Building A 500 Inch Mopar Wedge Engine - Wedged To The Max Part Two
We Install Our Engine And Head To The Track For Testing
From the April, 2006 issue of Mopar Muscle
By Dave Young
Photography by Dave Young
Well, our 500-inch Wedge looks impressive between the fenders of our '68 Cuda, but how will it run? We were shooting for some low-nine-second timeslips, so read on and find out if we achieved our goal.
In last month's "Wedged to the Max, Part one" article, we assembled the parts and built a 500ci race wedge to be installed in our '68 Barracuda drag car. We were shooting for some low-nine-second timeslips from our somewhat hefty A-Body and knew that it would take a well thought out combination to achieve our goal. Remember, the biggest limitation of this build is the stock, two-bolt main, 440 block. We toughened up the bottom end with a Chenoweth main girdle, but we're still going to limit our shift points to around 7,000 rpm and go through the traps in the quarter at around 7,300 rpm until we install the second feed line of our dual-line oil system. We plan to race this car nearly every weekend and plan to freshen the motor only once each season so our combination needs to be durable. we completed the engine build in last month's issue, but we were pressed for time to make Florida's winter bracket series so we planned to tune the motor where it would feel at home-the track. This is a somewhat old-school approach as engine dynos seem to be the way of the future, but in this issue we'll show how track tuning can be just as effective as dyno tuning and a lot more fun.
After final assembling and priming our long-block, it was time to drop our wedge into the engine bay. Once off the stand, we installed our SFI-approved flexplate and marked it to properly install the torque converter bolts. Remember the converter bolts only line up with the flexplate one way, so marking it with paint early will keep the trial and error down later. The center link of our car's steering system also needed to be removed to install the engine. This is a back-half car that still retains its stock suspension up front, so the only way to get a rear sump pan in is to have the steering link pass through it. Yes, this is a hassle when pulling the engine, but the advantage of a rear sump oil system in a drag car is well worth it. For exhaust, we're using Hooker's Super Competition fenderwell exit headers. The primary tubes of these headers are a little longer than we'd like, sacrificing some horsepower, but the only other option is to go to expensive custom-built units, and our budget won't allow that. The nice thing about the Hooker headers is the fit and finish are great. Even with Indy SR heads, which have raised exhaust ports, no modifications were required to install the headers.
With the long-block bolted to the transmission, and the motor plate mounted securely to the framerails, we had a couple of new items to fit into our engine bay. First, a Moroso crankcase vacuum pump and the associated hoses, hardware, and evacuation tank was installed. We mounted the pump on the driver-side motor plate, had our Indy valve covers welded up to eliminate the breathers, and had a dash 12 male AN-style fitting welded to the driver-side cover to feed our evacuation pump. The other side of the pump is routed to the evacuation tank, which we mounted to the driver-side inner fender. The evacuation pump kit comes with multiple V-belt pulleys that can be used to adjust the rpm that the pump turns; we will initially run ours at one-half crankshaft speed as the instructions with the kit suggest. We also installed Moroso's adjustable vacuum relief valve to regulate our crankcase to four inches of vacuum as a baseline. There are several advantages to running a vacuum pump on a motor like this, but the biggest advantage is it allows the use of low-tension compression rings. The crankcase vacuum helps seal the rings to the cylinder wall, freeing up horsepower through the reduced friction of the rings against the cylinder.
Dropping our 500-inch wedge...
Dropping our 500-inch wedge into our Barracuda is just the beginning of our project. A new Flex-A-Lite radiator and Moroso evacuation pump will be installed before firing it up at the shop for initial break-in. The real tuning will take place at the track where we will experiment with jetting and timing changes until we achieve our best elapsed time.
Moroso's crankcase evacuation...
Moroso's crankcase evacuation kit comes with everything necessary for installation except the drivebelt, which is a common V-belt available from any auto parts store. We'll take advantage of the ability to run lower tension compression rings when using the vacuum pump, sending a few more ponies to the rear wheels.
We mounted our pump to the...
We mounted our pump to the driver side of our vehicle's motor plate. Notice how our valve cover has been modified to incorporate a dash 12 AN-style fitting, which will be routed to the inlet side of the vacuum pump. The kit came with all of the brackets and hardware to complete the installation.
The evacuation tank is mounted...
The evacuation tank is mounted to the driverside inner fender. this will have to be drained occasionally, so leave enough room under the tank for something to catch its contents. The fit and finish of our Moroso pieces was top notch.
Next, we installed Flex-A-Lite's new aluminum radiator that incorporates versatile fins or heat sinks on the outside of the tanks. This revolutionary design not only helps the efficiency of the radiator, but the design of the heat sink fins gives infinite locations for mounting the radiator and accessories like cooling fans and transmission coolers that are normally located on or near the radiator. Remember, this is a bracket car, and we want consistent performance. Being the quickest car in a bracket race does give you a couple of advantages, but being consistent wins races. A quality radiator helps cool the car quicker between rounds, allowing for a consistent engine temperature even in the late rounds when there is not much cool-down time available. Consistent engine temperature is important for consistent elapsed times, a necessity in bracket racing.
Once everything was installed and double checked, we filled the fluids and fired the engine up for break-in. Since this is a roller cam motor we don't need to perform the normal twenty-minute cam break-in cycle, we just need to build some heat in the motor to seat the rings and check for leaks. Also, our Crane camshaft installation card specifies to set the valve lash when the engine is hot, so we'll accomplish that just after break-in. Our engine fired immediately, and we set the ignition timing to a baseline of 36-degrees total advance and set the idle mixture and idle speed on the carburetor. We still weren't sure how it would perform at the track, but this thing sure sounded healthy. Nothing gets our adrenalin pumping like the cackle of 500 inches of a 13-to-one compression big-block singing through open headers. Before we took it to the track, however, we had to finish our work at the shop. After tuning the carb, setting the timing, and allowing it to come to temperature, we gave the throttle a couple of whacks to make sure everything sounded ok and then shut it down to set valve lash and change the oil. We always drain the engine oil after break-in, taking a sample to look for any foreign material and cutting open the oil filter to check the element for excessive metal particles. All we found was a small amount of fine bronze dust, which is normal for a new bronze geared intermediate shaft breaking in on a billet roller camshaft, so we deemed the engine healthy and headed for the track.
Any professional racer will tell you the key to winning drag races is consistency. The same goes for tuning a car at the track. The data you collect by making passes down the drag strip means nothing unless the car is staged consistently, shifted consistently, and driven down the same lane accounting for changes in the weather as you test. Also, if the car isn't hooking up properly each pass, your data will be skewed, so any traction issues should be resolved prior to making tuning changes.
We decided to install a Flex-A-Lite...
We decided to install a Flex-A-Lite aluminum radiator in our Barracuda for a couple of reasons. First, for a given heat dissipation an aluminum radiator is lighter than conventional brass units. Second, this new design incorporates finned "heat sinks" on the outside of the tanks, adding to its ability to dissipate heat and providing infinite mounting locations for cooling system accessories.
These T-bolts fit into the...
These T-bolts fit into the radiator tank's heat sinks and can be used to mount the radiator in the car, as well as for mounting your cooling fan and transmission cooler. These eliminate the plastic retainers poked through the radiator core that we've never really liked.
With our engine and new accessories...
With our engine and new accessories installed, we fired her up for initial tuning and break-in. We really just need to bring the engine up to temperature and check for leaks and proper operation of the car's systems before taking it to the track. Our billet roller cam doesn't require the 20 minute or so break-in at elevated rpm that a flat tappet would, and modern rings are pretty much seated as soon as the engine comes to temperature the first time. We do change the oil and inspect the filter after initial break-in; ours looked ok, and we were off to the track.
For our testing we went to the Lakeland Drag Strip to make some shake-down passes. We're fortunate here in Florida to have several area drag strips at our disposal for racing and testing. every week a drag strip in the United States shuts down permanently, and only half as many new tracks open. If we don't support our local tracks we may eventually be forced to pay $750 a day for dyno time to tune our engines instead of the $12 it cost us to make as many passes as we wanted on a Thursday night at our local track. we encourage our readers to head to their local drag strip and have some fun. Believe it or not, drag racing, not sitting in a parking lot with lawn chairs, is what these cars were designed to do.
On our first pass down Lakeland's eighth-mile we wanted to seat the clutches and bands in our fresh transmission and make sure everything felt good and worked correctly, so we limited our right foot's travel to about one-third throttle. The resulting 6.90-second elapsed time had us encouraged that this combination had potential to achieve our goal of low nines in the quarter. With everything working correctly, we made a full throttle, just over half-track pass that resulted in a 6.26-second elapsed time and a stout 1.32-second wheelstanding 60 foot time. Back in the pits we pulled a spark plug and saw that it was nearly snow white, so a jetting change was in order. When jetting we step up or down in increments of two until we are close, then fine-tune by making jetting changes of one size at a time. With 92 jets in both primary and secondary metering blocks, we made our first full pass running a 6.04-second elapsed time at 114 mph. Technically, this equates to a 9.48-second quarter-mile, so we did reach our goal, but we knew we had more in it. By richening the jetting further, the car responded with quicker elapsed times and higher mph until stabilizing at an e.t. of 6.00 at 115.5 mph with 97 jets in both ends of our King Demon. We then bumped the ignition timing up four degrees to 40-degrees total advance and ran our quickest elapsed time of our test night at 5.98 seconds at 116.8 mph! This equates to a quarter-mile e.t. of 9.38 seconds, putting us solidly in the low nines. Always remember that weather changes will change the power your engine makes. Cooler temperatures and higher barometric pressure will improve the output of your engine; weather needs to be tracked and considered when tuning. Our weather stayed consistent throughout our test session, so we were sure our improvements were due to our tuning changes and not improving atmospheric conditions. Our test time was running out for the night, but we were comfortable our tune-up was now much closer than when we started, and reading the spark plugs verified that our mixture was now in the safe zone of enrichment, so we decided to call it a night.
Unless you have a provision...
Unless you have a provision for an oxygen sensor or other means to determine air/fuel ratio, taking plug readings prior to making jet changes is your best bet. After a half pass showed snow white plugs indicating our mixture was on the lean side, we installed number 92 jets front and rear to continue with our tuning.
It's important to note that...
It's important to note that since our application is drag racing only and will only see wide-open throttle operation, the power valve provisions of our King Demon carburetor have been blocked off as shown here. This will necessitate larger main jetting to give our engine the correct fuel/air ratio. For our baseline, we chose number 90 jets and will read the plugs and time slips to make adjustments.
Each time we richened the...
Each time we richened the mixture by increasing jet size, we saw an improvement in e.t. and mph. The e.t. on a timeslip tells how well the car is working, but the mph is a direct relation to horsepower, so we pay more attention to mph when jetting our carburetor. When we reached our performance plateau at number 97 jets, we stopped jetting and moved on to other areas of tuning.
Consistency is the name of...
Consistency is the name of the game in bracket racing and the same goes for the fuel used when tuning your car. We get our Rockett Brand 118-octane fuel by the drum, so we don't have to rely on what the track can supply. Remember that different brands of fuels, while having the same octane rating, have different percentages of lead, oxygen, and alcohol, which respond differently to jetting changes. By having our own independent supply of fuel we know we're using the same fuel we tuned our motor with, helping take the guesswork out of diagnosing fuel related issues if they occur. (Editor's Note: Notice the lack of long pants and use of sandals. Please do not try this at home, we are trained... something-or-other.)
With our jetting close, we...
With our jetting close, we bumped the ignition timing from our baseline of 36-degrees total advance to 40-degrees total advance, resulting in a gain of two-hundredths of a second and almost one mph. This engine definitely likes more ignition timing, and we will likely see further gains by experimenting in this area later. Remember, we found the timing tab on our timing cover to be some four degrees off true top dead center, so subtract four from our above numbers to attain our engine's true ignition timing.
Remember that we're limiting our rpm to 7,000 until we can install the second oil feed line to our oiling system, and our camshaft actually makes power up above 8,000 rpm. Once our oil system is complete, we will certainly shave some elapsed time by raising our shift points closer to 7,500 rpm. We will also add more ignition timing to the engine as it responded well to our first increase in timing. Our rule of thumb is to add ignition timing until no further increase in performance is seen, or until the engine begins running noticeably warmer (an indication of detonation) during a pass down the track. Our engine was happy and responded well to 40-degrees total advance, so we'll bump the timing again during our next test session. This may seem like a lot of ignition timing, but remember unless you have checked the tab on your timing cover for accuracy the numbers are somewhat ambiguous. We checked our tab during assembly when we were degreeing the camshaft and found it to be some four degrees off true top dead center, so our 40 degrees of advance is actually only 36 degrees. Optimum ignition timing varies widely from engine to engine and is dictated not only by compression and fuel octane, but by cylinder head and piston design, weight and gearing of the vehicle, and other variables. We always begin at around 36-degrees total advance on aluminum headed big-blocks and adjust to whatever makes the car run quickest without overheating.
So there you have it, our 500-inch wedge accomplished the goal we set of low-nines in our nearly 3,100-pound Barracuda. We will experiment later with more tuning and induction changes to try to improve our combination, but for now we're just going to race it. after our initial testing session we entered the Southern Nostalgia Nationals at Lakeland Motorsports Park and won our class both days of the two-day event! The following weekend we entered the Georgia Southern Bracket Nationals where we went several rounds each day among a field compiled of 90-percent dragsters (which in our opinion are purpose-built race vehicles, not cars) driven by the best bracket racers from around the country. The first race we'll enter at a quarter-mile strip is the Snowbird Nationals in Bradenton, Florida, and we'll keep you posted as to how we run at that event.
We shift our own gears in...
We shift our own gears in this car and use a tachometer that incorporates a shift light so we can be consistent. We only make one change at a time when tuning our cars so we know if the change we made actually helped or hurt. Missing a shift could skew the data on our time slip, so our driving technique has to be duplicated each pass down the track. Once we get the rest of our Milodon dual-line oil system installed, we'll bump our shift points up closer to 7,500 rpm to take advantage of our engine's top-end power.
Performing a consistent burnout...
Performing a consistent burnout is also important when testing or racing your car. We begin our burnout in second gear and shift to third as soon as the tires are spinning freely. Experience has taught us how long to perform the burnout in our car to get the tires sufficiently heated so they stick. Doing a simple count in our head proves to be the best way to time our burnouts so they are consistent. We also creep into the staging beams slowly and stage as shallow as possible so we know the car is in exactly the same place each time we launch. Deep staging can improve reaction time, but will slow the cars elapsed time because the car doesn't get the run on the track it does when shallow staged. Whatever technique you're comfortable with, just make sure you do it consistently so your timeslip accurately reflects the changes you make when tuning.
Traction is an issue anytime...
Traction is an issue anytime you're testing at the track. If the car spins your timeslip will reflect it by showing slower elapsed times. Most spinning occurs in the first 60 feet of the track, so the incremental times between 60 feet, 330 feet, 660 feet, 1,000 feet, and the traps can still be used to judge performance with some accuracy. As a measure against tire spin, we set our rear tire pressure with a couple of cars in front of us in staging so our tire pressure is consistent when we begin our burnout.