VOLUME XIII,  ISSUE 3 - JULY- AUGUST,  2018

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Tech Stuff

Updating a Drag Car for a Faster Elapsed Time

 

Words and photos by Chris Holley

With recent upgrades to the author’s 1969 Dodge Dart, the stage has been set to implement the necessary updates for the quicker quarter-mile elapsed times (ET) the Dart will soon eclipse. Dropping into the 10-second zone requires several updates to the car to be compliant with the National Hot Rod Association (NHRA), the International Hot Rod Association (IHRA), and, in some cases, local track rules. The best way to determine what is required, based upon your ET, is to refer to the sanctioning body’s rule book. The rule books usually can be found with a few clicks of the keyboard while searching the internet. In the rule book, there are detailed break downs of the required safety equipment and allowed components for a vehicle based upon the class and by the vehicle’s ET.

 

The Dart only needed two updates to be 10-second compliant. We will cover what should be a relatively painless installation of a locking dipstick and header tethers that will satisfy the NHRA/IHRA requirements, but before we get into the latest upgrades to the Dart, let’s go back in time to March 17, 2002, when the Dart and the author made our debut on the now defunct eighth-mile Southeastern International Dragway in Dallas, Georgia.

 

After purchasing the Dart in the summer of 1989, the Dart was sporadically driven on the street while I completed my various college degrees. In 1999, I finally got serious about setting the Dart up to be a dedicated race car. Little did I know it would take almost three more years to get the Dart to the track.

 

On that eventful early spring day in 2002, the Dart was finally ready to run. The Edelbrock aluminum headed 340 sported just under an 11:1 compression ratio, a Direct Connection Purple camshaft with a .557” lift, an 830 cfm Holley carb, and a stock bottom end. A reverse manual Cheetah valve body shifted the 904 Torqueflite that passed the torque to a 4.88 geared 8 ¾” rear end. To meet the safety requirements that I expected the Dart to run (in the 11.50-13.99 quarter-mile ET or 7.35-8.59 eighth-mile ET ranges), the Dart met the minimum NHRA safety requirements. Those necessities included a liquid overflow reservoir to contain the radiator overflow, at least one operating taillight (both operated), the transmission had a reverse lockout to prevent reverse engagement by mistake, a driveshaft loop had been installed meeting the 2:4 regulation due to the use of rear slicks, a Snell approved helmet was purchased, and I had a valid driver’s license.

 

While preparing the Dart, several additional safety requirements were added to the Dart that met a quicker ET range than the Dart was expected to run. With the anticipation of eventually adding a spool to the rear end, Moser aftermarket rear axles were installed in compliance with regulation 2:11, and extended length studs were added to comply with regulation 5.2. Without the addition of a spool, aftermarket axles were not required until a 10.99 ET. An SFI 18.1 approved harmonic balancer was installed on the 340 even though it was not required until the 10.99 ET. To meet regulation 8.4, a properly labeled (On-Off or Push-Pull) master cut off switch had been added to the rear of the Dart because the battery had been relocated to the trunk. Lastly, SFI 16.1 five-point seat belts and an SFI 3.2A/15 fire retardant jacket ensured my safety in the event of a serious problem even though the factory seat belts in conjunction with full length pants and a t-shirt were acceptable for the ET expectations of the Dart.

 

After all the preparation, how did the Dart do in the eighth-mile? The Dart laid down a rather flat 8.195 ET at 83.60 mph with a 1.794-second 60-foot time. After some tuning in the pits, the day’s best ET had dropped to an 8.117 at 84.59 mph. Over the next few weeks and with better tuning, the elapsed times continued to drop, and within three weeks, the 7-second barrier was broken. Advancing the camshaft, constant ignition timing adjustments, and refined launch technique had the Dart running in the 7.60s in less than three months from the initial run. The installation of a PTC torque converter and an SFI 29.1 flexplate dropped the Dart’s ETs into the 7.40s by the fall of 2002.

 

At the time, the roll bar requirements were an 11.99 ET NHRA (11.50 ET IHRA) or quicker in a quarter-mile run (7.50 NHRA or 7.35 IHRA for eighth-mile), and lacking a roll bar, I started adding weight to an approved weight box in the trunk. For the next year, I focused on improving my driving skills, and I added weight as necessary to keep the Dart’s ETs legal for the track upon which I was racing.

 

In the fall of 2003, I moved to central Pennsylvania as I had accepted a new teaching position at Pennsylvania College of Technology. I made certain I moved to an area with plenty of tracks within driving distance of my new home. The closest tracks were Numidia Dragway (NHRA) and Beaver Springs Dragway (IHRA). Further drives could reach South Mountain Dragway and Maple Grove Dragway. Cecil County Dragway, Island Dragway, Atco Dragway, and Skyview Dragway (opened in the mid-2000s) were hauls but were options as well. Having never driven the Dart on a quarter-mile track, there was an expectation of high 11-second runs based upon the eighth-mile times the Dart ran. The 4.88:1 gears were yanked out of the 8¾”, and a 4:10:1 set was installed in the housing. Tired of adding weight to the Dart to meet the roll bar rules in GA, Beaver Springs was the track that was selected due to the IHRA 11.50-second requirement for a roll bar compared to the, I felt, easily achievable NHRA requirement of a 11.99-second time.

 

The first day at Beaver Springs and my first ever run on a quarter-mile track resulted in a 12.098 ET at 111.84 mph. I had hoped for more, but it was a start. By the end of the day, the ET had dropped to a 12.005 at 111.85 mph. The plan to run at Beaver Springs Dragway looked like a good strategy because the Dart was already knocking on the 11-second zone, which at an NHRA track meant playing with weight again. Interestingly, after the first day at Beaver Springs there was a late-night thrash to figure out why the Dart seemed to be laying down in the back eighth of the track, and the next morning was the first points race at BSD. Off the trailer, things were better. The Dart clicked off an 11.739 ET at 113.90 mph. For the rest of 2004, the Dart ran in the 11.70s at BSD while at Numidia and Maple Grove the Dart was limited to 12 seconds flat. At Maple Grove, the Dart had to carry an additional 155 pounds to slow the Dart down, and even at the eighth-mile South Mountain Dragway, the Dart had to carry an additional 30-45 pounds to slow it to the 7.50 ET restriction. The weight game was played in 2004 and 2005 for all the NHRA tracks, while the Dart ran without any extra weight at the IHRA tracks.

 

To finally get around the requirements for all the additional weight, an 8-point roll bar was installed before the 2006 racing season. The roll bar would allow the Dart to be run to the 9.99-second ET range provided the firewall had not been altered or the mph did not exceed 135 mph. Finally, no more weight shuffling to slow the Dart down. After the roll bar was completed, NHRA dropped their quarter-mile roll bar requirements from 11.99 seconds to 11.50 seconds, but I had a bar in by then, so I was in good shape if I ever dropped below 11.49 seconds. The removal of the front bench seat and the back seat offset the weight addition of the installation of the roll bar and the single racing seat.

 

The Dart dipped into the low 11.50s at BSD, which were ETs usually only capable of being achieved at Maple Grove when the weight had not been added. The rigidity of the chassis due to the roll bar and the addition of Cal-trac bars and mono-leaf springs had dropped the 60-foot times into the low- to mid-1.50 range. The removal of the bench seats and the replacement of the heavy Super Stock springs with a lightweight race seat and the Cal-trac springs and bars dropped the Dart’s weight down to 2853 lbs. (without the driver).

 

From 2006 through 2015, the Dart was freshened as necessary, but the combination remained the same. With each successive engine rebuild, something new was added to the engine: lighter rods, lighter pistons, lower friction piston rings. The same camshaft that was installed in 1990 remained through all the rebuilds. Along the way, an A&A low band apply valve body for the 904 was installed. Better quality internals were also added to the transmission. To meet future safety requirements a transmission blanket, later replaced by an SFI 4.1 transmission (and bellhousing) shield was added even though the 10-second zone had not been breached. SFI 10.99-approved roll bar padding replaced the original roll bar padding.

 

After winning a pair of back-to-back BSD track championships, the focus slowly shifted from racing every weekend to racing special series events or just events I really enjoyed. This change in priorities corresponded with my increased freelance workload. One of the results of this increased freelance work was editorials that focused on track testing parts on the Dart, such as intake manifolds, carburetors, carburetor spacers, alternators, and front-end suspension components. The addition of an optimal manifold, carb spacer, and carburetor along with a looser drag racing-focused front end resulted in the Dart’s ETs dropping into the low 11-second range. The Dart ran a weather corrected 11.05 ET with eighth-mile times consistently in the 7.03-7.06 ET range at BSD, so at Maple Grove the Dart would be well into the 10-second zone if the atmospheric conditions were correct. Everything on the Dart would currently pass tech at any track for the 10.99 or faster ET, with the exception of needing a locking dipstick and header tethers.

 

The installation of the header tethers and locking dipstick and tube should have been one of the easiest tech editorials I have ever done, and with the header tethers it was. However, the dipstick tube was impossible. Let’s start with the header tethers.

 

While there are several NHRA/IHRA approved header tether kits that can be purchased from any of the volume retailers, the price range seemed fairly costly. The prices ranged from $99 to $220 depending upon what options were required and the manufacturer. Not wanting to pay that much, a search for the individual parts that would be necessary led us to Poorman Motorsports.

Instead of purchasing the parts in a kit, we priced the parts individually and found the overall cost was more affordable than a complete kit. We purchased two 14” tethers and four 3” diameter pipe clamps with T-bolts. All the header tether parts meet the NHRA/IHRA requirements as stated in the installation guide.

 

Online we ordered the NHRA-approved clamps and tether cables for a total of just over $50. We ordered four 3” clamps and two 10” tethers for our Hooker headers and collectors. The installation was straight forward. All that was necessary was sliding the clamp’s T-bolt through the loop of the tether, and then the clamp was loosely installed on the header. The other end of the tether loop was slipped over the T-bolt of another clamp, and the clamp was installed on the collector. With both clamps installed, the clamps were lined up with a little slack in the tether. Both clamps were torqued. The same procedure was performed on the other header, and this concluded the installation of the tethers. The installation took about 15 minutes.

 

Before attaching the header tethers to the Dart’s headers, one looped end of the tether cable was fitted over the clamp’s T-bolt, which was pushed through the trunnion and fastened with a nylon sleeved nut. The second tether cable and another clamp were set up in the same fashion for the other header on the Dart’s 340.

The clamp/tether assembly was installed on our Dynomax 3” bullet muffler. Once we had the clamp located were we wanted it, the tether cable was extended toward the front of the Dart, and the T-bolt’s nut was snugged down for now while the rest of the assembly occurred.

A second clamp was slipped onto the header collector before the flange. The looped end of the tether cable was slipped onto the clamp’s T-bolt, and the clamp was assembled.

With a little slack on the tether cable, the T-bolt nuts were tightened on each clamp. The torque value on the nuts was 60 in-lbs. There was no need to overtighten the T-bolts and nuts.

The passenger side tether cable was installed in the same fashion as the driver side. The necessity of the tether kit is to ensure a muffler (or bolt on header collector) does not become free if the fastener hardware loosened and was lost. The disconnected muffler could be run over by either competitor or fly into the bleachers, resulting in injuries or property damage to the racers or the onlookers.

 

The ease of installing the tethers gave us confidence that we would swiftly finish the dipstick and tube installation. We purchased the locking dipstick and tube from a well-known manufacturer of transmission components, and it quickly became apparent that the dipstick tube was not going to fit the 904 transmission.

We needed to have an NHRA approved locking transmission dipstick for the 904 Torqueflite. The locking transmission dipstick guarantees the dipstick will not be pushed up and out of the dipstick tube if the transmission fluid got hot and expanded up the dipstick tube.

The factory dipstick only had friction to hold it in place, and that would not meet the rules for 10.99 seconds or quicker, so after 49-years of service, the dipstick and tube would be replaced with an aftermarket locking dipstick and tube.

 

With the factory dipstick tube removed, the aftermarket tube would not clear the transmission and bellhousing shield. We fought with the aftermarket tube for over an hour, and we made several bends and dings to the tube, but we could not get the tube to fit into the transmission and line up with the transmission bell housing anchor bolt. We eventually gave up; the tube was not going to fit.

In the past, we drilled holes into the firewall to gain access to the aftermarket Allen bolts that secure the bellhousing of the transmission to the engine. Each Allen bolt is extra length to fasten the SFI approved bellhousing and transmission shield in place. These holes provide a quick and easy way to remove and install the bolts when an engine or transmission removal is required.

With the dipstick tube bolt removed, the factory dipstick and dipstick tube were pulled from the Torqueflite transmission. A small amount of transmission fluid will spill from the dipstick tube hole in the transmission, so have an oil catch pan available to minimize the cleanup.

The top dipstick and tube are the original parts that came with the Dart in 1969. The bottom dipstick and tube are from a reputable aftermarket manufacturer. At the top, there is the plug that fit into the access hole in the firewall and the bolt that secured the dipstick tube to the transmission bellhousing.

We installed the grommet that came with the new dipstick tube into the hole in the transmission. The new dipstick tube was a struggle to get into the grommet. The dipstick tube was longer, slightly larger in diameter, and bent in a different shape than the factory dipstick tube.

We could not get the transmission dipstick tube to fit. The lip between the firewall and the floor pan was flattened with a hammer and drift to try and gain access. We ended up bending the aftermarket transmission tube in several places to try and get the tube to fit properly.

After several hours attempting to install the aftermarket dipstick tube, we came up with another option. The factory dipstick tube was re-installed and secured, but we would modify the aftermarket locking dipstick to fit the factory dipstick tube.

To make the aftermarket dipstick the correct length (compared to the factory dipstick), we had to cut off about 2” from the aftermarket dipstick. We used a pneumatic cut-off wheel to trim and smooth the end of the dipstick.

 

We could not remove the bell housing shield, so what could we do? We ended up measuring the factory dipstick from the seal to the hash marks on the dipstick, and we transferred those measurements to the aftermarket dipstick. We used a scratch awl to make the marks on the aftermarket dipstick. After the measurements were transferred, we trimmed the longer aftermarket dipstick to a length that matched the factory dipstick. We reinstalled the factory dipstick tube and added transmission fluid. The 340 was started and the transmission was run through the gears as the engine and transmission came up to temperature. Once up to temp, the transmission selector was left in neutral, and we measured the fluid level with the factory dipstick. The fluid level was topped off and again checked with the factory dipstick. With the fluid level corrected, we installed the modified aftermarket dipstick. The level was checked on the dipstick to ensure the transferred marks on the dipstick indicated the fluid level was correct as the factory dipstick had indicated. The level was correct. We were in business, and now we had a compliant locking dipstick and tube.

This closeup shows the smoothed end of the aftermarket dipstick. The hashmark area on the factory dipstick was measured and then a matching area was scribed onto the aftermarket dipstick. The cutoff portion of the dipstick was discarded.

The aftermarket locking dipstick slid into the factory dipstick tube without any difficulty. The lock works perfectly with the factory tube. We passed tech without any sweat with the locking dipstick. With the newly installed locking dipstick and tethered mufflers, we are guaranteed to be legal at any track we attend.

 

That concludes the installation to certify the Dart is 10.99-second compliant for any sanctioning body. It has always been the contention to have the Dart exceed the ET safety requirements for the ET the Dart currently runs. As it turns out, this belief resulted in a minimal dollar and time investment to update the Dart for the 10.99-second barrier, and all of the years the Dart has been raced with the extra safety equipment has provided a safe and successful ride that I have been able to enjoy. For more information about the rules books, perform a search of the NHRA or the IHRA website to view the requirements for your ET range. 

 

-the Professor

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