Compression Ratio Chart

The calculations below assume your pistons are at zero deck. Let's say your compression calculates out to be 11.28:1 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 11.13, and if left .010 in the hole, then it would drop to approx. 10.99 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 4.125 head gasket diameter, and a .040 head gasket thickness in our calculations to come up with our comp. ratio values.

We have highlighted in red the compression ratio for the bore size and piston volume of this assembly using several popular combustion chamber sizes.

Scat 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 25% stronger than stock OEM cast cranks and 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. This crank is suitable for use up to approx. 500-525 hp.

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.

Scat Connecting Rods

Genuine Scat Competition Bushed Rods with ARP 12 point 7/16" cap screws are now used in all of our rotating assemblies and 383 Stroker engines.

As seen the in close-up picture below, Scat Competition rods have a very solid build quality.

The quality of the Scat rods is unsurpassed by any of the low cost no-name rods on the market  and they exceed the quality of some of the branded names as well.

The Scat Pro-Comp 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 cap screws.

Take notice of the design of these rods. They are far superior to conventional style I-beam rods. We are now using this rod in all of our Stage 4 and up SBC engines. We also use this rod in our big block 540/555 engines, making approx. 700+hp

If you do a search on the Scat Pro-Comp 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 general appearance in the pictures. These rods do look impressive. The style is reminiscent of a steel billet rod.

The fact that these rods are incredibly strong and well made, coupled with the fact they are light weight and offer better clearance than any H-Beam rod on the market, made it an easy decision to use them in all of our high horsepower street/strip engines.

The Scat rods do have genuine ARP 8740 Series 12 point cap screws. These rods offer excellent block clearance in the lower end of the cylinders. Full base cams will require a considerable amount of clearancing. We strongly recommend using a reduce base cam with this assembly. Be sure to do a roll over test after installing each rod.

Genuine ARP 8740 cap screws.

The Scat rods do have genuine ARP 8740 Series 12 point cap screws. These rods offer excellent block clearance in the lower end of the cylinders.

We have noticed some sellers using generic rods and crankshafts in their rotating assemblies. These non-branded (no-name) rods and cranks are often poor quality in many ways. You will notice many sellers fail to mention the actual brand of these products. 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. Failures of such critical parts in your engine may result in catastrophic damage. Machine shops are sometimes able to correct some of the problems with these low quality rods and cranks, but at great expense to the customer. As for the questionable alloy these items may be produced from and the potentially incorrect heat treating methods used, little can be done to verify this and nothing can be done to correct it. As you may have noticed, this is why we specify the name, brand, and series of every part used in our assemblies.

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 assembly with a proofed set of rods. This is an excellent choice for those wanting to build the engine on their own.

HASTINGS 2M SERIES MOLY RINGS, KING MAIN AND ROD BEARINGS INCLUDED.

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 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.

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.

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. 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 quality of our parts. We have also seen sellers offering parts that are not compatible with what most people are building. Such is the case with 4 valve relief pistons. Those type pistons are sure to not clear the valves when using any decent sized cam. 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 the assembly 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 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 upgrade 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.

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.

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. This is due to the fact that Clevite A series bearings use a slightly harder aluminum alloy.

Upgrade to Clevite "A" Series bearings is $17.50 (These are what we use on all of our engines that have a cast nodular crank.)

Upgrade to Clevite "H/HN" Series bearings is $106.00 (Use only on 4340 forged crank upgrade.)

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 assembly you may add any of these upgrades to your shopping cart.

Rod proofing/sizing: 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 proofing/sizing upgrade is $49.00 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.

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.

ARP-2000 rod bolts: This is one upgrade that we find to be very valuable. The rod bolts are most likely to fail under hard use, moreso than the rod itself. When a rod bolt fails during high RPM, total engine destruction is usually the result. The ARP-2000 rod bolts are a very good upgrade, in our opinion. We actually have few, if any, problems with the regular ARP-8740 bolts, but those who run hard always upgrade to the ARP-2000 rod bolts. The ARP-2000 rod bolts also torque at a higher number, and this increased clamping force is also a factor in keeping the big end of the rod stable and true to size. The ARP-2000 bolts are installed in the rods.

Cost of this ARP 2000 rod bolt 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.

Scat 4340 Forged Crank: The forged Scat crank has a rating of 800+ HP. This is the ultimate upgrade 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 upgrade also comes with the HP 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 do offer this upgrade as part of many of our assemblies in some of our other listings. They have the key words, "fully forged," in the title.

Cost of this forged crank upgrade is $585.00 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.

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