I am in the process of building my single plane multiport efi conversion. I am looking into trying a TBI throttle body. The short block behind it will be fairly healthy. A 383 single plane with the LT4 hot cam and 11.0 CR. Any way I have a few questions about the TBI stuff.

1. I have read that the moddified throttle bodies are able to flow almost 600cfm. I will not be using the injectors or anything on top, would I have a little better flow?

2. I will be using a '730 ecm that I can burn chips for. I know that the '730 is looking for a TPS voltage of .54. The TBI throttle body unit's TPS is non-adjustable from what I have read, is there a way to make it adjustable?

3. Is it also possible to bore out or machine TBI throttle bodies like a TPI throttle. Say take it to a bigger bore with bigger blades?

 

1) about 670CFM is doable with a 2.0" bore TB from a 454.

2) stock voltage is the same on TBI's, it should be close to 54mv's at idle, and goes to above 4v at WOT, same as TPI. There are some sensors that I hear have the slots for adjustment.

3) Some people have punched them out beyond 2", not sure how far, one of the 454 truck guys on here probably knows the answer to that.

If you are going with a MPFI single plane conversion, you might just consider getting the 1000cfm holley 4bbl dry flow unit, price isn't that bad, that would completely take airflow needs out of the picture.