Super Duty 421 Pontiac Engine 1962 SD421

  • 1400.00 £
  • Published date: June 8, 2024
    • Desford, Leicestershire, United Kingdom

Super Duty 421 Pontiac Engine 1962 SD421

⭕ nearly complete, rather unique, 1962 Super Duty 421 Engine.

Parts consist of a 5381XX 421 block, 5441XX Heads, 97703XX Intake, 5429XX Forged Crank, SD Forged Rods, M/T Forged pistons,SD valve covers(1963 originals), SD421 Oil Pump, a extended oil pan, windage tray, and various parts,(balancer, water pump, oil filter housing, pushrods, etc). Also included is a vintage Racer Brown camshaft in the original box that came with this motor.

If youre into Pontiacs, there is no need for me to explain what a SD421 is, or how rare they are. This particular engine is rather unique even as SD421s go. It was built in late 1962 or early 1963 in Dearborn Heights Michigan, as a 495 cid stroker, (4.185 bore x 4.5 stroke). (Factory 421 was 4.09375 x 4.0).

The crankshaft is a 990 forged unit that was made to 4.5 stroke by Moldex in 1962. This was done using a raw 990 forging, not a welded-up 4.0 version. The crankshaft was then delivered a couples miles away to Leonard Gonzales at Leos Custom Motors in Dearborn Heights MI, for final balancing and assembly with the SD rods and custom Mickey Thompson pistons. Engraved on the crank is Leos Custom Motors 11/19/62. Leos is still in operation today, being run by Leonards grandson, from whom I obtained the above info.
The crankshaft has been magged and has no cracks. The rod and main journals have been polished and show no wear, still measure standard size. Excellent Crankshaft.

The block is 4 bolt main, has the correct chamfers at the top of the bores, and has been cleaned and magged,(no cracks). Casting number is 538181, date is A262. What is interesting about this block from a numbers-matching restoration point of view, is that there are no numbers or codes or VIN stamped on the front of the block, (or anywhere else for that matter). Obviously sold over-the-counter and never installed in a production car. The only casting number, (other than the block casting and date), is a large SP cast on the driver side of block, ( Special Part?, Service Part? I dont know). The bores are rusty from sitting so many years, and may require sleeves, but the block would definitely be worth saving for a correct SD restoration.

The rods are the forged SD units, that have had the small end fitted for bronze bushings. The M/T forged flattop pistons are full floating, and will be included with the engine for completeness, even though they are corroded and cant be used.

Phone number ✆ 0116 527 5714
Desford, Leicestershire

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