cdoc164

I bought a 57 Chevy BelAir with an LT1 that came from a mid-90's Impala. How can I find out specifically what year model the LT1 is?

NewEnglandFormula

well the LT1 came in impalas from 94-96. you can get the casting numbers from the rear of the block or head casting numbers, assuming the heads were not swapped. if they are iron heads then its a true 94-96 impala b-body LT1. if they are aluminium heads they have been swapped from another engine.

kgkern01

iTrader: (10)

Also to add to the above post, 94 has a non-vented, spline drive opti, the 95 has a vented opti, and a 96 has vented opti with a crank sensor on the timing cover. The opti and timing cover is really the only way to tell besides the head casting numbers, and that is if they made multiple castings of the heads like they did for the aluminum heads. The blocks are not year specific, there are only 2 casting numbers, one for the 4.3 L99 and another for the 5.7 LT1/LT4. Even though the Vette, (most) factory replacement blocks, and LT4 are all 4-bolt main, they have the same casting number as the 2-bolt main LT1.