340 block help

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SBDart

SBDart

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I just bought a 340 block. Not knowing the the head face had
Copper inserted in to the head facing.
I took it to the machine shop and they said they would not machine it because they
Was afraid that they would deck it and they would cut out the copper an it might cut
To deep an put holes in the head facing.and they would have to weld back in wear the copper
Was. An would cost as much as what I paid for the block .
So what do I do now????

It's is how the use to seal the heads in
The good old days . By putting in copper around the top of the
Head facing to help seal the head. Because the head gasket back in
The day would not seal.
 

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Never heard of this. Some HP engines, shop would "O ring" the block deck, and copper wire rings would be used, but they are not PERMANENT

If you Google "O ring engine block" you'll find lots of info. If this is something different, don't know
 
I hate to say it, but you may be better off getting another block...
 
Pull the orings out and deck the grooves out.

If your machine shop doesn't know this, YOU NEED A BETTER MACHINE SHOP.

The block is more that useable. Just fix it.
 
need to measure how deep grooves are. you might cut block way too much. another method would be, remove copper wire, deck block, then insert new wire that is slightly smaller dia. that will not stick up into gasket. it'll fill the groove. it has to fit width wise to make a flat surface. just food for thought!!!! after inserting wire, bolt on a head with no gasket, tighten down to mash wire level with deck. then see where you are.
 
Its all a guessing game until the decks are measured. I second finding a better shop.

What is the bore?
 
Could use a better picture of the deck but if it is O-ringed there is no problem using this block the way it is. The wire is supposed to stick up from the deck a few thousands and imbed itself in the head gasket. I ran a O-ringed block for years, street/strip car. It does not cause a problem. You can run it and not worry.
 
dano said:
Its all a guessing game until the decks are measured. I second finding a better shop.

What is the bore?
Click to expand...

I need 4.07 the block is what I was told that is was 30 overs
 
I hope this helps some more pics
 

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As was mentioned - the block was O-ringed at some time in it's past and a copper wire was put into the groove. If your shop had any clue about race engines, and Mopar or Ford small blocks in particular they'd understand the ramifications of that. You can either mill off the groove, which may leave you with a weak unstable deck surface depending on the depth of the groove - or clean the old compressed copper out and after machining put new copper wire in it - or put some sort of spacer or shim material in the groove to support a standard gasket. All depends on what's there, and what you're doing.
But regardless of that - it sounds like this shop is over it's head and you're asking for more heartache and expense by continuing to use them on this project.
 
moper said:
As was mentioned - the block was O-ringed at some time in it's past and a copper wire was put into the groove. If your shop had any clue about race engines, and Mopar or Ford small blocks in particular they'd understand the ramifications of that. You can either mill off the groove, which may leave you with a weak unstable deck surface depending on the depth of the groove - or clean the old compressed copper out and after machining put new copper wire in it - or put some sort of spacer or shim material in the groove to support a standard gasket. All depends on what's there, and what you're doing.
But regardless of that - it sounds like this shop is over it's head and you're asking for more heartache and expense by continuing to use them on this project.
Click to expand...

^^^^^^^^^^
 
C'mon guys you are making this way too hard for the OP. Freaking o rings have been used for decades (and still are). Typically, the wire is .039 diameter (sometimes .042). So using the .039 wire example, you need the GROOVE DEPTH to be a little over 1/2 the diameter so the wire will press into and stay in the groove. That means that someone machined about a .022-.025 deep groove in the deck. That's all the deeper it is.

I can tell you I run ALL my 340 stuff a MINIMUM of .030 OUT OF THE DECK or you will never get close to the original 10.5:1 compression ratio (assuming open chamber heads). So take a pick, find the gap where the wire butts together and dig the wires out. Then deck until they are gone and preassemble and check for compression. All of this stuff SHOULD be done anyway, but I know it's not because guys always say I have 10:1 ISH compress, or about 10:1, or close to...you get the idea.. It needs to be MEASURED. You can't guess on compression ratio, or use the piston volume the piston guys give you.


The other option, which I have used to fix your issue when the block is in the car works and I have used it many times. Since your stuff is on the floor I would do the above. But, you can take the wires out, clean up the grooves VERY well, take JB weld and fill the grooves with it, leaving the JB weld a little proud. When it dries, take a long board and sand the decks down until it's flat. Throw gaskets on it and go. Works every time.


So two easy, simple ways to fix it.

Find a new machine shop.
 
find another machine shop x2 I've taken .100 off with no problems just had to cut the intake a little, cheaper then new block.
 
I would worry first about how many times the block has been decked and if it's already over bored? Usually engines with this mod in the past were used hard!!! Has it been sonic checked or checked for cracks?
 
Don't take my head off for this question, but could you resleeve the block?
 
EL5DEMON340 said:
I would worry first about how many times the block has been decked and if it's already over bored? Usually engines with this mod in the past were used hard!!! Has it been sonic checked or checked for cracks?
Click to expand...

This is why I said the deck could be weaker. Yo unever know what was done before especially given "back in the day" only custom pistons would have been tall enough to give any real compression without cutting the decks a bit.


"Don't take my head off for this question, but could you resleeve the block? "

Sleeving in terms of these engines is to repair the wear surface - meaning the bore... It won't adress any issues with the surface of the deck.
 
Ok I found machine shop that said they could do the work with out any questions ask
They said what they would do is take out the copper seals then deck the block. Then they would check the height of my Pistons to the top of the deck of the head surface. To see if the piston is below or above deck. And if it's above deck will have to get custom short piston or use a 50 thousand head gaskets
Depending on the height or how much Of the piston is out of the head surface.
 
Great before they do any machining have the bores sonic checked And crack check the block.
 
I have already said to them that I want they to have it mag to check for cracks
 
I don't know what use you intend for this engine, but if you are OK with hypereutectic pistons, then the SRP pistons for the 340 have a lower compression height; i.e., they will be lower in the bores, about .018" down in the bore with a stock deck height. They have an advertised compression height of 1.804". If you need that a bit lower, then some shops can pretty easily mill a bit off of the pistons tops. There may be other good choices.

But all of this depends on the heads you plan to use; do you have a set of heads selected?

Let us know how much the shop ends up cutting the deck down.
 
Have them check the deck height before they do any additional decking! Simple machine shop protocol!!
 
cosgig said:
Have them check the deck height before they do any additional decking! Simple machine shop protocol!!
Click to expand...

X2.
You do not deck, buy pistons, and then measure to se what's what. You measure to find out what is feasible and will give return on investment, then order the right stuff. Plus they will have to address that groove either by installing fresh wire and the right head gaskets, or by removing (or filling) it.
 
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