Low mileage 305 L03 in a 92 RS. Swap the swirl port L03 heads for a set of aluminum L98/ZZ4s (one full head for free in a swap for a Saginaw 3 speed), mounted on the stock bottom end. Ported TBI manifold or aftermarket if I can source one out. I already have a Turbo City TBI unit with 2 inch bores. Slap some headers on it and 3 inch catback. Tune that LT1/4 cam with Tunercat and run her out.

Thoughts? Any idea on what kinda hp people with similar builds have done? Input and suggestions on what to mix in and or substitute?

 

Hi there,
I am planning a kinda-sorta similar build, and I have been reading up on what I need. from reading several build threads, looks like they recommend switching fuel pumps from the old TBI pump to the TPI pump, to increase fuel flow. It sounds like a good idea, since you are trying to increase airflow thru the engine, you will need extra fuel flow to match.

I am planning on doing the same mods to my throttle body and injectors, so I am also planning on swapping the fuel pump to match. Hope this helps.

 

How are you going to bolt the TBI manifold to the aluminum heads? The center two bolts on each side are at different angles.

3" cat-back exhaust is only going to be beneficial if you have a high-flow catalyst.

I don't see any point to trying to hot-rod a 305. If you're going to play games with tuning the computer anyway, start with a 350.

 

If your gonna change heads you might as well run a dual plane carbed intake to match the heads w a TBI adapter plate. The carbed intakes flow much better than the TBI ones do.

 

He's right on the intake, you need one that will match up with those heads. I belive edelbrock sells TBI manifolds, see if those will fit.

 

It is easy to slot the four center bolt holes on the intake to fit the original SBC bolt pattern. BTDT.

More important is that the stock TBI intake has no performance potential. So better off getting a carb intake and using an adapter on it. Just be sure that it isn't a 'stock' replacement intake such as a Performer series.

And no air-gap style intakes either...

RBob.

 

Here is a good thread on using the '113 heads on a 305 (L03):

https://www.thirdgen.org/forums/tbi/...num-heads.html

RBob.