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Username Post: 454 block        (Topic#361557)
steve65 
"5th Year" Gold Supporting Member
Posts: 856
steve65
Age: 62
Loc: New Westminster BC
Reg: 09-25-13
06-29-20 07:25 AM - Post#2797432    

Does any one know how much they would have had to deck the block to have removed the engine ID numbers?
I just got this one back from hot tanking and pressure testing. It has been rebuilt before as it had .020 over pistons in it, just wondering if it was decked just to square things up? Or maybe something else?
Thanks for any help,
Steve

Attachment: Block_pad.jpg (288.79 KB) 0 View(s)




Steve Duncan
66 Impala 2dr Coupe
Not sure of color yet
work in progress



 




Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1249
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
06-30-20 07:55 AM - Post#2797525    
    In response to steve65

The deck height is the measurement they are looking at versus the piston top.
It could be done to square things up and to get at set number above the top of the piston,
It is also done to increase compression ratio, how much it does I don't know,
is it dynamic or theoretical compression ratio or what other verbiage could possible be brought up.
Taking deck height to 0.005 will remove those numbers.
I am not a machinist, millwright, mechanical engineer, metallurgist or a spelling bee contestant.
I think I got it covered with all that.


VC56S 2 door Sedan, 40 Years

[image]https://www.chevytalk.org/fusionbb/fbbavatars/a v-3564-1354211547.jpg[/image]


Edited by Bad56Sedan on 06-30-20 07:59 AM. Reason for edit: this should draw them out

 
IgnitionMan 
Valued Contributor
Posts: 3759

Reg: 04-15-05
06-30-20 08:05 AM - Post#2797527    
    In response to steve65

It could also have been done for the right reason, to attain ZERO deck for proper use of a pack type head gasket to get correct quench distance.

Most Chevrolet blocks were between .020 and .025 taller than the flat deck on their pistons for decades, and a .020 thick steel shim gasket was used to get the correct quench distance. This allowed the block to be clean up decked during a rebuild, or to fix a sinking issue on the deck that blew head gaskets.

Only way you are going to know is to install the crank, and a rod/bearing, and a piston with the correct compression height (pin to deck position), and measure the down distance the deck of the piston gives in the block at full TDC.



 
steve65 
"5th Year" Gold Supporting Member
Posts: 856
steve65
Age: 62
Loc: New Westminster BC
Reg: 09-25-13
06-30-20 08:37 AM - Post#2797533    
    In response to Bad56Sedan

Thanks guys, appreciate the responses. I'm surprised it only takes that small of a cut to remove the numbers.
It is going back to another machine shop to be bored .030 over (pistons will have 10 cc dome) and have the oil gallery plugs, cam bearings and frost plugs installed.
Crank has already been turned .020 under, so once the block is done I will put one piston in on each side and start measuring things up.
Steve


Steve Duncan
66 Impala 2dr Coupe
Not sure of color yet
work in progress



 
Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1249
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
06-30-20 11:17 AM - Post#2797547    
    In response to steve65

Only 0.005" was left above the top of the pistons, how much the deck was cut I'm not sure.
It was enough to remove the block ID.

VC56S 2 door Sedan, 40 Years

[image]https://www.chevytalk.org/fusionbb/fbbavatars/a v-3564-1354211547.jpg[/image]


 
55MAS 
Senior Member
Posts: 1524

Loc: North Coast, Ohio
Reg: 12-19-01
06-30-20 01:02 PM - Post#2797553    
    In response to IgnitionMan

  • IgnitionMan Said:
It could also have been done for the right reason, to attain ZERO deck for proper use of a pack type head gasket to get correct quench distance.

Most Chevrolet blocks were between .020 and .025 taller than the flat deck on their pistons for decades, and a .020 thick steel shim gasket was used to get the correct quench distance. This allowed the block to be clean up decked during a rebuild, or to fix a sinking issue on the deck that blew head gaskets.

Only way you are going to know is to install the crank, and a rod/bearing, and a piston with the correct compression height (pin to deck position)< and measure the down distance the deck of the piston gives in the block at full TDC.



The deck height can be measured directly on the block itself without any rotating parts. OP probably doesn't have the tools but a competent shop will.






 
IgnitionMan 
Valued Contributor
Posts: 3759

Reg: 04-15-05
06-30-20 03:49 PM - Post#2797572    
    In response to 55MAS

And, ALL pistons have the exact same compression height???

I don't think so, that is why it is essential to build a piston set for each bank, and MEASURE, to get it RIGHT.

I have a few block deck height gauges, I built them a long time ago, and use them on every block, but, to get the end result, I do the two pistons in the block with rods, bearings and crank in place, to get it right.

Math is a great thing, unless it is "The New Math".



 
55MAS 
Senior Member
Posts: 1524

Loc: North Coast, Ohio
Reg: 12-19-01
07-01-20 01:34 PM - Post#2797656    
    In response to IgnitionMan

  • IgnitionMan Said:
And, ALL pistons have the exact same compression height???

I don't think so, that is why it is essential to build a piston set for each bank, and MEASURE, to get it RIGHT.

I have a few block deck height gauges, I built them a long time ago, and use them on every block, but, to get the end result, I do the two pistons in the block with rods, bearings and crank in place, to get it right.

Math is a great thing, unless it is "The New Math".



I am talking about a single part, an engine block. NOT measuring variations between piston and rod assemblies. It does not require additional engine parts to make measurements on a single cast and machined object.







 
IgnitionMan 
Valued Contributor
Posts: 3759

Reg: 04-15-05
07-01-20 05:11 PM - Post#2797672    
    In response to 55MAS

Oh, doesn't it? that's news, not only to me, but a whole bunch of other people that know how to do the things right.

If you don't know how far the piston is down in the bore, how can you calculate the cut needed for ZERO DECK?

Obviously, you can't. But, then, according to some, all compression heights, actual rod lengths, strokes for a particular engine series are same, same, aren't they.

I'm glad you aren't rebuildng my engines.



 
55MAS 
Senior Member
Posts: 1524

Loc: North Coast, Ohio
Reg: 12-19-01
07-02-20 03:16 PM - Post#2797746    
    In response to IgnitionMan

  • IgnitionMan Said:
Oh, doesn't it? that's news, not only to me, but a whole bunch of other people that know how to do the things right.

If you don't know how far the piston is down in the bore, how can you calculate the cut needed for ZERO DECK?

Obviously, you can't. But, then, according to some, all compression heights, actual rod lengths, strokes for a particular engine series are same, same, aren't they.

I'm glad you aren't rebuildng my engines.



I am talking about a design dimension on a single manufactured part. Guess you can't read a drawing nor have machined from from one CAD models. Good thing you are on the ground and have nothing to do with flight vehicles. Sorry I wondered into your little world. Time to exit.






 
IgnitionMan 
Valued Contributor
Posts: 3759

Reg: 04-15-05
07-03-20 02:09 PM - Post#2797808    
    In response to 55MAS

You aren't that smart, for sure.

I know exactly what I am doing, you have shown you only have limited knowledge of the parts, drawings and procedures on how to use these things properly.

Too bad, but you will have to live with it.



 




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