![SBC CHEVY 421 ASSEMBLY SCAT WISECO +5.5cc DOME 4.155 PISTONS 2PC RMS-350 MAINS](https://old.skipwhiteperformance.com/media/cache/35/7d/357d002e5fc5fdbedaa0bab93f8c26d9.jpg)
SBC CHEVY 421 ASSEMBLY SCAT WISECO +5.5cc DOME 4.155 PISTONS 2PC RMS-350 MAINS
Available
$2,750.00
Product Information
UPC | 353414764669 |
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Product Type | Shipped Product |
Shipping Cost | $158.50 |
Number of reviews | 0 |
FULLY BALANCED SBC CHEVY 421 ROTATING ASSEMBLY WITH WISECO FORGED +5.5cc DOME PISTONS.
4.155 BORE X 3.875 STROKE, MANLEY PRO-SERIES INTERNALLY BALANCED 4340 FORGED CRANKSHAFT, 6.0. SCAT COMPETITION RODS. FITS 2PC REAR MAIN SEAL BLOCKS WITH 350 MAINS.
SEE OUR OTHER LISTINGS FOR THIS ASSEMBLY WITH 400 MAINS.
This assembly is for use in aftermarket blocks such as Dart SHP or Little M and many others.
Our eBay user id is: skipwhite, and our eBay store name is whiteperformance1. You may have noticed other sellers using a similar name offering similar products. These other sellers have capitalized on our name as we see it, and many customers searching for us will inadvertently find them, thinking we are one in the same company. There is only one "Skip White." We are the original premier eBay seller under this name since approximately 2003. We have no other eBay names, nor are we associated with any other company regardless of the similarity in the name or location. Our official company name is Skip White Performance. Please see the article in the lower part of this ad for a more detailed explanation
The picture above is a file photo. See the detailed info below for the actual pictures and items included in this assembly.
Fully balanced in house.
READ THIS LISTING COMPLETELY BEFORE YOU BUY ELSEWHERE!
This assembly comes with a Manley Pro-Series internally balanced 4340 crankshaft and 4340 Scat rods, Mahle moly rings, King bearings, and a heavy duty 168 or 153 tooth flexplate and a Pro-Race brand SFI damper. See our other listings for various piston bores in flat, dish, and dome style, as well as 1 pc or 2 pc rms style cranks. See details for all the actual specs of this assembly. In the lower section of this ad is information on the various upgrades we offer in our other listings.
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We offer these assemblies in 1 pc rms. and 2 pc rms. dish, dome or flat top pistons, as well as other bore sizes. See details below for the actual specs.
Crankshaft Specs.
- Crankshaft: Manley Pro-Series, Internally, (Neutral) Balanced.
- Crankshaft Stroke: 3.875"
- Crankshaft Material : Forged 4340
- Journal Diameter: 350 Mains. We also offer this with 400 mains in our other listings.
- Rear Main Seal: 2pc RMS
- Rods: Genuine Scat
- Rod Type: Scat Pro-Competition, I-beam, Bronze Bushed.
- Rod Length: 6.0"
- Rod Material: Forged 4340 Alloy.
- Rod Bolt/Cap Screw: ARP 2000 Cap Screws.
- Pistons: Wiseco Fully Forged. High Performance for street/strip use.
- Piston Size: 4.155"
- Dome Volume: +5.5cc Dome Top
- Compression Height: 1.080
- Piston Material: Forged 2618 Aircraft Alloy
- Piston Rings: Total Seal High Performance, Moly, Standard Tension.
- Ring Size and Fit: 1.5mm 1.5mm 3.0mm file fit.
- Ring Material: Ductile Iron/Cast/Stainless/Moly
- Main Bearings: Clevite or King MB557HP High Performance
- Rod Bearings: Clevite or King CR807HP High Performance
- Balance: In House on CWT balancer.
- Damper: Pro Race SFI Damper 6.61" Internally balanced.
- Flexplate: Heavy Duty Internally Balanced. 168 tooth or 153 tooth. Manual Trans. flywheels available.
Compression Ratio Chart
The calculations below assume your pistons are at zero deck. Let's say your compression calculates out to be 10.50:1 for example based on having the pistons at zero deck (flush with the deck), but your pistons were going to be .005 in the hole, then the comp. ratio would only drop to 10.36, and if left .010 in the hole, then it would drop to approx. 10.22 We do recommend having your block decked to allow the piston to set anywhere from flush (zero) to .005 in the hole for optimal performance. We used a 4.200 head gasket diameter, and a .040 head gasket thickness in our calculations to come up with our comp. ratio values.
Part Number |
Cylinder Head Volume |
|||
65cc |
72cc |
75cc |
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421 Assembly |
Static Compression Ratio |
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4.155 Bore |
13.39 |
12.26 |
11.83 |
Our custom made Wiseco pistons are rated very high in the street/strip performance industry. Wiseco normally offer several grades of pistons, starting with the lower grade Pro-Tru Street version made with 4032 forged alloy. The next level up would be the professional series that are much more expensive and made from 2618 aircraft alloy and have fully machined crowns rather than the as cast crowns that are on the Pro-Tru series. Our Wiseco pistons are custom made for us, and have both of these premium features, 2618 Alloy, and fully machined crowns. All premium grade forged pistons on the market have these two unique features and usually cost around $800-$1100 per set.
We have built approximately 8000 engines using the Wiseco pistons over the past 10 years. The engines have been for street rod and strip use. We have seen no problems, nor have there been any complaints. They are an excellent product in every respect.
Important note
Many customers have asked us what size they should bore their block at to allow for a proper piston to wall clearance. The required clearance is built into the piston already. For example if these pistons show a given size such as 4.030 then that is exactly what you will bore the block to. The actual size of the pistons when measured at the skirt, 1/2 inch above the tang will show to be approx. 4.026. The needed clearance is built in. Should you be using these pistons in a marine app. where the boat receives it's water from the lake, then an additional 1.5-2.0 thous. would be added to your final bore size, and some forced induction apps may also require a slight increase in bore size.
These pistons are totally suitable for use with mid level nitrous or blower setups. Extreme level builds that are making hp numbers in the 1000 hp range will require a set of custom made extreme duty pistons.
Our Wiseco 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 Wiseco pistons have a compression height that is .015 taller than nearly all 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, you will only have to remove approx. .010 off the deck surface of a virgin block to achieve a zero deck. This also allows for future deck re-surfacing and still not ending too far below stock deck height.
Leaving the deck on your block thick makes for a stronger block that resists flexing and also runs cooler, as the deck thickness has a lot to do with the dissipation of heat. Blocks with decks cut down to any great amount are also prone to cracking. This is why our pistons are designed to sit flush, (zero deck) at .010 below stock deck height.
Since nearly all catalog pistons on the market sit .025 below the surface of a virgin block, the only way to achieve a zero deck using such pistons would be to cut .025 off the deck surface. This compromises the integrity of the block, in our opinion. Should you decide to leave the block deck higher up, using such pistons creates a new issue of having a very poor quench/squish zone. The only way you could really take advantage of a catalog piston is by having a block that needs to or has already been butchered down to 9.00 deck height. At that point, we don't think you should use such a block. Having the piston sitting flush with the deck, (zero deck) is very desirable, regardless of the fact that your overall compression ratio is slightly higher than if it were sitting below the deck.
We have found that 95% of our customers are using a virgin block or a block that is close to stock deck height. This is why we have designed our pistons to have a taller compression height. On very rare occasions, you may end up with a block that has the piston out of the hole by a few thousandths and this not a problem at all. Most head gaskets are approx. .040 thick, and should you end up with a quench zone of around .035, then that is perfectly ok. If the quench zone ends up too far below .035, then there are plenty of .050 thick head gaskets on the market. One more benefit to this is that most machine shops charge much more to deck a block down from stock deck height to 9.00 than they would to do a light cleanup, and that's all that's needed when using our Wiseco pistons.
The pictures below are file photos of our Wiseco pistons.
![photo SBC20DOME20TOP.jpg](https://i860.photobucket.com/albums/ab168/skipwhite/Pistons/SBC20DOME20TOP.jpg)
The New Manley Pro-Series #190480, 4340 Forged Crankshaft.
The picture below is a generic file photo
The picture below is a file photo. Actual appearance will be different.
Some of the benefits of the new Manley Pro-Series crankshaft.
Manley Pro Series crankshafts are considered a top tier level crank as compared to the more common brands available. They feature forged 4340 construction and undergo a multi-step heat-treatment process and are then nitrided for added strength. The crankshafts are stress-relieved, shot-peened, and magnafluxed. Manley Pro Series crankshafts have micro-polished large .125 in. radius journals, gun-drilled mains, and lightened rod journals for weight reduction. The counterweights are fully profiled and they are designed for internal balancing. These crankshafts will include a spec. sheet that validates journal sizes and checks for taper on each journal as well as finish quality. As of this date, 4/15/24 We have now upgraded all of our 421, 427 and 434 short block kits and engines with the Manley Pro Series crank.
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 6 inch SCAT COMPETITION SERIES rods with ARP-2000 cap screws.
The Scat Pro-Competition extreme duty I-beam rods should not be mistaken for ProComp rods. These rods are made exclusively by Scat, and have nothing to do with the ProComp company. The critical sizing and installation of the ARP cap screws is performed on a Sunnen machine in the USA by Scat Industries. These rods are excellent for those wanting the extra security offered by a rod with 7/16" ARP 2000 cap screws. The ARP 2000 rod bolts are a superior rod bolt compared the ARP 8740 rod bolts, and usually cost approx. $89.50 more. As of this date, 7/5/24 the ARP 2000 rod bolts will be included in all of our 421, 427 and 434 engine builds.
If you do a search on the Scat Pro-Competition rods, you will find a vast amount of info on many car forums. All of the info is 100% positive. These rods are run in engines that not only produce high horsepower levels, but also run at continuous RPM. Notice the appearance in the pictures. These rods do look impressive. The style is reminiscent of an Oliver premium rod.
The fact that these rods are incredibly strong and well made, coupled with the fact they are light weight and offer better cam clearance than any H-Beam rod on the market, made it an easy decision to use them in most of our high horsepower street/strip engines.
Our Scat rods are bronze bushed, and unlike Eagle I beam rods, these are fully forged 4340 alloy.
Genuine ARP 2000 cap screws.
We have noticed some engine builders using low cost generic rods, bolts, 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.
Total Seal High Performance Rings.
KING OR CLEVITE BRAND BEARINGS, DEPENDING ON AVAILABILITY MAIN AND ROD BEARINGS INCLUDED.
MOST OFTEN WE USE THE CLEVITE BEARINGS, BUT DUE TO SHORTAGES WE ARE SOMETIMES FORCED TO USE THE KING HP BEAINGS. THEY ARE BOTH HIGH QUALITY BEARINGS.
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 Pro-Sport SFI 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.
WARNING: The crank has a dowel pin installed in it. You must align the flexplate or flywheel to the dowel pin. The assembly was balanced with this pin installed.
We offer premium grade Ram brand SFI Billet Steel flywheels for manual transmission use at an additional cost. See our other listings. This assembly includes a flexplate for automatic transmission use at no additional cost.
When choosing a flywheel for manual transmission use, be sure to know what tooth count you need. There are two sizes available, and it is of the utmost importance to select the flywheel that is correct for this assembly. There are several factors that must be addressed when choosing your correct flywheel. The tooth count must be correct. This is very important. There are two sizes available, and it is the bellhousing size on the transmission that determines this. Another important factor is if the assembly your purchasing is internally balanced often referred to as neutral balanced or if it is an externally balanced assembly, often referred to as externally balanced. All of our assembly ads will have this information in them. Big block and small block engines will also have a different bolt pattern in most cases. To sum it up, there are three important factors to look for when selecting the correct flywheel, tooth count, int. or ext bal. and whether or not you have a big block or small block engine. The Ram brand flywheels we offer are very high quality.
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.
Rust warning.
If you are going to store your rotating assembly or short block kit for any length of time, it is very important that you protect these parts by spraying a light coat of rust preventive substance on all bare metal parts. This is especially important for those storing these parts in a high moisture or humid environment. Very light surface rust is easily removable and will cause no harm, but heavy rust can damage these parts and be very costly to fix.
Our thoughts on what the competition has to offer.
Many rotating assemblies 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 assembly. The failure rate with the parts used in our assembly is near non-existent. These are the same parts we use in our engine program. 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 assemblies that include parts that have high failure rates. Many of these parts also pose a great problem with assembly 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 combination and quality of our parts. We have also seen sellers offering parts that are not compatible with what most people are building. The low grade dampers and flexplates are often a problem. Another area of concern would be balancing. Not sure how much attention these sellers are giving the assembly in this area. We spend up to two hours balancing an assembly, and using the very best up to date CWT balancing equipment on the market. If the assembly is not balanced properly, it will cost you horse power, and it can damage the bearings in the engine, not to mention there is nothing worse than an engine that lacks a smooth feel and sound when ran in the upper rpm range.
We offer this assembly 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.
Note: The upgrade prices below are subject to change. Refer to the actual ugrade listing for the exact price of these upgrades. The changes are usually very small if any.
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 $24.50 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 assembly you may add any of these upgrades to your shopping cart.
On occasion we are unable to obtain the Pioneer brand SFI flexplate and will substitute it for the Scat SFI brand plate pictured below. The quality is equal in every aspect.
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 $39.50 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 assembly you may add any of these upgrades to your shopping cart.
Rod to cam clearance and sizing: We know exactly where and how much to cut the rods for correct cam clearance, and 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.
The clearancing we will do assumes the use of a reduced base cam. We do not recommend a full base circle cam in this assembly.
Cost of this rod to cam clearancing and sizing upgrade is $89.50 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 assembly you may add any of these upgrades to your shopping cart.
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 assembly you may add any of these upgrades to your shopping cart.
Scat H-Beam Rod Upgrade: Recommended for those running hard. The Scat Competition rods that come with this assembly are sufficient for most street rod uses, but the Scat H-beam rods will most likely offer more security against rod breakage under hard use. The H-beam rods have a 750+ HP rating.
H-Beam rods will require the use of a reduced base circle cam.
Cost of this Scat H-Beam rod upgrade is $89.50 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 assembly you may add any of these upgrades to your shopping cart.
Some of these upgrades 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. Pricing of upgrades subject to change.
A note from Skip White, company president.
Many people have asked how is it that we can sell this assembly for such a low price. To answer this; we buy our products at master WD (warehouse distributor) level for all of the items in this assembly, and we are selling direct to the public. We are a volume sales based company. Our profit is based on sheer volume, with a very low markup. It is this large volume purchasing that allows us to buy products at a much lower price and we simply pass these savings on to our customers. This is our main competitive edge.
Skip White
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