We’ve been kind of quiet lately on the progress of Project Track Attack, and that’s because of a couple of reasons. We’ve gone about as far as we could go suspension-wise with our Control Freak Suspensions coilover upgrade, as well as our Master Power Brakes upgrades. With the Silver Sport Transmisisons A41, QA1 carbon-fiber driveshaft, and Moser Engineering rearend upgrades to the drivetrain, we had all of the components in place for the next transformation: the engine build.
The plan from the start — way back in 2012 when we made our first upgrade and introduced Project Track Attack a few months later — was to build the car up to handle more power at some point down the road. Too often, a car is acquired and the engine gets replaced with something more powerful, then the rest of the components begin to suffer the consequences. We went the other direction and built up the rest of the car, primarily because the old Poly 318 was a fairly fresh build — and it served us very well.
Small-Block Top End Build
It was time for something new, however, and we brought you Part 1 last fall to introduce the new LA 408ci stroker build. We got the short block dialed in with a rotating assembly from Scat Crankshafts and buttoned it down with ARP fasteners. Because we’re doing things a little different for this build, we ran into a few issues and had to do some re-thinking before we could finish the top end. So we reached out to Edelbrock, Comp Cams, and Cometic gaskets to put it all together.
Again, like we did with Part 1, instead of just telling you how the engine was bolted together, we’re taking another approach at how to choose the right components, what some of the terminology means, and why some choices are better than others. There are literally hundreds of videos and articles with all the details an experienced builder wants to know, like valve sizes, cam profiles, and deck height. But, if you’re setting out to have your first engine built there are some basics you need to know, and that is our approach. Remember: don’t let experienced builders intimidate you about your build — because at one point in their life, they had the same questions you do, and had to be taught. Nobody is born with the knowledge necessary to build a performance engine — it is all learned.
Our first choice for cylinder heads went to the Edelbrock Magnum head (Part #61775) for a few reasons. The OE Magnum engines were a boost up in power. Although the LA head to the Magnum block (why would you do that?) is not the best decision, the Magnum head swaps over to the LA without any issues other than delivering oil through the lifters/pushrods.
The Magnum heads just flow better, they have more bolts to secure the valve covers — meaning less seepage. And, Edelbrock’s Magnum heads will accept the Chevy small-block 1.6 rockers on a 3/8-inch stud mount — meaning a lower price-point on rocker arms. We all know Mopar pretty much tops it out in price when it comes to the Big Three and building engines.
With this choice in cylinder heads, it left us with a few head scratchers when it came to choosing the right components. Mixing and matching like this — LA block and Magnum heads — is nothing new. But somehow, we felt like we were entering unchartered territory at times. The first thing we needed to do, once we selected our cylinder heads, was to get our cam, lifters, and rocker arms ordered.
While building a standard LA small-block, it’s very straight forward: order everything for the LA. But this can be a problem if you’re not clear with what you’re doing, or what you intend to end up with. For that, we reached out to our friends at COMP Cams and gave them the cylinder-head specs, our goals with regards to the final build and horsepower, and we let the team at COMP work their magic.
Choices When Selecting A Camshaft
In many scenarios, you visit a website and choose ‘camshafts’ and you’re greeted with choices: Hydraulic Flat, Hydraulic Roller, Mechanical Flat, and Mechanical Roller. We asked COMP’s David McCarver how cam selection is best chosen, and he said, “I generally like to know what the application is first, then we can determine which style of cam is best suited. Money, at times, can and will play a part in determining the type of cam selected.”
It does stand to reason that when you’re building an engine you want to install the best parts, and sometimes it comes at a premium. Budget, however, can also be a huge factor, so if you’re doing a budget-build they will need to know where your limits are. But, if you’re intentions are to build a stout engine with better components, you might find “budget-friendly” and “high-performance” are on opposite branches of the decision tree.
David told us, “A hydraulic roller cam is typically the better choice for a performance build. Since every car manufacturer today utilizes hydraulic roller engines, and with the changes in the way engine oil is manufactured, break in time is reduced significantly.” With a hydraulic roller, this reduction in break-in time means no more starting up the car and letting it run at 2,000 – 2,500 rpm for 20 – 25 minutes, like we did with our flat tappet build on the Poly 318. For this build, using a good break-in oil is all that’s needed.
If you don’t break in a flat tappet camshaft properly, you just might see your build go up in smoke. “What this does is allows the crank to throw oil onto the camshaft to keep it lubricated while breaking in the cam,” David said. “If you do not keep the rpm up, the cam will not get enough oil to stay lubricated, which can and will end badly.”
Some of the common technology/terminology about camshafts:
- Overlap: The amount of time between when the exhaust valve closes and the intake valve opens.
- Centerline: The angle between intake and exhaust lobes highest points.
- Duration: How long the valve is off its seat in crankshaft degrees.
- Nose: The smallest portion of the camshaft lobe.
- Heel: The largest portion of the camshaft lobe.
- Opening/Closing Ramp: The part of the cam when the valve begins to open or starts to close.
Though experienced builders are typically aware of what they seek in a cam profile, there are differences between profiles that can greatly affect how your engine will run. Unless you’ve used a particular profile before that resulted in the performance you expected, it’s always best to let the professionals make the decision on cam profiles. Don’t listen to the guy in the garage boasting about his cam and then try to order the same cam — unless you’re building the same engine. It will matter whether you’re running high compression or low compression, and whether you’re running boost — even then, it matters whether it’s supercharging or turbocharging.
Because we’re running hydraulic roller lifters, we asked about prepping them. We’ve heard a few variations, but David suggested the lifters be cleaned and then soaked in a bucket of oil overnight, completely submerging them. He said, “You want to make sure all components are fully lubricated. Do not take lifters out of box and put them straight in the engine.”
Chevy Rocker Arms On A Mopar
Our Edelbrock Magnum heads are set up with a stud mount instead of the typical shaft mount found on the LA cylinder heads. The shaft mount can provide more stability, but it also comes at a higher cost. You don’t always have a choice in this matter, either. Our Edelbrock heads are 3/8-inch stud mount, based on a 1.6 ratio Chevy roller rocker arm (COMP Part #1602-16). That’s a little higher lift than the LA’s 1.5 ratio, and plays a part in cam selection, too.
Choosing a cam based on a lower rocker-arm ratio could create more lift than the combination is good for. Smitty Smith, at Edelbrock, said, “Your cam is trying to push your lifters beyond the specs of the rocker arms, and that’s when things start breaking.” So you do need to make sure the person building your cam profile is aware of the cylinder head specs as well as the rocker-arm ratio.
Since we decided to mix things up, that meant we didn’t exactly have a valid part number for the pushrods. For starters, the Magnum rockers get oil through the pushrods, so a Magnum head on the LA block (like we have), requires the Magnum’s oil-through pushrods. If a standard pushrod is used, then oil cannot be delivered to the rockers properly, ending in premature failure. We had the heads assembled, and a set of pushrods were ordered from our measurements, and then they were installed. Again, it’s nothing new, but this is part of the process and will be custom per your build, not chosen from a parts catalog.
Just like a flat tappet-style rocker, roller rockers need maintenance as well, but it does depend on the application. David said, “There will always be some maintenance to rocker arms. On a race engine, whether drag or circle track, while checking lash you should notice if anything is off. When an engine is being freshened, you should thoroughly inspect the rockers to make sure the trunnions and roller tips are moving freely.” Occasionally, you’ll want to look over the entire rocker for any signs of wear.
Setting up the rockers, you want to make sure they are centered over the valve stem, don’t assume that a roller rocker corrects itself or that it won’t matter. You can still get some wear if things move on you or if the alignment is off. This is one reason why having a professional build your first engine is going to save you from costly mistakes. This doesn’t imply you can’t try to build your own, but like anything, having someone with experience looking over your shoulder is a wise decision.
We never want to discourage anyone from building their own engine, but missing out on a few important steps can cause problems. As Smitty said, “That’s when things start breaking.” We were careful to make sure all of those involved were aware of every facet of our build, from horsepower goals to the type of driving we’re doing with the car, as it all matters.
Along the way, we learned of a few trick parts to help make this build a little more stout and able to handle our lofty horsepower goals, which we feel should be in the 700- to 800-horsepower range. We do still have some surprises up our proverbial sleeves, but before we get to that part of the build we wanted to discuss a few of the special components we used in this build. We’ll share those in our next article coming up: Things that you don’t see.
As always, we relied on the pros to get us the right parts and learned a little bit along the way about the different choices available and what is best for our build. Be sure to reach out to COMP Cams for your next build for your valvetrain, and for cylinder heads you have plenty of choices for Bow Ties and Blue Ovals, but Edelbrock’s Magnum heads were our choice for this Mopar Stroker. Putting it all together, Cometic gaskets and nothing but ARP fasteners will do the job for us.