Picked up an 88 W250 with 360 engine, 727 automatic, and 4 barrel carburetor. I have a wore out 318 TBI engine with PCM from a 91 with a 4spd manual tranny. Will the 318 manifold and throttle boby work on the 88 carbureted motor? It appears the throtle body will fit both, but the injectors are different, and I don't know about the adaptability of the PCMs. There are quite a few diferent applications for PCMs in the throttle body injection years. I don't need the 4BBL power and thinking with my light footed driving habits the TBI would do considerably better on fuel economy.

Been thinking I should maybe look for a complete TBI setup with manifold PCM, and harness from a 360 for the 727 automatic tranny.

 

You want to mix an engine, trans, injectors, distributer, and a specific computer that all do not match. I think you are looking for a problem. Even if everything were matched and worked I don't think you will get better mileage. At least I haven't experienced it. What size is the 4BBL?

 

It has the stock quadrajet. And it is a former US government truck so it has the federal emissions equipment on it.

 

The quadrajet has very small primaries and therefore when driven conservatively will give very good mileage. It also uses vacuum secondaries and air valves that allow its rather large secondaries to be used on a wide variety of different cubic inch engines without over carbureting the smaller engines. Because of these points most of the carb trucks I have seen get better mileage than the TBI trucks and also give better performance.

The PCMs in our trucks are not adaptable at all. They are specific to each individual set up.

 

I was working at a chevrolet dealer when the Qjets were in infancy, and when adjusted correctly a 350 powered 4X4 could get up to 16-17 MPG on the highway with a lightfooted driver. But I have zero experience with the TBI setups and people I know have said the best thing that ever happened to Dodge truck fuel mileage was getting rid of the TBI for MPI, That's why I asked here. I know getting MPI is only practical if replacing a carbed engine with a complete MPI egine with complete electronic control and harnesses to match.

Thanks for the feedback.