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The following are some additional thoughts and information about Chevy V-8 small and big block
engines. They're in no particular order and can be browsed at your leisure. If you
have some notes or tips that you think our viewers would benefit from, drop us an
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Don't forget to BOOKMARK this page or add it to your "FAVORITE" pages. If you are running a website feel free to add this page to your "LINKS" page. In the Fall of '99, GM/Performance Parts introduced the "HT 383" Gen.I smallblock crate motor (PN-12497317). This engine block has a 4" bore and uses a forged 3.80" stroke, one-piece rear main seal crank (PN-1248936) with 5.7" PM stroker clearanced rods. The 350 style 4-bolt blocks have been machined for stroker crank clearance on the pan rails. It produces 325 @ 4500 rpm and 415 ft./lbs. of torque @ 3500. The HT 383 crate motor uses the Vortec "L31" cast iron heads with 9.1-1 CR, a hydraulic roller cam and 1.5 self aligning rockers. The block is a Gen. I design with 4-bolt main caps and one-piece rear main seal. It comes with an aluminum split plane intake, water pump, damper, flexplate and oil pan. A "HT 383" short block is also available under PN-12498332. A bare, 4-bolt, one-piece rear main seal "HT 383" block, clearanced for a stroker crank, is sold under PN-88959106. The new 3.80" stroke forged 4340 crank (PN-12489436) found in the new 2000 "HT 383" smallblock crate motor opens up some interesting possibilites. It will be available for those looking to run a larger stroke smallblock. The new crank will fit into any one-peice rear main seal block like the Gen.I ZZ4 and Gen.II LT1 or LT4. GM/Performance Parts is also now selling clearanced 5.7" connecting rods for SBC stroker motors. They are used in the new "HT 383" crate motors, but will work in other applications. PN-12497870 gets you a set of 8, PN-12497624 gets you a single rod. These are powdered metal (PM) rods. There is also a new 8" front damper offered for these cranks under PN-12498008. |
The GM/Performance Parts new 2004 catalog is out. Get PN-88963762 for $6.95. The catalog is also available on CD-ROM under PN-88963765 for $8.95.
If you are building a small journal 283 motor, keep in mind that early 283 blocks used forged cranks with small diameter counterweights. Later in the 1960's some 283 cranks had larger diameter counterweights which required that the block be factory relieved in the webbing between the bottoms of the cylinder barrels. You can see the extra machining done by flipping the block over and looking for semi-circular reliefs. Early blocks don't have this machining and look flat across between the cylinder barrels. If you try to put a 60's 283 3" stroke crank into an early 50's 283 block, it may fit the main journal sadddle surfaces, but the counterweights may hit the block webbing and/or the bottom of the cylinder barrels.
If you are building a big block Chevy with a flat tappet cam, (solid or hydraulic lifters) be careful during the initial engine break in. It is very easy to lose a cam lobe and lifter during initial break in. This is especially true with a higher than stock lift cam and higher pressure valve springs. The increased pushrod angles found on the BBC and poor preparation can make cam lobe failure after initial fireup a distinct possibility. You can help prevent this cam lobe failure by making sure the engine is prelubed prior to intial fireup. Use a good high pressure lube on the cam lobes and lifter bottoms during assembly. If possible use a lighter pressure stock valve spring (or if using a valve spring with multiple springs, take out some of the inner springs) to intially run the engine. Then switch to the heavier pressure springs after break in. When the engine is first fired up, keep the engine rpms at 2,500 or above, don't let the engine idle for 20 minutes or longer. This keeps lots of oil splashing up on the cam lobes. Make sure the engine can be run for this time period by having enough fuel available, ignition timing set correctly, coolant available for the motor, valve lash set correctly, etc. The idea is not to crank the motor over excessively before it starts up for the first time. If your BBC flat tappet cam survives this initial break in period, it will be good to go for many miles. After the initial engine breakin, drain the oil and change the oil filter. Roller cams generally do not suffer these types of cam lobe failures during initial engine fireup.
We are asked about the 366 BBC "tall deck" truck engines often. Unfortunately they are not worth using as a performance motor. Safe overbore is .060" and that doesn't make much. They can be stroked but then you can't find pistons to match "off the shelf" and so custom pistons are required. You can "harvest" the heads, oil pan, valve covers, crank and rods from them to use on another larger bore Mark IV BBC. Otherwise, don't waste your time or money. The 366 makes a good low power heavy duty truck mule engine or an excellent boat anchor.
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