i have a 85 k5 with a bad 305 motor. i would like to replace the 305 with a 350 or 383 build. what will i need to modify to make this work and be emisson legal still. the stock quad jet carb has a plug in the front of it what is that for and is it computor controled. can i replace the quad jet with a holley 650 and not have any issues with the way it runs. any help would be very appreciated. as far as i know a 350 will drop right in and all my 305 parts should convert over is this true as well. thanks for all the help guys just trying to build a nice k5

 

i did a 305 to 350 swap. all the stuff on the front of the engine will work. the starter and fly wheel were different. but i went from a 77 350 to a 87 305 so i dont know if the year change had anything to do with it.

 

^^^ dunno why you had to do anything



You wont have to change any externals , unless you go to a 400

 

thanks guys this helps a lot im goign to drive an extra hr sun to pick this engine up. i found a complete 1985 350 block for 40 bucks i would like to make a 383 out of it but if plans dont go that way ill get a rebuild kit from summit for 400 and have the machine shop do the block and heads. since i am goign to have my 305 heads rebuilt and use them on the 350 block for better compression ratio. from what i hear the 305 heads are better then the stock 350 heads so i will go that route thanks for the input so far

 

The engine is a direct replacement... if you replace the carb, you will need to make sure that the new one has a factory bolt pattern or just go with an aluminum intake as well.
Also, 305 heads will give you a better compression ratio but they will not flow nearly as much due to their small valves among other things.

 

Yea. One of the flywheels had a different diameter and the starter was set in a bit to make up for it. Luckily my buddy had his starter and fly wheel still.

But no big deal