2012 Goodguys Lone Star Spring Nationals

I went to the Goodguys Spring Nationals in Dallas this past weekend.  I took a few pictures of cars running the autocross.  The pictures are not that great but someone asked me to share them so I decided to upload them.  I've about 200 other pictures which look better (as the cars are not moving).

 

Weekend Fine Tuning

This weekend it rained almost the entire weekend.  It was not too cold so I spent a fair amount of time working on the car. 

I tried to install the DB Electrical 3223 mini-starter yesterday.  The starter is slightly too large to fit into the block plate opening.  After I set the two side by side, I noticed the snout on the end of the starter is not long enough.  If the starter were to engage, it appears it would be about a half inch too short.  I emailed the DB Electrical about the issue to see if they have one which will work for me.

I spent some time using the new A/F gauge to tune the car.  When I started, the car was idling at 1,000 RPM, vacuum was at 15", and the A/F ratio was 11:1 (quite rich).  I took the carburetor off and adjusted the secondary throttle blades to open them up some.  This would allow me to close the idle set screw some exposing less of the transition slot in the primaries.

After this adjustment, I could set the idle down to about 800 RPM without trouble.  This obviously decreased my vacuum down to the 12-13 range.  However, my A/F ratio was then at 13:1. 

I'd turned in the secondary throttle blade adjustment screw a 1/4 turn about two years ago.  My first change set it a little more open than original.  I pulled it off and turned the screw in some more to open the secondaries.  This lets me close the primaries, exposing less of the transition slot.  I made these changes and now have the 12-13" vacuum, 13:1 A/F, and still idle at around 800 RPM.

I really need a new distributor as I'm currently only able to run about 14 degrees advance (due to 22 mechanical minimum with my factory distributor).  I need to have that to 18 or 20.  When I tested it this weekend (without driving), setting the timing to 18 gives me 15" of vacuum and leaves my A/F about the same.  Unfortunately, I can't leave it this way as I'll have 40 degrees total advance.

While tuning, I noticed the rattle noise I heard under the car was the exhaust rattling against a parking brake bracket.  I loosened up the clamps once it cooled down and repositioned them.  This stopped the rattle noise.

I also worked on the shifter some as it makes a rattle noise when in second gear.  I have already used the rebuild kit.  This time, I stretched out the springs some to stiffen up the assembly.  I also put some grease in the cups on the sides of the shifter to make sure they were lubricated.  I then tightened it all together with some medium thread locker on the bolts.  I'm afraid the rattle is caused by a loose set pin which is in the bottom part that the shift lever connects to.  I'll find out when I get to drive it a little more.

I drove the car around the block late this evening and found the A/F ratio is all over the place while driving.  I tried to isolate each circuit when driving but it is difficult.  I'm running very lean (16+:1) when accelerating but drop back to a reasonable level when cruising.  It is still a little wet on the roads so I'll wait until it dries up some to do more testing.

Installation of Wide Band Air/Fuel Gauge

The AutoMeter Sport Comp wide band air/fuel gauge (ATM-3370) I ordered arrived from Summit last Thursday.  At first glace, I didn't believe the gauge was 2 1/16" diameter.  I've grown so accustom to the 2 5/8" gauges in my cluster it just seemed way too small.  However, it looks nice, matches all the others, came with a O2 sensor, all required wiring, and a bung to weld into the exhaust. 

I welded in the exhaust bung into the passenger side collector last night.  I'm still using the exhaust I put together with some 45 degree bends I purchased at a local auto parts place.  I plan to replace it in the future and route the exhaust a little better.  However, for now, it is working fine (except the parking brake doesn't work) and provides almost as much ground clearance as possible.

I thought I'd need to buy a bracket for the gauge as one was not supplied but I found one in my spare parts stash.  I installed the gauge using some existing screw holes in the bottom of the dash.  I then connected all the wiring needed for the gauge to operate.  I temporarily tied up the wiring under the dash as I've not decided if I'm going to leave it in or just use it for tuning and then remove the gauge.

It is getting late so I did not want to spend too much time tuning the car tonight.  I did start up the car to check the gauge as it requires at least 12.5v (a running engine) to show any signs of operation.  After a few minutes of driving, the choke shut off and the car was idling at 900 RPM.  The a/f ratio was only 10:1 which is rather rich. 

I shut off the engine as I did not want to get sucked into working on it as I would not stop and the neighbors would all be cussing me for running the car late (it is a little loud).  I might drive it to work tomorrow or I'll just wait to this weekend to do some more testing.  Until then, I need to research tuning a car by a wide band gauge.

Performance Test - Before Tuning

I ordered an AutoMeter Sport Comp A/F guage kit (ATM-3370) and a high torque starter a few days ago.  Before fine tuning the carburetor, I though I'd get a baseline run with my Passport Performance Meter. 

The results are much slower than I expected.  I was not going to run up to a 1/4 mile.  Instead, I decided to just focus on 1/8 mile measurements.  I could then just pull out onto a local highway which is rarely used, get centered in the lane, and then accelerate and test it without really breaking any speed limits. 

These are the results:
0-60           7.35 seconds (1 second better than before)
60'              2.53 seconds (.42 seconds faster than before)
1/8 ET      10.25 seconds (.65 seconds faster than before)
1/8 MPH  67.8 (2.4 seconds slower than before)

For the money I've put in the  motor, this is simply pitiful. Granted, I took off and loss traction big time.  I know my air/fuel mixtures are off and my timing is not right.  I guess I'll get to experiment and find out exactly how much those type changes can help.  I might get another test in first just to see if these results can be duplicated.