I have a 4.3 v6, 98' GMC sierra 1500. I want to swap it out for a 350 but im unsure if it will mate with the original tranny. also i dont want to murder my mpg. Is there any way to salvage a reasonable mpg and keep decent power from the 350? A friend had mentioned a specific cam shaft...?

 

The transmission will bolt up. You might be surprised at how similar the gas mileage is between the 2 motors. The 5.7 doesn't have to work near as hard. You will need to get the computer for the 350.

 

thats kinda what i figured...wel;l the milage is ****ty right now anyways. A buddy mentioned the camshaft pushes about 400hp outta the 350 tho.. know anything about it?

 

Are you trying to keep the fuel injection?

 

id like to yes

 

You are limited on computer friendly cams in these trucks. So the 400 HP is a REAL stretch. I am not sure what you are looking for, but the stock 5.7 Vortec is going to be night and day difference from your 4.3! I hope you have a donor vehicle because there is going to be wiring and stuff that will be needed to do the swap. I did an older TBI 305 - 350 swap and it was more than I thought it was going to be. Hopefully someone on here has done a Vortec swap and will chime in here. Good luck either way!

 

idk right now im lookin through some neighbors feilds for a 350, wether it be injected or carberated it dont matter to me... but yeah i kinda figured the wiring would be a pain..

 

Yeah unfortunately it is more cost affective to sell the truck you have and buy one the way you want it. I speak from experience...when I swapped my 305 for a 350 I spent $2500 to do it, but I did it right and you couldn't tell it didn't come that way. The power was slightly better, as there was nothing wrong with my 305, but my wallet was considerably lighter! In hindsight I would have left the 305 in it.