building a TALL DECK 496 stroke BBC

[grumpyvette]

got a truck block? want a 496 vs a 427

if you have or can purchase a tall deck 427 bbc engine..there are potential mods you can make..

 

now Im well aware most of you may not ever use a bbc engine, but if you do...heres some info

IF the rest of the basic engine is servicable,Id rebuild it with a mild port clean up,a valve job,a re-ring and new bearings, plus the tall deck block allows you to use longer connecting rods and a 4.25" stroke crank, to build a 496 displacement 10:1 cpr engine ,youll need the block bored and honed at .060 over(4.310 bore) done very easily,just the increase in displacement and compression (with the correct, crank, rods and pistons) matched to a reasonable cam will make a very noticable power increase

kits like this are available for the standard 9.8" blocks

 

http://www.sallee-chevrolet.com/Sca...embly_Kits.html

 

crank rods. pistons, ballanced for about $1400

add a cam like this

http://store.summitracing.com/default.as...p;x=29&y=14

 

and with no other changes to the basic engine youll have a noticable power increase

Id expect to spend under $3000 and have a reasonably effective street combo

 

but since your useing a tall deck block youll want to purchase all the parts seperately

 

chevy has produced two comon bbc block heights, the comon pass car 9.8" deck block and the taller less comon 10.2" truck block, truck blocks allow more clearance but they move the heads further appart so spacers or differant intakes and a few other parts are necessary, I personally PREFER truck blocks as they tend to be thicker and cheaper, as fewer people want to use them

 

it should be OBVIOUS that youll need to do a MINIMUM of homework BEFORE ordering parts for a 496 bbc stroker kit to fit a tall deck block

 

here this calculator will help

http://kb-silvolite.com/calc.php?action=piston_comp

 

the standard BBC has a 9.8" deck height, the TALL block has a 10.2" deck thats .400 taller, so youll want to use standard 454 pistons to keep the cost low and make up the differance in connecting rod length for a better rod/stroke ratio.

keep in mind youll want to use longer rods and lighter pistons for a better rod/stroke ratio WITHOUT getting into CUSTOM parts

the comon longer than stock,bbc rod lengths available are 6.385",6.585",6.8"

 

BUT ,look a standard 454 bbc has a 4" stroke, 6.135 rod and a 9.8" deck so the pistons got a 01.665" pin height the same block with a 3.76" stroke crank from a 427 would use a 01.785 pin height, neither will work in a 4.25" stroke 10.2" deck block application

 

these pistons below have a 1.27 pin height

 

http://kb-silvolite.com/performance...ls&P_id=358

 

the tall deck with its 10.200 deck and a 1.27" pin will require a 6.8" rod

 

http://store.summitracing.com/default.as...p;x=35&y=14

 

1.27"piston pin height, + 6.8" rod length + 1/2 of 4.25" stroke(thats 2.125") equals 10.195" or .005 below the 10.2" deck on a tall deck block

thats a 1.6:1 rod/stroke ratio, or close to the 1.63:1 a 350 chevy has and better than the original 454s 1.53:1 ratio, even thought the strokes been increased

 

a combo like that should exceed 550 ft lbs and 500hp easily

[5foot2]

I've been thinking of going the other way. Off and on I've been thinking of going with a bb 400 mopar setup with a stroker crank bumping it to 451. I could go the easy way out and just use a rb 440, but I'm thinking the bb block would make fitting headers easier. It's also lighter than the rb block, and the std bbc. Do you have an idea of the room available for fab'n headers with a tall deck bbc grumpy?

[dr_hunt]

Question for grumpy. I've never used the tall deck blocks for a foundation, what type of clearancing is needed to add stroke to those blocks?

[grumpyvette]

if your installing a 4" or 4.25" stroke crank in a tall deck BBC the clearance work is minimal, with most cranks,(keep in mind theres differant dia. counterweights etc.) in fact usually easier than the clearance work done to install a 3.75" stroke crank in a 350 block to build a 383 sbc.

once you get past a 4.25" stroke, youll need to be carefull as theres passages in the lower block skirt that you could get into if you get carried away grinding, and 4.375" is about the max, youll want to get an aftermarket block past that stroke

[Pyro]

I have a 454 in my LWB 70 c10. It has a very mild RV roller comp cam, 8.75:1 cr, 781 heads with some big valves, and mild port work (unshouding and bowl smoothing). Even with a 3.08 diff gear and 400th automatic, my 4000+lb truck kills my slighlty modified 78 280z (260 cam with crane springs, P90 head, F54 block, 5spd, 2.5 exhaust) anywhere from 0 to 125mph! However, my turbo car is a different story.

 

I was thinking about doing a 496 cid kit but I seem to have enough power already! (I can't believe I said that!). I just use the truck to trailer my V8 Z to the track. The mileage is pretty bad at 8/12 mpg but 0-60 mph is in the 6's, thanks to the alburn LSD diff , 2000 stall, and 275's in the rear.

 

When building a bbc it is very important to set the bearings up tight! 0.0015 to 0.002 on the mains and rods, and 0.003 on the rear main. If you set the bearing clearances on a bbc like a sbc, it will eat cams like a pig eats slop.

[grumpyvette]

BBC engines have developed a reputation for eating cam lobes because most guys either don,t break the cam in correctly or are not willing to make the mods necessary to supply the extra oil flow that prevents oit from HAPPENING with the INCREASED PRESSUREs aftermarket cams with thier higher lift, durration,ETC. and springs produce

first ID strongly suggest a high voluum oil pump and a windage screen with a baffled high voluum pan,

use the solids with the extra oil bleed hole that feeds oil to the lifter/cam lobe contact area

http://www.crower.com/misc/m_cat.shtml (pr107)

 

both crower and comp cams sell them, but they are fairly expensive compared to standard solid lifters, I tend to use them when I can get them but it might be overkill on the oil flow to some extent because I use this tool too put a slight groove in the lifter bores that constantly sprays oil onto the cam lobe at a point just before it rolls under the lifter base

 

http://www.compcams.com/catalog/335.html

 

if youve adjusted the valves correctly the lifter spins at all rpm levels,but that does NOT mean it wears EVENLY at all rpm levels due to several factors if you look closely AT FLAT TAPPET CAMS , youll see that the center of the cam lobe is NOT centered under the lifter and that the lifter surface is slightly angled , BOTH these factors force the lifter to spin in its bore as the lobe passes under the lifter slightly off center.

SOME of the reasons the higher rpm durring the break in phase is important is that

 

(1) the faster RPMs the better chances the lobe passes under the lifter floated on an oil film and the less time the oil film has to squeeze out between them

 

(2) the higher the RPM the greater the oil voluum and pressure the engine pumps and the more oil flow is available at the lobes

 

(3)the higher the rpm level the more oil is thrown from the rods onto the cam lobes

 

(4)the higher the rpm the greater the lifters weight and inertia tends to compensate for the springs pressure and lower the net pressure as the lifter passes over the cam lobes nose

 

(5) at higher rpm speed the better chance a small wedge of oil is trapped between the lifter base and lobe from the oil thrown from the lobes surface by centrifical force

 

(6) two differant metal surfaces scraping past each other at low speeds may tend to wear and GALL as the oil is sqeezed out but two differant hardness steel surfaces that impact each other at higher speeds covered with oil tend to work harden as they mate and will tend to be seperated by that oil

 

(7)as the lifter spins in its bore the contact point between the lobe and lifter base constantly changes and rotates with the lobe contact point not resisting its passage and the higher the rpms the faster the lifter rotates and the less time the lobe spends at any one point

 

BTW ADD E.O.S. to the oil and MOLY break-in lube to the cam

before starting the engine and prefill the filter and pre-prime the oil system before starting the engine.

I normally pour it in just before starting the engines cam break in,procedure. because I want to make sure that nothing in the oil/E.O.S. mix can settle out from sitting over a long period of time. now if your running a flat tappet cam you should have also used a moly cam lube on the lobes and be useing a mineral base oil for the break-in procedure, and youll need to do an oil and filter change after about the first 3-4 hours running time to remove that moly cam lube from the engine after its served its purpose of protecting the cams lobes and lifters at start up, aND AS THE LOBES/LIFTERS LAPPED IN. MOSTLY to prevent that moly grease and E.O.S from potentially partially clogging the filter after that mix cools down,but also because both those lubes might leave deposites in the combustion chamber ,over time that might aggravate detonation.

even G.M. suggests that E.O.S. is not a great long term oil suppliment, and that its main function is to add extra oil film strength durring new engine break in.

 

1052367

ENGOILSUP

EOS - Engine Assembly Prelube

Specifically formulated as an engine assembly lubricant. E.O.S. provides outstanding protection against run-in wear and piston scuffing as well as run-in camshaft lobe and lifter scuffing resulting from insufficient lubrication

don,t forget a few magnets in the oil pan goes a long way towards trapping unwanted metalic dust formed from the cam and rings lapping in durring break-in that might otherwise get imbedded in your bearings or cause other problems

heres the magnets I use in every engine

 

http://www.wondermagnets.com/cgi-bin/edatcat/WMSstore.pl?user_action=detail&catalogno=0035

 

http://www.cranecams.com/?show=reasonsForFailure

[Michael]

I'm one of the victims of the BBC cam lobe wipe problem. It happened to me with a very mild hydraulic roller from Comp Cams, DESPITE following proper break-in procedure. Since then I've learned of lots of people having trouble specifically with Comps Cams hydraulic flat-tappet cams. The other day I spoke with an engine builder who flat-out said that he no longer trusts Comps' off-the-shelf build quality (he says that their custom grinds are still OK).

 

In the new iteration of my engine, I've got a Milodon high-volume oil pump and a Hamburger 8-qt pan with windage screen. However, the only oil-system mod that I made was radiusing the oil passage in the rear main cap - I didn't make any mods to the lifter bores, and now that the short block is assembled, it's too late. Crank main tolerances are quite loose, at least by Pyro's recommendations: 0.0025".

 

I am going with a mechanical roller cam, partially because I want to hedge my bets on the cam-wiping issue. I'm getting top-of-the-line roller lifters and a custom-ground cam from Isky. The required valve spring pressure worries me a little, though; about 200 seat pressure, 500 open.

[Guest cubicdollars]

HeyGrumpyVette

 

I ran accross this post over a year ago after Ipicked up a 1978 427 tall deck truck block and I based my build off of it.

 

1978 Tall Deck 427 truck block Casting # 364776

 

Callies Compstar H beam rods Part Number CSB6800 ES3BP42BDS, Length 6.800 (0.665 over stock)

 

Callies Dragonslayer Part Number BBP42B-DS, 4.250 Stroke ( 0.250 over stock)

 

SRP Flat Top's with single Valve relief Part Number 142982, 4.350 Bore, 1.270 compression height (0.100 over stock )

 

World Products Grumpy Jenkins series cast Rect port heads, 320cc runners, 118cc combustion chamber, 2.30 stainless intake valves, 1.90 Stainless Exhaust valves.

 

Comp Cams pro Magnum roller rockers.

 

The camshaft will be a solid roller custom grind from Camshaft Inovations.

 

The Intake will be Dart high rise with a CSU Blow though 850 Carb.

 

The supercharger will be an ATI Centrifigual F2 cog drive as well as an intercooler.

 

I am hoping to make around 950 HP on pump gas with this combo

 

I am in the process of marking for the clearencing of the rod bolts, they hit on the lower inboard and outboard cylinder walls.

 

Here are some photo's , enjoy....

 

 

 

 

[Pyro]

Turns out there was a problem with the lifter bores on my 454. Even with a hydro roller cam, the lifters made noise. Stumped, so I measured the lifter bores and for some reason they only had a 0.0005 to 0.0007" clearance.??? Proper clearance is a 0.001 to 0.002" for a flat tappet and 0.0015 to 0.002 for a roller lifter. I should had the lifter bores drill and rebushed, but instead, I just machined down a set of hydro flat tappet lifters 0.0005". And installed an over-cam oiling system by BC Engineering. So far, so good. And I'm using ZDDP oil additive in regular gasoline engine oil since the new diesel engine oil lost it's zinc also.

[baja265]

i have 427 tall deck truck #473478 and #353049 head, if i want stroke to 496 with flat top piston i know need .060 bore + 4.25 crankshaft.

what rod length and piston type should i use?

 

got a truck block? want a 496 vs a 427

if you have or can purchase a tall deck 427 bbc engine..there are potential mods you can make..

 

now Im well aware most of you may not ever use a bbc engine, but if you do...heres some info

IF the rest of the basic engine is servicable,Id rebuild it with a mild port clean up,a valve job,a re-ring and new bearings, plus the tall deck block allows you to use longer connecting rods and a 4.25" stroke crank, to build a 496 displacement 10:1 cpr engine ,youll need the block bored and honed at .060 over(4.310 bore) done very easily,just the increase in displacement and compression (with the correct, crank, rods and pistons) matched to a reasonable cam will make a very noticable power increase

kits like this are available for the standard 9.8" blocks

 

http://www.sallee-chevrolet.com/Sca...embly_Kits.html

 

crank rods. pistons, ballanced for about $1400

add a cam like this

http://store.summitracing.com/default.as...p;x=29&y=14

 

and with no other changes to the basic engine youll have a noticable power increase

Id expect to spend under $3000 and have a reasonably effective street combo

 

but since your useing a tall deck block youll want to purchase all the parts seperately

 

chevy has produced two comon bbc block heights, the comon pass car 9.8" deck block and the taller less comon 10.2" truck block, truck blocks allow more clearance but they move the heads further appart so spacers or differant intakes and a few other parts are necessary, I personally PREFER truck blocks as they tend to be thicker and cheaper, as fewer people want to use them

 

it should be OBVIOUS that youll need to do a MINIMUM of homework BEFORE ordering parts for a 496 bbc stroker kit to fit a tall deck block

 

here this calculator will help

http://kb-silvolite.com/calc.php?action=piston_comp

 

the standard BBC has a 9.8" deck height, the TALL block has a 10.2" deck thats .400 taller, so youll want to use standard 454 pistons to keep the cost low and make up the differance in connecting rod length for a better rod/stroke ratio.

keep in mind youll want to use longer rods and lighter pistons for a better rod/stroke ratio WITHOUT getting into CUSTOM parts

the comon longer than stock,bbc rod lengths available are 6.385",6.585",6.8"

 

BUT ,look a standard 454 bbc has a 4" stroke, 6.135 rod and a 9.8" deck so the pistons got a 01.665" pin height the same block with a 3.76" stroke crank from a 427 would use a 01.785 pin height, neither will work in a 4.25" stroke 10.2" deck block application

 

these pistons below have a 1.27 pin height

 

http://kb-silvolite.com/performance...ls&P_id=358

 

the tall deck with its 10.200 deck and a 1.27" pin will require a 6.8" rod

 

http://store.summitracing.com/default.as...p;x=35&y=14

 

1.27"piston pin height, + 6.8" rod length + 1/2 of 4.25" stroke(thats 2.125") equals 10.195" or .005 below the 10.2" deck on a tall deck block

thats a 1.6:1 rod/stroke ratio, or close to the 1.63:1 a 350 chevy has and better than the original 454s 1.53:1 ratio, even thought the strokes been increased

 

a combo like that should exceed 550 ft lbs and 500hp easily

[Michael]

353049 heads enjoy an excellent reputation amongst OEM cast-iron heads, and their large combustion chamber should work well with a 496 (because of the large swept volume of the stroker). On a 496 with 15cc domed pistons, 0.040†head gasket and pistons set at zero deck height, static compression ratio works out to around 9.7 with the 122cc heads.

 

However, I am tempted to object: if one is willing to afford the cost of a stroker crank, rods and pistons, plus the associated machining and balancing, would it not make more sense to invest in some better aftermarket heads, such as the AFR 315s? I wouldn’t build a modern big block without good aluminum heads and a roller cam.