350/th350 question

[86gmc23]

I just bought a rebuilt 350 and rebuilt th350 with a b&m shift kit already installed.  Just finalized install and took it for test drive.  Engine runs great but th350 didn't shift into 2nd until around 45mph under a hard acceleration, not WOT. Got up to 65mph and didn't shift into 3rd. Was on residential Street so I didn't want to keep going to find 3rd. Slowing down then giving gas again it had no power. Any suggestions on what to look for or check? Any help would be much appreciated. 

[CipherLogic]

Did you hook up the transmission modulator to vacuum source? If not this will happen.


If it is plugged into a vacuum source, make sure line isnt blocked/pinched. Could be a bad modulator.

[86gmc23]

Right now it's tee'd off of the distributor vacuum line,  does it need a separate source? I have another modulator I can swap with it as well.

[CipherLogic]

Where do you have your distributor plumbed into?

I am not 100% certain about the T, I would plumb it in to its own source.

[rich weyand]

Usually it is plumbed to its own source on the back of the intake manifold between the carb and the disti.  It may be taking too long to suck the diaphragm down on that connection, or you could have a vacuum leak in the rubber line.  The trans connection to the intake manifold on mine is a hard line all the way.

[CipherLogic]

Usually it is plumbed to its own source on the back of the intake manifold between the carb and the disti.  It may be taking too long to suck the diaphragm down on that connection, or you could have a vacuum leak in the rubber line.  The trans connection to the intake manifold on mine is a hard line all the way.

I have the distributor ran off the carb's vacuum, brake booster on the rear of the carb and everything else ran off a tree on the back manifold port.

[86gmc23]

I'll fix the vacuum routing and try again before swapping modulators. Thanks for all the help.

[parisherj]

Most of the time dist vacuum is a timed vacuum. like they said hook it to its own full time vacuum source and try it.

[86gmc23]

Ran new lines, just need to pick up a fitting for the vacuum port on intake. Both will have own separate lines.

My oil pressure gauge was faulty and just checked it with hand held gauge and it's down around 10-15psi, can anything other than oil pump cause this?

Looking at oil pumps, should I replace pump only or all components with it as well? Also is high flow pump needed or no, looking at Melting pumps from advanced.

[Irish_Alley]

10-15 psi warm? but run the distributor off a ported vacuum. rich should be able to tell you why

[86gmc23]

Start up hit about 25psi then fell close to 10psi, never let it warm up during test. 

Distributor is currently run off port on right side of carb,  if it needs to be ran from ported I certainly will change it. If that's the case can the trans be ran off carb?

[Irish_Alley]

sorry meant that dont run the distributor off ported run both on manifold vacuum. i wont say anything about the oil pressure but my 350 at start up hits 50 once warm 15 if i run her too hard it will drop to 10. but this is with a motor thats been in a couple of my trucks and neither one was babied

[rich weyand]

Here's why to run the distributor off manifold vacuum (the lower port) and not "timed" or "ported" vacuum.
http://www.corvetteactioncenter.com/forums/c3-technical-performance/60830-ported-vs-manifold-source-vacuum-advance.html

[86gmc23]

How are those different vacuum sources identified? I think I have an idea but want to be sure.

[rich weyand]

Ported, or timed, vacuum will run to an orifice in the carb body above the throttle plate.  Manifold vacuum is either off the manifold itself or via an orifice in the carb body below the throttle plate.  So Ported vacuum will be higher on the carb body than manifold vacuum.  You don't say what kind of carb you have, but on the Carter and Edelbrock, manifold vacuum is on the driver's side of center, and ported vacuum is on the passenger's side of center, on the front of the carb.