1965 396-325hp Engine number decode. - Impala Tech
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post #1 of 6 (permalink) Old 03-15-2017, 08:01 PM Thread Starter
 
 
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1965 396-325hp Engine number decode.

Hi guys, I just helping a buddy with his 65 SS convertible 396-325hp 4 speed car. Can you guys help me break down the engine numbers that I took off the passenger side of the engine block behind the alternator. I know the engines was made in Tonawanda Feb 20 1965. The engine number is T0220JQ19U173239.Im pretty sure I read them correctly. Its only got 50,000 miles on this car with original black buckets interior. Im going to look for the build sheet, hopefully its still under the drivers seat. Thanks.
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post #2 of 6 (permalink) Old 03-15-2017, 08:31 PM
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Well engine code "JQ" was used in 1969 in the Chevelle with a 265 horse (base) 396 with a TH400. I also looked for an "IO" application code, which is for a 1966 325 horse 396 in an Impala (full size; it doesn't actually list Impala). "IQ" was used for a 390 horse 427 in the 1966 Corvette, but not the full size Chevy, and it was in front of a PowerGlide. In 1968 same app code was used for the same engine (390 horse 427) but in front of a TH400 in a Corvette.

19U173239 should match your last six numbers on the car's VIN as BBC motors had a partial VIN stamped from 1965 and up. The T is for the Tonawanda foundry in NY, and the 2/20 is when the engine was built (assembled not the casting date). The two letters between this are supposed to be the application code. But because they were all hand stamped it is sometimes difficult to read the numbers or letters.

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post #3 of 6 (permalink) Old 03-16-2017, 09:00 AM
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Quote:
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Well engine code "JQ" was used in 1969 in the Chevelle with a 265 horse (base) 396 with a TH400.
I checked in about 3 different sites and got the same info as Dave did on "JQ", although my info shows "B" Body (Full Size Chevys). This is also the engine that came with a 2-Barrel Carb.

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post #4 of 6 (permalink) Old 03-16-2017, 09:59 AM Thread Starter
 
 
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Hi guys thanks for helping out. I know the engine is a real early production 1965. The engine numbers dont match the cars vin. 166675F204194 . you never know, the first engine might have hand grenaded and warranty installed a new one. I will go and get the casting number off the back of the block. Wouldn't the vin indicate if it was a bb or sb?
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post #5 of 6 (permalink) Old 03-16-2017, 10:31 AM
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VIN only distinguishes between a six or eight. A replacement service engine wouldn't have the numbers 19U173239 stamped on the ID pad; that is the partial VIN from the car the motor was removed from.

The first three or four month supply of casting for the 1965 396 blocks were cast as a 409 displacement. Those blocks can be bored out to 4.313" +0.060" for a final safe bore size of 4.375" depending upon core shift. This was a very desirable block to have as a bigger bore improves the breathing capability of the BBC (the valves are shrouded by the combustion chamber (the reason Chevy went to an open chamber in 1969) and the block (why a 396 has a chunk carved out of the area around the intake valve). Racers loved this year block, and a lot if not all of them of them, gave their all at the drag strip in top fuel engines.

The other issue with a 1965 and 1966 block is the oiling is different than the 1967-'96 big blocks (just as with the first small block was different from the 283 and up motors). Chevy went back to a grooved cam journal to supply oil to the top end in these year big blocks and the aftermarket charges $75 more to grind the cam for these years.

To know when your block was cast look at the date codes cast on the back of the block. The codes are good for ten years so the numbers wrap every decade to be reused again on those blocks made later, but since displacement kept changing with time few engines except the SBC 350 where made for more than ten years without a major physical change that distinguishes them from the decade before (the 1967 350 can not be distinguished from the 1977 block as both share the same date code: the 1987 and up had a one piece rear main seal that makes for a visibly different block).

Big Dave
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post #6 of 6 (permalink) Old 03-16-2017, 11:08 AM
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Quote:
Originally Posted by ssconvertible View Post
Hi guys thanks for helping out. I know the engine is a real early production 1965. The engine numbers dont match the cars vin. 166675F204194 . you never know, the first engine might have hand grenaded and warranty installed a new one. I will go and get the casting number off the back of the block. Wouldn't the vin indicate if it was a bb or sb?
The Casting Numbers will also help, but as Dave has mentioned, the most important thing would be the Date Code, which is on the back of the block but can be hard to see if the engine is still in the car.

The "T0220" only tells us the Month and the Day, but not the Year, which the Date Code will provide.

But if the Casting Numbers are easier to provide, then just provide them first.

-Parting Out over 75 '58 to '73 Full Size Chevy Cars-

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