Big Block FORD VRS. Big Block CHEVY "LOOK THESE FACTS OVER"

[DynoTom]

FORD : All production Ford 385 Series blocks have a 10.300+" deck height. We don't need to search high & low for a production tall deck block like the chevy guys do. All Ford blocks are "tall" deck and can be found anywhere. Further, the Ford's 10.300" deck height is still higher than the chevy tall deck's 10.200" deck height.

CHEVY :All passenger car chevy blocks have a 9.800" deck height. Chevy guys need to look high & low for their elusive 10.200" tall deck truck block, and the enthusiasts want big bucks for them. In the end, their 10.200" tall deck truck block still comes up short when compared to Ford's standard issue 10.300" block

FORD :The Ford's lifter valley has oil drainback galleries at the rear so as to direct oil straight to the pan while also diverting it away from the rotating assembly (where oil can rob horsepower). Also, the center section of the valley is raised so as to bring the crankcase ventilation holes above the oil level and also creates a "trench" between the cylinder banks and lifter bores which channels oil to the drainback galleries.


CHEVY :The chevy's lifter valley has no oil drainback galleries. And due to the raised, single ventilation hole at the front of the block, most of the oil in the lifter valley has no choice but to drain through the middle of the lifter valley and directly onto the rotating assembly (where the oil robs horsepower). This is a notorius problem with the production chevy's and there are aftermarket kits attempting to address this poor block characteristic.


FORD :The cam-to-crank centerline is higher in the Ford (6.078"). This enables us to run cams as big as necessary for our huge stroker motors (or our 9000+ rpm screamer motors) and breathe easily. Also, Ford lifters have a greater diameter (0.875") which makes for a more "friendly" cam profile for flat tappet cams. The higher cam centerline also makes for shorter (and effectively stiffer) pushrods.


CHEVY : The cam-to-crank centerline in the chevy is too close in a performance applicaton (5.152"; Gen 2 blocks raised to 5.552"), as it effectively restricts the maximum cam lobe height...in the early blocks, the cam lobes will actually hit the rotating assembly if the cam is too big. Such an aggressive cam would wreak havoc on the chevy's smaller (0.842") flat tappet lifters anyway. Longer pushrods are more prone to fail, too


FORD :The production Ford blocks can handle enough stroke to conceivably create a 572 cubic inch engine without the need to clearance the block to accomodate the stroker crank. The stroker kits for the Ford fit like a glove.


CHEVY :Not only is the production chevy block incapable of accomodating a stroker engine package as big as the Ford, but it also requires grinding / clearancing of the crankcase to fit a stroker crankshaft in the first place.


FORD :The Ford has a 4.900" bore spacing. This allows for bigger cylinder bores and pistons, better cooling between cylinders, and larger engine displacement capability from the oem block.


CHEVY :The chevy is stuck with a 4.840" bore spacing. This restricts the extent of oversize pistons compared to the Ford. Ford's stock boresize is bigger than the 427/454 by over .100".


FORD :The Ford's head bolt holes are blind and stay nice and clean for decades of faithful service. The countersunk threads are more protected and chasing is not needed after block decking.


CHEVY :The Chevy head bolt holes go into the water jackets, which corrodes the bolt threads. Headbolt threads often strip--both on the bolt and in the block.


FORD :The symmetrically spaced massive 9/16" head bolts support a 140 foot-pound clamping force and do it with a minumum of bore distortion, thanks to the head bolt holes being anchored directly into the block material and not only into the deck. With head bolts of this size and capability, Ford's don't need any more bolts in almost every application


CHEVY :The chevy's irregularly spaced wimpy 7/16" head bolts limit head clamping to only 65-75 foot-pounds (almost half that of Ford). Even at this low spec, a torque plate is highly advisable because of bore distortion; the head bolt's anchor into threads in the cylinder deck and so the deck easily gets pulled out of shape (it's not much thicker than the small block chevy deck).



Ford 429/460 Rod Ratio: 1.84/1.72

Large stroker cranks from OEM cranks

Symetrical ports for better fuel distribution

Good compression ratios with flat top pistons (72-96 cc combustion chambers)




Chevy 396/427/454 Rod Ratio: 1.63/1.63/1.53

Need aftermarket crank to get big displacement

Non-symetrical intake ports

Huge, heavy dome pistons required to get just 10.5:1 c/r (98-122cc combustion chambers)