BrandonG

Hello all,
I have a one owner (I am number 2). 77 Cutlass Brougham. It currently has a factory rocket 350, TH350 combo.
I recently acquired a built 403. The 403 comes with a built trans.
My question is this - while the engine is out is there any known modifications I should do during the swap?
I will keep it an AC Car but open to suggestions. I am planning on a high torque starter (for small body size), short tube headers, and a new HEI style distributor.

Thanks all,

fleming442

That's awesome! Might want to investigate the rear gear and trans mating action. Is the trans swap like for like (TH350 to TH350, etc)?
I'd go for full length headers.

70W-32

Keep your factory HEI, replace the cap, rotor, and wires with quality parts(not ebay Chinese parts).
Buy an advance curve kit and put in the lighter springs to bring in the advance quicker.
Most of the aftermarket HEIs are Chinese crap, so your better off rebuilding the factory unit.
Would be a good idea to pull the 403 heads and have them milled to up the compression ratio(right now its about 7.9 to 10.
Use a thin Cometic gasket, not the thick Felpro's.
Re-use all you brackets, pulleys, waterpump and accessories from the 350, they will all bolt to the 403, and keep your belts aligned
Save some money and have the rear axle ratio change to a 3.08 or 3.23, that will really wake up the acceleration

texxas

You will need a dual hump transmission crossmember from a 73-74 GM A or G body to accommodate dual exhaust with those headers, or modify the one in your car to fit.

pherbicide

Beautiful '77, I wish mine was in that condition