Gm 67-95 350 Chevy 4 Bolt Main Machined Bare Block on 2040-parts.com

Promar Performance 350 Chevy 4 Bolt Main Machined Bare Block

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You are viewing a 350 Chevy 4 Bolt Main Machined Bare Block. This is a completely machined seasoned virgin block. Available in bore sizes 4.030 4.040 4.060 specify at purchase. Available for any years from 67-95 (specific casting numbers may not be available) (Does not include LT1 block). These blocks have no repairs or sleeves. (Minor thread repair possible) Has been thermally cleaned in our ACE pyrolytic furnace and shot blasted Block has been thoroughly magnafluxed using our state of the art DCM. Cylinders have been bored on our F5 Rotler CNC boring bar to ensure cylinders are a perfect 90 degrees to crankshaft. Block has been line honed on our Sunnen CH-100 Horizontal Line hone to ensure perfect bearing crush and alignment. The cylinders have been Plateau Honed on our CV616 Sunnen hone to ensure long moly ring life and sealing. Deck surfaces have been parallel surfaced for use with composite gaskets (MLS surface finish available upon request). Block is cleaned in our AXE Hot tank.  Inspected, and sealed in a plastic bag ready to ship. Blocks avail to ship within 3-5 business days. Also shipping is FREE in the United States with the exception of Alaska and Hawaii.

Upgrade!  ARP main bolts for $44.99

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Click Here to view our engine Frequently Asked Questions page

Please take a minute and view our step by step procedures of how we remanufacture our engines

STEP 1) ENGINE BLOCK DISASSEMBLY  

Dirty Engine Block

All blocks are visually inspected for casting defects prior to their disassembly. The parts are then removed and individually inspected for damage and cause of failure. The oil and water passage plugs are removed to insure optimum results during the thermal cleaning process. Only premium castings are used for our marine blocks, all castings are replaced in all salt-water applications. Our high performance engines are built with premium cores. In many applications new castings are used, as we never employ repaired castings or sleeved blocks. To retain your classic car's original block casting, Promar employs the artistry of our skilled casting repair technicians.

  STEP 2) ENGINE BLOCK THERMAL CLEANING  

Oven-Cleaned Engine Block

The thermal cleaning system gives our customers the closest thing to a new casting, taking engine parts to a whole new level of clean. The heaters emit uniformly controlled heat, which is evenly distributed throughout the chamber. This method totally eliminates the concentration of intense heat or flame entering the chamber, which could overheat, warp or melt parts. The load is heated to 650-800 F (340-427C) in an oxygen deficient atmosphere, where the combustible hydrocarbons decompose and parts leave the oven completely dry. This baking process used on cast iron blocks only employs the Ace RKE 230 oven. Ash residue is easily removed by stainless steel shot blasting which is the next step in the cleaning process.

  STEP 3) ENGINE BLOCK SHOT BLASTING  

Engine Block After Shot Blasting

Our shot-blasting machine employs a cleaning method using stainless steel shot. This finishing process is used by Promar to remove surface contamination such as rust and irregularities from blocks. The result of this method is a cleaner smoother surface finish to make easy the detection of surface and subsurface casting defects during quality inspection. To insure stress free casting, the peening process is used to impart compression strength to metal parts. This is accomplished by metal shot pellets acting like miniature ball peen hammers as they strike the entire surface of the block. All iron castings are put through this process before a preliminary inspection for defects is done. This process using the AR HB41 is employed for cast iron blocks only and facilitates a more accurate magnetic particle inspection.

  STEP 4) ENGINE BLOCK MAGNAFLUXING  

Engine Block Crack Detection

Magnetic particle inspection is the most definitive method of detecting cracks and imperfections in any ferrous engine parts. This procedure assures the highest quality cast iron blocks. The next process is pressure testing, but first, let us explain how aluminum blocks are cleaned, pressure tested and checked for casting defects.

  STEP 5) ENGINE BLOCK HIGH PRESSURE WASH  

AXE SW20 OS Spray Cleaning System

The first stop for a qualified aluminum engine block is our AXE SW20 OS spray cleaning system. With twice the spraying power and a dramatically increased number of multi integrated spray nozzles, this state of the art system assures Promar that all oil, dirt and foreign material is removed from even the smallest of oiling holes. Cleanliness of the aluminum engine block is essential to insure an accurate inspection. This process is used on all aluminum engine blocks as a first step prior to the second step of ultrasonic cleaning.

  STEP 6) ENGINE BLOCK SONIC CLEANING  

GMC 1818B Ultra Sonic Cleaner

Promar's second process in the cleaning of aluminum blocks is the ultrasonic cleaning method, long known as the "benchmark" in cleaning. Hundreds of specifications reference an ultrasonically cleaned part as the ultimate target for cleanliness. Ultrasonic cavitation is able to clean right down to the surface of a part and beyond. It is also able to reach internal areas, which are not accessible by using other cleaning means including spray and mechanical agitation. The forceful nature of ultrasonic energy provides the physical "push" required to break the mechanical and ionic bonds that hold very small particles to surfaces. Once cleaned the block is sent for pressure testing.

  STEP 7) ENGINE BLOCK PRESSURE TESTING  

Delta 6000 Pressure Tester Machine

Promar uses the Delta Pressure tester to double check for pin holes after magnafluxing and dye testing are completed. Cracks and defects not detected during the first process are found at this time. This second process insures the integrity of all castings used in Promar products.

  STEP 8) ENGINE BLOCK PREPARATION  

Engine Block Preparation

A complete visual inspection of the block is performed. Repairs will be made to minor casting defects, removal of broken bolts are performed as well as repair and tapping of threads. Gasket surface repairs are performed to minimize stock removal. The next step is align honing.

  STEP 9) ENGINE BLOCK ALIGN HONE  

Engine Block Align Honing Process

Align honing is the best method for precision alignment of main bearing bores. Promar uses the Sunnen CH-100 machine for all of its benefits and features, as we can minimize stock removal, usually less than .003" (.076 mm) off the caps compared to as much as .010" (.254 mm) with boring.

Use of this machine maximizes precision and corrects distortion caused by warpage and cap stretch. This align hone procedure exceeds original factory accuracy for alignment, roundness and size and precedes the engine boring process.

  STEP 10) ENGINE BLOCK BORING  

Rottler F54X Boring Bar

Promar employs the Rottler F54X boring bar with its large diameter and hard chromed spindle. This spindle is supported on adjustable tapered bearings for superior accuracy. The F54X uses a precision ground ball screw to control feed rate and cutter position. By controlling these factors the machine can repeat cutter position accuracy to .0002" (.005mm). With its digital programmable cycles, the F54X allows boring depth to be programmed to .0001" (.0025mm). The next process to follow boring is milling.

    STEP 11) ENGINE BLOCK MILLING   Milling machines that are used by Promar are set up specifically for blocks. The Winona Van Norman M3000 machines are used for their variable feed rate, which is essential to acquire proper Ra finish for each block. Ra finish determination is based on the type of block, be it aluminum or cast iron, and by the type of gasket used for each specific application. These machines utilize CBN (cubic boron nitride) cutters, which are second in hardness only to a diamond. During the cutting process heat from friction is absorbed and carried off by the discarded metal chips thus resulting in improved accuracy and excellent surface finish. The surface finish is then checked by using the Mitutoyo SJ-301. The Mitutoyo SJ-301 is utilized twice, once after resurfacing and again before final assembly Promar insures proper measurement of Ra by using the SJ-301. The next process is rod reconditioning.       STEP 12) ENGINE BLOCK ROD RECONDITIONING  

Sunnen LBB-1600

The ideal equipment for precision rod reconditioning and pin fitting is the Sunnen LBB-1600 Hone, which measures accuracy within .0001". This hone method is preferred all over the world for its ability to produce a round and straight honed bore equal to or better than the manufacturer's new rods. All high performance engines are fitted with ARP high strength bolts and nuts prior to rod reconditioning. Once reconditioning of the rods is accomplished the next step is honing of the cylinders.

    STEP 13) ENGINE BLOCK HONING   The cylinder honing process assures precision sizing plus exact Ra finish in every cylinder in any type block. Promar finds that the automatic Sunnen CV-616 Cylinder Hone ensures better than original factory accuracy and corrects taper and out-of-round. Another benefit is that it produces surface finish, size, roundness and straightness tolerances equal to or better than original manufacturer's specs. The CV-616 produces consistent precision surface finish with uniform crosshatch pattern in each cylinder.
CV-616 provides base metal finish, free from fractured metal for immediate ring seating and positive oil control. It works for passenger cars, high performance engines, trucks, diesel and industrial blocks. This precision machinery hones any material including aluminum, cast iron and any alloy.

Promar insures proper measurement of Ra by utilizing the Mitutoyo SJ-301 twice, once after honing and again before final assembly. Final assembly is not started until all blocks go through a final wash.

      STEP 14) ENGINE BLOCK HIGH PRESSURE WASH  

AXE SW 20-OS

Following these precise machining procedures, our blocks undergo a second high pressure wash cycle to guarantee the removal of any debris that may have adhered or become dislodged during the machining process. Absolute cleanliness is necessary for the next step, which is final assembly. After the blocks receive a final wash we clean all parts ultrasonically.

  STEP 15) ENGINE BLOCK SONIC CLEANING  

GMC-1818B Ultra Sonic Cleaner

Promar's second process is ultra sonic cleaning of all parts old and new prior to assembly of the engine. This Ultrasonic Cleaning Method is long known as the "benchmark" in cleaning. Hundreds of specifications reference an ultrasonically cleaned part as the ultimate target for cleanliness. Ultrasonic cavitation is able to clean right down to the surface of a part and beyond. It is also able to reach internal areas, which are not accessible by using other cleaning means including spray and mechanical agitation. The forceful nature of ultrasonic energy provides the physical "push" required to break the mechanical and ionic bonds that hold very small particles to surfaces. Once the parts are cleaned, they are now ready to be assembled in our Promar engine.

  STEP 16) ENGINE BLOCK ASSEMBLY   At Promar there are no assembly lines. All engines are custom built. Each assembler does a visual inspection of the block, heads, crankshaft and all-inclusive parts prior to assembly. The Ra tester is used to check all cylinder bores, crankshaft journals and gasket surfaces. All parts such as crankshafts, bearings, cylinder bores, pistons, rings, connection rods, main saddles, lifter and camshaft bores are miced for proper size.

Each block is fitted with new full circle cam bearings, oil restrictors, relief valves, new water and oil plugs. The crankshaft is fitted in the block with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. New rings are then fitted in each bore to assure proper end gap. Each new piston is checked for proper clearance in each bore. The rings are installed on the piston and assembled into the bores. Each assembly is supplied with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. A new camshaft is then fitted into cam bearings bores and all new timing components are installed and double-checked by an assembly manager.

Cylinder heads are then installed with new head bolts and new Felpro or Victor head gaskets. The block now receives new lifters, push rods and rocker arms which are adjusted and a second check completed by an assembly manager. Each cylinder is then accurately checked for seal integrity to assure no compression or water leaks. At this point the engine is primed with special lubricant and a new oil pump. The residual parts of the gasket set are sent along with the engine. The assembly manager then conducts the final inspection of the engine.

All engines come with an installation manual. Bulletins about your specific engine are also enclosed in the packaging. Promar engines are secured onto a wooden pallet where vulnerable parts are protected from damage by corner covers. The entire block is wrapped in a durable plastic sheath to protect your engine from outside elements.

           

CONTACT US

If you have any questions, please feel free to call toll free Monday-Friday 8am-5pm EST @ 1-800-422-6022 or local @ 1-973-684-1500.