Originally Posted by Mrwood
I have a 350 in my 88 chevy truck, will a 305 interchange with it.
The 305 will physically bolt in but the year of the heads will determine whether the intake will bolt up or not. The 305 will need to be a 1986 thru 1995 or else you get into issues where the heads will not match your intake's bolt pattern.
Additionally, the computer will be all messed up you'll have to do one of several things:
1) Get a 305 TBI and computer to have the correct match between injector capacity and computer control, otherwise the mixture will be excessively rich beyond what the O2 sensor has authority to control.
2) Keep the current TBI and computer then install a custom chip that knows it has large injectors on a smaller engine and makes the correction. Chips like this are about 300 to 400 dollars.
3) Convert to a carb, this will also take a custom intake, will create problems with existing computer driven elements such as the speedo. A to D resolvers can be bought but your back to not cheap.
4) Rebuild or replace the 350 with another TBI swirl port headed engine will prove to be the least expensive, simpler approach.
5) What ever engine used the cam needs to be close to what's in the 350 otherwise you quickly get into a custom chip. The good old days of just swapping stuff around are gone. Long gone already.