"hey GRUMPY?
Just bought a 427 long motor. Stock except .040" over. eng casting no is 3999294. Got some heads for it, casting no 3986133. Heads are mentioned in a few different chevy numbers lists, but half say closed chamber and the others say open?!?! What should I measure to confirm? I want +400 hp at the wheels, with a stage 3 shift kitted Turbo Hydro 400 trans. Wondering what cam to go with? solid or hydraulic? roller rockers? Going to run Quaddie carby, cos I love them. Making our own sheetmetal intake too. Want to try and reverse the water flow, to keep heads colder and bottom end hotter. Anyone got experience with this? Sorry for all the newbie questions."
the tall deck 427 block you have is a good place to start from, the heads are far less desirable, most guys building the tall deck blocks build a 496 stroker with a longer 6.385" connecting rod, and 4.25" stroker crank, and much lighter forged pistons,to take full advantage of the taller deck height, the current pistons are far too heavy to make high rpm power, the tall deck block used a heavy flat top low compression piston with 4 rings , not three like most car pistons ,requiring a taller piston and resulting taller block deck, its designed for low rpm torque.
the cam you select will depend on the heads, and intake, and compression ratio, and final displacement and your cars gearing, generally, youll want a fairly tight LSA around 108 and about a 10:1 cpr on a street car, duration and lift will be dictated by the other factors mentioned, obviously if you stay with a stock low cpr 427 it takes a smaller cam that a 10:1 cpr 496
3999294....427T......68-84...4-bolt
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
heads like these will far out perform your current heads easily worth an additional 100 plus hp
http://www.summitracing.com/parts/BRO-2061010/
http://gearheadgeek.com/ghgj/index.php/ ... -s?start=1
a properly designed 496 can easily make 550-600 hp with minor mods on off the shelf parts
the key is getting the head flow ,compression ,and cam timing to match the intended power curve
a properly built 496 can easily produce far more horsepower and torque that the heavy rotating assembly in your current 427 designed for low rpm torque and long term durability only
READ THE LINKS AND SUB LINKS,it could easily save you weeks of work and hundreds of dollars, and if you take the effort youll be far ahead of those guys that glance thru and don,t take the time to understand the concepts
viewtopic.php?f=69&t=3153
viewtopic.php?f=69&t=916
viewtopic.php?f=52&t=3960&p=10600&hilit=open+oval#p10600
viewtopic.php?f=69&t=170
http://www.edelbrock.com/automotive_new ... 0/2916.pdf
viewtopic.php?f=51&t=93&p=9023&hilit=mortec#p9023
viewtopic.php?f=51&t=2692&p=13225&hilit=tall+deck+intake#p13225
viewtopic.php?f=44&t=101
viewtopic.php?f=69&t=6132&p=19023#p19023
Thanks for your informative replys and links. I need all the help I can get! The engine is for a 1938 Bedford truck cabin rod I am building, body built by GM Holden, pre-world war II, in Melbourne. I am building a chassis for it, to mainly street it, but also for the odd Sunday at my local drag strip. Am currently estimating under 2500 lb for the car. 427T, TH400 box, 3.9-ish gears (9"), 4 link, air bags all round, flat bed tray. Power to weight should be ok
What does this look like to you, in terms of overall package, for about US$2600? I am unsure about the rods' ProComp brand, it being so new on the scene in Australia. Appreciate any feedback.
Scat Manufacturing 1-42390BI BBC 10.200 Deck 4340 Forged Competition Rotating Assembly with I-Beam Rods, 4.500" Bore x 4.500" Stroke x 6.535" Rod
4340 Forged Standard Weight Crank, Pro Comp I-Beam Connecting Rods with 7/16†Cap Screws, 1.395" Compression Ht. Premium Forged Pistons, Rings, Rod Bearings & Main Bearings
Internally Balanced
Crank:4-454-4500-6535
Rods:2-454-6535-2200
Stroke:4.500"
Rod:6.535"
Piston
remium Forged Dish
Bore:4.500"
Compression 58cc:8.8
Compression 64 cc:8.5
Compression 70cc:8.2
your going to need to have that block checked again, if its a tall deck 427 block your NEVER going to be able to bore it past about 4.310 and maintain a rigid cylinder wall that will maintain a good ring seal, and 4.375 is about the max stroke if you very carefully machine clearances, most guys go with a 4.25" stroke and a 4.310 bore and build a 496 displacement big block with 6.385 rods.
btw most BBC head have 100cc-122cc combustion chamber sizes and those CC quoted are SMALL BLOCK HEAD SIZES
main_page=calculators&zenid=823ce2c9e2ffa691864d832c10107df0
the best solution from a performance perspective is to do the required calculations to select the longest length connecting rod and the lowest weight piston,
of a decent design that will reduce the reciprocating mass significantly more.
the tall deck has a 10.2" deck height, a good dual plane aluminum high rise intake manifold will tend to provide the best compromise if you use a low compression and mild cam duration,
while it might seem like a waste of time, now, reading the links and sub-links will provide a good base to work from, later and save you a great deal of wasted time and money
you have a choice, you can slap the components you own together, now and live with what you have built regardless of the results , or you can put some real thought into making the result perform and carefully select parts and significantly boost power... yes that routes more expensive up front, but in the long term it tends to get better results and cost LESS.
common BB CHEVY piston compression heights are
1.270"
1.395"
1.520"
1.645"
1.765"
remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
OR
the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height
if you wonder why I suggest using SCAT (H) beam style cap screw connecting rods vs stock or most (I) beam designs this picture should show the increased cam to connecting rod clearance
notice the pin height in the pistons pictured above allow a longer or shorter connecting rod length
heres a selection of commonly available big block chevy connecting rod lengths
https://www.uempistons.com/index.ph...e=deck&zenid=823ce2c9e2ffa691864d832c10107df0
https://www.uempistons.com/index.php?main_page=calculators&zenid=823ce2c9e2ffa691864d832c10107df0
1.765 compression height, pistons in standard 9.8" deck block, a 10.2" tall deck requires a longer connecting rod
most likely a 6.535" aftermarket connecting rod
threads you should read through carefully,and the sub links in them are below,
the tall deck block is put to much better use building a 496 with a 4.25" stroke and a .060 over bore and 6.385" connecting rods
http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/
http://garage.grumpysperformance.co...g-block-head-comparison.319/page-2#post-61658
http://www.maliburacing.com/patrick_budd_article.htm
http://garage.grumpysperformance.com/index.php?threads/427-tall-deck-bbc.14451/
http://garage.grumpysperformance.com/index.php?threads/big-block-chevy-info.710/#post-60299
http://garage.grumpysperformance.co...-displacement-street-engine.10961/#post-50668
Grumpy, what is this required number likely to be, on most of the cams you like to use? (Intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees) This is required in this calculator I am using to consider compression ratios. I think it's one you've recommended.
address to calculator here:
http://kb-silvolite.com/calc.php?action=comp
Looking at using a 4.25" crank, 6.8" 'H' rods and a piston compression height of 1.27". Gives me a rod/stroke ratio of 1.6:1. What sort of pistons should I be looking for, using Brodix "Big Brodie" heads, with a 119cc chamber and 300cc intake runners, 2.25 intakes and 1.88 exh. Want between 10:1 and 11:1 compression. Waiting for deck height confirmation, but if its a stock 10.2", then I have .005" clearance with this combo, plus .040" for the gasket! Appreciate your help and suggestions!
in an ideal world you want the cylinder walls on cylinders to be at least .180 thick at the THINNEST, point, if they are thinner than .140 Id seriously consider either buying an aftermarket block with a thicker casting or filling the block water passages up to the lower edge of the freeze plugs to add a good deal more rigidity to the cylinder walls to reduce flex and increase ring seal.
READ THESE
viewtopic.php?f=51&t=588&p=764&hilit=sonic#p764
viewtopic.php?f=51&t=976&p=1827#p1827
HERES A CHART to find the intake valve close point at .050 lift, you then add 15 degrees to use that particular calculator
viewtopic.php?f=52&t=4299
If the rest of you figures are correct youll want about a 20cc-24cc dome on the piston and a cam with about a 55 degree intake valve close point at .050 lift
but most un-milled blocks will have a .023 deck height not .005
now for best power a cam with a 104-108 LSA is about correct but you can afford to use a wider 110-112 LSA, and loose a few hp but make the combo easier to drive and tune on the street, and have a wider torque curve
viewtopic.php?f=52&t=82
viewtopic.php?f=52&t=1070
viewtopic.php?f=52&t=727
Grumpy,
So, I did some homework with the info you have offered me.
I have tentatively chosen a piston with 24cc top, and a Comp Cams 11-450-8 cam.
It has IVC @.050 of 44 deg.
Power is in the region of 600hp (using the numbers for a 454) The Comp Cams calculator would not consider the 4.31 bore, so could not refer to 496 cu. in.
I used a 'domestic dual plane' for carb. with an 850 cfm
I then ran all the effective number in the compression calc you offered:
COMPRESSION RATIO CALCULATOR
Static and Dynamic Compression Ratio
(Considers Cam Timing and Rod Ratio)
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) 199
Cylinder Head Vol (cubic in.) 7.259
Piston Head Volume (cc) -24
Piston Head Vol (cubic in.) -1.464
Gasket Thickness (in.) .040
Swept Volume (cubic in.) 62.006
Gasket Bore (in.) 4.31
T.D.C. Volume (cubic in.) 6.715
Cylinder Bore Diameter (in.) 4.31
Gasket Volume (cubic in.) 0.584
Deck Clearance (in.) .023 Note: Neg. nubmer above deck, Pos. number below deck
Deck Volume (cubic in.) 0.336
Stroke (in.) STATIC COMPRESSION RATIO 10.234
OPTIONAL DATA
Rod Length (in.) 6.8
Adjusted Stroke (in.) 3.468
Intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees 59
DYNAMIC EFFECTIVE COMPRESSION RATIO 8.535
What are your thoughts on this combo?
Darn you know some serious stuff. I am loving the resource you are for me.
Id suggest a thinner head gasket to get the quench distance a bit closer and retarding this cam
http://www.summitracing.com/parts/CCA-11-460-8/
4 degrees as a better match to your application
Just bought a 427 long motor. Stock except .040" over. eng casting no is 3999294. Got some heads for it, casting no 3986133. Heads are mentioned in a few different chevy numbers lists, but half say closed chamber and the others say open?!?! What should I measure to confirm? I want +400 hp at the wheels, with a stage 3 shift kitted Turbo Hydro 400 trans. Wondering what cam to go with? solid or hydraulic? roller rockers? Going to run Quaddie carby, cos I love them. Making our own sheetmetal intake too. Want to try and reverse the water flow, to keep heads colder and bottom end hotter. Anyone got experience with this? Sorry for all the newbie questions."
the tall deck 427 block you have is a good place to start from, the heads are far less desirable, most guys building the tall deck blocks build a 496 stroker with a longer 6.385" connecting rod, and 4.25" stroker crank, and much lighter forged pistons,to take full advantage of the taller deck height, the current pistons are far too heavy to make high rpm power, the tall deck block used a heavy flat top low compression piston with 4 rings , not three like most car pistons ,requiring a taller piston and resulting taller block deck, its designed for low rpm torque.
the cam you select will depend on the heads, and intake, and compression ratio, and final displacement and your cars gearing, generally, youll want a fairly tight LSA around 108 and about a 10:1 cpr on a street car, duration and lift will be dictated by the other factors mentioned, obviously if you stay with a stock low cpr 427 it takes a smaller cam that a 10:1 cpr 496
3999294....427T......68-84...4-bolt
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
heads like these will far out perform your current heads easily worth an additional 100 plus hp
http://www.summitracing.com/parts/BRO-2061010/
http://gearheadgeek.com/ghgj/index.php/ ... -s?start=1
a properly designed 496 can easily make 550-600 hp with minor mods on off the shelf parts
the key is getting the head flow ,compression ,and cam timing to match the intended power curve
a properly built 496 can easily produce far more horsepower and torque that the heavy rotating assembly in your current 427 designed for low rpm torque and long term durability only
READ THE LINKS AND SUB LINKS,it could easily save you weeks of work and hundreds of dollars, and if you take the effort youll be far ahead of those guys that glance thru and don,t take the time to understand the concepts
viewtopic.php?f=69&t=3153
viewtopic.php?f=69&t=916
viewtopic.php?f=52&t=3960&p=10600&hilit=open+oval#p10600
viewtopic.php?f=69&t=170
http://www.edelbrock.com/automotive_new ... 0/2916.pdf
viewtopic.php?f=51&t=93&p=9023&hilit=mortec#p9023
viewtopic.php?f=51&t=2692&p=13225&hilit=tall+deck+intake#p13225
viewtopic.php?f=44&t=101
viewtopic.php?f=69&t=6132&p=19023#p19023
Thanks for your informative replys and links. I need all the help I can get! The engine is for a 1938 Bedford truck cabin rod I am building, body built by GM Holden, pre-world war II, in Melbourne. I am building a chassis for it, to mainly street it, but also for the odd Sunday at my local drag strip. Am currently estimating under 2500 lb for the car. 427T, TH400 box, 3.9-ish gears (9"), 4 link, air bags all round, flat bed tray. Power to weight should be ok
What does this look like to you, in terms of overall package, for about US$2600? I am unsure about the rods' ProComp brand, it being so new on the scene in Australia. Appreciate any feedback.
Scat Manufacturing 1-42390BI BBC 10.200 Deck 4340 Forged Competition Rotating Assembly with I-Beam Rods, 4.500" Bore x 4.500" Stroke x 6.535" Rod
4340 Forged Standard Weight Crank, Pro Comp I-Beam Connecting Rods with 7/16†Cap Screws, 1.395" Compression Ht. Premium Forged Pistons, Rings, Rod Bearings & Main Bearings
Internally Balanced
Crank:4-454-4500-6535
Rods:2-454-6535-2200
Stroke:4.500"
Rod:6.535"
Piston
remium Forged DishBore:4.500"
Compression 58cc:8.8
Compression 64 cc:8.5
Compression 70cc:8.2
your going to need to have that block checked again, if its a tall deck 427 block your NEVER going to be able to bore it past about 4.310 and maintain a rigid cylinder wall that will maintain a good ring seal, and 4.375 is about the max stroke if you very carefully machine clearances, most guys go with a 4.25" stroke and a 4.310 bore and build a 496 displacement big block with 6.385 rods.
btw most BBC head have 100cc-122cc combustion chamber sizes and those CC quoted are SMALL BLOCK HEAD SIZES
main_page=calculators&zenid=823ce2c9e2ffa691864d832c10107df0
the best solution from a performance perspective is to do the required calculations to select the longest length connecting rod and the lowest weight piston,
of a decent design that will reduce the reciprocating mass significantly more.
the tall deck has a 10.2" deck height, a good dual plane aluminum high rise intake manifold will tend to provide the best compromise if you use a low compression and mild cam duration,
while it might seem like a waste of time, now, reading the links and sub-links will provide a good base to work from, later and save you a great deal of wasted time and money
you have a choice, you can slap the components you own together, now and live with what you have built regardless of the results , or you can put some real thought into making the result perform and carefully select parts and significantly boost power... yes that routes more expensive up front, but in the long term it tends to get better results and cost LESS.
common BB CHEVY piston compression heights are
1.270"
1.395"
1.520"
1.645"
1.765"
remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
OR
the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height
if you wonder why I suggest using SCAT (H) beam style cap screw connecting rods vs stock or most (I) beam designs this picture should show the increased cam to connecting rod clearance
notice the pin height in the pistons pictured above allow a longer or shorter connecting rod length
heres a selection of commonly available big block chevy connecting rod lengths
https://www.uempistons.com/index.ph...e=deck&zenid=823ce2c9e2ffa691864d832c10107df0
https://www.uempistons.com/index.php?main_page=calculators&zenid=823ce2c9e2ffa691864d832c10107df0
1.765 compression height, pistons in standard 9.8" deck block, a 10.2" tall deck requires a longer connecting rod
most likely a 6.535" aftermarket connecting rod
threads you should read through carefully,and the sub links in them are below,
the tall deck block is put to much better use building a 496 with a 4.25" stroke and a .060 over bore and 6.385" connecting rods
http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/
http://garage.grumpysperformance.co...g-block-head-comparison.319/page-2#post-61658
http://www.maliburacing.com/patrick_budd_article.htm
http://garage.grumpysperformance.com/index.php?threads/427-tall-deck-bbc.14451/
http://garage.grumpysperformance.com/index.php?threads/big-block-chevy-info.710/#post-60299
http://garage.grumpysperformance.co...-displacement-street-engine.10961/#post-50668
Grumpy, what is this required number likely to be, on most of the cams you like to use? (Intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees) This is required in this calculator I am using to consider compression ratios. I think it's one you've recommended.
address to calculator here:
http://kb-silvolite.com/calc.php?action=comp
Looking at using a 4.25" crank, 6.8" 'H' rods and a piston compression height of 1.27". Gives me a rod/stroke ratio of 1.6:1. What sort of pistons should I be looking for, using Brodix "Big Brodie" heads, with a 119cc chamber and 300cc intake runners, 2.25 intakes and 1.88 exh. Want between 10:1 and 11:1 compression. Waiting for deck height confirmation, but if its a stock 10.2", then I have .005" clearance with this combo, plus .040" for the gasket! Appreciate your help and suggestions!
in an ideal world you want the cylinder walls on cylinders to be at least .180 thick at the THINNEST, point, if they are thinner than .140 Id seriously consider either buying an aftermarket block with a thicker casting or filling the block water passages up to the lower edge of the freeze plugs to add a good deal more rigidity to the cylinder walls to reduce flex and increase ring seal.
READ THESE
viewtopic.php?f=51&t=588&p=764&hilit=sonic#p764
viewtopic.php?f=51&t=976&p=1827#p1827
HERES A CHART to find the intake valve close point at .050 lift, you then add 15 degrees to use that particular calculator
viewtopic.php?f=52&t=4299
If the rest of you figures are correct youll want about a 20cc-24cc dome on the piston and a cam with about a 55 degree intake valve close point at .050 lift
but most un-milled blocks will have a .023 deck height not .005
now for best power a cam with a 104-108 LSA is about correct but you can afford to use a wider 110-112 LSA, and loose a few hp but make the combo easier to drive and tune on the street, and have a wider torque curve
viewtopic.php?f=52&t=82
viewtopic.php?f=52&t=1070
viewtopic.php?f=52&t=727
Grumpy,
So, I did some homework with the info you have offered me.
I have tentatively chosen a piston with 24cc top, and a Comp Cams 11-450-8 cam.
It has IVC @.050 of 44 deg.
Power is in the region of 600hp (using the numbers for a 454) The Comp Cams calculator would not consider the 4.31 bore, so could not refer to 496 cu. in.
I used a 'domestic dual plane' for carb. with an 850 cfm
I then ran all the effective number in the compression calc you offered:
COMPRESSION RATIO CALCULATOR
Static and Dynamic Compression Ratio
(Considers Cam Timing and Rod Ratio)
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) 199
Cylinder Head Vol (cubic in.) 7.259
Piston Head Volume (cc) -24
Piston Head Vol (cubic in.) -1.464
Gasket Thickness (in.) .040
Swept Volume (cubic in.) 62.006
Gasket Bore (in.) 4.31
T.D.C. Volume (cubic in.) 6.715
Cylinder Bore Diameter (in.) 4.31
Gasket Volume (cubic in.) 0.584
Deck Clearance (in.) .023 Note: Neg. nubmer above deck, Pos. number below deck
Deck Volume (cubic in.) 0.336
Stroke (in.) STATIC COMPRESSION RATIO 10.234
OPTIONAL DATA
Rod Length (in.) 6.8
Adjusted Stroke (in.) 3.468
Intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees 59
DYNAMIC EFFECTIVE COMPRESSION RATIO 8.535
What are your thoughts on this combo?
Darn you know some serious stuff. I am loving the resource you are for me.
Id suggest a thinner head gasket to get the quench distance a bit closer and retarding this cam
http://www.summitracing.com/parts/CCA-11-460-8/
4 degrees as a better match to your application
Last edited by a moderator: