DOIN' THE TWEAK

If a person were to buy a factory machine that turned 10 second ETs and could cruise at 200 MPH all day long, I would venture to say they would STILL try to tweak it to squeeze that little bit extra out if it! Call it what you will, Crazy, Obsessive, Greedy or Stupid, we Motorheads simply cannot resist. Like the challenge in the Lay's Potato Chip commercial of the 70's,
"Betcha' Can't Eat Just One!"
Some things are more powerful than life itself, the urge to tweak is one of 'em!

There is a problem with that though, and as anyone who's ever tweaked their engine well knows, the line between "Tweakin'" and "Modifyin'" gets kinda fuzzy. I mean, just where is that point where one transforms into the other?! I have read many articles, through the years, where the author starts out talking about how they are going to "Super Tune" the featured car to squeeze a little more power out of it. By the time you get halfway through the article, they have swapped heads and are busy replacing the pistons with 12.5 to 1 TRW forgings, hardly what I would consider a tweak though many would disagree with me! If you want to have a little fun testing this theory, try listening in on some of the conversations going on at the next cruise or car show you attend. Better yet, get the fun started yourself. After the initial "Nice Car" compliment, ask the owner if his engine is stock, then get out your "Motorhead's Translation Booklet" because unless you are really experienced in the lingo, you might completely misunderstand what's being said. Here is what that conversation might sound like....
complete with translations!

"Nice Car!!"..."Thanks"
Translation: "Dang!!! This car is perfect!!! Can I have it???"..."After all that work & money it BETTER look nice!!"

"What size engine??"..."It's a 455!"
Translation: "Hmmmm, looks like a chromed up 289!"..."Whatta ya think Pal, it ain't no chromed up 289!"

NOW comes the million dollar question!

"Is it stock??"..."Yeah, mostly, though it has been tweaked."
Translation: "How built is it??"....."Yep, it still has spark plugs, just like the day it rolled off the line!!"

Ok, so that is a bit of a stretch and done mostly to poke a little fun at ourselves BUT, it is true that tweaking and modifying are two different animals. The purist would say that when you take what is already there and make adjustments or changes that allow you to squeeze out more power, it's been tweaked. On the other hand, if you take what's there and replace it with parts that were never on that engine to begin with, you've modified. I think though, the reality of it is we need to break things down a bit further and say that any mod that does not require pulling the engine or the removal of major engine components, could still be considered a tweak. Keeping that philosophy in mind, let's get into tweaking the Super Duty!

MAKING LIFE EASY

That's exactly what the boys at PMD did for us performance lovers where the SD was concerned, made life easy. I made mention of it in some of my earlier writings but it bears repeating here. The Super Duty 455 was designed and built as an all out racing engine, then was detuned to appease the Feds at the EPA. But the detuning appears to have been done very methodically which makes it a tweaker's dream! In the words of C.J. Baker in an article he wrote for "Hot Rod Magazine" back in October of 1972, "The result is an outstanding street performer that is embarrassingly easy to restore to a high-performance configuration." To demonstrate this, let's look at the cam selection process. The SD was designed with a camshaft that had a profile very similar to the Ram Air IV stick, which was too hot for the EPA. In response, the engineers profiled a new cam in such a way that simply changing the rocker arms would bring it right back to their original choice. No need to pull the engine or the cam, simply remove the valve covers, swap out the 1.5 rockers with 1.65 pieces and you're back to optimum. Of course, letting more in requires the ability to let more out and back in 74, the recommended choice was a set of tuned 32" JR Headers. I actually bought a set in 75 and found that the collector flange fell right at the perfect spot on the exhaust pipes to simply hacksaw, flange, add some dumps and bolt together. Coincidence perhaps, but I would have to say not. I never did use those headers because I didn't want to butcher up my original system and replacement pipes were already no longer available from the dealership, but the fact remains, with just those two simple changes, around 120 horses were put back where they belonged, gained mostly from the exhaust relief.

Needless to say, this drew the attention of the high performance magazines of the day with many writing articles on super tuning the Super Duty. I have to say however, most got carried away going well beyond tweaking. In fact, some actually got into sawing the heads in half and making "Silastic Molds" of the passages. This is not something I'd be able to do in my garage on a Saturday night trying to squeeze out a few more ponies hoping to edge out some guy in a grudge match. Luckily there was one article, again, written by CJ Baker for "Hot Rod Magazine" in June of 73, that hit the mark. This is the real stuff that us Backyard Motorheads can run with and the sort of tweaks that the SD engine loves!!!

PUT AWAY YOUR SILASTIC MOLD MACHINE
YOU WON'T BE NEEDING IT HERE!

The goal of the article was to show how little was needed to squeeze a few extra horses out of an already powerful engine,
not to take a stock mid-13 second car & turn it into an 11 second bullet.
In order to do this, they started at the top..Carburation!

In keeping with the engineer's plans of an easy return to power, the Super Duty already wore an 850 CFM crown in the form of a Rochester Quadrajet carb. Since it already had great flow, it was simply a matter of optimizing what was already there by replacing the secondary metering rods with something a bit richer. The rods of choice were coded "CK" and in those days, were readily available. Anyone who's ever played with a Q-Jet would know how quick and easy it is to replace these rods! After doing that, the author made sure all the carb screws, bolts and vacuum fittings were tight then proceeded to disconnect and plug the vacuum advance hoses to the distributor. In the days when I was running the streets, I went one step further and removed the secondary delay valve which brought my back barrels in much sooner. With the fuel tweaks in place,
the next step was to heat up & speed up the spark.

Plugs are such an easy thing to replace (especially in a 4 speed Non-A/C car) but what works good for a night of racing VS what's right for everyday driving are two different animals. Going for a "Colder" plug was the choice and a set of AC 438TS racing plugs, set at .035", replaced the stock units. Working backwards from there, it was time to make the spark come sooner. In order to please the EPA, full spark advance did not occur until the engine was cranking out 5 grand!! Again, an easy thing to overcome with the installation of a simple spark advance curve kit. In this particular article, they chose to use the springs that gave full advance at 2400 RPM and though this was a hot set-up for the strip, I found it to be a bit much for a night of street racing. Instead, I held my full advance to somewhere between 3200 and 3400 RPM. This gave me the best of both worlds, civil in daily driving yet right there when I'd need it but best of all, there was no need to switch it back. I could leave it just like that for everyday use. All that was left to do engine wise, was free up the exhaust flow and this was done by simply cutting the pipes and installing four bolt flanges. These could be easily unbolted for runnin', then rebolted for behavin'! With all that done they popped out the scoop block off plate, reinstalled the shaker assembly and headed into the next phase of tweakin'!

SD PILOT, THIS IS THE CONTROL TOWER....
GET THAT BABY ON THE GROUND!!

One of the Super Duty's greatest characteristics is actually the one that steals the most horses from it.......
That bone jarring, pavement punishing burnout it does SO well!
Dump the clutch at 4 grand and you are in for a thrill as the hood scoop slams to the right!! You can literally see and feel the body flexing and twisting as if she wants to rip herself in half while the energy plows it's way throughout the car!! The smell of clutch and rubber fill the air as your blood quickly gets replaced with adrenaline! But for all the power and torque being thrown around, in spite of the outright lie your speedometer is telling you, man and machine have actually not progressed forward much at all. What we have here is a failure to "Hook-Up" and in that, there is a lot of room for tweaking. I might add, not just mechanical tweaking, but technique too. In any event, putting the power to the ground
is the next step in the super tuning process.

To put it in as simple terms as possible, the engine produces power and sends it to the ends of the crankshaft. At the front of the engine, the power is used to run accessories such as an alternator or A/C compressor while at the rear of your mill, the power is used to move the vehicle. But the jump from crankshaft to concrete is a big one filled with obstacles and as any tweaker knows, the more roadblocks you can remove, the better the performance will be! In this case, the author of the article drove head first into the automatic tranny.

Realizing that the 5000 RPM shift points were barely scratching the SD's seven grand potential, the easiest thing to do was bump those shift points up a tad. They accomplished this by removing the governor (four bolts and a cover) and filing just a 1/16 of an inch off of the inner weights. This gave a very conservative 5500 RPM shift point and definately helped to squeeze a bit more out of the drivetrain without a major reconstruction. Sure, much more could have been done to the tranny, but they'd have fallen into that trap of going too far. I think this kept the article on track with it's stated goal!

GET A GRIP ON IT

The last step in this process was to get some rubber on the back that could take advantage of the SD's torque. As I found out my first time on the strip, coming out of the hole Todd style at 4500 RPM on the stock street radials, gave me one heck of a burn out, but spun me almost backwards! The poor guy running his Corvette in the next lane over was filling his shorts as my rear bumper approached his door, it was not a pretty sight. As was pointed out in the Hot Rod article, as well as Car and Driver's original road test, almost 59% of the Super Duty Trans Am's 3900 pounds is over the front tires. Because of that, doing all you can to gain traction is a must. Hot Rod chose a set of M&H tires with an 11 inch tread width. In order to make them fit, they did a little hammer work on the inner fenders, something I would not be willing to do. I think going with a 10" slick should give you plenty of stick'em without the backyard body work. I don't remember what size slicks I used years ago, but I do know they fit just fine and helped out a lot. Either way, the T/A featured in the article was down to 13.15@106.83 from it's stock 13.54@104.29. That's actually a fairly significant gain for the little that was done. Swapping out the stock 3.42 axle for a 3.73 or 3.90 gear would have put this car into the 12's for sure.
That's tweakin' at it's finest and makes for a hard car to beat on a Saturday night!!

GET OUT THE OIL BABY

One final note and I was hesitant to write it here because it involves something extremely critical to any engine's health, the oil!! Before getting into the subject, please keep in mind that this is something you do at your own risk since it's not PMD recommended. Over and over, in just about all the Super Duty articles written through the years, reference is made to the fact that the SD was built with provisions for a dry sump oiling system. Most of the writers call it "nifty" or "neat" but it's really much more than that. It offers so many benefits that I have been tempted to install one on my engine and may do that yet! Beyond giving the ultimate in oil control, I'm considering it because it's been estimated that a dry sump system could add up to 40 horses to your engine, that's a LOT of power to be gained. Even more incredible is the fact that by draining out one quart of the six the SD system carries, you can gain 25 horses along with 27 more pounds of torque. I'm sure many of you are saying "NO WAY", but it was dyno tested and proven in an article written by Marian Davis for Hot Rod Magazine back in September of 1989 titled "Super Tuning The Super Duty". The subject of the write up was the Super Duty engine that was in Don Kennedy's record holder NHRA SS/GT Firebird. This "Horsepower Jackpot" was discovered while dyno tuning his 10.10 second, Super Duty powered third generation F-Body and I've used this little secret to my advantage for years. I've found one quart low poses no problem for me as long as I keep a close watch on the oil level.

It's also time to add a closing to this page, Although I've covered some fairly specific details as they relate to the Super Duty, Tweaking is a never ending process that applies to ALL machinery!!
If you've never tried your hand at it, perhaps it's time to go for it, BUT be forwarned,
the Potato Chip Guy was right...You Can't Eat Just One!!!!

CLICK ON MY CAR TO GO

TO THE NAVIGATION PAGE