This is intended for a
first time drag racer that wants to go racing for the first time. This
will be the first topic of a three part series. The second two parts
will be:
2) Understanding the tree (Sportsman, Pro or Instant Green formats)
3) Launch techniques & shifting
Now let’s make sure your car is ready for the strip!
I’m going to assume the following:
1) Car is stock or near stock
2) You are willing to perform a major tune up and make sure your motor
and engine compartment is clean
3) You are willing perform some basic safety checks to your car before
you get to the track
Major tune up:
I’m of the opinion that since you have decided to race your car you
would like it to perform up to your expectations. In order to do this,
your going to have to make sure the car is running in top notch
condition.
Tools: Spark plug wrench, screw-in compression tester, ohms meter,
feeler gauge (if you are running points!), tachometer and dwell meter
(Again for the point’s guys) and masking tape.
Parts: Spark plugs, cap & rotor (Accel has brass contacts) (Points if
you still run them and plug wires if needed) air filter, (PVC valve &
fuel filter if needed) and a can of carburetor cleaner. You may want to
change the oil and filter at this time with quality motor oil. I like
diesel motor oil as it designed to deal with the ash and fuel in the oil
better than most modern oils.
Reference manual: Chrysler Plymouth Chassis Service manual 1971 (CPSC).
By the way, I’m not a technician of any kind, but I have been involved
with Mopar Muscle Cars since 1973 when I was in high School..
Let’s begin by documenting the baseline for the motor BEFORE we make any
changes. Remember, without a baseline, we wouldn’t be able to understand
how changes effect our combination. Find an unported vacuum plug
(usually on the secondary side of a four barrel carburetor, and hookup
your vacuum gauge (I suspend my gauge with a coat hanger from underneath
the hood). Disconnect and plug the vacuum port to the distributor. We’ll
also need a tachometer / dwell meter (Dwell meter for the points) and
timing light. Let’s also DISCONNECT the vacuum advance to the
distributor and block the port on the carburetor.
With the air cleaner removed, start the motor and note idle speed Rpm,
initial timing and vacuum reading AFTER the motor has warmed up. If it’s
messy inside or around the carburetor, shoot some of the carburetor
cleaner into all parts of the carburetor while holding the throttle
open. Do it NOW before we take our baseline readings. Take the same
baseline reading at about 2500Rpm (Hopefully Total Mechanical Timing &
vacuum). Then reconnect the vacuum port to the distributor and again
check the total timing with vacuum advanced and vacuum. We are expecting
STEADY readings in the timing and vacuum. If they are “moving around” at
a constant Rpm, we have a problem. Vacuum can fluctuate an inch or so at
idle.
Examples:
Initial timing: 18.5 @ 950Rpm neutral w/11 inches of vacuum
Total: 36.0 @ 2100Rpm w/21 inches of vacuum
Total w/vacuum can 53 degrees @ 2100Rpm w/21 inches of vacuum
Now that we have warmed up the motor and baseline our readings, let’s
remove the air cleaner and pull the spark plug wires off the plugs
labeling them as you go (I ALWAYS have my heat resistant gloves on for
this task!). Facing the motor from the front of the car, the right
cylinder bank (driver) is odd (1, 3, 5, 7) and the left (passenger)
cylinder bank is even (2, 4, 6, 8) same for all V8 Mopar engines.
Release the cap from the distributor and remove the cap and wires as one
unit from the motor noting (write it down!) the wire loom placement.
Pull the plugs and label them with masking tape as to each cylinder they
came out of. Holding the throttle wide open with a screwdriver, perform
a compression test on each cylinder. Crank the motor over for until you
have the highest reading (usually about 3-5 revolutions). Write down the
reading for each cylinder by cylinder bank. All cylinders should be
within 10% from highest to lowest. Typical reading may range from a low
of 110-125 range on stock low compression motors to 170-190 range on
blue printed high compression stock appearing motors. If your motor
falls within these ranges (low to high), your anywhere from ok to
outstanding.
If you have a cylinder with more than 10% lower compression as above,
shoot some oil in that cylinder and retest. If the compression comes up,
you may have a problem with the rings. If the cylinder still will not
hold compression, you may have a problem with a valve or head gasket and
need to perform a leak-down test.
Next, test the resistance of the spark plug cables and cap by using the
ohms meter. Do not remove the cables from the cap for this test. If the
resistance is more than 30,000ohms (CPSC), you need new wires. Excessive
resistance will prevent the coil from producing sufficient spark output.
If you see any cracks or worn marks on the cap or rotor, replace them
now. PLEASE replace one wire at a time on the new cap following the old
cap as a guide!
Let’s check the fuel pressure with the vacuum/fuel pressure gauge.
Follow the instructions of your gauge by attaching it to the fuel line
before the carburetor, with the motor cranking, typically 5-8Lbs (CPSC).
R&R the fuel filter at this time. You can blow through the old fuel
filter to determine if it is clogged.
The PVC valve can be checked by the old pull it out and rattle it
method. If it doesn’t rattle, replace it. Always run a PVC valve on a
“stock” type car. It provides a negative pull on the crankcase and will
eliminate valve cover leakage due to blow-by.
Now let’s MAKE SURE the throttle is opening the carburetor all the way!
The chock must be wide open and the fast idle cam must be released (not
interfering). Disconnect the cable from the carburetor by pulling the
clip from the pin and manually full open the carburetor. Have a helper
in the car fully push the gas peddle to the floor. Reinstall the pin and
clip. If it can be reinstalled with the gas peddle on the floor, adjust
the linkage on the bracket accordingly. After this adjustment, make sure
the carburetor closes all the way and returns to idle!
Let’s install the new spark plugs gapped at .035 - .037 for stock type
ignition systems including Chrysler Black, Blue and Orange Box systems.
Install the rotor, cap and plug wires as they were disassembled.
We’re ready to fire up the motor now so we’ll need the timing light. If
you DO NOT UNDERSTAND all the components of timing, initial mechanical,
centrifugal advance and vacuum advance, just set the initial timing per
your engines factory specs PLUS THREE - FIVE DEGREES. For instance, the
factory setting for a 1971 340 is 5 degrees before TDC, change that to 8
– 10 BTDC. This is an old hotrod trick that WILL WORK if you do not know
what your total timing is or when it comes in. If advancing the timing
leads to PINGING, the “marbles in the motor” sound, BACK the timing down
to OR add a few gallons of high octane leaded racing gasoline. Believe
me, your engine will really like you adding a couple of gallons of 104
or higher octane racing gasoline per thankful. It WILL make a
difference!
Let’s set the idle speed and adjust the idle mixture screws (usually
anywhere from three – five turns out from lightly seated), again per
specification with the distributor vacuum advance STILL disconnected.
Take vacuum reading again and compare to the original settings. Let’s
reconnect the distributor vacuum advance, disconnect the vacuum gauge
from the back of the carburetor and block the port. Also, make sure your
throttle return springs are well connected and strong. This should be
considered a safety item.
Automatic 727 and 904 transmissions, we should check to make sure the
throttle rod is adjusted properly. I’m not going to get into setting up
your transmission for racing or street driving, just a couple of simple
checks. If you have a three section throttle rod, the two types of
adjustment we are going to discuss are the horizontal or carburetor rod
and the vertical or intermediate rod which connect to the vertical rod
with a ball socket assembly at the back of the transmission upper bell
crank assembly.
The horizontal rod should not impede the carburetor from opening at wide
open throttle (WOT). At WOT, the horizontal rod should have a small
amount of play (You should be able to pull the rod back a little). When
the throttle is closed, the horizontal rode should contact the
carburetor lever pin without exerting force on it. Remember to make sure
the horizontal return spring is ALWAYS in place when driving the car.
The vertical rod and be used to adjust both shift points when the
transmission is in drive. By unsnapping the ball socket, you can turn
the vertical rod and adjust shift points. The longer the rod, the higher
the shift point. When testing this, only make one turn at a time. Each
turn may correspond to 100 – 300Rpm change.
We’re almost done so let’s check a few safety items.
Shocks: Are they leaking or worn out? Worn out front shocks will help
transfer weight at the drag strip. Worn out rear shocks may contribute
to wheel hop!
Front-end alignment: Does your car drive straight or pull when driving?
Get this taken care of BEFORE you head to the track!
Brakes: Again, does the car pull at all when braking? Get this taken
care of BEFORE you head to the track!
Tires: Visually inspect your tires for any separation or damage. Since
you are probably running DOT approved (street tires) make sure they are
balanced on a high speed machine and do not vibrate. Make sure the air
pressure is also set to the maximum allowed setting both front and rear.
We’ll take more about air pressure in one of the next installments. Air
pressure should be set when the tires are cold.
Coolant recovery tank: All tracks require you to have a recovery or
overflow tank when you race. If you don’t have one, and most pre 1973
Mopars do not, install one from an auto parts store.
Helmet: You are REQUIRED to where a helmet if your car is running below
a 14.00 second elapsed time in the quarter mile.
REMEMBER: You’re Mopar Muscle Car is very capable of traveling at more
than 100Mph as you exit the end of a quarter mile race track! You must
be prepared for any emergence condition including accident avoidant and
panic stops. With everything in good working order, your Mopar Muscle
Car is VERY capable of handling these conditions.
Here are some baseline numbers that most stock Mopar Muscle Cars will
run in the quarter mile in optimum running condition.
340 A-Body: 14.75 or lower
383 B-Body & E-Body: 14.75 or lower
440 B-Body & E-Body: 14.25 or lower
426 B-Body & E-Body: 14.00 or lower
The next two installments will be “Understanding the tree (Sportsman,
Pro or Instant Green formats) and “Launch techniques & shifting”
If anyone has anything to add, please contact me so I can update this
information. REMEMBER, this is intended for stock or near stock type
cars and drivers that have little or not experience.
