Hi All, I built a 393 for my 1990 F150 2wd and have been driving it for a year. It is used mainly to tow my vintage modified on a open trailer to the races. It has a marine cam for better torque and 4 hole injectors because of the cubic inch. It tows well but seems to run a little rich and the mileage without the trailer at best is 15 mpg. I thought about putting the stock 19 lb injectors in but I don't want it to be too lean. Anyone else have a 393 as a truck motor?

 

You can't just change injectors ***** nilly without reprogramming the PCM, so what injectors are you using and what is the PCM programmed for?

 

The 1990 has a OBD1 computer. As far as I know it can't be reprogrammed. I have 24 lb 4 hole injectors in now. The truck had 19 lb single hole from the the factory

 

You're using a stock 5.8 computer? What cylinder heads? What cam?

 

Yes stock computer and heads. I'm using the 351W marine cam which is a torque cam. That's the only mods I have done beside eliminating the converter and EGR valve

 

OK, then you should be using the stock 19lb injectors.

 

Ok thank you for your help