I was recently asked if a block really needed to be decked after a neighbor blew a head gasket?
if you don,t know what that, decking the block means,
its basically re-surfacing , or removing a few thousands of material from the block surface where the cylinder heads bolt on,
the head gasket is sandwiched between the block deck and cylinder heads and compressed with the head bolt tension.
for the gasket to provide the proper seal it must be between two flat, smooth parallel surfaces that are measured from the crank centerline.
most factory blocks are about .020-.025 taller than the listed deck height,
to allow a deck trim/mill to straighten and make the head gasket sealing surface true,
without milling the engine deck height under the listed deck height.
having a used block deck milled .005 to true up the surface is rather common before a rebuild, obviously, with most factory cast blocks having about a .024 over the design specs in deck height, this can be done more than once in an engines life and head gaskets vary from about .015-.080 to allow you to get proper quench
It might be a surprise to many guys but a $10,
METAL CARPENTERS SQUARE and feeler gauges, can be used ,
to verify a block thats is significantly warped
on the deck surface.
now just because you blow a head gasket its not almost mandatory,
but it could be required ,that you might need the block deck re-machined,
....the hotter the engine got and the longer the engine ran,
with a defective head gasket ,
the more likely the block needs to be re-decked.
it should be obvious that careful inspection and accurate measurement is required,
and
if in doubt, bring it to a local trusted machine shop
for cleaning inspection and having the,
new cam bearings and new brass freeze plugs installed
Here is a cutaway illustration of a piston at top dead center to show deck height in action.
hey measure the piston deck height after the machined block has the rotating assembly test fitted
Deck Heights of Popular Domestic V8 Engines
Chevy
BlockDeck Height
283-350-400 SBC ----------------------9.025
LS Gen III/IV/V------------------------9.240
396-454 MK IV Gen V/VI BBC------ 9.80
348-409 ---------------------------------9.60
366-427 Truck Tall Deck BBC --------10.20
Ford
BlockDeck Height
289-302 -----------------------------------8.206
Boss 302 / SVO------------------------ 8.201/ 8.210
4.6L – 5.0L Modular-------------------- 8.937
351W------------------------------- 9.480 - 9.503
351 C Boss --------------------------9.206
351M -------------------------------10.297
Ford Racing 351W ----------------9.206 – 9.503
351C, 400-2V ---------------------10.292 – 10.302
FE 332-428 ------------------------10.17
429-460 “385” ---------------------10.300 – 10.310 – 10.322
4.6L-5.0L Mod --------------------- 8.937
5.4L Mod ---------------------------10.079
Chrysler
273-318- Poly ----------------------9.60
273-318-340-360 LA -------------- 9.60
Chrysler LA Race -------------------9.56
361-383-400 B ---------------------9.98
413-426-440 RB -------------------10.725
426 Hemi ---------------------------10.725
5.7L- 6.4L Hemi ------------------- 9.240
Buick
400-430-455 -----------------------10.57
Oldsmobile
400-425-455 ----------------------- 10.625
Pontiac
326-350-389-400-428-455 ---------10.20
lots of good related linked info
yeah I'M AWARE MANY PEOPLE SKIP READING RELATED LINKS
BUT THEY ALSO EVENTUALLY WILL REALIZE IT COSTS THEM MORE,
TIME, EFFORT AND CASH TO DO THAT IN THE LONG TERM
AN HOUR OR TWO SPENT READING LINKS USUALLY IS TIME VERY WELL SPENT
https://www.enginebuildermag.com/20...avoid-when-resurfacing-cylinder-heads-blocks/
http://garage.grumpysperformance.com/index.php?threads/block-prep.125/
https://www.hotrod.com/articles/ctrp-0701-engine-block-prep/#:~:text=Decking the Block Decking is,square up" the cylinder heads.
https://www.enginelabs.com/news/hit-the-deck-what-you-should-know-about-engine-block-deck-height/
http://garage.grumpysperformance.com/index.php?threads/head-gasket-roughness-ra.15927/#post-95850
https://drivcat.com/Docs/1425.pdf
http://garage.grumpysperformance.co...402-bbc-with-a-4-454-crank-or-even-4-25.2165/
http://garage.grumpysperformance.co...ng-piston-pin-height-compression-height.5064/
http://garage.grumpysperformance.com/index.php?threads/milling-heads-and-intakes.2988/#post-38975
http://garage.grumpysperformance.com/index.php?threads/head-gasket.10085/#post-39429
http://www.performanceracingengine.com/Engine_Block_Deck_Squaring.html
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-68861
https://www.chevydiy.com/gaskets-fasteners-guide-big-block-chevy-engines/
http://garage.grumpysperformance.co...ore-clearance-on-your-block.14251/#post-72471
http://garage.grumpysperformance.co...late-honing-makes-a-differance.588/#post-7313
http://garage.grumpysperformance.com/index.php?threads/flex-hone.9538/#post-35100
http://garage.grumpysperformance.co...ing-piston-to-bore-ring-seal.3897/#post-26602
http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/
https://blog.k1technologies.com/what-is-deck-height-how-to-calculate-and-what-it-means
if you don,t know what that, decking the block means,
its basically re-surfacing , or removing a few thousands of material from the block surface where the cylinder heads bolt on,
the head gasket is sandwiched between the block deck and cylinder heads and compressed with the head bolt tension.
for the gasket to provide the proper seal it must be between two flat, smooth parallel surfaces that are measured from the crank centerline.
most factory blocks are about .020-.025 taller than the listed deck height,
to allow a deck trim/mill to straighten and make the head gasket sealing surface true,
without milling the engine deck height under the listed deck height.
having a used block deck milled .005 to true up the surface is rather common before a rebuild, obviously, with most factory cast blocks having about a .024 over the design specs in deck height, this can be done more than once in an engines life and head gaskets vary from about .015-.080 to allow you to get proper quench
It might be a surprise to many guys but a $10,
METAL CARPENTERS SQUARE and feeler gauges, can be used ,
to verify a block thats is significantly warped
on the deck surface.now just because you blow a head gasket its not almost mandatory,
but it could be required ,that you might need the block deck re-machined,
....the hotter the engine got and the longer the engine ran,
with a defective head gasket ,
the more likely the block needs to be re-decked.
it should be obvious that careful inspection and accurate measurement is required,
and
if in doubt, bring it to a local trusted machine shop
for cleaning inspection and having the,
new cam bearings and new brass freeze plugs installed
Here is a cutaway illustration of a piston at top dead center to show deck height in action.
hey measure the piston deck height after the machined block has the rotating assembly test fitted
Deck Heights of Popular Domestic V8 Engines
Chevy
BlockDeck Height
283-350-400 SBC ----------------------9.025
LS Gen III/IV/V------------------------9.240
396-454 MK IV Gen V/VI BBC------ 9.80
348-409 ---------------------------------9.60
366-427 Truck Tall Deck BBC --------10.20
Ford
BlockDeck Height
289-302 -----------------------------------8.206
Boss 302 / SVO------------------------ 8.201/ 8.210
4.6L – 5.0L Modular-------------------- 8.937
351W------------------------------- 9.480 - 9.503
351 C Boss --------------------------9.206
351M -------------------------------10.297
Ford Racing 351W ----------------9.206 – 9.503
351C, 400-2V ---------------------10.292 – 10.302
FE 332-428 ------------------------10.17
429-460 “385” ---------------------10.300 – 10.310 – 10.322
4.6L-5.0L Mod --------------------- 8.937
5.4L Mod ---------------------------10.079
Chrysler
273-318- Poly ----------------------9.60
273-318-340-360 LA -------------- 9.60
Chrysler LA Race -------------------9.56
361-383-400 B ---------------------9.98
413-426-440 RB -------------------10.725
426 Hemi ---------------------------10.725
5.7L- 6.4L Hemi ------------------- 9.240
Buick
400-430-455 -----------------------10.57
Oldsmobile
400-425-455 ----------------------- 10.625
Pontiac
326-350-389-400-428-455 ---------10.20
lots of good related linked info
yeah I'M AWARE MANY PEOPLE SKIP READING RELATED LINKS
BUT THEY ALSO EVENTUALLY WILL REALIZE IT COSTS THEM MORE,
TIME, EFFORT AND CASH TO DO THAT IN THE LONG TERM
AN HOUR OR TWO SPENT READING LINKS USUALLY IS TIME VERY WELL SPENT
https://www.enginebuildermag.com/20...avoid-when-resurfacing-cylinder-heads-blocks/
http://garage.grumpysperformance.com/index.php?threads/block-prep.125/
https://www.hotrod.com/articles/ctrp-0701-engine-block-prep/#:~:text=Decking the Block Decking is,square up" the cylinder heads.
https://www.enginelabs.com/news/hit-the-deck-what-you-should-know-about-engine-block-deck-height/
http://garage.grumpysperformance.com/index.php?threads/head-gasket-roughness-ra.15927/#post-95850
https://drivcat.com/Docs/1425.pdf
http://garage.grumpysperformance.co...402-bbc-with-a-4-454-crank-or-even-4-25.2165/
http://garage.grumpysperformance.co...ng-piston-pin-height-compression-height.5064/
http://garage.grumpysperformance.com/index.php?threads/milling-heads-and-intakes.2988/#post-38975
http://garage.grumpysperformance.com/index.php?threads/head-gasket.10085/#post-39429
http://www.performanceracingengine.com/Engine_Block_Deck_Squaring.html
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-68861
https://www.chevydiy.com/gaskets-fasteners-guide-big-block-chevy-engines/
http://garage.grumpysperformance.co...ore-clearance-on-your-block.14251/#post-72471
http://garage.grumpysperformance.co...late-honing-makes-a-differance.588/#post-7313
http://garage.grumpysperformance.com/index.php?threads/flex-hone.9538/#post-35100
http://garage.grumpysperformance.co...ing-piston-to-bore-ring-seal.3897/#post-26602
http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/
https://blog.k1technologies.com/what-is-deck-height-how-to-calculate-and-what-it-means
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