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decking original block

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shovelluv

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My engine builder wants to deck my Numbers matching block and take a little off on the heads to clean things up. He says he strongly suggests it. The problem I have is the HP, date code and engine number will come off the pad. I have plenty of pics of the original stamping and still have the VIN stamped by the motor mount and casting numbers and casting dates. For the sake of the motor I do want to have it cleaned up but will it hurt the value when I get it all done? Just want to others opinions. Its a pretty much stock rebuild but the block had to be bored.
 
You don't mention what engine you have, but I assume it is a RB block. I agree with the shop that it should be decked, but since the intake does not seal to the valley rails, it is not necessary to cut them and remover the stampings. Just cut the block decks to match, and leave the rails (valley) alone. Cut the heads 0.010", and take 0.010" off of the intake surface of the heads and you will be fine.
 
Decking the only removes material above the bores not area where pad is.
Not sure about a 383.
 
I’m assuming that you’re working on a low deck big block and if so just have him not take a pass over that part of the pad. You need to make him understand that he cannot machine those numbers off. If it were me I ask to watch while they machine that surface or put the matching block aside and put another block in the car.
 
Last edited:
Fran Blacker said:
Decking the only removes material above the bores not area where pad is.
Not sure about a 383.
Click to expand...
You are both correct and incorrect all at the same time... :thumbsup:

When a V6 & V8 block is "Squared", and the intake seals to the valley rails, you must cur an amount from the rails so that the intake isn't held up and prevent it from sealing the waterjackets... As I stated, the BB Nopar does not seal to the rails because it has a valley pan, so it is not necessary to cut the rails.
 
Now, I looked at pics of a "B" block, and the stamp pad is in front of the pass deck, and at the same height. To that point, a good machinist can stop the mill before it hits the stampings as the pad is quite large. It is possible to miss the stampings, they just have to pay attention.

you want to see close? This is a '69 DZ 302, numbers matching $100000+ Camaro. I was at a "Pucker Factor" of 10 on this one... I had to file the lower part of the rail in the pic because I could not cut any more safely.

IMG_1019.JPG
 
Here is a 400 "B" block, and you can see the large pad with plenty of safety room...

400 Block.jpg
 
69Bee said:
You don't mention what engine you have, but I assume it is a RB block. I agree with the shop that it should be decked, but since the intake does not seal to the valley rails, it is not necessary to cut them and remover the stampings. Just cut the block decks to match, and leave the rails (valley) alone. Cut the heads 0.010", and take 0.010" off of the intake surface of the heads and you will be fine.
Click to expand...
Not necessarily true. If you cut enough off of the head surface the end rails get shorter in length and no longer match up to the head. The rail is now too tall and the valley pan will no longer seal. We decked one of my 440’s and had to machine the end rails down. Luckily it wasn’t a numbers matching car since the numbers got machined off along with some of the end rails.
 
MCODECUDA said:
Not necessarily true. If you cut enough off of the head surface the end rails get shorter in length and no longer match up to the head. The rail is now too tall and the valley pan will no longer seal. We decked one of my 440’s and had to machine the end rails down. Luckily it wasn’t a numbers matching car since the numbers got machined off along with some of the end rails.
Click to expand...
Again, yes & no. You had a large deviation due to cutting a lot off of the block decks. If they just get cleaned and matched, it isn't really that big of a deal, a little extra sealer will suffice. Also, if the machinist is careful, he can reverse/stop the feed once the rail is cut and it should miss the stamp on the "RB" block. There is always the option to re-stamp if needed.

Everything aside, we basically agree as each block requirement is different, but yes, a "RB" id definitely different and harder to protect.
 
My other concern is intake seal when the block is decked. Is it that critical?
 
shovelluv said:
My other concern is intake seal when the block is decked. Is it that critical?
Click to expand...
The intake only seals to the heads. After the block is cut, and the heads cut, an amount should be cut from the intake side of each head so that the intake will sit deeper between the heads. When the block and heads are cut, the "V" gets closer together, making the intake sit higher and misaligning the intake bolts. The fix is to cut the intake side of the heads to widen up the "V", thus letting the intake sit deeper, and the bolt holes are lined up again.

Milling Info: Head Milling vs. (mopar1.us)

Engine/Head Type: Chrysler B/RB engine 79/81/83cc chamber
Amount to mill to reduce chamber volume by 1cc: .0042 Per cc
Proper amount to mill port sides of intake for correct alignment and sealing for each .010 removed the on heads or block: .0123"
Proper amount needed to mill intake ends for correct alignment and sealing for each .010 removed on the heads or block: not required


,
 
shovelluv said:
My engine builder wants to deck my Numbers matching block and take a little off on the heads to clean things up. He says he strongly suggests it. The problem I have is the HP, date code and engine number will come off the pad. I have plenty of pics of the original stamping and still have the VIN stamped by the motor mount and casting numbers and casting dates. For the sake of the motor I do want to have it cleaned up but will it hurt the value when I get it all done? Just want to others opinions. Its a pretty much stock rebuild but the block had to be bored.
Click to expand...

See if his equipment can be set up so that it can stop before the end of the block. Some older equipment has to make a full pass back and forth but newer equipment, especially CNC stuff can be programmed to stop and reverse. If he has older equipment that has to travel the full stroke back and forth then you'll either have to find a new shop or restamp the block.
 
You want your engine to run right ?? & not take it back out/apart and redo again ?? Well, since it takes $$$$ , time , expertise , greasy busted knuckles, makes a mess and you can't drive the car during that rebuild - etc. If it was a $300K matching #'s _____ pick your model ! It's not even reasonable to half *** the machine work , do it right , ONCE - take a pic, re-stamp, put a sticker on it - LOL ! Do what it needs to Rebuild engine correctly , 1st time !!! Don't play games with the machine work bc of #
 
Don't for get to mill down the intake. If you move the head's down the intake will not want to seat to the head's. Had this problem with a 440 we had decked and head's milled. Just my two cent's their. But the numbers on the block by the oil pan is the real number people look for. So it wont hurt your value. The vin number will match to the car.
 
If doing a stock rebuild, and the surfaces are flat (but not square) you don't need to cut the block (or heads.)
If the block or heads are NOT flat, they need to be cut so they seal. This could be a minimal cut that still may not "square" the block.
How far out of square is the block? maybe 0.010" front to back? It does not sound like you are trying to cut the deck so the pistons are at zero deck height.
With a minimal 0.010" or less cut on block and heads, using the normal Fel-Pro head gasket which is close to 0.040", where the stock shim is 0.020", the intake should fit fine.
As for the block numbers, I would think they could stop before the pad with the numbers stamped?
 
1danc... I completely agree with you and thats why I think going to have him do it. I am going to talk to him this morning and see if if its possible that he can stop before the numbers. I thought about re-stamping it in there since I have plenty of good pictures of the pad but I dont have the correct font and size. I also dont want to throw up any red flags when I go to sell it. Thanks
 
Last edited:
blue69runner said:
Don't for get to mill down the intake. If you move the head's down the intake will not want to seat to the head's. Had this problem with a 440 we had decked and head's milled. Just my two cent's their. But the numbers on the block by the oil pan is the real number people look for. So it wont hurt your value. The vin number will match to the car.
Click to expand...
Please refer to my post #12. You cut the intake side of the head, NOT the manifold. The valley rails and intake side of the head are cut so that the manifold is not married to the engine, and the engine can have any manifold put on without having to cut it to match first.
 
I hope it works out well for you, I've seen alot of people cut corners and it never pays off , do the machine work correctly the first time - there are other ways to verify that engine as said, with nothing to hide I would borrow and/or buy stamp dies and redo #'s even if not perfect match / building engine with correct machining procedures is #1 - check / double check all measurements, use quality parts, assume nothing ! You'll be able to have confidence in the rebuild - you started out right, ask questions ???? Now go get dirty brother !! ✌
 
If it is a number matching block, and that is important to you, i would NOT take a chance on the machinist caring enough to not machine them off.
I simply would NOT deck the block.
Or, you could threaten to sue him for the decrease in value if he does machine the numbers off.
 
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