lq swap into 81?

[kelley1]

Do I have lq4 or lq9 engines? I have two engines, dont know history on vehicle they came out of. I do have numbers on both.
1st engine- stamp on block is 6.0 12551364 and 317 on heads
2nd is- IV 6.0 number 12576181 block and has 823 on heads.
Hopefully some can tell me what I have and which would be a better swap for hp and tq

[6880 Mike]

All 81s came with L-81 smallblock 350CID Chevrolet engines. There were no optional engines available from the factory.

There is a pad on the block at the front of the right head which will have the engine identification stamp and the VIN derivitive of the vehicle the engine was originally installed in.

Check the pads on the two engines you have and jot down the stamps. All 81 Corvette engines will be coded ZDA, ZDB, ZDC, or ZDD.

[kelley1]

Thanks for the reply, but I am thinking of swapping engines. I have 2 6.0's not sure if they are 4 or 9's

[garys 68]

post over a LS1tech, 317s came on LQ4s and 9s. The pistons in the 9s are higher compression and comes with the LS1 cam.
Btw, ruuning and LQ9 with Richmond 6 spped in my 68. Great engine, 400 hp and ft/lbs with just exhaust and tune.

[D_B]

Originally Posted by kelley1

Thanks for the reply, but I am thinking of swapping engines. I have 2 6.0's not sure if they are 4 or 9's

The LQ4 is the lower compression engine and has dished pistons for a SCR of 9.5:1. The LQ9 is the higher compression engine with flat top pistons, and a SCR of 10.0:1.

They typically used different auto transmissions too so the flex plates might have been different but I'm not sure about that.

Near as I can tell, they were the same engines with the exception of the compression ratio so peek in a plug hole and see if you can see whether it's a flat top piston or a dish piston.

If the piston is dished it's an LQ4, if it's flat then it's an LQ9.

[6880 Mike]

Originally Posted by kelley1

...I have 2 6.0's not sure if they are 4 or 9's...

They should have identifying suffix codes, either on the pad or on a bar code sticker.

[mjollnir]

Kelly, I own a 81 too and I'm swapping a LQ4 in it so we could help each others with common issues