You can get an aluminum large oval port head from GM/Performance Parts. This "Signature Series" head will fit any Mark IV, Gen.V or Gen.VI big block. These heads are available bare, or complete with 2.19"/1.88" or 2.25"/1.88" valves. Up until 1996, Chevy only made cast iron oval port heads for use in production vehicles.

Putting a Gen.V or Gen.VI 454 or 502 into your early Chevelle or Camaro? Need a four quart oil pan that will clear everything under the motor and fits the one-piece rear main oil seal blocks? Try oil pan kit PN-12495360 from GM/Performance Parts. The stock Gen.V and VI truck oil pans hold six quarts, but won't fit the early Chevelles or Camaros.

Big blocks, cast in 1965 and '66, used a "grooved" rear cam bearing with a matching "groove" in the rear journal of the camshaft itself. This groove provided an oil passage to the lifter oil galleries. 1967 model and later Mark IV blocks have an annular groove oiling passage cast into the block itself. The blocks cast from the '67 model year on use a smooth, non-grooved cam bearing and the rear cam journal for these '67 and later blocks is smooth and does not use a grooved rear cam journal. The reason this is important is that if the wrong cam bearing gets used in the '65-'66 blocks, no oil gets to the lifter galleries or up to the rocker arms. The '65-'66 grooved cam bearing has three oil holes to feed the cam journal and the two lifter gallery passages. The '67 and later cam bearing is smooth and only has one oiling hole in it. A few of the cam makers will provide a big block cam with the groove cut in the rear camshaft journal, but you can have your machinist cut a groove that is 3/16" wide and 7/64" deep in the center of the rear cam journal if you have a big block cast in the '65 or '66 model year.

Chevy used two different basic styles of water pumps over the years, a "short" pump and a "tall" pump which was introduced in 1969. You need to match your pulleys and accessory brackets to match whichever pump style you use so that everything works and fan belts line up. The "short" pumps can get you a few extra inches of space if you are doing an engine conversion and the available space is tight. Later models using a serpentine belt system have used a "reverse rotation" water pump. Corvettes over the years have used a slightly different style pump. GM pulleys over the years have come in different diameters. You can play with these different diameters a little to underdrive some of your accessories like the water pump or alternator. However make sure the accessories turn over fast enough to keep the engine cool and the battery charged.

If you latch on to a early 366 or 427 tall deck truck motor you may find that it used a gear drive for the camshaft. Chevy and GMC used just two gears to drive the cam which was a "reverse" rotation grind. You can switch these early tall deck motors over to a different "normal rotation" chain driven cam, but make sure you also change the distributor drive gear to a "normal" rotation gear.

If you are thinking about rebuilding a set of old "camelhump" heads or using a set of 1960's or 70's vintage cast iron production heads, check this out first. The '96 and later smallblock "Vortec" 350 cast iron heads are a very hot item. These "L31" heads with casting number 10239906 and 12558062 or PN-12529093 (bare), flow great numbers for a production head, even better than the Phase 2 Bowtie cast iron head, when fitted with 2.02/1.60" valves and bowl ported. The complete heads (PN-12558060) come with 1.94"/1.5" valves and pressed in rocker studs, but can easily be fitted with 2.02"/1.6" valves and screw in studs. Chamber volumes are 64cc and intake port volumes are 170cc. The Vortec heads have raised intake ports and "fast burn" chambers. The heads require the use of narrow body "self-aligning" rocker arms and center bolt valve covers. They will bolt to any Gen.1 block.

The price per pair for new complete Vortec "L31" 350 SBC heads (PN-12558060) is about $485.00 (as of 11/1/03), with 1.94"/1.5" valves, springs and retainers from GM/Performance Parts. You can then use the valve sizes you want to use and drill and tap for screw in studs. However, the intake manifold bolt holes are in different locations than previous Gen.1 heads. Only four intake bolts are used on each side to fit the "Vortec" style intake, instead of the usual six on each side. The correct Vortec intake manifold bolts are found under PN-12550027. Use Vortec intake gasket PN-12529094. The stock Vortec L31 valve springs are good for lifts up to .475"-.480" maximum. If you use a cam with more lift you'll need to change the springs and have the valve guides machined down to clear seals and retainers.

You can try to redrill and tap the heads to fit the older style Gen.1 intakes, but why bother. Edelbrock has aluminum two and four barrel "Vortec" style intakes out that have the correct bolt hole positions. Edelbrock PN-7116 is their "Performer RPM", dual plane, high rise intake for the "Vortec" heads, while Edelbrock PN-2116 is their "Performer" street dual plane for 4-barrels. They also have two "Vortec" versions of the new "Super Victor" aluminum, high rise, open plenum race manifolds. PN-2912 is for 2-barrel restricted class racers and PN-2913 fits a 4-barrel intake to the "Vortec" RPO "L-31" heads. Vortec style intakes are also available for TBI and TPI setups.

GM/Performance Parts has a dual plane aluminum four barrel intake that is PN-12366573 and fits the unique Vortec intake manifold bolt pattern. GM also has a aluminum open plenum high rise (PN-12496822) intake for the Vortec L31 heads.

The new Gen.III "LS1" motors have a different firing order than previous smallblocks. The firing order for the Gen.III smallblock and the 2001 8.1 liter (496 cubic inch) big block is 1-8-7-2-6-5-4-3. Eight individual ignition coils are computer controlled. No conventional distributor is used. The new firing order smooths out the running motor and eliminates the previous problem of the #5 and #7 cylinders firing right next to one another and causing fuel and air distribution problems. In case you were wondering, the firing order for the Gen.I, II and previous "Vortec" motors is 1-8-4-3-6-5-7-2.

Cloyes, the timing chain folks, have a new timing cover for Gen.I smallblocks (Cloyes PN-9-221). It's a cast aluminum cover that has a removable cover plate over the cam timing gear so that you can check or change cam phasing without pulling the cover off. The cover also has an externally adjustable, built in cam button to keep roller cam "walk" to a minimum. It has a nice smooth finish and is a sturdy piece. Price isn't bad either, under $100.00 retail.

When checking casting dates, remember that the "model year" runs from about September thru July. For example, the 1976 model year could show casting dates that could run from August of 1975 thru July of 1976. So it is possible to have a 1976 model year 350 that was cast and assembled into a vehicle in November 1975. There have been a few exceptions caused by factory strike delays or the early introduction of a particular vehicle. Its even possible that some of the casting dates on an engine may show that some parts were made in one calender year and other parts in the following year. You could have a block cast in late December of '71 and a set of heads made in early January, 1972 and showing an engine assembly date of January 10th, 1972. If the spread between parts casting dates starts being large, like a couple of months apart, be careful and check everything closely if you are considering a "numbers matching" vehicles.

If you have a stock production big block Chevy cylinder head with oval ports, chances are it has exhaust valve rotators under the exhaust valve springs. If you change the valve springs to ones with higher pressures you need to replace the stock rotators with a "rotator eliminator" kit. The stock rotators don't stand up to increased valve spring pressures. Crane Cams, Competition Cams and Federal-Mogul all make inexpensive "rotator eliminator" kits which sit in the exhaust spring pockets and are the same thickness as a stock rotator.

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