I have a numbers matching 327 block and looking into stroking it. The machinist wants to deck it.
Can the block be decked without destroying/removing the ID numbers

ive had mine repunched after decking.

A GOOD machine shop should be able to stop the decking operation short of the numbers and then hand file/dress it square so that you don't lose them.

And I don't care if you deck and re-stamp back to stock, it's still a re-stamp so AIN'T no longer stock by me!

pdq67

and decking and stroking a motor still is stock??????
I think not.

No ,but it could be put back to stock with the original crank.
Can't restore the milled off codes as the broach marks are different.

DONT let him Deck it. If you are building a hot rod engine, find another block. Your 327 is a 2 bolt anyway. Put it under your bench and use a 350 4 bolt block as the foundation for your stroker.
JMO.

as explained to me from machine shop years ago about stopping before the numbers:
" some heads will overlap the area near the number pad causing leaks and or a warp issue."
all would be ok as long as your sure this doesnt happen upon assembly.

If you are stroking it then your not worried about originality anyway. Deck it or get another block.

The block was bored to 030 in 1982 when I was in HS
Granted it is no longer "original" but how many of our Camaros truly are (powerglide, stock suspension, AM radio, 2.73 gears, original heads and 2bbl manifold, all of which I have shoved in boxes) very few.
In 50 yrs if my kids want to sell the car, I think a buyer is going to be looking for a numbers matching block (is there anything else that is "number matching" on a car) that is completely unaltered if possible, but I think they would not be too dissatisfied with a VIN mathcing 030.

I dont want to restamp the engine.

The builder just talked about decking it...but he knows it is number matching. People in town say he is good but I did not ask about the number issue. I am not really sure what "decking" is. I believe it is shaving off a little of the block for compression?
Correct me if I am wrong..Stroking is boring 030 (done 27 yrs ago) and replacing the crank. No other modification to the block? I dont want to alter the block any more.

Rick

Most blocks don't need to be decked. Unless there's something seriously wrong with it I'd leave it alone..

Decking a block is a neccesary evil for performance. Dial in that quench and give your head gaskets a fresh flat surface to seal to. If you are that worried about numbers matching then you should check the deck for squareness. If it's out of spec you have no choice. Otherwise lube it up and put in under a tarp.

No, boring is the .030" for bigger over-sized pistons to take care of cylinder ring wear taper.

Stroking is increasing the length of the stroke of the piston up and down travel. This entails using a longer stroked crank and necessary piston pin compression height b/c if you add stroke and try to use your pistons, the stroke increase will pull them down farther half the added stroke at the bottom, BUT will also push them that half farther up past the block's deck!!

New, stroker pistons are required UNLESS you shorten the rods and this may not be possible b/c the pistons pin bosses may hit the crank's counterweights and lock up!! Then you either buy longer rods OR cam-cut machine the crank's counterweights and then rebalance everything and possibly have to add slugs of heavy-metal/(made out of Tungsten), (read, expensive here!)..

Blocks are decked to square all four corners and to make sure all pistons sit the same from the deck down-in-the-hole (DITH) at top dead center.

Heads are decked, (i.e., planed/milled) to make sure they are flat and not warped. And to make the chambers smaller to increase compression.

Shop Class is over for today and I'm testing everybody on this tomorrow!!

He, He!!

pdq67

The interesting point here is if the block is original but needs to be decked, if you don't deck it, it now becomes a boat anchor and little else. What is the value of the "born with engine block" if the block can not be made servicable without destroying the pad stamp?

alan

I have hand dressed my blocks and heads flat using a fine bastard toothed triangle file by lightly filing from bolt-hole to bolt-hole and also spraying everything down w/ WD-40!

This is an old pdq67 "feelie" thing that works for me!

You will see how the bolt-holes threads pull the block up ever so slightly and this is the part that needs to be lightly dressed down. Same deal w/ the heads. I also use a 45 degree chamfer bit to chamfer the holes at this time like stock.

The file will start cutting away the "dirt/rust" first, then next the higher metal so watch AND "feel" here b/c you only want it SMOOTH all over!! I've seen a Machinist use 600(?) grit "wet-r-dry" sandpaper and a big steel flat gauge block to do this too..

And spray plenty of WD-40 to flush everything clean while you do this......

pdq67

Most blocks don't need to be decked. Unless there's something seriously wrong with it I'd leave it alone..

I'm with Mark here. Many machine shops want to deck every block, but unless it is out of square, there is no reason to do so. IF it was going to be a racing engine, seeing lots of revs for extended times, then decking it and trying to make everything "perfect" at the time of rebuild makes sense. Decking makes certain that everything is "true" to the crankshaft bearing bores, but it (decking) is unnecessary on 99% of rebuilds.

Did the engine have a head gasket leak?

You can ask the machine shop to check the decks for flatness. You lay a straightedge (typically a flat steel bar that is made for this) on the deck lengthwise, then try to slide a 0.003 inch feeler gage under it along the deck. If the 0.003 goes under the straightedge, there's a dip in the deck. If a 0.005 inch gage slides under, then it will need to be decked.

Now, some machine shops use a type of boring bar that locates on the deck, and the deck has to be perfectly flat to make sure the bores are not machined off center. If that's the case, you may need to try to find a different machine shop.

So, what I guess I am saying is ask the shop to demonstrate why the block needs to be decked. If it's just because they "do it all the time" or because of the type of boring equipment they use, try to find another shop.

And there is NOTHING wrong w/ a deck located boring bar in the hands of a GOOD Machinist!!

Sure, it's not SOTA, but there's been millions of engines bored FINE using them!!

pdq67

A good machine shop can deck the block and save the numbers. I have had the 427 in my Nova and the original 350 in my 70 Z28 decked. Both have the original numbers still there. The machinist has to stop the cutter when it gets to the stamp. Takes a little more work, but can definitely be done.