fueling w/ Holley TB

[kjones6039]

Please excuse my fairly long post.

Setup:

MS II v.3 w/ relay board & 2.89 B&G code

383 cid SBC
Holley 500-19 Pro-Jection 900 cfm 4Bbl TB w/4 85# injectors

This setup starts well (cold and warm), maintains a strong idle at 950 rpm and responds well to throttle advance. (in the shop)

My dilemma:

The TB linkage is 1:1. Meaning that all 4 barrels open as soon as the throttle is applied. Holley handles this, with their high $ setup, by delaying fuel to the rear injectors until after the rear barrels begin to open. I replicated this by modifying the Fidle circuit on the relay board so that bank 2 is powered by Fidle at a predetermined TP (could be RPM also) and that works very well. Needless to say, when TPS reaches the preset value (say 20%) the rear injectors start dumping fuel as determined by VE table1. I am finding tuning that transition to be somewhat difficult.

My question(s):

Am I off base in my approach of delaying the rear injectors in this manner?

Does it make sense to anyone (besides me) to use VE table2 to control the fuel to the rear injectors, which in my mind would allow me to tune for a modicum of economy while running at lighter throttle settings and still have the needed fuel available much like a 4 barrel carb with progressive linkage?

I am open to any criticism/suggestions on how to approach this!

Thanks in advance,

Ken

[Matt Cramer]

We ran a Holley 4 barrel TBI on our Nova. It didn't make any more power than the 2 barrel GM TBI, probably because our engine didn't need all that much airflow. However, we simply ran all four injectors off the same table with no delay on the rear injectors.

If you want to try retaining that feature, I would put the front two injectors on bank 1 and the rear two injectors on bank 2, and use separate VE tables. That will let you dial in a much smoother transition.

[kjones6039]

If you want to try retaining that feature, I would put the front two injectors on bank 1 and the rear two injectors on bank 2, and use separate VE tables. That will let you dial in a much smoother transition.

Thanks Matt,

I tried your suggestion this evening and it worked pretty well. Will need a lot of tuning to get it right but I think it will accomplish what I'm aiming for. I am hoping that Phil will have a solution for using VEAL to tune bank2 with a single WB. I know he had a workaround for the Extra code.

Thanks again for the help as always!

Ken