Cylinder wall thickness

theman440 · 11-29-2017, 03:40 PM

A question for the engine builders here on CR - What would be a minimum cyl wall thickness you would want to see? The block is a factory Mopar 440 for a bracket car shootin for 700-750 hp.

Thank you

GTX JOHN · 12-01-2017, 05:46 AM

I would want .175 or more at finished overbore in a big block mopar or .135 in small block mopar.

theman440 · 12-01-2017, 08:16 PM

Thanks John,

Are you back in town? - you happen to have a sonic checker? call me I still need some wheels.

Paul Precht · 12-21-2017, 11:45 PM

The only blocks that are that are thick are the 413 industrial and motorhome, most 440s are less than .175" before boring and 700HP would be about the safe limit IMO. The aftermarket blocks are the way to go if you can get one. The 400 blocks are a bit stronger in the web area and more rigid due to the shorter cylinder length. A 400 block filled Halco machine grout and Pro-Gram Engineering main caps would be a good start.

Todd Gross · 12-28-2017, 08:52 AM

There were some thick blocks in 67-69 era. Back when I was more adventurous, we took some old blocks, filled them, bored/honed to 4.560 and put a 4.625 stroke to make an alcohol 604" It required a main girdle and good caps to hold things since the cylinder walls were at .060" +/- a little.
They didn't stay round very long as one might expect. That was back around 1990 and the only aftermarket blocks were KB. Thought it was worth a try. It wasn't.

GTX JOHN · 01-01-2018, 11:35 PM

We have seen thick and thin blocks......No matter what year
the 440 blocks are. Just have to check them.

Chuck Gallagher · 01-08-2021, 11:42 AM

Jeff:
Engine blocks are like home made cakes from an oven. The quality really depends on the ingredients, and the maker, and the available controls as to how well they turn out..
Two identical (brand) blocks from different foundries, both following the same prints, are not usually going to be the same. A block with a higher carbon content and precision casting core control could be more likely to hold the cylinder walls shape (round and straight) and have stronger main webs then a much thicker block that had lower carbon in the iron and poorer control of the casting cores.
High volume production blocks generally are not going to result in castings that will hold their shape at the horsepower levels (600+) racers want. This is why todays purpose designed racing blocks are, in the majority of cases, cast using compacted graphite which is more robust but also more expensive.
So before investing in machining any recycled production block, I would recommend that you test the block for hardness of the material and the amount of core shift that may be present and if a new racing equivalent is available from a reliable source.
You don't want to end up with an engine with a cracked main web or seven perfect and one bad cylinder.
Chuck Gallagher

Rich Biebel · 01-08-2021, 12:34 PM

What Chuck said is accurate and back in my engine shop days we hardness tested and sonic tested most Small Block Chevys and any block that was going to be potentially used for a race engine....

The Hardness test was easy using a Brinell tester and the blocks had a pretty wide spread on the numbers that you got on the test..

An ideal block was at the high end of the hardness scale and had thrust walls that would be .200" or more when finished.

You can easily see a badly core shifted block just by the cam hole and the machined surface at the face of it. The sonic test will show the cylinder walls being offset usually on a block with visible shift at the cam hole...

I was buidling a 383 for a friend and the block was so offset I could not get rods to clear one side at the bottom of the cylinders and the other side went right by......I changed what rods I was using for it just to make the fit and not grind the heck out of the block and potentially break thru to the water jacket....The crank and cam were not centered in the casting by a fair amount.....GM had some real odd ways of machining engine parts.....BB Chevy Iron heads is a good example.......Guide bores not centered with the guide OD

The Brinell numbers were from a low of around 200 to a high of around 245.....

A nice early 4 bolt 010 block with nodular caps was the best you could hope to find with good hardness and cylinder wall thickness....

Aftermarket blocks are a ton better......

Ralph A Powell · 01-26-2021, 10:43 AM

Aftermarket blocks have much better tooling ( has been used in production for years) and in most cases poured in lower volume foundries.

11-29-2017, 03:40 PM	#1
theman440 Member Join Date: Apr 2013 Location: Fabulous Las Vegas Posts: 114 Likes: 29 Liked 24 Times in 13 Posts	Cylinder wall thickness A question for the engine builders here on CR - What would be a minimum cyl wall thickness you would want to see? The block is a factory Mopar 440 for a bracket car shootin for 700-750 hp. Thank you __________________ Jeff Dudgeon '66 Coronet #10771 - bracket puke "the Flying Brick"

12-01-2017, 05:46 AM	#2
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,598 Likes: 2,389 Liked 2,129 Times in 613 Posts	Re: Cylinder wall thickness I would want .175 or more at finished overbore in a big block mopar or .135 in small block mopar. __________________ John Irving 741 Stock 741 Super Stock

12-01-2017, 08:16 PM	#3
theman440 Member Join Date: Apr 2013 Location: Fabulous Las Vegas Posts: 114 Likes: 29 Liked 24 Times in 13 Posts	Re: Cylinder wall thickness Thanks John, Are you back in town? - you happen to have a sonic checker? call me I still need some wheels. __________________ Jeff Dudgeon '66 Coronet #10771 - bracket puke "the Flying Brick"

12-21-2017, 11:45 PM	#4
Paul Precht Senior Member Join Date: Dec 2001 Location: Elysburg, Pa Posts: 707 Likes: 313 Liked 256 Times in 98 Posts	Re: Cylinder wall thickness The only blocks that are that are thick are the 413 industrial and motorhome, most 440s are less than .175" before boring and 700HP would be about the safe limit IMO. The aftermarket blocks are the way to go if you can get one. The 400 blocks are a bit stronger in the web area and more rigid due to the shorter cylinder length. A 400 block filled Halco machine grout and Pro-Gram Engineering main caps would be a good start.

12-28-2017, 08:52 AM	#5
Todd Gross Member Join Date: Mar 2016 Location: Crete, IL Posts: 169 Likes: 237 Liked 56 Times in 24 Posts	Re: Cylinder wall thickness There were some thick blocks in 67-69 era. Back when I was more adventurous, we took some old blocks, filled them, bored/honed to 4.560 and put a 4.625 stroke to make an alcohol 604" It required a main girdle and good caps to hold things since the cylinder walls were at .060" +/- a little. They didn't stay round very long as one might expect. That was back around 1990 and the only aftermarket blocks were KB. Thought it was worth a try. It wasn't. __________________ Todd Gross 3323 FS/E,F

01-01-2018, 11:35 PM	#6
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,598 Likes: 2,389 Liked 2,129 Times in 613 Posts	Re: Cylinder wall thickness We have seen thick and thin blocks......No matter what year the 440 blocks are. Just have to check them. __________________ John Irving 741 Stock 741 Super Stock

01-08-2021, 11:42 AM	#7
Chuck Gallagher Junior Member Join Date: Apr 2013 Location: NC (nothing compares) Posts: 48 Likes: 33 Liked 133 Times in 28 Posts	Re: Cylinder wall thickness Jeff: Engine blocks are like home made cakes from an oven. The quality really depends on the ingredients, and the maker, and the available controls as to how well they turn out.. Two identical (brand) blocks from different foundries, both following the same prints, are not usually going to be the same. A block with a higher carbon content and precision casting core control could be more likely to hold the cylinder walls shape (round and straight) and have stronger main webs then a much thicker block that had lower carbon in the iron and poorer control of the casting cores. High volume production blocks generally are not going to result in castings that will hold their shape at the horsepower levels (600+) racers want. This is why todays purpose designed racing blocks are, in the majority of cases, cast using compacted graphite which is more robust but also more expensive. So before investing in machining any recycled production block, I would recommend that you test the block for hardness of the material and the amount of core shift that may be present and if a new racing equivalent is available from a reliable source. You don't want to end up with an engine with a cracked main web or seven perfect and one bad cylinder. Chuck Gallagher Last edited by Chuck Gallagher; 01-08-2021 at 11:46 AM.

01-08-2021, 12:34 PM	#8
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,307 Likes: 25 Liked 537 Times in 211 Posts	Re: Cylinder wall thickness What Chuck said is accurate and back in my engine shop days we hardness tested and sonic tested most Small Block Chevys and any block that was going to be potentially used for a race engine.... The Hardness test was easy using a Brinell tester and the blocks had a pretty wide spread on the numbers that you got on the test.. An ideal block was at the high end of the hardness scale and had thrust walls that would be .200" or more when finished. You can easily see a badly core shifted block just by the cam hole and the machined surface at the face of it. The sonic test will show the cylinder walls being offset usually on a block with visible shift at the cam hole... I was buidling a 383 for a friend and the block was so offset I could not get rods to clear one side at the bottom of the cylinders and the other side went right by......I changed what rods I was using for it just to make the fit and not grind the heck out of the block and potentially break thru to the water jacket....The crank and cam were not centered in the casting by a fair amount.....GM had some real odd ways of machining engine parts.....BB Chevy Iron heads is a good example.......Guide bores not centered with the guide OD The Brinell numbers were from a low of around 200 to a high of around 245..... A nice early 4 bolt 010 block with nodular caps was the best you could hope to find with good hardness and cylinder wall thickness.... Aftermarket blocks are a ton better...... __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 01-08-2021 at 12:38 PM.

01-26-2021, 10:43 AM	#9
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 372 Likes: 1 Liked 213 Times in 130 Posts	Re: Cylinder wall thickness Aftermarket blocks have much better tooling ( has been used in production for years) and in most cases poured in lower volume foundries.