Assuming you are talking about a 4bbl intake with an TBI to 4bbl adapter plate. It would work MUCH better than the OEM monojet intake. I saw a dyno test with a 2bbl carb and 1 barrel intake on a Ford 300 I6 where to Ford engine lost power with the 2bbl car and 1 bbl intake. The swapped a 4 bbl intake onto it and kept the 2bbl carb on an adapter and gained power everywhere.
Also keep in mind injector flow rates correspond with horsepower more than CID. I swapped an older P-van 292 to TBI for a friend of mine that owned a roach coach with one years ago. Ended up using a 2.8 TBI unit from a S10. The 292 was 115 HP the way it rolled out of GM. The 2.8 was 120 hp. The 4.3 is 160-190 depending on Z or B vin in the Astro/Safari. No matter which way you do it the chip needs to be heavily reworked. The I6 requires much more timing than the swirl ports on the V6/V8. I would try bringing the timing up to about 10-12° with the connector unplugged. Should give about 30-32° total advance at WOT and more like 48-52° at 3,000 rpm free reving unloaded. The smaller throttle bores and smaller injectors of the 2.8 TBI were a better match for the Anemic 292 I6. Putting a V6/V8 TBI unit on a stock I6 is like putting a 750 double pumper on a stock 305.
You need to get an ALDL cable to Datalog, TunerProRT and a convert am ECM to a flash chip along with a Chip Burner from Moates.net. I really like datalogging with WinALDL for the old 160 baud rate ECMs. My steps to making it run right would be as follows once you are able to datalog and burn chips. Find the OEM timing curves for a factory 250 distributor. Convert the specs for the vacuum advance from vacuum specs to manifold pressure. The centrifical advance should be straight foward. Whatever the OEM base timing is gets programmed in the lowest RPM 100 kpa table cell. Then add the centrifical advance to that number and fill in the various rpm values. At the point interpolate the values between what you know. Vacuum advance comes next. Will say 0 degrees at 5 in/hg and say 10 degrees at 12 in/hg. Then fill in those values to the table. Remember that Vacuum is Baro minus MAP KPA. At sea level 100.4 KPa is roughly 30 in/hg manifold pressure.
If you read 18 in/hg on a vacuum gauge that is a manifold pressure of about 12 in/hg which IIRC is in the 40-45 kpa range. From there measure the fuel pressure and calculate the injector flow rate and corresponding BPWC for your 250. Once those changes are made you will need to datalog and record the BLM values. The BLM values can then be used to adjust the VE tables. The I6 is going to also want ALOT of AE fuel added to the TPS and MAP AE fuel tables. I would probably double what is there for the stock V6 as a starting point for the I6. Better to have the engine blow a little black smoke than have it shot a fireball out of the TBI.
Bookmarks