400 sbc steamholes

[circletracker]

What's the thought out there with plugging the steam holes in the block and also plugging the larger holes at the top of the deck with 3/4" pipe plugs and reducing those holes to about 5/16" dia.?

[stock car driver]

What's the thought out there with plugging the steam holes in the block and also plugging the larger holes at the top of the deck with 3/4" pipe plugs and reducing those holes to about 5/16" dia.?

Thats what I do to all my 400 block motors, never burnt thru a gasket near the steam holes yet...

Do it all before decking the block.

[parrot69777]

We do that on every 400 block. Makes the cylinders stronger and you don't have to worry about the block cracking inbetween the cylinders and into the head bolt hole.

[forty40]

Chevrolet SBC 400 cu in cylinder blocks were manufactured with the so called steam holes to prevent steam from being generated in the simese cylinder bore. This was done to insure longevity of the engine in everyday use, where low RPM for extended periods in city driving may be encountered. There used to be the idea that a mechanical threaded plug with a smaller drilled hole would in some way stiffen the block and prevent unwanted heating issues. If the cylinder block is going to be used in a racing application at above 3500 RPM, the steam holes left as is are suitable or if plugged and drilled will also work. There is nothing documented or a general stiffness to the deck that can be calculated showing any advantage with or without plugs. They add no cylinder wall stiffness in any way and adequate wall thickness has much more influence in power lost or gained and the propensity to cylinder cracking.

[parrot69777]

Obviously you have never honed a block with torque plates.....can easily see the difference.

[forty40]

Embellished information may be credible in the secret society of gnostic engine machining, but in this world a casual observation of surface finish with indefinable, immeasurable characteristics has no bearing on the question at hand.

Do threaded deck plugs improve cylinder efficiency thereby increasing engine performance?

Show your column stiffness calculations or at a minimum statistically relevant 15 instances each, with contrasting parameters, simply stated with and w/o plugs. Produce test data supporting the contention that mechanical fasteners installed in a production cast cylinder block improve overall block efficiency and eventual engine improvement. If that information is not readily at hand, then attach links to SAE technical papers, either seminar instruction or white papers supporting the position. If presenting calculations for hoop stress, include tolerances attributable to dimensional variation in production castings manufactured nearly 20 years ago. Give everyone the outline of your premise. Include in the outline but not limited to macro exam for spherodized carbon, hardness, yield, UTS, along with specific measurements of wall T, deck T, and a UT scan for subsurface discontinuities. That is of course unless the evaluation is based on commercial gray iron, which cylinder blocks are not.

With an interest in finding what the best of the best are doing, we acquired a finish machined cast cylinder block from a nationally known engine builder in northeast Tennessee (VH). How many deck plugs were installed…none. So, in this one minor issue of cylinder block preparation, do we go with the example of a national reputation for performance or rely on pseudo-performance information attempting to be authoritative. Simply stating “I install plugs in all my stuff” has no informational value when not validated by test data or calculation, nothing more than gibberish intended as credible.

[joedoozer]

Embellished information may be credible in the secret society of gnostic engine machining, but in this world a casual observation of surface finish with indefinable, immeasurable characteristics has no bearing on the question at hand.

Do threaded deck plugs improve cylinder efficiency thereby increasing engine performance?

Show your column stiffness calculations or at a minimum statistically relevant 15 instances each, with contrasting parameters, simply stated with and w/o plugs. Produce test data supporting the contention that mechanical fasteners installed in a production cast cylinder block improve overall block efficiency and eventual engine improvement. If that information is not readily at hand, then attach links to SAE technical papers, either seminar instruction or white papers supporting the position. If presenting calculations for hoop stress, include tolerances attributable to dimensional variation in production castings manufactured nearly 20 years ago. Give everyone the outline of your premise. Include in the outline but not limited to macro exam for spherodized carbon, hardness, yield, UTS, along with specific measurements of wall T, deck T, and a UT scan for subsurface discontinuities. That is of course unless the evaluation is based on commercial gray iron, which cylinder blocks are not.

With an interest in finding what the best of the best are doing, we acquired a finish machined cast cylinder block from a nationally known engine builder in northeast Tennessee (VH). How many deck plugs were installed…none. So, in this one minor issue of cylinder block preparation, do we go with the example of a national reputation for performance or rely on pseudo-performance information attempting to be authoritative. Simply stating “I install plugs in all my stuff” has no informational value when not validated by test data or calculation, nothing more than gibberish intended as credible.

But...but....but.....this is the foundation that 4M is built :). Just a joke, so don't get all red in the face :mad:.

[stock car driver]

Embellished information may be credible in the secret society of gnostic engine machining, but in this world a casual observation of surface finish with indefinable, immeasurable characteristics has no bearing on the question at hand.

Do threaded deck plugs improve cylinder efficiency thereby increasing engine performance?

Show your column stiffness calculations or at a minimum statistically relevant 15 instances each, with contrasting parameters, simply stated with and w/o plugs. Produce test data supporting the contention that mechanical fasteners installed in a production cast cylinder block improve overall block efficiency and eventual engine improvement. If that information is not readily at hand, then attach links to SAE technical papers, either seminar instruction or white papers supporting the position. If presenting calculations for hoop stress, include tolerances attributable to dimensional variation in production castings manufactured nearly 20 years ago. Give everyone the outline of your premise. Include in the outline but not limited to macro exam for spherodized carbon, hardness, yield, UTS, along with specific measurements of wall T, deck T, and a UT scan for subsurface discontinuities. That is of course unless the evaluation is based on commercial gray iron, which cylinder blocks are not.

With an interest in finding what the best of the best are doing, we acquired a finish machined cast cylinder block from a nationally known engine builder in northeast Tennessee (VH). How many deck plugs were installed…none. So, in this one minor issue of cylinder block preparation, do we go with the example of a national reputation for performance or rely on pseudo-performance information attempting to be authoritative. Simply stating “I install plugs in all my stuff” has no informational value when not validated by test data or calculation, nothing more than gibberish intended as credible.



Those of us who race and have built a lot of 400 block motors know that they do NOT ever crack in the steam holes if the steam holes are not there.

There is no need for them in a race motor and it does not matter if it makes more power that is completely irrelevant.

Nobody will be fooled by your post because its full of b.s data or long, lol.

jj

[parrot69777]

Sounds like he is either a lawyer or an engineer. Both could talk all day and still say nothing.

[Race Dog]

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Some people like cake
Some people like icecream
Some like cake & icecream

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