Lay a machinists rule across the deck and see how much it is wapred with a feeler guage. I don't recall the maximum spec, but I've never had an engine decked and never had any problems with head gaskets. If it's already flat, no need to deck it for a street engine.

 

Alum heads need a flat deck so IMHO I would ZERO deck the block.

If you are building the motor other then a stock restoration what difference to you does it make if you lose the #s. Unless this is a special motor I don't see it as that big of a deal and will have little effect on the value of the car.

Some shops can save the #s and then as you know many re-stamp.

Take pictures and document the original stamping.

 

I disagree about the value. I know youre a resto mod guy but I'm not going to lose the numbers on the born with block that came with my car.

Jason

I went through the same issue since I wanted to build up my motor before putting if back in. I ended up just keeping the original one out of the car and had a 383 built for it. Now I don't have to worry about decking or messing up the original motor because it is on a stand in a closet in my basement. I took it all apart cleaned and oiled it and put it back together for when I put it back in the car or it can go with it if I ever sell it.

Derek

Storage is at a premium and I dont have a place to keep it.

Spend your money on a balance job - you'll be ahead.
As most here, I have not had a problem sealing heads with a steel shim head gasket,
but then, it was a cast iron head on a cast iron block.

I did have the shop remove the dowel pins, hand them to me, and 'honed' the block deck and heads with a new honing stone and WD40. Now they are flat.
Then I ground down the dowel pins for a slip fit into the block and reinstalled them.

Balance job? Are you talking about the rotating assembly? Im going to see if they can measure the deck when its disassembled and possibly iust hone it if needed with a file or something.

 

Jason

I went through the same issue since I wanted to build up my motor before putting if back in. I ended up just keeping the original one out of the car and had a 383 built for it. Now I don't have to worry about decking or messing up the original motor because it is on a stand in a closet in my basement. I took it all apart cleaned and oiled it and put it back together for when I put it back in the car or it can go with it if I ever sell it.

Derek

 

Spend your money on a balance job - you'll be ahead.
As most here, I have not had a problem sealing heads with a steel shim head gasket,
but then, it was a cast iron head on a cast iron block.

I did have the shop remove the dowel pins, hand them to me, and 'honed' the block deck and heads with a new honing stone and WD40. Now they are flat.
Then I ground down the dowel pins for a slip fit into the block and reinstalled them.

 

Yes, balance the rotating assembly, pistons, their pins, rings selected, rods with the bolts selected, either OE bolts or aftermarket bolts, their bearings selected,
crankshaft, harmonic balancer, flywheel, pressure plate or flexplate. Ensure you get the balance card after the job is done.

No file, you need a honing stone, a new one, for removing the brooch marks.

 

Deckng is needed only if the surface is warpd, or if youaretrying to squeez every last HP out of a motor. You can do a performance build without decking...

 

What's wrong with being a resto mod guy? Welcome aboard with the motor build you're doing.

 

Swap the same piston-rod combo to all 4 corners and depth mike it. Odds are the decks are not close to the same front to back and side to side. I've seen them off .017" front to back. That's a pretty big change in the compression ratio. The only way to know is to measure it. Some engines need it more than others.

 

You beat me to it
I have seen them up to 24 th out front to rear and not square too.

 

I have had 2 rebuilds on my matching numbers block... Both times the deck was skimed
Now there is a huge difference between skimming to get perfect level and decking
Skimming to level is simply a matter of doing a couple passes till the 'hollow is taken out... generally 1 to 2/ 1000"
Even running over the vin numbers will not remove the numbers IF the deck is SKIMMED level and not simply dropped in in the mill set to say 5/1000 (to make sure) turn the switch on and go have a cuppa coffee while charging u the labour.

And that is how it was described to me by the machine shop that does my work.

And yeah As Everet mentions get the engine dynamically balanced.. which means supply every thing between the harmonic balancers bolts to the Flex plate/ clutch plate bolts Including clutch ...

 

Get the block checked first to see what it looks like. Or as mentioned, check it yourself.

In most cases for a stock or relatively stock rebuild, decking is not needed. Even with changing to aluminum heads, you should be OK.

 

Having my motor rebuilt in the next few weeks. Spoke with 2 very respected machine shops here and both seemed to say it's damn near impossible to deck a block and keep the vin stamp. From what they've said, it's a 18" pad or something close to that that's used and basically very difficult to properly deck the block while keeping the numbers.

One shop seemed to have no issues with just re-stamping the block which took them right off my list. The other said they could just not deck it, but then wouldn't be able to guarantee a good seal with the new heads. They could do it by hand though but again, wouldn't guarantee a proper head gasket seal without a machine decking.

So...I ask you. Do I really need to deck the block when doing a rebuild? There are no current issues with head gasket sealing. The new heads are going to be either AFR or Dart aluminum.

Thanks,
Jason

Decking the block is up to the machinist. I could see mine was warped when I pulled the motor apart so I went along with the machine shop.

They did a heckuva job! They were able to get the cut in just enough and save the numbers. My machinist is into classic cars and has a 67 first-gen himself. And anytime I stop at his shop there's always a first-gen or 2 in there for fixing up.

Here's a pic of my machined block with the numbers mostly visible.

 

I would document then restamp. Its not fraud its how its done.

Now if it was a 302 or a BB I would not just becuase those motors are faked much more often. But a base V8 I wouldnt sweat it man. Dont forget to balance too!

 

FWIW my block was decked to .010" and the numbers on the pad are clear as day, and I run aluminum heads, and this is after several thousand miles with the old iron heads. Tkae off .010, and it will probably clean up, and you can run a .025" gasket and nail the quench.