BBC CHEVY 632 CUBIC INCH COMPLETE MERLIN IV SHORT BLOCK KIT.
4.600 bore x 4.750 stroke, SCAT 4340 FORGED CRANK & SCAT 6.700 H-BEAM RODS.
JE PROFESSIONAL 2618 AIRCRAFT ALLOY FORGED +3cc DOME PISTONS.
This short block kit is not assembled.
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The photo above and below are file photos. Actual appearance may vary. This picture is to give you an idea of what all is included. All parts are brand new, first line, unblemished, and balanced. This short block kit is not assembled. See our other listings for the assembled version of this short block. We will update our pictures soon.
THIS KIT INCLUDES:
A brand new World Merlin IV block that has been decked, bored and honed to specs, coated cam bearings, Scat crankshaft and 4340 Scat rods, JE forged pistons, high performance rings, King bearings, and a heavy duty 168 or 153 tooth flexplate and a Pro-Race brand damper. The assembly is fully balanced. See details for all the actual specs. In the lower section of this ad is information on the various upgrades we offer in our other listings.
Our short block kits are custom built to your specifications (e.g., piston configurations, compression ratio, and upgrades).
The block is bored to size with our new Centroid touch probe machine. Few machine shops have a machine of this accuracy.
We also deck the blocks to an RA finish of approx. 15 or better. The decking procedure is also done by our Centroid CNC machine.
We often find many brand new blocks to have a sloping deck of up to 4 thous. When we're finished decking the block it is within approx. .001 accuracy from end to end. Many machine shops fail to catch this as the machinery they use does not allow for such accuracy.
We then plate hone the block with our new Sunnen SV10 diamond hone machine. This is also a very advanced machine that hones the block with a finish unlike conventional machines.
The final step is to clean the block in our high pressure block washer. You should always re-wash your block before assembly. This is to assure that the block is free of contaminants.
Pictured below is the rotating assembly that comes with the short block kit.
File photo. Pistons will be JE +3cc dome tops.
READ THIS LISTING COMPLETELY BEFORE YOU BUY ELSEWHERE!
Crankshaft: Genuine Scat
Crankshaft Stroke: 4.750"
Crankshaft Material : 4340 Forged.
Journal Diameter: STD BBC
Rear Main Seal: 2pc RMS
Connecting Rod Specs.
Rods: Genuine Scat
Rod Type: Scat Geniune H-Beam.
Rod Length: 6.700"
Rod Material: Forged 4340 Alloy.
Rod Bolt/Cap Screw: ARP 8740 Cap Screws.
Piston & Ring Specs.
Pistons: JE Custom Built Fully Forged. High Performance for street/strip use.
Piston Size: 4.600"
Dome Volume: +3cc Dome Top
Compression Height: 1.115
Piston Material: Forged 2618 Aircraft Alloy
Piston Rings: Mahle High Performance, Moly, Standard Tension.
Ring Size and Fit: 1/16 1/16 3/16 File Fit.
Ring Material: Ductile Iron/Cast/Stainless/Moly
Bearing, Damper, and Flexplate Specs.
Main Bearings: King MB557HP High Performance.
Rod Bearings: King CR807HP High Performance.
Balance: In House on CWT balancer.
Damper: Pro-Race brand damper
Flexplate: Heavy Duty 168 tooth or 153 tooth. Manual Trans. flywheels available.
BBC WORLD PRODUCTS MERLIN IV BLOCK BORE 10.200" TALL DECK HEIGHT
We now use all of the Merlin IV blocks in all of our BBC engine builds as of 7/17/2018. The Merlin block is light years ahead in overall construction as compared to any of the other blocks on the market. The main caps all have ARP hardware. Dimensional specs are spot on, and this has been an issue with other blocks we have used in the past. Many of the top engine builders, ourselves included, have found the new Merlin IV block to be superior to other blocks in numerous ways.
World Products has completely redesigned the famed Merlin Big Block Chevy casting, incorporating numerous improvements and new features to virtually every area of the block.
Designated the Merlin IV, this new block is offered in all popular sizes and deck heights and is sure to be a favorite among racers and professional engine builders.
Compression Ratio Chart
The calculations below were done with pistons at .005 below the deck. We usually deck the bbc blocks down to allow the pistons to sit .003-.005 below the deck. Zero deck is most optimal on sbc engines, but bbc pistons tend to have a bit more piston rock than the sbc pistons. We used a 4.630 head gasket diameter, and a .040 head gasket thickness in our calculations to come up with our comp. ratio values.
JE PROFESSIONAL SERIES FULLY FORGED PISTONS, RATED AT 1000+ HP. JE PISTONS ARE 100% MANUFACTURED IN THE USA.
JE CUSTOM MADE FULLY FORGED PISTONS. JE PISTONS ARE 100% MANUFACTURED IN THE USA. THESE ARE CUSTOM BUILT AND HAVE LATERAL GAS PORTING. TOOL STEEL GRADE WRIST PINS.
The pistons used in this engine are a +3cc dome top.
The JE forged pistons are rated very high in the street/strip performance industry. They are made using the 2618 aircraft alloy and have fully machined crowns. We prefer the 2618 alloy over the lower cost 4032 alloy. This alloy may fragment from the effects of detonation and if this happens, it can be very destructive to the engine. Those types of pistons are fine for stock or mild engine builds, but should never be used in carbureted engines built to high horse power levels. The forged 2618 alloy piston is much more resistant to the effects of detonation and heat.
The wrist pins that are included are made from a tool steel grade material, and have thicker than normal walls. These are a very expensive type of wrist pin, and capable of handling very high amounts of horse power.
Our JE Forged pistons are custom designed with an increase in compression height. This has many advantages. Here are a few facts about compression height and deck height.
Our custom made pistons have a compression height that is .010 taller on bbc pistons, and .015 taller on sbc pistons, as compared to most all of the catalog pistons on the market. We find this to be a very valuable feature.
Since our pistons sit at a taller than normal compression height, we only have to remove approx. .005-.010 off the deck surface of the block. Our goal is set the piston at zero deck (flush with the deck surface). This maintains the deck's thickness, making it much stronger than a block that has been cut down .025. The engine will also run a bit cooler with a thicker deck. It's well known that the deck dissipates much of the built up heat an engine generates. This also allows for future deck re-surfacing without compromising the integrity of the block. On our bbc engines, we actually leave the piston about .003 to .005 in the hole to allow for possible piston rock. Our sbc engines will have the pistons setting right at zero with the deck.
These pistons are also suitable for use with nitrous or blower setups. For the slight increase in cost, this is the best value on the market.
Scat 4340 Forged Crankshaft.
The picture below is a generic file photo of a Scat crankshaft. You will receive the correct model packaged in the original Scat box.
Some of the benefits of the Scat crankshaft supplied with this assembly:
The material used in this crankshaft is manufactured from an exclusive Space Age material that was designed for high strength and fatigue resistance. The Scat cranks are the best value you will ever find. The Scat crankshafts are the best way to build a strong bottom end for, street rods, dirt and circle track racing, and drag strip racing.
The forged Scat crank has a rating of 800+ HP. This is the ultimate choice for those wanting to run hard. Nos, blowers, turbos, are not an issue with this crank. Even without such power adders, this Crank offers great protection under the most severe conditions. This crank also comes with the high Performance King bearings. Should you decide to run power adders in the future, this would be essential. The fatigue life of the 4340 crank over the cast nodular is also greatly extended.
We recommend that you check the thrust clearance on the crank before assembling the engine. This is recommended on any crankshaft, regardless of brand or cost. Also be sure to check your main and rod journal size.
Our choice of rods are the Genuine Scat brand heavy duty 6.700 H-beam rods with ARP 2000 cap screws.
These rods offer excellent block clearance in the lower end of the cylinders.
Genuine ARP 2000 cap screws.
The Scat rods do have genuine ARP 2000 Series 12 point cap screws. Some cams may require slight clearancing of the rods. Be sure to do a roll over test after installing each rod.
We have noticed some engine builders using low cost generic rods and crankshafts in their engines. These non-branded, (no-name) products are often poor quality in many ways. You will notice many of the low end engine builders fail to mention the actual brand of the rods or cranks used in their engines. Upon further investigation you will find such parts not to be a branded name product. They may label these parts with a name, but one that is totally unrecognizable in the industry. Our experience in years past with such rods and cranks has been disappointing to say the least. Besides the obvious issues such as incorrect sizing and machining that is difficult to correct, the questionable alloy these items may be produced from and the potentially incorrect heat treating methods used, could prove to be disastrous. Little can be done to verify this and nothing can be done to correct it. Failures of such critical parts will usually result in catastrophic damage to the engine. As you may have noticed, this is why we specify the brand name and series of every part used in our engines.
Many of the inferior "no-name" rods on the market will also have "no-name" rod bolts in them. We have seen these bolts before, and they are very low quality. They don't have ARP's rolled thread design, and they don't torque down with the same characteristics as a genuine ARP bolt. It's not just a matter of having a different brand bolt in the rods; these bolts are low quality in many ways. They have been known to fail in engines to a much greater degree than a high quality rod bolt, and this failure usually causes catastrophic damage in the engine. Beware of rods that don't mention the rod bolt brand. As far as we're concerned, ARP bolts are the only brand we would ever use or accept in a set of rods.
Before the engine is assembled, we strongly suggest checking the rods on a Sunnen machine for sizing on both ends. We recommend this with any rod regardless of cost or brand. It is not uncommon to find some of the rods requiring a slight bump through the hone for perfection in sizing and roundness. We also offer this kit with a proofed set of rods. This is an excellent choice for those wanting to build the engine on their own.
Mahle High Performance Rings.
KING MAIN AND ROD BEARINGS INCLUDED.
Pro Race Brand harmonic damper, 7.0" diameter, included. These are very high quality items.
We have noticed others using a low grade knockoff brand damper/balancer, and we have encountered them in the past. They are substandard in appearance, and are often out of spec. The timing marks were also poorly marked on some of the balancers we have come across. You don't want a balancer coming off or one that is improperly weighted. Another problem with low grade dampers is the elastomer bonding can lose its adherence to the inner and outer structure. This problem is referred to as a slipped damper. We have only encountered this once in 10 years with the Pro-Race brand dampers.
We know of several competitors including these balancers with rotating assemblies. The ProStreet brand is far superior to most any we have ever seen. They were once known as a knockoff product, and have become one the best values on the market, without comprising quality whatsoever.
HEAVY DUTY FLEXPLATE INCLUDED.
HEAVY DUTY FLEXPLATE. This flexplate will resist cracking. One good telltale in identifying a low quality flexplate is the lack of welding on each side where the plate mates to the ring gear. They usually have a pale grey color to them, as they are not coated, and will rust quickly. Ours are welded on both sides, and are much thicker than an OE plate, and are either zinc dichromate or black powder coated. We would never use the thinner OE style plate on an assembly like this.
We do offer this assembly with a manual flywheel. See our other listings. In most cases we do have both sizes, 153 and 168 tooth, available.
WARNING: the flexplate and crank have a dowel pin hole. You must align the flexplate and crank dowel pin holes, but do not use a dowel pin. The flexplate was aligned to the crank when we balanced the assembly, and must be installed the same way.
Our CWT 5500 Balancer.
We do our own balancing with our new state of the art CWT 5500 Series balancers. The CWT 5500 is the ultimate for precision balancing. We now have three of these in our machine shop. We consider this machine to be highly advanced compared to the Hines balancer we once used. We balance every rotating assembly we sell within 2 grams or less at no extra charge. A balance sheet is included with your assembly.
Three CWT balance machines under one roof is a rare sight.
Our crew wrapping up for the day. Pardon the mess.
Our thoughts on what the competition has to offer.
Many short block kits we see on the market are not using the most suitable parts. We hope you can value the fact that we have put together an above average short block kit. The failure rate with the parts we use is near non-existent. It was through trial and error in years past that taught us where to draw the line with low cost parts. We are out-priced by many others selling short block kits that include parts with high failure rates. Many of these parts also pose a great problem due to the fact they require additional machining and can end up costing you a great deal more money and time. If you're going to have a machine shop build your engine, we strongly advise you get an opinion from them on the parts you're going to be bringing to them. Rest assured they will find no problem with the quality of our parts. We have also seen sellers offering parts that are not compatible with what most people are building. We have seen several sellers offering no-name brand rods with an assembly. These type of rods also have no-name bolts in them. It is our strong advice to avoid this grade of rods. The low grade dampers and flexplates are also another problem. Another area of concern would be balancing. Not sure how much attention these sellers are giving in this area. We spend up to two hours balancing an assembly, and using the very best up to date balancing equipment on the market. If the assembly is not balanced properly, it will hammer the bearings out of the engine, not to mention there is nothing worse than an engine that lacks a smooth feel and sound when under load.
We offer this short block kit with selected upgrades. Listed below are some of the most requested ones. Many not only improve performance, but further enhance the reliability and longevity of your engine, along with resale value.
SFI Certified Flexplate: This is a very low cost upgrade and may be required when racing your car at certain tracks. The flexplate that comes with this assembly is a heavy duty plate, but the SFI certified plate is one step up in quality and safety. This SFI plate is made in North America. We noticed these have much less run-out and warpage than we see with many other plates on the market. Plates with too much run-out and warpage can cause a host of problems for your transmission and starter, and affect balancing. The low cost to upgrade to this is well worth, it in our opinion.
Cost of this upgrade is $16.50 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
SFI Rated Billet Steel flywheel upgrade/option for manual transmission. Upgrade to a SFI billet steel flywheel 168-tooth or 153-tooth for manual transmissions. We highly recommend the SFI billet steel flywheel for those running hard. These are fully cnc'd and far superior in many ways compared to the regular cast iron flywheel.
Cost for the SFI billet flywheel option is $169.00 We have this upgrade/option featured in our other listings. There will be a Chevy 153 tooth and a Chevy 168 tooth size available. Be sure you know the size you need. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this engine you may add any of these upgrades to your shopping cart. Click here to add upgrades.
SFI damper: Offers an extreme level of safety against breakage, and is very resistant against slippage of the elastomer damping material. SFI dampers are not only made from a better grade of steel, they are also constructed differently and have a much better appearance. They usually last much longer than a non-SFI damper. Many drag strips require this on engines producing high horse power levels. The SFI certification is laser etched into the side. Damper failure rates are much higher on engines using a non-sfi damper coupled with hp ratings exceeding 500 and turning 5600 rpm or higher.
Cost of the SFI damper upgrade is $69.50 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Crank polishing: Extends bearing life, reduces oil temp, frees up a slight amount of average horsepower. This is a very low cost upgrade, and in the world of mass production, most cranks do not come with a true polished finish. This is why most machine shops have a machine to do this. The difference is dramatic between a crank right out of the box and one that we have polished. Bearing companies claim that cranks that have better finishes on the journals will survive the break-in better, and have much longer bearing life. We do a two-step process and bring the RA numbers down in the single digit range. We have the most advanced crank polishing machine on the market.
Cost for the crank polishing upgrade is $38.50 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Clevite Bearings: We find the Clevite bearings to be a somewhat better product overall. Clevite is what we now use in all of our engines. This is not to say that King bearings are faulty in any way, but under certain conditions, we have seen fewer problems develop with Clevite bearings during break-in. We have sold King bearings for many years and do not hear of problems from our customers, but our experience on the dyno has shown the Clevite bearings have a better surface appearance upon tear-down after many dyno passes.
Upgrade to Clevite "H/HN" Series (with forged crank) bearings is $55.00
We have these Clevite bearing upgrades featured in our other listings. You can see these and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Rod sizing: Sizing the big end and wrist pin bushing on the Sunnen machine saves a trip to the machine shop. All rods, regardless of brand, should be checked for sizing on a Sunnen machine, and corrected if needed. You will seldom see a complete set of rods that have perfect sizing on both ends right out of the box.
Cost of this rod sizing upgrade is $50.00 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Race balancing: This is for those who want the engine to operate virtually vibration free at high rpm. Extends engine life and frees up a few more horse power. This is a somewhat labor intensive procedure and is not required, but the feel of an absolutely vibration free engine at high rpm is desirable by many. The standard balance job that is included with this assembly at no extra charge is certainly sufficient. With a race balance job, all pistons and rods are match weighed to within 2/10's of a gram or less, and the final balance is brought down to around 1 gram plus or minus. An ultra smooth engine at high rpm has a noticeable feel and sound to it. If you do not opt for this upgrade, the assembly will still be fully balanced. We spend a good hour and a half doing the regular balance work, and it will certainly meet your needs.
Cost of this race balancing upgrade is $125.00 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Block prep package: This upgrade includes notching the block on our Centroid cnc machine to allow additional clearance for the crank if necessary. We also de-burr the block, hone the lifter bores to spec, chamfer the top of the cylinders, and lifter bores, and install the special cam bearings and freeze plugs. The block is then thoroughly cleaned in our block washing machine. We find this upgrade essential for those lacking the proper equipment or knowledge to perform this correctly.
Cost of this block prep package FOR A 632 ONLY is $250.00 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this short block kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
BBC Short Block Kit Assembly upgrade: This upgrade includes everything in the Block Prep Package plus assembling the short block kit. If you choose this upgrade, DO NOT also include the block prep package in your cart.
Cost of this BBC Short Block Kit Assembly upgrade is $450.00 We have this upgrade featured in our other listings. You can see this and other upgrade options in our ebay store under the "UPGRADES" category, or simply do a search with the key word, "Upgrade" in the search bar when shopping in our ebay store. Before you finalize your purchase of this short block kit, you may add any of these upgrades to your shopping cart. Click here to add upgrades.
Preparing the block in our Centroid cnc machine for precise notching, if necessary.
The blocks are washed in a dedicated block cleaning machine.
Pictured above is the final rinsing and drying to remove the cleaning solvents.
The upgrades above are all available in our other listings. Some of these are often requested by those building an engine without a machine shop. We find most of these upgrades very valuable for those wanting to take longevity and durability to the next level. They are all bottom end related, and that's an area worth investing a few more dollars into, in our opinion, especially if you're planning on running long and/or hard. These upgrades are also valuable for your build history on your engine, and would certainly increase the resale value of your engine, should you ever sell it.
We are not responsible for collateral damage caused by the use of this product.