just put a new 4.2 in my truck thought it would give my f150 a little more get up and go, boy was i wrong . any thoughts on how to pep this slug up any ?? its a f150 4x4 auto. geared 3:55,

 

I doubt seriously if youre going to see much difference between the old engine,and new one.It of course depends on how bad the condition of the old one,and the compression of the new one.
If you put a factory new engine in it,I would think the compressions are up there,but if its a rebuild,the rings may not have had the chance to seat yet.
In any case the 4.2 in its original state(OEM) wasnt a powerhouse to begin with.I have this engine in my 97 150XL,LWB with an automatic tranny.
Its been a workhorse,and Im very pleased with its toughness over the years.
If you think about it,this engine is smaller than the 4.3 that GM put in most of its smaller trucks,Blazer,S-10 etc.and its in a full size truck.
Im relatively sure there are some aftermarket mods that can be done to boost performance,but its been my experience that whenever you deviate from OEM equipment,you(sooner or later) loose reliability,performance,and economy,not to mention resale value.
Sorry about not having any more promising suggestions..

Happy Thanksgiving

You might want to look into the condition of the exhaust system.I just replaced both cats on mine from bearriver converters(Sponsor),and she definately has more spunk.

 

Other than swapping to a v8, you could change your gear ratio front and rear to 4.10s... it wouldnt be cheap but it would make a huge difference.

 

All the things we do to our modulars work on the V6 too. Tuner, Efans, gears, or a turbo would all give you what you want.