305 vortec to 350 crate motor swap exhaust question

[mrvsfriend]

I just bought a crate 350 vortec, going from a 305, and was wondering what all i need to do wih the single cat setup from the 305, will it run with the 305 y piped exhaust? Do i need to swap the pcm for a 350?

 

[L31MaxExpress]

I just bought a crate 350 vortec, going from a 305, and was wondering what all i need to do wih the single cat setup from the 305, will it run with the 305 y piped exhaust? Do i need to swap the pcm for a 350?

You need a 350 tune but you need the 350 tune setup for the single cat and the 02 configuration or else it will run terribly. I would really suggest an aftermarket dual cat set like magnaflow makes for the 350s. The 305s actually run better with 350 dual cats than the single cat setup. When GM tested those engines the 305s already ran more exhaust back pressure than the 350s.

 

[mrvsfriend]

Thanks for the advice (again)

 

[L31MaxExpress]

Thanks for the advice (again)

No problem I guess I should say if you swap to the 350 exhaust and 02 sensor configuration you can run a stock 350 tune.

 

[mrvsfriend]

Is there any benefit to reflashing vs swapping the pcm? Any special tools required?

 

[mrvsfriend]

You mentioned a 411 van pcm in another post, would that need to be reflashed for the truck or plug and play?

 

[letitsnow]

Maybe have Blackbear tune your current pcm?

 

[mrvsfriend]

Figure id po'st some pictures of the new motor.

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[mrvsfriend]

Took some time cleaning the intake manifolds and rebuilding the fuel injectors, also painted what i could on the frame. I`ll be rebuilding the nv3500 transmission while the motor is out as well.

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[Enigma540]

While it's right there, and opened up, I'd junk the factory poppets right now, unless they are new.