Hello again Mustang and Ford fans. As the temperature heats up, we have many upcoming events. I'm looking forward to seeing y'all with your ponies.

This weekend, on July 15th, we have our annual club picnic at Bonn Park, which is at the corner of Wahsatch Avenue and Jackson Street. It's just about due east of Penrose Hospital. Festivities will start at 4 p.m. The club will provide sandwiches, chips, and soft drinks; members should bring side dishes and desserts. This will also be our monthly meeting, so be prepared to talk business as well. One particular topic is whether to continue meeting at Phil Long Ford, or going back to Maggie Mae's--expect to vote.

The next big local car event is the Good Times Car Show in Old Colorado City at Bancroft Park on July 30th. For those who would like to show their cars and park together, we will meet at the Eighth Street Auto Zone at 6:30 a.m. Move-in starts at 7 am, so don't be late. In addition to the show, there will be a cruise to Cruisers in Woodland Park on the evening of the 29th starting at 5 p.m. For more information, call Dave Alexander at 597-9002, Dave Del Monico at

390-8902, or Neil Quatkemeyer at 392-3715.

In addition to the July activities, we will have two August events before you receive the next newsletter. We will discuss these events at the picnic, but I included the information here to ensure everyone gets the word.

On August 5th, our club will cruise to Cruisers in Woodland Park. We will meet at the inclined railway engine at the park in Manitou Springs. Simply follow Colorado Avenue until you see the engine. Do not take Highway 24 or you will miss the engine. Let's plan on gathering at 4 p.m., and we will drive on up to cruisers for dinner. I'm setting up this event, so if you have any questions, call me at 392-8926.

On August 13th is the All Ford Day at Bandimere. For those of you who haven't been to this meet yet, you are in for a treat. The day's activities include a show, drag racing, and a swap meet. We will meet at the McDonalds at North Academy and Highway 83 at 6:30 a.m., and will caravan up to Bandimere. Should you need any more information, call Ross Schwyhart at 520-1670.

On the 9th of July, we had two club members participate in Tour Tejon, which was held at Pikes Peak Community College. Henry Bresciani brought his gorgeous '69 Mach I, and I showed my '69. Henry could not compete in the show since he was an organizer, but fortunately, I ended up getting a trophy. Unfortunately due to late changes in date and location, the show had a rather light turn out. I spoke with one of the organizers, and he said they intend to move the show back into May and might even move back to its downtown location for next year. Let's hope so--I for one would like to see this event regain its former glory.

As always, if you have any questions or comments, feel free to contact any Board member to include myself. Remember this is your club; let us know what type of activities you would like to see.

Bryan Lowry

Club News

The method of controlling engine load is by throttling the air entering the engine. This is done by the throttle plates opening position, which are set by the driver through the throttle pedal

The engine is an air pump. If 100% efficient, it would move air volume at full throttle by the following formula: Engine volume (cubic feet per minute) = engine rpm X engine displacement (cubic inches) /2 volume per revolution / 1728 cubic inches per cubic foot.

For a 289 engine running at max RPM of 6500 rpm the formula is: 6500 X 289/2/1728 = 544 CFM (cubic feet per minute)

But the engine isn’t 100 % efficient. Called volumetric efficiency, a basic street motor may be 80 %, a high perf motor 85%, and an all out race motor 95%. Let’s use 90% for a good semi race motor: 544 CFM X .90 = 490 CFM. This is how carbs are sized.

But all this is at sea level and we are at about 5000 feet, and our engine is pumping air of less density. Kind of a negative supercharger. The normal barometric pressure at sea level is 29.92 inches of mercury & 24.89 at 5000 feet. This ratio is .832. With this pressure difference, the carb acts as if it were larger at high altitude. Since delta pressure changes as the square of the area, the carb size effect is only equal to the square root of the pressure ratio or .912.

So if we want to find the proper carb size for the above engine at 5000 feet altitude, we take 490 CFM X .912 or 447 CFM.

Following is a chart for those that don’t like to calculate. It shows carb size for different rpm & engine displacements. It is figured for better than average street performance engines using 90% efficiency and 5000 foot altitude.

RPM 3500 5000 5500 6000 6500 7000

CID

289 241 344 378 413 447 481 CFM

302 252 359 395 432 467 503 CFM

331 277 396 435 475 514 553 CFM

351 293 418 459 502 543 584 CFM

427 359 508 559 610 661 711 CFM

460 383 546 601 657 710 765 CFM

Now lets look at a basic 225HP 289cid motor with juice cam and automatic trans. It rarely gets above 3000 RPM. So with 80% efficiency it would want 163 cfm at 5000 feet and 178cfm at sea level. Wow, that makes the Ford shoe box and 390 cfm Holley seem massive. So, you can see why a vacuum secondary carb is very desirable for an engine of this type. It attempts to change the cfm rating as the engine pumping volume changes. It can run on the front barrels which are, in most Ford Holleys, half the flow of the full 4 barrel carb, then gradually open the secondarys as the load and rpm changes.