OneDirt’s project car, a street stock late ’70s Camaro, had experienced a run of bad luck: overheating problems, over-revving problems, transmission failure, and finally – a blown engine. Maxx was in serious need of some professional help. We rounded up the wagons and had a meeting to determine what our next step would be. Obviously, we had to get some of our friends involved in the planning of building a bulletproof engine that a first year driver couldn’t blow up, yet stay within the rules and budget of a grassroots race team. OneDirt and friends have come up with the ultimate in grunt for MAXX.
We started with a broken in four-bolt main Chevy block that had a standard bore, but showed a ridge that was almost as large as the Continental Divide. There were some doubts that the bores would clean up at thirty thousandths over standard, but as luck would have it, we ended up with a good clean block at .030 over. Torres Machinery hot tanked and jet cleaned the block to remove any grit and grime from the freshly machined bullet. We were starting with a clean slate and needed some beefy performance parts and needed to stay within a budget.
KB Hypereutectic Performance Pistons
Pro Power recommended the KB hypereutectic pistons for the build because hypereutectic pistons can run at a tighter clearance and have bigger valve reliefs. Tighter sidewall clearance with good piston rings will provide more horsepower in a naturally aspirated “limited” engine class, where flat top pistons are required. “This is where the most horsepower can be made in this class,” states Metlika. “A good piston / ring combination is essential.” We mounted these pistons on a steel stock replacement rod, 5.7-inch long.
- Keith Black Hypereutectic Performance Pistons
- Part Number KB231-030
- Flat Top with two valve relief
- Effective Head Volume: 6cc
- Bore: 4.030″
- 5.7″ Connecting Rod Required for a 3.480 stroke
- Compression Height: 1.561″
- Crank to deck clearance: 9.025″
- Piston weight: 485 grams
- Piston Pin weight: 102 grams
- Pin Diameter: 0.9272″
- Piston to wall clearance (2 BBL gas application):.0015″-.0045″
Total Seal Piston Rings
One of the crown jewels in this budget build, total seal gapless piston rings are easy to break in and are proven to provide more horsepower than a conventional ring set. These rings do not fit into a “gray area” in the rules – they are perfectly legal, and as Metlika explained, “these rings are part of the joy of buying aftermarket parts.” We expect to see gains as high as 30% in horsepower using these rings with our piston and rod combination.
Piston Ring Specs:
- Part Number: TL3690 35
- Bore: 4.035
- Ring Sizes: 1/16 Top, 1/16 Gapless Second, 3/16 Low Tension Oil rings
Once again relying on Pro Power’s expertise with this type of engine build, Metlika recommended the King Engine Bearings for the rod end bearings as well as the main bearings. He explained that the King bearings are a bi-metal construction, whereas most conventional bearings are a tri-metal construction. “The bi-metal constructed bearings offer resistance to temperature while still being able to handle high loads, plus they are 30% lighter than tri-metal bearings,” states Metlika. The “Alecular” material used in the construction of the bearings provides embeddability to catch and hold particles, so they don’t scratch the crankshaft journals. This is a good thing for a dirt track engine – we had to have these.
Connecting Rod Bearing Specs – Part Number: CR807SI
Main Bearing Specs: Part Number: MB557SI
Professional Products PowerForce Harmonic Dampener
Understanding that we wanted to be able to get the engine turning quickly to get off the corners as fast as possible, Metlika recommended the PowerForce Harmonic Damper. According to Metlika, this dampener is “very reasonably priced and does the job as well as any performance balancer.” We bought this harmonic dampener in order to take advantage of every ounce of lowered rotating mass possible.
- Part Number: 80010
- Dimensions: 6.1″ OD x .75″ thick
- Material: 1045 Steel
Melling Select M Oil Pump
Metlika advised us not to “cheat yourself on your lubrication system,” and selected the Melling Select M oil pump, which has a 25% increase in oil volume over the stock GM pump. While still a cast steel unit, the housing and cover are CNC machined and a steel rod with a steel coupler is included. The pickup is a press in 5/8 diameter screened tube.
- Part Number: 10550
- Type: Cast Steel, High Volume
Cast Steel Crankshaft
Pro Power offers a line of engine components that is designed to provide customers with high-end performance at bargain prices. We chose the cast 350 Chevy crankshaft from Pro Power. Metlika explained that this crankshaft is “affordable” but very durable.
- Type: Cast Steel
- Main Journals: 2.449″
- Rod Journals: 2.100″
- Stroke: 3.480″
- Required Connecting Rod: 5.7″
- Balance: Internal
COMP Cams Hydraulic Cam, Hydraulic Lifters, and Timing Assembly
Here’s where our motor really shines. We got ahold of Ashley Newman at COMP Cams for a custom selected camshaft that fit in the rules of our local tracks. Surprisingly, Newman guided us to a hydraulic camshaft and lifter setup. Based on the information that we provided, Newman decided that a hydraulic camshaft would be better for the weight of our bomber stock on the short, tight track at Victorville Auto Raceway. It kept us within the lift rules and allowed us to use a stock valve train.
To go with our COMP Cams camshaft, we ordered the matching COMP hydraulic lifters, which are COMP’s performance hydraulic flat tappet lifter. Featuring a nice tight tolerance for mechanical internals with one piece push rod seats and a lubricated cam face, these are the perfect companion for our camshaft.
About Our Cam Selection
COMP Cams walked us through the cam selection process, making it easier to get the right part the first time. Ashley Newman of COMP actually started working with us on this project at the end of last year when we rebuilt the heads. Knowing that we were going to build a short block this year that would be using those cylinder heads, Newman designed the entire valvetrain around the camshaft that we would be using in the short block build. This is key to building a street stock engine in a class with cam lift rules, and still getting the best performance possible. This is not a service offered exclusively to OneDirt by COMP Cams – anyone can call the technical service line at COMP and get the same red carpet treatment that we got.
“Choosing a wider lobe separation will provide the grunt that you are looking for, and do it smoothly, while the cam duration makes the most of getting fuel in and exhaust out efficiently,” explained Newman. Additionally, this cam is fairly maintenance free and very powerful on the track with a stock type engine. Given that Newman is a Rislone USCS Modified Series Champion as well as a camshaft expert, we thought it best to go with his recommendation.
The Build at Torres Machine Shop
Starting with a bare block that had just been baked clean and the bores cleaned up to thirty thousandths over, our guys over at Torres Machining and Performance began our Chevy 350 short block build. Joe Torres installed the cam bearings, while Luis Torres started prepping the block and hanging the rods.
Luis explained that assembling the pistons and rods correctly is essential to the life of an engine. “We have a routine that we like to follow for the small block Chevy pistons that begins with making sure that the pistons we are using are mounted on the rods correctly,” Luis tells us. Because we were using pistons with a two valve relief top, Luis reminded us to “lay out the pistons as they would be assembled in the engine, making sure that the valve reliefs are facing inboard to the center of the engine, and the rods with the bearing locks are facing away from the center of the engine.”
After he had finished assembling the piston and rods, Luis began installing the piston rings. Preparation is key when assembling the rings on the pistons, and checking each ring for any machining burrs or debris is a great place to start. Machining had to measure each ring in the cylinder bores and check the ring gap. Luis pointed out that the hypereutectic pistons expand less than stock cast pistons, so the gap on the rings is different than what is normally listed in the ring installation instructions. To be safe, Luis recommends using the ring gap procedures listed in the piston manufacturer’s instructions.
Using a piston top, Luis inserts each ring in the cylinder bore that it is to be installed in and pushes it down the bore at least one inch, to avoid any taper from bore recession. Making certain the ring is square in the bore, he measures the ring gap. He then files the rings with a hand-operated ring filing machine if any material needs to be taken off. According to Luis, he uses ten full turns at a maximum on the ring filer, then rechecks the ring gap in the cylinder bore. After each ring is custom fit for each cylinder, the rings are laid out for installation on the pistons and rods, and installed on each piston respectively.
While Luis was installing the rings, Joe Torres was installing the main bearings and crankshaft. Dirt is an engine’s worse enemy, so Joe’s first task was to ensure that the bearings and bearing bores were totally clean. Installing the bearing halves with the grooves into the block and applying a liberal coat of Royal Purple Assembly Lubrication to the bearing halves, the rear main oil seal was place into position.
Joe then lowered the crankshaft into the block. He repeated the same process for the bearing caps and bearing shells, which were cleaned before assembling the bearings into the caps. After coating the bearings with another liberal dose of assembly lube, the Torres brothers began installing the bearing caps on the block. Ours was a four-bolt main bearing block, with each bearing cap held into place by two short bolts and two longer bolts.
Joe reminded us to make sure that the bearing cap was fully seated into the notch on the block by tapping it into place with a plastic or rubber mallet. Assembling the caps into the block starting with the center cap and working outward, Torres torqued the two longer bolts to 75 foot pounds and the shorter bolts to 65 foot pounds, using a torquing pattern similar to the pattern used to torque an intake manifold.
Joe then lowered the crankshaft into the block and repeated the same process for the bearing caps and bearing shells, which were cleaned before assembling the bearings into the caps. After coating the bearings with another liberal dose of assembly lube, the Torres brothers began installing the bearing caps on the block. Ours was a four-bolt main bearing block, with each bearing cap held into place by two short bolts and two longer bolts.
Joe reminded us to make sure the bearing cap was fully seated into the notch on the block by tapping it into place with a plastic or rubber mallet. Assembling the caps into the block, starting with the center cap and working outward, Torres torqued the two longer bolts to 75 foot pounds and the shorter bolts to 65 foot pounds using a torquing pattern similar to the pattern used to torque an intake manifold.
Once the final torque was applied to all bolts, Torres checked the movement of the crankshaft to ensure that there was no binding or tightening at any point in the crank’s revolution. “The force required to turn the crankshaft over should be no greater than the effort of pushing the counterweights with your thumb,” Luis explained. If you feel binding or extra effort is required to turn the crankshaft, you should stop and isolate the problem by loosening one cap at a time and rechecking the crank rotation.
We asked about the rear main oil seal drag, and asked if there would be any noticeable binding caused by the neoprene seal. Joe responded by saying that any seal drag is virtually undetectable, providing you have used oil on the mating surface during assembly.
With the crankshaft installed, Luis could install the piston and connecting rod assemblies in the block. Luis had numbered the top of the pistons so that he could rapidly install them without fear of putting a piston in the wrong cylinder bore. On some piston sets there is a front and back to the piston, so it is imperative that the pistons be installed according to the manufacturer’s instructions. We are using flattop pistons with two valve reliefs so there’s not much to worry about, but pistons that have domes and valve reliefs with a forward mark on the piston tops can get a little more complicated.
Some small block Chevy motors from the ’60s had offset connecting rod pins, which can cause considerable damage if they are not installed in the proper bank. Our pistons went in with no difficulty at all, so we progressed to the next stage of the engine build after making sure that the rod bolts were all torqued to 45 foot pounds (the recommended torque value for 3/8″ bolts).
Next it was time to install the brain of the engine. COMP Cams hooked us up with a great camshaft for our engine combination. This service is offered to everyone free of charge, simply by calling their technical service line. You’ll have to pay for the camshaft, but the technical expertise and advice is free. The price was right, so we took advantage of getting the right cam for our engine and application by talking to the technical service professionals for 30 minutes at a time.
Installing the camshaft requires a little finesse so that the cam bearings aren’t galled when the cam is inserted into the block. Luis Torres advises mounting the camshaft sprocket on the cam before attempting to slide the cam into the bearings – this gives the installer a better grip on the front of the cam for ease of installation.
COMP includes a very good lubricant with their cams, and it is important to use it – a lot of it. The greatest danger that a camshaft will see in its life is the first five minutes of run time on a rebuild. While lubricating the journals is important, the lobes of the camshaft need to covered thoroughly.
When the camshaft is fully inserted into the block, it’s a good time to check the clearance of the camshaft and timing cover. It’s always a good idea to check clearance between the face of the sprocket and the timing cover – use a cam button if needed. We decided to set the cam timing at zero by using the timing marks on the timing chain sprockets.
Timing the Cam
Chevy engines use a “dot on dot” timing mark alignment system, and this works well for street stock engines. If you want your camshaft timing to be perfect, then you will want to follow the degreeing instructions with your cam. Degreeing a cam ensures that the valve operating events are precise, thereby taking advantage of all the technology that went into making the camshaft and the selection thereof. Using COMP Cams recommended “intake centerline” timing method requires the cylinder heads to be installed, and becuase we were working with a short block, we just checked that the piston was at TDC and installed the timing set with the dot to dot marks lined up.
We starting by bringing the #1 piston to absolute top dead center, and double checking that the timing set was installed and the camshaft sprocket lined up with the crankshaft sprocket mark. We installed our degree wheel on the crankshaft snout. Using a piece of wire (or in our case a welding rod), a timing pointer was manufactured that pointed to the 0 degree mark on the degree wheel. Using a dial indicator mounted on a magnetic base, we put the dial indicator’s measuring point on the top of the piston and rotated the crankshaft in both directions until the highest point of the piston was determined. This is absolute top dead center. We adjusted our degree wheel and pointer to reflect zero degree or top dead center, and from there, we checked the timing sprocket alignment marks to ensure that they were aligned.
Finishing the Short Block
We wrapped up the short block build by tightening the cam sprocket bolts to 20 foot pounds, making sure that we used thread locker. Joe Torres installed the Melling oil pump with an ARP oil pump stud and torqued it to 65 foot pounds. The timing chain cover was installed with liberal use of
silicone sealant, tightening the bolts down to 9 foot pounds. Use caution here, because too much torque will strip these small bolts. With the front cover on, the block was rotated upside down on the engine stand and the oil pan was installed. Follow the instructions that came with the gasket set when installing the gasket. There are usually a couple of areas where extra silicone sealant is called for. We could finally install our harmonic balancer. Luis was pretty insistent that “you should never, ever, use a hammer and beat your balancer into place.” He claims that the only way to install the balancer correctly is to use a harmonic balancer installation tool, which will draw the balancer into position without damaging the face of the balancer or the snout of the crankshaft.
With that, our short block was ready to haul back to the OneDirt shop for compete assembly and installation in Madd Maxx. We were feeling pretty good about our drivetrain, as well as our chances for the rest of the racing season. Armed with the knowledge that we were well within the rules for our class, we set our sites on July and the next Street Stock race.
Our Top Ten Street Stock Engine Building Tips:
1 – Do your homework
Look up the casting numbers and any engine assembly and suffix codes cast into the block. These codes can give you a great deal of information when you decode them. For example, on small block Chevy 350’s you may see 010 and 020 on the face of the engine block behind the timing chain cover. These numbers indicate that the block was made with one percent extra tin and two percent extra nickel. These blocks are highly desirable because the added constituents in the molten metal not only make it pour better into the casting mold, but make the cylinder barrels more durable and harder. Don’t overlook any casting code!
2 – Get rid of the crud
Use a stiff bristled brush to remove all of the cast iron particles, dust and grit from every passageway. Pay attention to oil galleries, oil pressure sender hole and the main bearing oil drillings. The area where the fuel pump pushrod hole is located collects particles as well, so don’t forget these often overlooked areas. The time you spend cleaning the passages will pay off in longer engine bearing life. Grit left from the machining process will kill a soft aluminum bearing quickly.
3 – Choose the right fastener and fasten it correctly
Cylinder head studs work very well in supercharged or turbo applications and when extreme service is required. Cylinder head studs ensure even gasket crush and proper sealing in higher compression engines. Engines in a street stock class are unlikely to approach the area where the integrity of the gasket is threatened, but improperly torqued bolts can lead to a blown head gasket.
Whether you choose to use head studs or head bolts, it is important to use the proper torquing technique. Never, ever, under any circumstance, tighten a dry bolt into your engine block. The friction of the threads turning on each other will be greatly increased, causing improper torque values. The amount of effort to turn a nut on a bolt, or to turn a bolt into a threaded blind hole, is called tare torque. Without some kind of lubrication, the effort to turn a fastener is inherently much higher.
Aviation mechanics are required to measure the “nut friction” or tare torque of a fastener not under a load as it is being tightened, and add that friction value to the desired torque value to represent a more accurate final torque value. Fortunately we don’t have to go to that extreme in stock applications. Using the proper lube on the fastener is all that is required. Use the list below as a guide:
Main Cap bolts and Connecting Rod bolts
Use Oil or Molylube cylinder head bolts and rocker arm screw-in studs. Use silicone sealant camshaft sprocket bolts, intake manifold bolts, flywheel / flexplate bolts and front damper bolt. Use oil exhaust manifold. Use anti-seize
4 – Coatings
Another area where technology has dramatically advanced is in coatings of internal engine parts. For street stock engine applications, there are a couple of areas where we can use these high tech coatings to our advantage. There’s been a lot of discussion about power gains from these coatings (which seem to be marginal), but the durability, heat reduction, ability to shed oil quickly, and longer part life associated with these coatings is well documented.
Using dry film lubricant on valve stems has shown less wear and less chance of seizing or galling in the guides. Bearings that have high tech coatings have shown the ability to withstand wear issues caused by oil pressure drop when the oil becomes aerated. Piston skirts that have been coated can significantly reduce friction and wear on the piston skirts. Many manufacturers have already incorporated high tech coatings as part of the finishing process, and it is well worth your time to investigate and purchase internal engine components that already have these coatings applied. Take advantage of this technology and your engine will live longer.
5 – Piston Rings
Look for pistons that have ring groove widths of 1/16″ on the top and second ring groove and the oil ring width of 3/16″. The stock GM cast piston ring groove widths are cut at a wider width, which increases friction. The smaller ring widths and low tension rings are generally considered high performance ring sets. Regardless of the kind of ring set that you use, getting the right gap is important, as there is power to be gained by doing so. If the end of the rings butt up against each other when thermal expansion occurs, the ends of the rings press against and score the cylinder walls. Needless to say, power drops off dramatically. Another option to consider is Total Seal rings like we used in our build.
6 – Oil Pump Drive Shaft
The stock SBC oil pump drive shaft utilizes a plastic coupler to hold the drive shaft to the oil pump. Aftermarket oil pump driveshafts use a metal coupler, which is a much stronger and more dependable piece. For circle track engine builders, the metal coupler on the oil pump drive is the only way to go – especially if you are using a high volume oil pump. However, be careful when ordering the oil pump driveshaft for an SBC 400. The 400 cubic inch small block uses an oil pump driveshaft that is milled down in the center section, to clear the wider main caps on the 400.
7 – Oil Pan Capacity
Don’t cheat yourself on lubrication! A good supply of oil to the engine is far more important than anything else associated with the operation of the powerplant. Stock small block Chevy engines come with a five quart pan, which is fine for street use but may not cut it on the track. A good seven quart oil pan with baffles and a side kick out sump for circle track racing is a necessity if you want your engine to perform well race after race. A larger oil supply will help minimize issues like aeration and pump cavitation when the car corners hard.
8 – Find a Good Machine Shop
This can be easier said than done. Finding a good machine shop is like discovering a gold mine, and sometimes it’s a matter of trial and error. However, there are some things that you can look for that will give you an indication of the caliber of the shop.
Cleanliness is a big factor. Dirt is an engine’s worst enemy, and if the machine shop is not well organized and not clean, how do you think the inside of your engine is going to look when they are finished assembling it? Finding a clean shop that has good lighting and is well organized is a step in the right direction.
Beyond that, it is a “gut feeling” situation. Inquire about the experience of the operators, but be advised that a response from the operator is likely to be like a resume – some areas may be exaggerated. Let the buyer beware.