost 2 weeks on low fluid not knowing what was wrong with it (a pretty stupid mistake I admit), and once my throttle got stuck wide open, so I shifted into neutral, and in my efforts not to blow the engine I threw it into park when it was still going about 20mph (not the best of choices). And its always had a bit of a delay when engaging from a dead stop. Thanks for the help.

 

Okay, here's the deal. <O</OIf it is in fact a 4L60, the transmission will not upshift until the TV cable is hooked up.

<O</O
If someone has converted this guy to a 350 (many did on this vintage of truck because of that lousy 700R4) then check to make sure you have good vacuum to the modulator.

<O</O
The pan on a 4L60 is rectangular; a 350 pan is square with one rear corner cut on a diagonal with two bolts in the diagonal. A 350C will have 1 bolt across that corner.

Oh, and don't worry 'bout dropping it into park at speed. The pawl won't engage until you're down around 1-2mph anyway.

<O</OAllan <O</O

 

Well, turns out I just didn't have a vacuum hose plugged in, simple fix. Though I was wondering, would the transmission shift better with the vacuum hose plugged directly into the intake manifold instead of the vacuum plug on the carb, or would there not be much of a difference? Thanks for the help.

 

it needs the connection at the carb to measure vacuum for the 3-4 upshift and for forced downshifts.

 

Ok, thanks, I'll leave it on the Carb.

 

I recently got a 2001 chevy silverado 1500 5.3L truck. It worked fine but as i brought it home it suddenly decides to not shift anymore. I manually have to shift it. I researched and changed the ATSLC FUSE 10A: automatic transmission shift lock control solenoid. Under the hood fuse box.
thats what one person said to do.

After i changed it it is still doing it. Any sugestions?

 

yo same truck and same problem.. ever get a answer on fixing it