Exeter Auto Supply

01/28/2014

In case you missed it, the 2014 Grand National Roadster Show in Pomona is now in the record books. The Smokin' White Owl was there for Exeter Auto Supply! Thanks to Randy Clark and the gang at Hot Rods and Custom Stuff for taking the car and having it at their display.

03/29/2013

Me and my pit crew at Pomona. I know the goggles are goofy, but they are what my Grandfather wore back in the day. My mother is holding his helmet.

03/20/2013

Here's Lyle working today, must be break time. A special thanks to Tay Offenhauser and Vince Humphries at Offenhauser Equipment for sending the logos to Randy Clark at Hot Rods & Custom Stuff for Lyle to use.

03/20/2013

Coming down to wire! Trying to finish up the dragster for Hot Rod magazine's 65th annivesary car show in Pomona this weekend. Here's Lyle Fisk showing his handy work with the lettering.

03/19/2013

How well do you know auto parts? Which one of the following items is not a real auto part.

A) Schrader valve
B) Macpherson Strut
C) Auxiliary Air Valve
D) Heikel injector
E) Heim joint

Post and let me know which one is not a real part.

03/19/2013

Car tip of the day, change your brake fluid. The brake fluid is one of the most over looked items of automotive maintenance. Think about the last time you had the brake fluid changed in your car, if ever. Brake fluid is the critical link between you and your brakes, if the fluid is not operating efficiently, your brakes are not operating efficiently.

Before I discuss why you need to change your brake fluid, I should describe what brake fluid is. Obviously it's a fluid. In all reality, water could be used to control your brakes. But the reason water is not used can be best described as a thermal dynamic and chemical problem. The process of stopping a car is the transfer of kinetic energy (movement) into thermal energy (heat) through friction. When you apply your brakes, the friction of the brake pads and/or shoes against the brake rotor or drum, respectively, creates heat which, in turn, slows down your vehicle. Water has a boiling point of 212 degrees F. The operating temperature of your braking system is much higher than that. If water were used, then the water in the brake system would boil and create steam. Steam, being a gas, can be compressed under pressure, unlike fluid. This compressive nature of steam would decrease the efficiency of your braking system resulting in your car not stopping as quickly.

The second nature of water, which makes it useless as brake fluid, is the interaction between the water and system components. Most brakes systems use steel and/or aluminum for main components. Water is corrosive to both of these materials. Over time, water will create rust and corrode the internal brake components, leading to brake system failure. To combat these two issues, brake fluid is genreally made from a Glycol-ether or silicone based fluid.

Now to the critical issue of why do you need to change your brake fluid. Glycol-ether based brake fluid, the most commonly used fluid, is hygroscopic. Basically, this means glycol-ether based brake fluid, absorbs water from the atmosphere. Overtime, the hygroscopic nature of brake fluid increases the percentage of water in the braking system. This increase of water leads to the fluid being less efficient than is originally was. As described above the water in the system decreases the boiling point of the brake fluid and increaes the corrosive properties of the fluid. If your brake fluid is not changed regularly, every two years, you decrease the service life of your hydraulic brake components (master cylinder, wheel cylinders, and calipers). So do yourself, and your car, a favor; change your brake fluid.

03/19/2013

In staying on topic of carburetion, how does it work? The simple answer to that question is based in Physics. Every carburetor can claim European heritage because it was the work of an Italian physicist, Giovanni Battista Venturi, and a Swiss scientist, Daniel Bernoulli, that form the basic priciples of the carburetion.

The carburetor's main function is to control the amount of air and fuel that goes into the engine in the right proportions at all engine rpm levels.

The carburetor utilizes air flow through the barrels to draw fuel out from the bowl(s). All carburetors work on two basic principles. One principle is the Bernoulli effect and the other is the venturi effect. Vacuum increases along with velocity in regard to The Bernoulli effect. If a carburetor is developed based on this principle it will have a fuel nozzle placed in the high velocity/low pressure (vacuum) region which allows the drawing of fuel into the air stream and atomizes it into a tiny mist of fuel droplets.

A carburetor that is developed and operates on the venturi effect will have a venturi (narrow passageway) in a tube that is responsible for increasing flow velocity. The carburetor will have a venturi area in the middle of the throat that increases velocity of the air stream. A booster venturi is placed in the main venturi area to further create air velocity plus create a region of very low pressure (vacuum). The fuel nozzle will be located in the booster venturi where there is the most vacuum. This allows fuel to be drawn into the air stream and atomized into tiny droplets. The position of the throttle plates/valves will determine how much air and fuel can enter the engine.

The needle and seat assembly acts as a shut off valve to maintain proper fuel levels in the carburetor float bowl at all times. As fuel is consumed the float will drop and allow the needle to drop off it's seat allowing more fuel to enter the bowl. As fuel enters the bowl it will raise the float level which will press against the needle assembly forcing it against the seat and shutting off fuel flow.

Each barrel of the carburetor will contain one main jet which acts as a restrictor that controls the amount of fuel that the carburetor can deliver to the engine. These main jets can be replaced with either larger or smaller jets depending on the fuel demands of the engine. The idle screws control the amount of fuel that enters the engine at idle. On a Holley carburetor, turning the mixture screws in leans out the air/fuel and turning them out richens the air/fuel mixture. The idle mixture screws should only be adjusted when the throttle blades/valves are nearly closed at engine idle. Carburetor tuning is a different topic.

03/16/2013

I get a lot of questions regarding what carburetor to use on any given engine. Here is a great article, written by The Carburetor Shop, explaining how to dermine what CFM carburetor to choose based on CID, RPM, and VE (Volumetric Efficiency).

Most car enthusiasts are familiar with (or have at least heard of) the following equation:

CFM = (RPM times CID) / 3456

This equation will give the required CFM for a multi-cylinder four-stroke internal combustion engine consisting of at least four cylinders (it may be used for fewer cylinders, with modifications) and a common plenum area for the intake; with a volumetric efficiency of 100 percent.

Unfortunately, many do not understand either the derivation of the equation OR its correct usage.

Derivation

CFM is airflow of the engine measured in cubic feet per minute.

RPM is the speed of the engine measured in revolutions per minute.

CID is the displacement of the engine measured in cubic inches.

The constant 3456 is more easily understood, and much more easily remembered if it is re-written (12 x 12 x 12 x 2). Note that the dimensions on the left side of the equation are in cubic FEET, and the dimensions on the right side of the equation are in cubic INCHES. As there are 12 inches in a foot, and we must then multiply 12 by 12 by 12 to keep the dimensions the same. The “2” is required because of the 4-stroke engine only drawing air on ever other revolution of the engine. The equation assumes 100 percent volumetric efficiency of the engine (more on this later).

Use/misuse of the equation

Many enthusiasts will take an arbitrary RPM that would be a “dream” RPM for their engine at WOT (wide open throttle), ignore the volumetric efficiency, and buy the next larger carburetor to the figure derived by plugging this dream RPM and the engine CID into the equation. This will yield less than desirable results for most street engines.

One should be reasonable in the maximum RPM figure used. If one doesn’t know, then one may concern a “Motors” manual in the reference section of one’s local library for WOT rated RPM. Once a CFM figure is obtained at 100 percent volumetric efficiency, apply an estimate of the volumetric efficiency of your engine to this figure. Examples will follow later. Some sample estimates of volumetric efficiency of various engines:

Pontiac V-8 400 CID Ram Air IV approximately 90 percent

Pontiac V-8 400 CID Ram Air III approximately 85 percent

Pontiac V-8 400 standard 4-barrel engine approximately 80 percent

Most 2-barrel V-8s and most USA-built 6-cylinders 75 percent

Once the 100 percent figure is obtained, the actual need may be obtained by multiplying the 100 percent figure by the appropriate percentage.

Since the equation varies as the RPM varies, it should be obvious that the equation may be used for both cruise, and WOT to obtain CFM requirements for both conditions.

Carburetor selection

The figures obtained above will refer to CFM using “wet” ratings. Remember that there are several different rating systems – see CFM RATINGS

When selecting the carburetor, use the WOT rating to determine the carburetor’s maximum airflow, and the cruise rating to as much as possible maximize airflow in the primary side of the carburetor at cruise. Why is this important? The two major factors in atomizing the fuel in the airstream are heat and air velocity. Given the same airflow requirement for carburetors of different size, it should be obvious that air velocity would be less in the larger carburetor. This usually requires that if the primary side of a four-barrel is too large, that extra fuel must be provided to provide the proper mixture. This is simply a waste of fuel. The lower air velocity will also create a “sluggish” engine at lower RPM’s. Often this issue can be better solved by the use of a spread-bore carburetor rather than a square-bore carburetor for engines of wide RPM range.

While this article is meant to be “brand-independent”, since I am most familiar with Carter and Rochester 4-barrels, primary and secondary flow data for popular Carter aftermarket carburetors is provided in the CFM Ratings article mentioned above.

Examples

Pontiac 400 CID basically stock with factory 2 barrel

CFM = CID * RPM / 3456 = 400 * 4600 / 3456 = 532 CFM at 100 percent VE

From estimate chart VE = 75 percent, or actual required CFM = 532 * 0.75 = 399 for a two-barrel

By adding a four-barrel and dual exhaust, the WOT RPM would increase to 5200, while the VE would improve to 80 percent

Thus for our modified 400, necessary WOT CFM = 400 * 5200 *.8 / 3456 = 481. Pontiac used a Carter 550 CFM as original equipment, which is entirely adequate for this application.

Calculating for cruise: CFM = 400 * 2200 * 0.75 / 3456 = 204 CFM on the primary side

Chevrolet 283 basically stock with factory 2 barrel

CFM = [CID * RPM / 3456] * 0.75 = [283 * 4600 / 3456] * 0.75 = 282 CFM for a two-barrel

By adding a four-barrel and dual exhaust, the WOT would increase to 5200, while the VE would improve to 80 percent

Thus for our modified 283, necessary WOT CFM = 283 * 5200 * 0.8 / 3456 = 341. The original Carter/Rochester four barrels flowed approximately 450, which was more than adequate.

Calculating for cruise CFM = 283 * 2200 *0.8 / 3456 = 144 CFM on the primary side

03/15/2013

Street Rodder has a very detailed article on the Chevrolet "W" family of engines (348 and 409 cid) written by Jay Storer. Exeter is listed for all your Offenhauser needs.
http://www.streetrodderweb.com/tech/0808sr_chevrolet_w_motor/viewall.html

Read about the legendary Chevrolet "W" Motor including the 409 and 348 - Street Rodder Magazine

03/15/2013

we'll be there!

NHRA MUSEUM JOINS HOT ROD HOMECOMING CAR SHOW, MARCH 23 & 24 AT FAIRPLEX!

03/14/2013

Dragster is finally down on four wheels. They got the inner moon discs installed. We're just waiting for Lyle Fisk to do the lettering and logos. Almost ready for Hot Rod Magazines 65th anniversary car show March 23-24 in Pomona.

03/13/2013

Here's a great article about Exeter Auto Supply's Smokin' White Owl built by Ollie Morris....enjoy!
http://hotrodscustomstuff.com/latest-stuff/ollie-morris-smokin-white-owl.html

Founded in 1989 Hot Rods and Custom Stuff is Southern California's premier Custom Hot Rod Shop! If you've ever picked up a magazine, walked a car show, or checked out the local cruise scene...chances are you've seen his work. A fixture in the Hot Rod world for over 40 years, Randy Clark and his shop...