T-400 shifting too quick
 

I have a big block and I just got a th400 built and have a 2600-2800 stall, gear 3:90 and a single plane intake. Its a street/strip car but the car see more of the street than the track:confused:

https://partimages.genpt.com/partimages/292530.jpg
Vacuum modulator connected to MANIFOLD vacuum?

66GMC - the carb

Some Modulators are adjustable, small screw inside tube where Hose connects. It will give a small 3-5mph range.
For more adjustment you'll need a Governor Recalibration Kit.
B&M Governor Recalibration Kits 20248 - SummitRacing.com
Modulator needs Full Manifold Vac, not Ported/Timed Vac source.

Yup ... I'd start with connecting the vacuum line directly to MANIFOLD vacuum.

Ssedan64 -will try

I have to drill a hole on the single plane intake. That means I have to remove it?

I recently did the governor mod on my th 350. Im all smiles now. Regular part throttle shifts with full throttle 5500 rpm shifts. It actually gets in to an rpm range the cam likes. :D

Yup, you need the governor recalibration kit. Easy to do, but you basically have to guess the springs and weights, then test drive it.
Took me 4 tries to nail mine down.

I was lucky, got it first try. Used stock springs and IIRC I went 4 grams total lighter on the weights. The original weights that were on the governor were a lot lighter than i expected.

Really? There are NO provisions on that intake?
There is usually one on the rear face of the manifold, below the carb mounting flange. If not, that's where I would CAREFULLY drill and tap a 1/8" NPT hole for a small vacuum hose-barb.

You may be able to do this by simply removing the carb and taping off the intake runners to prevent any material getting away on you. Drill and tap the hole, and then vacuum up the debris.

Use extreme care when tightening any pipe thread fittings on an aluminum intake, as the the thread is tapered and can crack the intake if over-tightened.

Its a single plane not the dual plane

Not necessarily. "Manifold" vacuum only means a full-time vacuum source that is there even at idle. "Ported" vacuum is NOT there at idle, and that's the main difference between the two (there are subtle differences besides that, but they do not apply here).

So you can use a carb port that has manifold vacuum just as easily as using a vacuum port that's in the intake manifold itself, if you follow me.

If you have a Holley, the metering block has a ported vacuum port- do not use that. You can use a port that's located on the baseplate, but still double check to see that it has full vacuum at idle.

An Edelbrock carb has a manifold vacuum port on the front, driver side.

That is the wrong place to get vacuum for the modulator. Use a full time port from the baseplate.

Cobalt327- thanks ima try that tomorrow