Holden V8 cranks

crank on the left is a 308 turbo crank. on the flywheel flange, it has two "flats" cast onto it. this tells us its a 308. the depth of the step for the spigot bush/convertor pilot, is (can't remember, will edit soon, 9/16" i think)deep. it can be used as turbo, trimatic or manual. all 5.0L/304 cranks are like this. all turbo pattern cranks are rope seal.
crank on right is 253. it has only one "flat". the depth of the step for the spigot is 7/16 deep, meaning that it is Aussie pattern crank, trimatic or manual. early 308 cranks were also like this, all 253 cranks are like this. all neo seal cranks are like this. they also can be used with turbo transmissions, but be sure to check convertor fitment.
if your crank has a nurled type finish on the rear seal surface, it is a rope seal, if it is smooth it is a neo seal.
neo seal cranks are smaller than rope in the diameter of the seal surface. a rope seal crank can be ground to suit a neo, but dont fit a neo crank to a rope block. I'm guessing a...

V8 Blocks

block on the left is an Aussie pattern neo seal block. it has small dowels, small casting boss around dowels, and only two strengthening ribs around seal. (centre one is oil gallery)

block on right is rope seal Aussie pattern. same size dowels, but larger bosses. four strengthening ribs around seal. 253 and 308 blocks have the same features.

turbo block

this is a turbo pattern block. it has larger dowels and a different bolt pattern (chev).
the top bolt location is closer to the crank and the side bolts are slightly offset to the Aussie pattern. the dowel position is also different.

all turbo blocks are rope seal

all 5.0L blocks are turbo pattern

the 5.0L block is also thicker beside the main bearing bolts to allow for 4 bolt mains

VR/S/T Commomodore are factory relieved for 3.48" stroke, VT has larger lifter bosses for roller camshaft.

X Heads

Head on right is a so called X head. I dont know the truth behind these heads, but I have heard all the myths about them. the most common story that I have heard is that they were off Brock Commodores after the "ledgendary B cast" head went out of production. if that is the case, then this certainly wasn't one of them. I measured every aspect of the runners, bowels, chambers and seats and compared them to a red motor head. there the bloody same, and this one was cast in 1978. it's just a std red pollution head with std valves and probably came off a 253.

maybe this isnt the X heads that everyone raves about, and if anyone can shed some fact on the issue, (already heard enough myths and stories) please let me know. cause if there are different X heads, I would love to see a pair. I'll even pay for them to be flowed.

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SBC X Rods

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VN/5.0L type (left) compared to SBC X Rod
VN rod has more material around the big and small ends, the beam is thicker and has a strengthening rib on the lower part of the beam.
VN rod bolts are 3/8"

SBC X rods are a strong rod, but are around 20 years behind the VN rod. SBC Large journal rods also have 3/8 Bolts

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253/308 Rod (left) compared to VN/5.0L Rod

253/308 rod has very little strength in the bigend area and bolt bosses. they are very weak in performance engines. Rod bolt sizes are 11/32.

VN/5.0L rods are stronger in every aspect. size difference can be seen very easily here.

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this picture shows front to rear of SBC rods.
rod on left is showing front face on left bank, 1 3 5 7, and right rod shows front on right bank, 2 4 6 8.

on the bigend there is a large chamfer on one side to suit the radius on the crank pin, and a larger contact face on the other. this is the side that both rods face each other.
beam is also off centre to bearing centre line.
confusing huh.

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5.0L Rods. So far I have found two different 5.0L rods. Both are manufactured by TRW, but have minor differences. The GM cast on the beam is different, but the main difference is the material around the rod bolt. The machined face on rod on left is much thinner than the one on the right.

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VN Group A 5.0L Head. Has been ported, but port shape is original.

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Neo seal V8 block. Same seal as SBC

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Rope seal V8 block

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Neo crank (right) and rope on left. rope seal is also Harrop crank. neo seal area is also smaller than rope.

305 350 cranks

SBC 305 and 350 cranks have the same stroke, same journal size, same casting number and different counter weights. without putting one on a balancing machine it is hard to tell what is what. with the two side by side you can see the different weights, but when you only have one crank, its hard to know. 305 cranks are machined on the side of the rear throw.

305 crank

on the lower throw, the ruler sits flat on both surfaces, and flat on the front two weights.

350 crank

350 crank is not machined on lower/rear throw. ruler only sits flat on front two weights.
I have also seen both 305 and 350 cranks with front three weights machined, due to different castings.

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VT 5.0L Roller Cam engine. Note the socket head cap screws on the earlier head bolt locations. GMH deleted these bosses, then reintroduced them. (absolutely no way did we molester the intake ports on these heads)

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Flat Tappet cam on left, Roller on right. The roller cam is much more rounded on the nose of the lobe. You can see how the roller will hold the valve at the higher end of the lift for longer. It is much more aggressive/steeper ramp, than the Flat Tappet cam in the lower lift. The valve speed of a Roller Cam on the lower part of its lift, is much faster. The Flat Tappet cam is very sedate throughout the lift, and moves slow at the higher end of the lift. The amount of time the valve is at high lift, is very minimal.

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Std fuel and race fuel jets for Holley carbs. Slight difference.

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Std port manifold, with raised port head.

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Offset rockers. Pushrod is offset, to allow for larger port cross section. Valve spacing remains std for ease and availability of rockers.