Originally Posted by Towerclimber
The 350 block that was in the truck is numbers 14010207 Attachment 98386
should I get a different block I really don't no anything about building engines
A decent enough block for building on it comes in 2 or 4 bolt versions, certainly the 4 bolt would be better for what you want to do. You'll have to pull the pan to see which main caps it has because there will not be any outside identification other than to say if this is a 3/4 ton or larger truck it will be 4 bolt. If it's a half ton it could be either but most likely will be a 2 bolt.
Before I get into pistons where I had to break off this morning let’s talk about roller cams since the subject has come up. The issue with flat tappet cams is the removal of Extreme Pressure components from oil along with the addition of high levels of detergents. This is a double whammy for flat tappet cam and lifter life especially where fast lift cams with high spring pressures are involved. Inexpensive cams just will not hold up any more under the lack EP compounds like ZDDP and the increased detergency which wipes the ZDDP of the needing surfaces. The OEMs began the switch to roller cams in the mid 1980's and completed it with 1996 model year which also coincides with complete implementation of OBD II vehicle management systems. I have advocated for cam thrust bumper installation on the Chevy with flat tappet cams for what is now decades as a help in reducing thrust wandering of the cam which adds a scrubbing motion between the lobe and lifter and tugs the distributor shaft enough to wiggle the timing several degrees. I figure that the lobes and lifters have enough to do without being responsible to maintain a thrust loading on the cam gear against the block. Many other respected brands have used a thrust plate as comes with the roller cam engines on their flat tappet engines for decades, so I've been less than enthusiastic about GM's claims that you hold thrust with angles on the lobes and convex surfaces on the lifter, as there other brands use the same angles across the lobe and convex surfaces on the lifter because that's the way a flat tappet system has to be designed to get any life expectancy from it so GM ain’t doing anything unique here. There is a current tendency to build some flat tappet cams and lifters from better materials ranging from surface hardening techniques such as nitriding or cold casing to using what is essentially nodular iron and ceramic composite surfaces but this stuff runs the cost up nearly or equal to a roller cam set up. So unless you're looking at racing in a rules limited class that requires a flat tappet cam these high cost flat tappets tend not to be used by the hot rod community which just lives with the failure rate of less expensive cams. So this is why people are recommending the later roller blocks because the roller lasts very well with contemporary EPA designed oils and while pricey compared to standard flat tappet cams are a lot less expensive to build with than aftermarket cams because you can use the factory roller lifters and dog bone alignment guides that are cheaper than the aftermarket rollers and guide mechanisms. Frankly, I think you can use an aftermarket flat tappet with low detergent racing oil and a ZDDP additive package, with a thrust bumper from the roller cam guys, and Beehive springs. The beehives with their complex interaction to spring harmonics because of the difference in wind diameter and spacing top to bottom, having a smaller thus lighter retainer, and the use of ovate rather than round wire makes the spring self damping of its harmonics. The lower pressures without loss of valve control greatly add to cam and lifter life by just reducing the loads between these working parts. To achieve the same control with dual or triple wound standard springs requires a lot more spring pressure and a much larger retainer. Ok that's lot but that's the whys and why-not’s of a flat tappet or factory roller tappet block.
The production Vortec head is a bit small on a 383 engine, and for competition is structurally inadequate. These are thin wall castings that will not absorb a lot of abuse. You can use them on a competition engine, but you've got to have a super good cooling system to keep them at reasonable operating temps so they don't crack. Even then it's risky around the center adjacent exhaust valves as this area runs much hotter than anywhere else so cracks form easily in this area or just outside this area because the head is trying to pucker up so it bends here. This also results in blown head gaskets between these center cylinders. Opening up the gasket holes between these cylinders and the use of 4 corner coolant returns is pretty helpful for these heads, any heads but especially these by putting more coolant flow onto this hot area.
Pistons, when I got interrupted this morning, are the choice between castings or forgings. Here if you're going for a rod length that puts the pin in the oil ring, you especially want a high silicon piston for strength, stiffness, and thermal stability. If a cast piston you want a hyper-eutectic, these are quite good but don't tolerate detonation long, not that anything does. For a forging I recommend a high silicon material like 4032, while 2618 is slightly ultimately stronger, the 4032 ain't that far behind while it's greater dimensional stability in harsh thermal situations make it less likely you'll have to test its ultimate strength. With high silicon pistons there is less expansion/contraction with temperature changes; this allows a tighter skirt clearance which keeps the ring package more square with the cylinder wall which in turn reduces both blow by and oil consumption. Those keep the cylinder pressure pushing on the piston while keeping detonation causing oil out of the combustion chamber. This reduces the work the rings have to do which lets you use a lower tension ring which decreases friction with the cylinder wall which then makes more power available to the crankshaft. Just follow the dots! For detonation control you want to stay away from pistons with circular dishes. These have too much distance between the piston and the squish/quench step of the head which reduces its function of holding detonation at bay. A flat top is best for this while not getting in the way of the burn like a domed piston. A suitable alternative is the D dish which puts any extra volume needed to manage compression under the valve pocket while retaining all the benefits of a flat top. I do not recommend the step dish which looks a lot like a D dish but has no raised edge on the spark-plug side of the piston. Do not buy inexpensive forgings, there are old fashion left-overs still being manufactured, while good 40-50 years ago for racring because that was the State Of The Art then, today there only good for street machines.
I will add before my fingers die that using a roller block with the one piece rear seal which are very nice indeed, the crank bolt circle is different (smaller) so a flywheel or flexplate purchase has to be included as what you've got won't fit those cranks. This also is place where keeping the engine internally balanced means that flywheels, flexplates and dampers can be swapped around without having to rebalance the crankshaft assembly.