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jkopp
10-02-2004, 10:07 AM
1993 NEWSLETTER ARCHIVE



HOLLEY CARB JETTING

In my never-ending quest for proper engine tuning, I am now trying out two inexpensive ways of determining proper carb jets. Very few of us amateur racers can find the solo track time necessary to do the standard recommendation, which seems to be: run-at-full-throttle-then-kill-the-engine-drift-into-the-pits-and-check-the-spark-plugs (particularly when "checking" the spark plugs on a V-8 at skin-scalding hot temperatures is not my idea of "fun".


So, the first method I am trying is to watch the exhaust header temperatures at different RPM ranges. I have mounted a Fluke Model 52 Digital Thermometer on my dashboard, with T1 and T2 thermocouples in the exhaust headers (one on each side). The thermocouples are by Computech Systems, Inc. (301-870-8383) part# CSI-4000 . I have been told by my engine guru that I should get worried about temperatures in the 1450 range, and VERY worried over 1500 degrees (too lean).


My second method is to use the Haltech (214-494-3073) mixture sensor advertised in Sports Car magazine ($239 complete), which uses an oxygen sensor in your exhaust collector like an modern emissions-controlled engine. Instead of sending the voltage output to an ECM-brain box like modern cars do, the output is displayed as a series of 30 LED lights in front of you. So, in theory, you can read in "real-time" the actual rich/lean nature of your exhaust.


The verdict? I'll let you know. One thing for sure - I have been running far too lean up to now, and I had better fatten my jets before pistons and valves start burning!!


ROLLBAR PADDING

Don't forget that ButlerBuilt Motorsports Equipment (1-800-621-SEAT), in addition to making and selling some top quality racing seats, also sells new roll bar padding material that does not melt in a fire. Apparently, there were some circle track racers that were burned by the dripping plastic after their roll bar padding melted in a fire. Good safety item.


HOW TO CALCULATE YOUR ROAD SPEED


If you are like me, you can no longer use your car's speedometer because of: (a) it was never accurate anyway; (b) your tires are a different size now; (c) you have changed your rear end gears; or, (d) you now have a roll cage brace that goes between it and your eyes. So here is a mathematical solution: http://www.buffspeed.net/images/image002.gif




Example:


How fast am I going at 4000 RPM in 5th gear? Given: B.F.Goodrich 255/50-16 tires have 26.06 diameter.
Camaro has a 0.74 ratio 5th gear.
Rear end ratio for this example = 3.73.
Thus:
http://www.buffspeed.net/images/image004.gif




Likewise, for these ratios, 4500 RPM = 126.4 MPH and so on. You can also calculate your speeds in 4th gear at different RPM to learn how fast you are going in and out of the various corners at your favorite racetrack. Great fun.



SAFETY ALERT #1

At the last MARRS race, Bob Liguori had the unfortunate occurrence of losing a brake line off of his front brake caliper. I have just added this to my check-off list. Check this line and make sure it is tight. Replace the bolt with a new one if it has too many "removals and reinstalls".


SAFETY ALERT #2


Also at the last MARRS race, I found my motor to be backfiring during practice, and came in to the paddock area only to discover that two of the exhaust header nuts were GONE and the rest had vibrated loose! Be sure to check the tightness of these nuts at the end of EVERY track day. They are hard to tighten due to limited access, but believe me - it is harder to replace the gasket AND tighten them!


SAFETY ALERT #3


The front studs are replaced when you change brake rotors, but not the rears!! I have ALWAYS used a high-quality torque wrench on my lug nuts, and never an impact wrench. However, I just snapped off two of the right rear wheels studs during a routine tire change. The solution? Change the rear studs to new ones at least once a season, and carry spares! If you snap one off at the track without spares, you are ALL DONE for the weekend.


Mustang Wheel Bearings - (by Scott Griffith)


An issue has recently surfaced that should be of interest owners of late model Mustang AS cars.


Ford Motor Company made a running change to the front wheel bearings in all Mustangs at the beginning of the 1988 model year. Earlier cars were equipped with standard Timken tapered roller bearings with steel cages. Cars produced after this change are delivered with Timken roller bearings with glass-filled Nylon 66 cages.


These bearings are quite adequate for street use, and have exhibited excellent reliability on passenger cars. However, in the extremely high temperature, high load use that these parts are subjected to on the racetrack, their reliability suffers. The Nylon roller cages can soften and distort, allowing the bearing to fail. Very few incidences of failure have been reported among track cars to date, but the potential for trouble to develop warrants immediate attention.


A phone conversation with Jim Lee at the Timken Tech Hotline revealed that the standard steel-caged bearings are much more appropriate for track use. I would like to strongly urge all late-model owners who will be running track events to at least tear down, check, and repack their front wheel bearings before presenting the car at tech. If your car is one of those that is running on the Nylon-caged bearings, I would urge you to consider replacing them with the heavier duty steel-caged versions, which are a direct replacement.


The part numbers for the steel-caged inner bearings are LM12749 for the bearing, and LM12710 for the race. For the outer bearing, the number is LM48548 for the bearing, and LM48510 for the race. These are available in sets as A?12 for the inner, and A?5 for the outer.


For most of you, this will be a dead issue. But if it has been a while since the last time you checked up on the health of your wheel bearings, or if you never have gotten around to it at all, please take the time to do so now.


PARTS LISTING FOR CAMARO 1LE FRONT BRAKES


Some folks have been asking what they need to convert their Camaro to the 1LE front brakes. So I combed through my parts book and found what (I think) is the list of all parts necessary to do the conversion. Here goes:

Description
Right side
Left side
Brake hose
1011 3076
1011 3075
Hose bolt
1404 7782
same
Caliper
1013 2828
1013 2827
Seal Kit
1010 4486
same
Pin
1014 0666
same
Caliper bracket plate
1013 2830
1013 2829
Bleeder screw
1407 1826
same
Steering knuckle
1801 6738
1801 6737
Bracket
1801 6034
same
Wheel Bearing
457049
same
Rotor
1801 6035
same
Wheel Bearing
457196
same
Wheel bearing seal
396 5092
same
Bearing dust caps
1400 3444
same


Note: Some of the above parts are the same as the non-1LE front disk brakes. For example, the inner wheel bearing and seal is the same for both brakes. However, I have included what I think is the complete listing of what you would need to do the job, including the replacement of things you may already have, but are worn out.


Some other handy items:


Bolt 1408 4051 (Qty - 4) Clip 1013 2842 (Qty - 2)
Washer 1408 0254 (Qty - 4)


So, find a Chevy dealer that will give you a 40% jobber discount, and price it out.

TOWING REGULATIONS


Some auto racing circles are now discussing highway towing regulations more, now that some state troopers are targeting racing towrigs. Did you know that in many states (maybe all?), if your rig is over 10,000 pounds combined weight you are subject to federal DOT regulations? Did you know that if you are hauling racing gasoline around, you better be in compliance with HAZMAT carrier guidelines? Do you have a MSDS (Material Safety Data Sheet) from the manufacturer to describe what to do in case of a spill or an accident on the highway? As your tow-rig gets bigger, so does your legal exposure. Get the info you need from your state's highway information bureau, before a highway patrolman causes you big headaches.

SOMETHING TO CONSIDER


At this year's Nevada Open Road Challenge (that wild race over closed public roads), the following report was copied from the Internet: "a Porsche 911 had a spontaneously deflating tire during the race. It was discovered that at speed the centrifugal force was enough to depress the valve stem spring and let the air out. The solution is to use metal valve caps which have rubber seals."

SAFETY HINT #1


In the GM parts book for Camaros, there appears part number 1407 9634, which is a support brace for the front sway bar mounting points. It was standard equipment on some 1991 Camaro models (and possibly others), and serves to provide some transverse support to the front sway bar brackets.

SAFETY HINT #2


Never re-use your front wheel bearing dust caps. Twice, I have seen dust caps fly off at speed on SSGT Camaros, because the dust caps were used for a second time. They are cheap, so carry spares. Every time you re-pack your front wheel bearings or remove the brake rotor, put on new dust caps. GM part # 1400 3444. Carry spares for your friends.

SAFETY HINT #3


SEATBELTS! Remember that your seatbelts and shoulder harness get weaker with age and exposure to heat and chemicals. Many race sanctioning bodies recommend that you replace your seat belt and shoulder harness every two years routinely. Remember that pushing the life of your seatbelts, is pushing your luck too.

SAFETY HINT #4


COOL SUITS! If you are using a "Polar Bear" Cool Suit or something like it, you already know how helpful they are on a hot day. One way you can extend the longevity of the cold temperature is to fill up those large plastic soda bottles with water and freeze them. When you get to the track, take one out, split the plastic with a knife, throw the plastic away, and pop that giant ice cube into the cooler, covering it with loose ice cubes from a bag. Will definitely last longer than straight bag ice. (The next horizon in driver cooling involves air-cooled helmets. Watch for all the helmet manufacturers announcing their own versions of the "Parker Pumper" -type systems).

SAFETY HINT #5


DRIVER'S SEATS! If you are still racing with your stock driver's seat, you should immediately consider replacing it with a proper racing seat. Two accidents at the 1993 SCCA Runoffs in Showroom Stock demonstrate the serious need for proper racing seats for driver protection. First, in SSB, a Mazda MX3 had an accident where the car flipped after turn 12 and the driver's seatback broke. The driver (Jay Wright) was seriously injured, severing his spinal cord at T-5 (the 5th thoracic vertebrae), which resulted in paralysis from the waist down. Rumor has it that his wife was at the track during the next few days appealing for racing seats in SS cars. Later, in the separate SSGT race, Mike Pettiford crashed heavily at turn 11 and chipped vertebrae in his neck. Another stock seat.

So, take full advantage of the best difference between AS rules and SSGT. Throw away that junk stock driver's seat, and protect yourself with a proper racing seat. Stock seats are weak, since the car manufacturers want them to be light, cheap, and easy to fold forward for rear seat access. This results in seatback weakness, especially under side loads. There are lots of sources for racing seats in the marketplace, but here is what I did. If you watch the Winston Cup NASCAR races when they are interviewing the drivers in their cars, you will often see the word "ButlerBuilt" on the driver's seat. This is a company located just down the street from the Charlotte Motor Speedway that supplies many of the top NASCAR teams with seats. Butler Motorsports Eqpt (1-800-621-SEAT) has several stock-size seats, but they also have a custom made seat that they can make to your measurements for $420. You measure yourself in several ways like you do for a custom driving suit, according to a form they mail to you. (Hint - make sure you keep your shoulder DOWN for measurement number 2, otherwise the chest sideplates will be made too high and will irritate your inner arm). The resulting seat will fit you so well, you feel like you could drive the space shuttle in it.

Another hint - also order their seat back bracket (#2215 - $20) and the right side head support for your seat. A solid seat back bracket is required on any racing seat, to brace the back of the seat to the roll cage. (Note - Last year, there was a tragic accident at Moroso in a vintage race when the seat back broke and the driver broke his spine. His roll cage and seatbelts all held fine, but the seatback broke and tore a 3" opening in his spine).

The right side head bracket will limit your helmet movement to the right, eliminating the danger of side whiplash. Floor mounting bars are available from Butler, and I understand that there was an article on proper installation of racing driver's seats in a recent issue (April?) of Circle Track magazine. I'm trying to locate that issue now.

Several folks on the Internet have been discussing the HANS ("Head And Neck Support") system that ex-IMSA racer Jim Downing is manufacturing and selling. This device is supposed to be the ultimate in head and neck safety for racing. The cost is $600 and it takes about 3 days to perform the modifications to your helmet. It has been written about in both a paper to the Society of Automotive Engineers (SAE) and an article in the April '93 issue of Stock Car Racing magazine. If any of you are using this device, please contact me so I can find out more about it and how you like it.

EXHAUST HEADER WRAP


I have been recently heard that some "header wrap" can cause so much heat retention in the headers that it can lead to early metal failure and disintegration of the headers themselves. Apparently, the reduction in under-hood temperatures is a real benefit for cars like ours that cannot use outside air ducts to the carburetor; however, it can lead to early replacement of the headers as part of a maintenance schedule! Any other experiences with this?

SAFETY HINT #6
(as seen in Stock Car Racing magazine) QuickCar has developed what they describe as the first fireproof window net. The net measures 24" x 18" and is constructed of Nomex fiber that QuickCar says will not burn or melt. Priced at $60. Call 404-867-9500.