Decking vintage engines

[@wot]

Probably a minor league question, but how do machine shops deck a block without touching the numbers? I may be doing a rebuild on my matching #s L78, and want to avoid a problem

[MosportGreen66]

I'm sure it varies from shop to shop but isn't it more or less standard procedure for a shop to ask their customers if they want the engine pad to remain intact during the decking?

[JRSully]

They use a special "Bridgeport" machine. Basically what is done is they us the standard decking/milling machine that does the circular motion. Once they get close to the end (stamp pad area), they stop that machine, draw a line where the head ends and the stamp pad begins. They mill the remainder of deck with that special Bridgeport machine that mills/decks in a straight line and they bring it right up to the line they scribed, leaving the original stamping/broaching intact.
make sure you have a guy that has done this before.! This what they did on my 70 L78. Good luck SULLY

[P.J.]

The machine for milling the block can be a bridge port or a horizontal milling machine. The tool that leaves the machineing marks on the block is a carbide fly cutter. that is a tool about 8 inches or larger in dia which serated to accept carbide inserts
that can be replaced as they dull. The carbide tips can be secured in the tool with a set screw. Then when the tool gets to the end of the scribed line the machine travell is then cross
fed to avoid the vin stamp.
hope that helps
suprss70

[Keith Tedford]

For a street driven engine, decking probably isn't needed unless the block is badly distorted. Perhaps I've just been lucky.

[WILMASBOYL78]

I agree with that thinking. Resurface heads and clean the deck of the block good. Use quality head gaskets and you shouldn't have a problem. I would be terrified the machinist would slip and remove the vin stamp and letter code. Not worth the risk!

wilma http://www.yenko.net/ubbthreads/images/graemlins/burnout.gif

[scuncio]

Have the deck surface checked regardless of whether you decide to cut it or not. Many BBCs I've come across have needed 0.015-0.020 cut to square them up.

[WILMASBOYL78]

Good advice!

wilma http://www.yenko.net/ubbthreads/images/graemlins/flag.gif