Stock computer/Stock tune Datalogging?

[Fast355]

Move the MAP sensor vacuum hose from the rear port above the IAC to the front manifold vacuum fitting on the throttle body. The Holley 670 TBI units have an issue when the MAP sensor is connected to the rear port. Your setup is going to want more than 12.5 PSI. I would try around 15 to start and it may want as much as 18-21 psi once you dive into tuning. I know this is abit of a bandaid fix to get it driveable, but put some timing in it too. Set the distributor at 6-8* BTDC with the timing wire disconnected and bump the fuel pressure up as high as you dare. The stock pump will likely only support up to 15-16 psi before the internal relief opens.

[rstroh]

Move the MAP sensor vacuum hose from the rear port above the IAC to the front manifold vacuum fitting on the throttle body. The Holley 670 TBI units have an issue when the MAP sensor is connected to the rear port. Your setup is going to want more than 12.5 PSI. I would try around 15 to start and it may want as much as 18-21 psi once you dive into tuning. I know this is abit of a bandaid fix to get it driveable, but put some timing in it too. Set the distributor at 6-8* BTDC with the timing wire disconnected and bump the fuel pressure up as high as you dare. The stock pump will likely only support up to 15-16 psi before the internal relief opens.

I have moved the map sensor to the front left port, which holley claims is manifold vacuum. I almost want to t into the brake booster line and see if that helps.

You really think it wants that much fuel pressure? I'll definitely try bumping it up later. And I agree with turning base timing up, it always bugged me that these tbi motors were supposed to be set at 0, when a regular small block should be at 7-10. I'll try that too. Thanks!!

[1project2many]

I almost want to t into the brake booster line and see if that helps.

Don't do that. The change in pressure when you apply the brakes will cause the ecm to add fuel.

[lionelhutz]

Where is the O2 sensor and is it a 1-wire or 3-wire or 4-wire?

[rstroh]

Where is the O2 sensor and is it a 1-wire or 3-wire or 4-wire?

It is maybe about a foot from the header flange in the exhaust pipe, (long tube) on the driver side, 3 wire.