engine tips

Ok so you want to build a High performance engine or atleast understand the do's and Dont's of putting together a fire breathing 8000 RPM Monster...Listed below are my general outlines that one could follow to make a high horse power motor. There is a lot of reading involved.

Oiling systems:

One of the most critical aspects of any engine is your oiling system which requires some special attention when rebuilding your motor.

Oil pump: Always use a high volume oil pump with a minimum of 60 lbs. of pressure. Higher oil pressure is critical in motors having a large main bearing . Remember, the oil pump must create enough pressure to push oil into the center of the main journal & then out to each respective rod bearing journal. While centrifugal force is trying to push the oil back out from the center of each main journa a buffer zone where the two pressures and flows meet. If your pump lacks adequate pressure, your rod bearings may starve for oil! Also, its a good idea on all mild rebuilds to replace the stock oil pump driveshaft with a heavy duty driveshaft and steel retainer ring. Do NOT use the stock nylon retainer ring! You will have problems down the road....

Oil Pan: Oil capacity is another issue. The stock oil pan is fine for engines that are not run past 5000 RPM. Engines that are run between 5000 and 7000 RPM frequently should use a 7 quart pan; otherwise, your high volume oil pump will run your stock pan dry as soon as you take the first corner. Another way to judge which oil pan may be best for your application is by the level of engine modifications you have applied stock or "street" work indicates a mildly modified engine where a stock oil pan should be sufficient, "street/strip" work indicates a health street motor that will be occasionally raced and should use the 7 quart pan and the "bracket" port work indicates a serious motor capable of higher horsepower, needing at least a 7 quart oil pan.

Misc.: On high output engines that use mechanical lifters, oil restrictors should be used. These restrictors are installed in the lifter oil gallery from the back of the engine. They restrict oil flow to the valve- train, which forces additional oil to flow to the main & rod bearings. We recommend 20W50 oil for engines running .0025" - .003" bearing clearances.

Cylinder heads/ Intake Manifolds:

The cylinder heads on Chevrolet small block engines are available from several manufacturers. If you buy used heads. Make sure you check the deck for flatness you don't want to buy a warped head. Also check for cracks, around bolt holes and valve seats. Beware of buying stripped heads, when you go to purchase all the valves, springs, retainers, and small parts you will find that you could of bought a completely finished set for less. When you come down to it you are better off with a good aftermarket or factory service replacement cylinder head from a cost/performance standpoint. There are a number of excellent aftermarket cylinder heads available for these engines that will provide substantial power right out of the box...and even more of a power increase when properly prepared. These heads are available in both cast iron (less expensive) or aluminum (lighter). Basically, this is your starting point in any engine project; once you decide on the amount of power you expect to build, you need to choose a cylinder head and corresponding port work that will best deliver that power!

We recommend different levels of port work for different levels of modifications. Below is a description of each different level of port work and a guideline for when each should be considered:

"Street": (oval port head design only) - Intake and exhaust "bowls" are reshaped and smoothed to promote better flow. This modification is recommended on engines with camshafts having intake duration measured @ .050" lift of less than 215. On some small block applications we recommend using a valve one size larger than stock.

"Street/strip": (oval port head design only) - In addition to the "Street" port work described above, the following additional modifications are performed: intake port entry is gasket matched . The port is squared and the port is widened in the area of the pushrod "bulges". The exhaust port exit raised. The exhaust port mouth widened, squared and blended into the port roof. The valve bowls are blended further, and the valve guides are streamlined.

This modification is recommended on engines with camshafts having intake duration measured @ .050" lift of more than 215 but less than 240. With this type of port work, we usually recommend the Edelbrock "Performer RPM" on milder camshaft applications (215 - 230) or the "Victor Jr." or one of the Brodix intakes on larger camshaft applications (230 - 240). Manifolds should be port matched to the heads.

"Bracket": (rectangular port head design only) - In addition to the "Street/Strip" port work described above, the following additional modifications are performed: Intake ports are completely ported and reshaped and the roof of port is blended. The exhaust port "mouth" is widened further that with "Street/Strip" porting. Combustion chamber is modified to remove any shrouding and finish polished.

This modification is recommended on engines with camshafts having intake duration measured @ .050" lift of more than 240. With this type of port work, we usually recommend the Edelbrock "Victor" series or one of the Brodix intakes on carbureted applications. Manifolds must be port matched to take full advantage of cylinder head modifications.

We do not recommend using the stock replacement valve seals. We recommend machining the tops of the valve guides to accept the Perfect Circle , "Viton" or "Teflon" seals. These are a "positive" seal; they wipe the excess oil from the valve stem & only allow enough oil down the guides for adequate lubrication, thereby controlling oil consumption.

Valvetrain components:

Valves: In all instances, must use stainless steel valves. The valves originally produced in these engines (prior to 1971) are not compatible with today's no lead fuels. Even in race-only applications, a number of racing fuels are no-lead and eventually, even all racing fuels will be unleaded. We use Manley valves in all of our applications and highly recommend their valves and valvetrain components. Some high RPM (8000+RPM) will require titanium valves.

Rocker arms: The stock rocker arm assemblies are adequate for milder street applications. The original rocker arms are not real strong. In addition, they generate a lot of unwanted heat! They should not be used with any of the "larger than stock" camshafts on the market.

For most applications, we recommend roller rocker arms. They provide several advantages: they reduce valvetrain friction considerably..which in turn frees up horsepower, reducing oil temperature, they also provide more accurate valvetrain geometry and they are substantially stronger than stock rocker arms. Roller cam applications using stiff valve springs (500+lbs open pressure) would benefit from a rocker arm stud girdle. Always match The Valve springs to a roller cam.

Pushrods: Please note that special engine modifications will require pushrods of shorter or longer length depending upon modifications performed. Always use a pushrod checker when sizing up your pushrods.

Retainers, keepers, springs: We do not recommend the use of the stock valve retainers, always replace these valve spring retainers with quality aftermarket chromoly retainers and hardened keepers. Never use stamped keepers! Always use high quality machined keepers. As for valve springs, allways follow the recommendations of the cam manufacturer. Be careful to install the springs at the correct installed height. In any application that will be raced on a regular basis, we recommend using a spring that is slightly stiffer than may be called for by the cam manufacturer, since the springs in this type of application will fatigue a bit faster than in a street application. Do not go overboard with the seat pressure on the valve spring, this will cause your cam lobes to flatten over time. There are many different springs that you can apply to most all applications with out overstressing the cam.

Timing Chain: We allways recommend double roller timing chains for all applications. There are several available on the market but be very careful to degree-in all camshafts.There are several several timing sets that are off several degrees that are sold through out the industry, so always use cloyes timing sets, we have found these to be the best! There are gear drives available for use with low and high rpm engines. While they're extremely accurate with respect to valve timing, they're expensive and tend to transfer unwanted crankshaft harmonics to the valvetrain and ignition.

A better (and much more expensive!) alternative is the Jesel belt drive. This system offers several advantages: the belt dampens any unwanted vibrations from the spinning crankshaft, the belt actually stretches less than a chain and the belt drive offers access to relatively simple cam timing change. For anyone building a serious race engine, this is the way to go as long as rules allow.

Camshaft & lifters: When choosing a camshaft, a few items must be considered. Some high performance camshafts are machined on a different "base circle" than the original factory camshaft. This "base circle" is the diameter of the cam lobe without the lift...the radius of the heel (non-lift) side time 2. To obtain more lift, many cam grinders will take more material off the heel of the cam to gain additional lift.

Mechanical lifter camshafts (mechanical flat tappet and roller tappet) will also require some means of adjustment required to maintain appropriate valve lash. While stock rocker arms do provide a means of lash adjustment, we don't recommend them since the valve springs typically used with these types of camshafts are too stiff for stock rocker arms, so upgrading to roller rocker arms will be a necessity.

Cylinder Block, Crankshaft, Connecting Rods & Pistons:

Any 4 bolt main small block is a pretty stout piece; capable of handling 500+ horsepower when properly prepared! The 2 bolt block is nearly as stout as the 4 bolt, and may be converted to a 4 bolt layout pretty easily. Chevrolet produced these blocks in two different deck heights,

Blocks: We recommend main studs be used in all 2 bolt applications and in all but stock 4 bolt rebuilds. The ARP main studs provide more clamping force than a stock bolt, thereby reducing cap walk under higher loads. In high horsepower (550+ for the 4 bolt, we don't recommend the 2 bolt block for more than 400 horsepower) applications, we recommend the use of billet main caps in conjunction with the main studs. The billet main caps offer 3 times the strength of stock main caps; they actually act as a girdle to the block. They fit into the registers more tightly than stock, thereby adding additional main cap stability. The 4 bolt cap is available in both straight and "splayed" bolt arrangement; the splayed bolt cap angles the outer bolts outward 18 degrees to utilize the inherent rigidity in the cylinder walls resulting in an arrangement that is stronger than the straight bolt cap arrangement. The Chevrolet "Bowtie" blocks and most aftermarket blocks are manufactured with this type of main cap arrangement and offer several additional strength as well as oiling advantages over the stock blocks.

We recommend the use of a torque plate when honing all blocks! A torque plate simulates the load of a cylinder head being torqued in place; this stress distorts the cylinders! In fact, the main caps should also be torqued in place before honing.. We do not recommend boring a production small block for street use more than .060". It is suggested that any production block bored more than .060" have the walls sonically tested to assure the block has adequate wall thickness & has not experienced core shift and water jackets filled with a block hardener. A longer stroke will require a raised camshaft. Aftermarket blocks such as the World Products "Merlin" may be safely bored to 4.625" and are available in 5 deck heights.

Crankshaft: The nodular iron crankshaft used in most big block engines is a reasonably strong piece, strong enough for most street/strip engines or nitrous applications using less than a 150 horsepower "shot". For high horsepower street/strip cars or nitrous applications using up to 300 horsepower "shot", we recommend using the factory steel crankshaft. More power? Choose one of the aftermarket 4340 forged steel or billet crankshafts.

For mild street or street/strip applications, we recommend no more than .0025" main bearing clearance on any application (.002" preferred). For high horsepower/high RPM applications, we suggest .0025" - .003". All rod bearing clearances should be .002" - .0025" for mild street or street/strip applications (.002" preferred) and for high horsepower/high RPM applications .003".

Connecting rods: We recommend the use of ARP rod bolts in all applications. They are superior in strength to the original bolts...and offer cheap insurance against catastrophic failure! In most street/strip applications, the stock connecting rods are sufficient; they should be reconditioned after the rod bolts are installed. Chevrolet produced some HD rods for the LS series engines which used a 7/16" bolt and were strong enough for all but the most serious high horsepower applications.

There are several aftermarket connecting rods available which are superior in strength to the factory rods and offer a better bore to stroke ratio (they are longer than stock). In applications using nitrous (more than 100hp), turned more than 6500 RPM or making 500 or more horsepower and not using the previouly mentioned LS6 rods, you should strongly consider one of the aftermarket "H" beam or high strength "I" beam connecting rods.

Aluminum rods are a consideration when building an all-out race engine. They offer advantages like light weight, absorb some of the shock loads associated with nitrous, they are less costly...just to name a few. Just remember that, depending upon the application, they must be changed every 50 races.

Balancing: We recommend all engines be balanced regardless of application...from stock to all out race motor, get it balanced! It has been our experience that balanced engines even idle smoother! When using an aftermarket crankshaft, rods, etc. or some combination, it is mandatory that the rotating assembly be balanced. Also, remember the small block chevys are internally balanced, the other small block motors(383, 400) are externally balanced! Also, anytime you change crankshafts, rods, different weight pistons, etc. your motor must be balanced!

Pistons & Rings: We do not recommend stock cast replacement pistons for any application. We only recommend "hypereutectic" cast pistons for mild street applications. "Hypereutectic" refers to the silicone content of the casting; in this case, the pistons have more than the norm of 12 - 16% silicone. This helps the pistons resist scuffing and adds to the overall strength of the casting. Additionally, these pistons are cast significantly thicker than stock in the pin boss, skirt and piston crown area...also adding to their strength. For mild street applications, this piston will work fine. For most of these applications, a quality chrome moly ring will provide good service life along with excellent cylinder sealing. In applications that are more "strip" than "street", we suggest you upgrade to a premium piston ring such as the "plasma" moly ring from Federal Mogul, as these rings will last longer under the harsh operating conditions.

For high horsepower applications, however, forged pistons are required. Any application that will turn more than 6000RPM, use a nitrous "shot" or run any boost will require a forged piston. The preferred material for forged pistons these days is 2618 aluminum; a material that is both strong and light. There are a number of forged TRW pistons available that replace the original factory forged piston (in fact, these were the factory piston! The factory bought them from TRW back in the '60s) and they provide a strong basis for all but the most serious race motor. We would also recommend using a 1/16", premium grade ring (as opposed to the stock 5/64" chrome moly) to reduce reciprocating weight and extend service life.

It is important to note that the shape of your piston dome must be matched to the shape of your cylinder head combustion chamber. As mentioned under the "cylinder head" discussion, Chevrolet made a number of different "closed" and "open" chamber cylinder heads for these engines. "Closed" chamber heads will only work with "closed" chamber pistons; "open" chamber heads will usually work with both...but there are exceptions! It is best to check with the piston manufacturer to verify a given piston will work with a given cylinder head.

Bearings: The replacement bearings available in today's market are sufficient for most street/strip applications. These tri-metal bearings will provide good service life in street/strip applications. For high-horsepower applications, we recommend upgrading to Federal Mogul "super duty" alloy bearings. These bearings have a stronger facing material and the steel backing is also of a higher grade material, making them less likely to distort or deform under extreme loads. These bearings do not have the typical tin overplate normally found on bearings; because they do not have this overplate, dirt will not in-bed in them as with typical bearings, so it is important to keep the oil clean in any engine using these bearings!

More Helpful Hints:

Always use a sound engine block. The block is the heart and soul of the engine, If you have a bad heart you will have a failure.

Always have your components professionally machined. You can do small work yourself, only if you know what you are doing. The best thing to do is to go to your engine builder and watch what he does. We had a builder that was in the business for a long time, he liked to talk and would let us help out. Learn from experience.

Polish every part till it shines like a mirror. This will help the flow of oil and slow down the effects of drag. If you are using stock connecting rods, look at the factory flashing that goes around the edge of it. You can lose weight and lose drag if you carefully remove it and polish it.

Check, and Double check your clearances between components. I have seen many a guy just bolt stuff together in the engine only to see it explode because they didn't check the clearance between pistons and valves when they assembled their motor.

Always match your parts to one another, do not use a stock Cast crankshaft and use forged rods or vise versa, your only asking for problems. I hate to see money explode. If this is something that you do Please find our mailing address and just give us your money.

Never hold a tight tolerance between critical components, if your in the field of making a motor scream at over 7000 rpm. The tighter the tolerance the less oil you have for lubrication between those components. Mind you that you don't want to have a large gap between the components and the bearings or you can expect more explosions. I have put motors together that you can turn the crank around with the connecting rods with pistons attached, with one finger, and that motor lasted almost 2 years or 40 races. Remember that friction is the worste enemy of your engine, the less friction you have the better off your going to be.

There are several things that you can do to make more power, just remember that the more power you make the stronger the crankshaft has to be. The crank is designed to flex with the forces of the rods moving it around. This is called torque. To much torque on an inferior part will cause failure.

Always use the proper torquing sequences and specified pounds when tightning your fasteners. Do not over tighten. Never try to guess at what the torque pounds are, Every bolt on your motor, whether it's a chevy, ford, or dodge engine uses specific poundages for each bolt. Never ever reuse head bolts, Main Bolts or Connecting rod bolts. These bolts will stretch and fatigue as they age, or just when torqued. Always retorque the bolts after they sit, you will want to check the pounds once they sit or get hot.

Always remember this. The more rotating mass you have to turn. I.E. Crank, pistons,connecting rods, the less horse power you will make. You must Balance, Balance, Balance your crank, Weight match your connecting rods and pistons. The lighter you can make these parts the more RPM you will turn.

With racing applications you want to add a thousandth or two for expansion under heat. I always give the rings a little to expand on when I put the rings on the pistons. There is a trick to putting a motor together that will hold up under severe use. Once you find that special combination it will only be a matter of finding other small things to encorporate to get more power.

Lets talk oil flow....This is a major must, but some areas you don't want a lot of oil to flow to. One instance is the crank, you do not want oil splashing up on the crank and under the pistons while under high rpm, you do however want oil to get to the main bearings,. The splashig oil will stall out a crank by creating a lot of resistance and hindering the oil flow to and away from critical main bearings and connecting rod bearings. If you knife edge the crank when you send your motor out to a professional, you can make a 10% gain in rpm. Restricting the flow to the top half of your motor will win you gains also. You do not need a quart of oil a second splashing on the rockers under the valve covers. All the oil has to drain back to the oil pan somewhere and it goes on top of the cam and then on the top of the crank, adding what else...? resistance. When you use solid lifters they do not require as much oil to the lifters and roller rockers as stock engines require.

Alway assemble your motor with the best gasket set you can get. Do not use generic $10.00 special. Remember that there are different thickness shimmed gaskets for the heads and with a few thousandth difference its noticable on the track. Do your research before you buy. I always get crushable copper gasket. Forms a better seal, and protects against leakage. The reusable gaskets are good only for use on valve covers.

No matter what type of rocker arm you are using you should always and I stress this. Check your valve lash every single week. Inspect, and adjust. This area of the motor is critical to your engines survival.

These are just some small hints that I will give up about motor basics..I don't want to lose my racing edge against some of you. Use this as a guide line when you build your motor. There are some really good books out there about building racing motors. Your best investment might be in one of these books.