I recently bought a 1990 RS that has a 305 with 106k miles on it. I want to do a swap, I was thinking about either a 350, 383, or a LS. What would be the easiest / most bang for my buck? Or would it be better to keep the 305 and rebuild it?

 

350...

 

What are you wanting the car to do? What don't you like about the 305? Where do you live?

 

I just want some more power, I’d also like to do the swap for the experience as it’s my father and I’s project car.

 

What is your budget and what are your goals?

 

350.

 

The question was "bang for the buck", not which is best or most powerful...

 

What kind of car would you like to keep up with?
That always seems to be a lot easier starter discussion than asking technical questions.

Power is easy these days, but a 400 Hp engine is around the practical limit of a lot of things on the car. Once you break that, you break the bank too with all the other things you have to throw at the car.

 

A 350 build with upwards of 275- 300HP which is plenty in these lightweight cars can be done fairly easy and even retaining the TBI. You might could do it with a 305 but it just takes more.. Keep in mind though everything just has to be upgraded and tuned. such as Fuel pump upgrade, bigger injectors, better manifold, full exhaust, etc. Holley Sniper or even a carb swap is an option as well

 

How much money do you have for this, and who will do the work?

Do you live in a state that has draconian smog laws?

 

 

A 350 is a pretty common and relatively straightforward swap for the 305 in your car. However, without knowing your budget, mechanical ability and garage/tool situation, it's hard to say if that makes the most sense.

Is there anything wrong with the 305? If it runs good, I would suggest keeping it, at least for now and focus on other supporting upgrades ahead of a motor swap. The 305TBI is very choked in its stock form and the bolt on upgrades will wake it up a lot and make it much more fun to drive. And, all of the upgrades transfer over to a 350 and would be recommended to support the 350 anyway.

This is what I would recommend:
-Replace the air cleaner assembly with a higher flow setup. The dual snorkel from the 83-85 305 HO is the preferred one, but hard to find these days. An open element style will work and will flow better than the stock setup, but will pull in warm air from the engine bay. Still though, it's better than the stock unit.
-Bump the base ignition timing from 0BTDC to 6BTDC and run 91 or 93 octane
-Replace the entire exhaust system from manifolds to the tailpipes. It's a single 2.25" exhaust and it's very restrictive. Either use the larger outlet exhaust manifolds and the 2.75" Y-pipe from a car that came with that, or aftermarket headers with either the 3" single converter y-pipe or dual 2.25" converter y-pipe. 3" cat-back exhaust system.
-Upgrade the rear end gears and add a posi. The stock rear gear is either a 2.73 if auto or 3.08 if manual. Swapping to a 3.42 or 3.73 will make a big difference and with the shorter rear gears you'll want a posi to avoid the peg leg one wheel peel.

Just doing the things I listed above will make a huge difference in how the car drives and how sporty it feels and all of that supports a 350 swap. I would not consider a larger motor without doing these upgrades ahead of time, or along with it, otherwise you won't get the results you are looking for from the larger motor. The other benefit here is that all of these upgrades can be done incrementally as funds, time and mechanical skill allow.