* Combustion Chamber Volume: 350 heads generally have larger combustion chambers than 305 heads. This will lower the compression ratio in your 305. Lower compression might require changes to your ignition timing and potentially your fuel mixture to avoid issues like detonation or poor performance. You might need to look at using head gaskets with different thicknesses to adjust the compression.
* Intake Manifold: The intake manifold designed for a 305 likely won't be ideal for 350 heads. The port size and shape will be different, leading to potential performance losses. A new intake manifold designed for 350 heads would be recommended.
* Exhaust Manifolds/Headers: These may also need to be changed or adapted to fit properly with the larger heads.
* Valve Springs: 350 heads may have different valve spring requirements than a 305. Ensure the valve springs are appropriate for your intended use and camshaft. Using incorrect springs can lead to valve float at higher RPMs.
* Head Bolts: While the heads will likely bolt on, you should use head bolts suitable for the aluminum heads and torque them to the correct specifications. Aluminum heads require different torque specs compared to iron heads.
In short, while physically possible, making this swap work effectively requires careful attention to detail and likely some additional components. Simply bolting on the heads won't guarantee optimal performance. You should consult a performance engine guide or a mechanic experienced with small-block Chevys before proceeding.
