Hib Halverson's Big Block From Hell Series

Part 14 ... The Big-Block from Hell, Trading Pretty for Practical New Induction System Pays Off in Performance

by Hib Halverson

We take the Big-Block from Hell somewhere and a lot of people want to see its dual four-barrel carburetors. They gaze lasciviously, like–if Pamela Anderson (before she had the implants removed) walked by, they wouldn't notice her famous boobs; they'd keep looking at those two carburetors.

In a straight line, the dual-fours made the car absolutely bad-to-the-bone. In our last drag strip test, with nothing new, other than 315/35ZR17 Goodyear GS-C rear tires (BBfH 13) and fresh, NGK R5674-7 V-Power Racing spark plugs; the car's first run (best of the night) was a 12.48/122.3, almost a tenth quicker than the last time we ran the car. I'm always amazed BBfH can do that with 3.36 gears, street tires, pump gas, mufflers and no power shifting. Though the car's 460-inch rat was built almost four years prior to this article being written, the car seems potent as ever.

Like an imaginary relationship with Ms. Anderson, the dual-quad experience was not without its slippery spots and two chronic problems finally got the best of us. First, we were never able to properly tune the system at part throttle. According to the K&N Fuel Monitor (p/n 85-2437) we'd installed in the car, fuel mixture when cruising at part-throttle, freeway speeds was wildly inconsistent. We tried several primary metering rod and jet combinations. Then, we thought the problem was with idle transfer circuit calibration so we went of a rampage of drilling idle fuel restrictions using up a bunch of primary booster assemblies in the process. After that, we gave up and just lived with the weirdness.

The other problem was flooding in turns. The Edelbrock Performer Series, 600 cfm four-barrel, two of which were on the BBfH, is a derivative of the 1960s, Carter AFB design and the their fuel metering systems have much in common. An AFB shortcoming was poor fuel handling under even moderate levels of lateral acceleration or braking. Clearly y, Edelbrock was unable to improve upon that problem.

Getting the Big-Block from Hell to exit turns smoothly was difficult because the engine was so loaded up and running rich due to fuel sloshing around the float bowls that smooth response to throttle input was impossible. Hard braking caused the same problem. In an autocross situation, these difficulties combined to make the car nearly impossible to drive. If the driver braked hard into a slow turn; the carbs went way-rich. If the driver then tried to accelerate hard out of the turn; the BBfH drove like an overweight ground slough. We tried different float level settings, but this was another problem without a solution.

Though I will miss the clusters of event goers they drew, in the interest of good performance, regrettably; the dual-quads had to go.

Hello, Holley!

We decided on a less pretty, but more practical approach (kinda like Pamela Anderson after the implants were removed) to induction. Our strategy was a dual-plane, high-rise intake manifold and a single, Holley carburetor.

Edelbrock supplied their excellent, Performer RPM 2-O (p/n 7161) for big-block Corvette, oval-port cylinder heads. Fitted with a carburetor, this manifold will not clear any stock Corvette hood. However, it does fit (just barely) under the Eckler's hood (p/n 10418) we have on the Big-Block from Hell.

We've always used Fel-Pro “Printoseal” intake gaskets (p/n 1212) which are reusable. All we did was clean the gasket's manifold surface, lower the intake manifold in place and torque the bolts to 30 ft/lbs. according to the pattern in the Corvette Service Manual.

Our new carburetor was a big, nasty, Holley 4150-series, four-barrel. This unit (p/n 0-4781), from Holley's line of “Street Performance” carbs, flows 850 cubic feet per minute, has mechanical secondaries, dual accelerator pumps, center-hung floats and the “four-corner” idle system. Though it's called “Street Performance,” the 0-4781's basic design has been proven through decades of NASCAR Winston Cup and SCCA Trans-Am racing.

A discussion of vacuum vs. mechanical secondaries could be an article in itself. Bottom line? In our case, 850 cfm is a good airflow capacity for a 460-inch motor running 6800 rpm. Considering the intake flow dynamics set up by our roller cam, the cylinder heads done by Mark DeGroff and the custom carburetor work we'll tell you about shortly; we felt mechanical secondaries would serve us better. On an engine not configured like ours, the mechanical secondary choice may not be a good one. Because a dissertation on carburetor selection is not the goal here; we'll refer you to a couple of books: Dave Emanuel's excellent Holley Carburetors (S-A Design Books) and Mike Urich's Holley Carburetors and Manifolds (HP Books). Both are available by mail from Motorbooks International.

Holley 4150s have either of two float designs: side-hung or center-hung. The center-hung units were developed in the '60s for racing and reduce air/fuel ratio variation caused by fuel slosh due to lateral acceleration and braking.

The four-corner idle system gives each carburetor barrel an idle circuit. This improves fuel distribution and idle quality on engines with big camshafts. The downside is that the idle screws are quite sensitive and one must strive to get each barrel to make approximately the same contribution to the overall idle mixture. With a little practice and watching a K&N Air/Fuel Ratio Meter; we got the hang of it.

The Holley 0-4781 is basically a race carburetor with a manual choke so we couldn't just stick it on the car and go for a ride. The 850's race-only, calibration was off the mark for street use. Additionally, the mechanical secondaries can present a response problem at low speeds, so we called in professional help.

At one time, Fuel Curve Engineering was a carburetor modification shop in Tryon, North Carolina. It was opened in California in 1981 by Holley carburetor wizards, Murray Jensen and Bob Szabo. In the late-'80s, Murray retired turning the business over to Bob and his wife, Kathleen. Fuel Curve's business is Holleys for anything that races. About half their customers are oval track competitors so, to get closer to this constituency, Bob and Kathleen moved down south back in '88.

Fuel Curve Engineering has applied their experience in tuning race carburetors to a line of very high performance, streetable carbs called “Saturday Night Specials.” Certain details of the Szabo's work are proprietary, but we can talk about major changes. First, Holley annular discharge boosters are installed in the primary barrels. This changes the timing of the primary main circuit and makes it more sensitive to the engine's vacuum signal. Both of those changes improve low speed response.

The secondary venturis are fully polished and fitted with Fuel Curve Engineering boosters. The most significant change, however, is the addition an intermediate circuit to improve control of air/fuel ratio at the point where the secondary idle transfer circuit is saturated but secondary main circuit operation is not fully efficient. This modification is the single most important change allowing a mechanical secondary four-barrel to work well on the street.

Two additional modifications were performed at our request: 1) a Holley electric choke kit (p/n 45-224). A compromise we'll always make with the Big-Block from Hell is an automatic choke. It makes starts trouble-free, eliminates fussing with adjustment of a mechanical choke and allows us to drive a near-race motor immediately rather than waiting through a warm-up. 2) Mill the choke horn down to the minimum necessary to seal the choke plate. This was done to increase the amount of space we'd have between the choke horn and the air cleaner top.

Installing the Fuel Curve 850 was a snap. We dropped a Holley Heat Shield assembly (p/n 108-70) over the Performer RPM's mounting studs, added the Saturday Night Special, tightened the nuts then installed a Holley, stainless-steel throttle return spring kit (p/n 20-89). Last thing we did was build a couple of neat brackets that adapted the stock Corvette throttle cable to the Holley and provided a connection for the throttle springs.

Occasionally, in the process of reprinting all these old BBfH stories for the Idaho Corvette Web Site, we run across a modification that did not stand the test of time. One of those is the Fuel Curve Engineering carburetor work. While the carb is still on the car and still works very well, Fuel Curve Engineering itself went out of business in 1997. While we don't like to promote a modification that no one can buy anymore, the work done to the carb was so critical to how the car runs, we decided to leave the discussion in this Internet version of BBfH Part 14. In a future installment of the series, due late 1999 or early 2000 we will have a new series of carb modification, available to anyone, that will either duplicate or improve upon the great work Fuel Curve did for us back in the early 90s.

BBfH meets B2...well, sorta.

SX Performance is a rare example of that “peace dividend” government wonks talked about once the cold war was over. In the early-'90s, its parent, aerospace manufacturer Essex Industries, endured cuts in defense spending. Essex products are hydraulic and fuel supply hardware for military aircraft. The Northrop B2 (the “stealth bomber”) uses Essex products.

Essex' SX subsidiary applied aerospace manufacturing techniques to fuel system pieces for racing or high-performance street use. It retained Corvette tuner, John Lingenfelter, to write the performance specifications and test prototypes on his NHRA Competition Eliminator dragster. It engineered and manufactures the stuff with techniques their parent company uses for making stealth bomber parts.

The SX pump (p/n 18201) is is capable of 80 gallons per hour at 45 psi fuel pressure. Perhaps this is overkill but we were attracted by its quality and that it gives us room to grow if we add nitrous oxide or convert to electronic fuel injection.

We installed the pump beneath the fuel tank using a bracket we built along with the aluminum ring mounts that come with the pump. The Big-Block from Hell already had pump wiring because the SX was replacing another electric unit. If you need to add wiring, the pump requires 10 amp service and that it be energized only when the ignition switch is in the “on” position.

If an SX pump feeds a carburetor, a special SX pressure regulator (p/n 15403) with a bypass outlet is required. Fuel cools the pump, so constant flow is necessary to prevent heat build-up in the fuel. The bypass, regardless of the engine's fuel needs, always sends a small part of the fuel flow back to the tank.

Some Corvettes will need to have a bypass line installed and a connection fitted to the fuel tank but, in BBfH's case, we lucked-out. About 1968, Chevrolet began installing fuel tank return lines to eliminate vapor lock. BBfH is a '71 so we used that return line for the bypass.

The SX fuel filter (p/n 41002) is a cylindrical unit with screw-on ends. A paper filter element is standard, but we upgraded to the optional, fine-wire screen filter element (p/n 41102). It's reusable and lasts virtually forever. To clean it, you unscrew one end of the filter, remove the element, soak it in solvent then blow dry.

We joined the filter to the regulator with an Aeroquip, -10 union (p/n FCM2054) and two Aeroquip o-rings (p/n FCM3476). Then, we had our machinist, Mark DeGroff weld-up a bracket we used to mount this assembly to the front of the right cylinder head. Now, it was time to connect everything.

Flexible Connections

First, we installed Aeroquip's “Versil_Flare” tube fittings on the ends of all steel fuel lines, except the one coming out of the fuel tank. The Versil_Flare allows connection of a SAE 37° compression fitting to a steel fuel line without welding anything. We used the 1/4-in. (p/ns FC2875-04, FF9605-4) and 3/8-in. (p/ns FC2875-06 and FF9605-06) sizes. Adapting the -06 Aeroquip AQP hose we'd use to the Versil_Flares required either Aeroquip steel reducers or steel unions, depending on the size of the Versil_Flare.

Next, we fitted our Fuel Curve Engineering four-barrel with the fuel inlet hose assembly (p/n FCP0101) Aeroquip sells for Holley 850s. After that, we assembled all the flexible connections using Aeroquip -06 AQP hose and either straight (p/n FCM1012), 45° (p/n FCM4022), 90° (p/n FCM4032) or 150° (p/n FCM4052) -06 Aeroquip fittings. The connections between the pump, filter/regulator unit and the fittings were made with Aeroquip aluminum -06 unions (p/n FCM2052) or -06/-10 union reducers (P/N FCM2162). There is no compression seal where these pieces screw into the SX hardware so the appropriate Aeroquip o-ring must be used.

The flexible connection between the fuel tank outlet and the fuel pump inlet took a foot of Goodyear, 3/8-in fuel injection hose, an Aeroquip, -10/1/2-in NPT adapter (p/n FCM2009) and a conventional 3/8-in brass, hose barb. As pressure in this line is atmospheric, the expense of braided hose and compression fittings was unnecessary.

Assembling Aeroquip AQP hose and fittings can be a chore. How to do it takes more space than we have here, so we suggest reading a copy of the “Aeroquip Performance Products”catalog. Besides a full listing of all Aeroquip performance and racing pieces, the back of this booklet contains detailed instructions on assembly.

A couple of tips: 1) Use Aeroquip's assembly lube. It eases the job. 2) Mock-up hose runs with cheap hose before you cut any AQP. This avoids expensive screw-ups due to incorrectly measured lengths or mistakes in routing. 3) During assembly, use a vise fitted with a set of Aeroquip's Vise-Jaw Inserts (p/n FCM3661). They are designed to securely hold 37° compression fittings during assembly without damaging the anodized finish. 4) Once assembled, Aeroquip hoses must be squeaky-clean of excess assembly lube, hose cutting residue or any other contaminants. Build-up hoses where you have access to a solvent tank. After making each hose, pressurize it for 15 seconds with solvent then blow the hose out with air. 5) During the installation process, avoid messing-up the fittings' wrench hexes by using a set of Aeroquip aluminum wrenches (p/n FCM3410).

A Breath of Fresh Air

We had a fabricator build us a cold air induction system that takes air from the base of the windshield, through the rear facing inlet in the hood and feeds it to an air box around the carburetor top. However, building it was difficult because the Edelbrock Performer RPM is much higher than the manifold we used before. In order to have room for an adequate air filter and fit all this under the existing hood; we had to lower the air box assembly over the carburetor.

This took a little thought. First, we measured a couple of different air filter bases that drop the filter around the carburetor. The most clearance came with a stock Corvette base (p/n A8965) we found in the Eckler's catalog. However, it wouldn't fit a Holley double-pumper due to interference between its PCV connection and the secondary accelerator pump linkage. We removed the tube, capped the hole, punched a new hole in a different spot and reattached the tube in a new position.

BBfH has always used K&N Engineering filters because they are low restriction and reusable. The Eckler's base takes a 14-in. diameter filter. Using the selection formula in K&N's catalog, we learned that a 460 inch big-block, running at 6800 rpm requires a 14-incher that is four inches high. K&N has a filter like that, however, even with the special base, we only had room for a 14x3.5 unit which might be restrictive.

For adequate filter area; we'd need greater diameter and, if we jumped to a 15-inch filter; the formula predicted we'd need a unit 3.35-in. tall. As luck has it, K&N makes a 15x3.37-in. filter for Mercedes Benz 190 sedans and it fits into the Corvette air filter base. We added a K&N, chrome air cleaner top and ended up with an excellent air filter assembly that fits under our Eckler's hood with about a 1/8-in. to spare.

The next task was fabricating the air box. It was built from 1/16-in sheet metal and 1-in. steel square stock then welded it to the modified Eckler's air filter base. Once the box was complete, we checked hood clearance one final time.

Oh, yea...how did we check hood clearance? Definitely low-tech, but it worked! We stuck little balls of modeling clay where we felt the clearance was critical. Then, we closed the hood, reopened it and measured the thickness of the squished clay.

The last step was to paint the air box to match the car's exterior. Once the paint dried, we applied sponge rubber to seal the box to the bottom of the hood.

Exposed: the Secrets of Holley Calibration

The installation complete, it was time to check carburetor jetting. The jets Fuel Curve Engineering installed in our 850 were pretty darn close. In fact, given atmospheric conditions similar to those present when Bob Szabo set-up the carburetor, we probably wouldn't have made any major changes to jetting at wide-open throttle.

Even a custom-built carburetor should have its jetting checked before it's run hard. Take this note of caution to heart: it would be a rare case where the exact calibration we used would be ideal for another car. If you are jetting your own big-block, Holley carburetor; use our set-up as only a starting point. Verify any new calibration with your own tests.

At wide-open throttle, our concern was atmospheric conditions. Air densities where the Fuel Curve Engineering dyno is and where we test the Big-Block from Hell were different. At part-throttle, compared to Fuel Curve's test engine, BBfH's 460 had much stronger vacuum signals due to differences in intake manifold, camshaft and cylinder heads.

We checked WOT jetting using the Valentine Research “g-analyst” a device that  directly measures acceleration, but is, unfortunately, no longer made. Each jet configuration was tried twice with a run in second gear, at wide-open-throttle from 2000-6500 rpm. This kept speed legal, allowing us to test on a back road close to our shop, and eliminated wheelspin. We quickly found we had to change spark plugs. Because our testing included easy street driving, the cold, NGKs, left over from our last drag strip passes with the dual-quads, fouled after about the third round trip. We went to the hotter plug we use for street driving, the NGK BPR6FS, then we restarted our tests.

After several jet runs, we connected the g_analyst to a laptop computer running and transferred the data using Valentine's, optional, g-Logger v2.02 software. This allowed us to view a larger block of data than we could on the g_analyst's display and to print each jet test.

The first pair baselined Fuel Curve Engineering's jetting. Not only would engine differences affect the outcome of our tests, but we were testing at a lower altitude and at a lower temperature, so we figured, the carburetor would be a bit lean. We switched to primary and secondary jets that were one, then two Holley jet numbers larger and tested each change. g_analyst data confirmed our lean suspicions. The car accelerated harder after each change.

In a another session two days later, we retested the previous session's last configuration, then tried jets one, then two numbers larger than that. The car's acceleration fell off both times. We went back to that session's baseline and acceleration performance was restored. From this, we concluded that jets (#76 primary, #86 secondary) two numbers larger than Fuel Curve Engineering's original calibration gave best performance.

The next jetting issue, was part-throttle. Most Holley 4150/-60 series carbs have three systems controlling fuel mixture to the primaries in the the wide range of operating conditions we call “part-throttle”. The idle transfer circuit determines fuel mixture off idle and at low speeds. At somewhat higher speeds, like freeway cruising and moderate acceleration, the air-fuel ratio is set by both the idle transfer circuit and the main jets. At what we call “high-part throttle” (but not WOT) conditions, the power circuit is added to the first two.

As mentioned before, the mix of the Edelbrock Performer RPM manifold, our DeGroff cylinder heads and the short-duration Crane Roller cam have the Big Block from Hell's engine generating a substantial vacuum signal at part throttle. The primary side of the Saturday Night Special retains the standard Holley calibration of the idle transfer and power circuits. Those two conditions combined to make our carburetor rich at part throttle. At this point, BBfH's K&N Air-Fuel Monitor really came in handy. It's real-time fuel mixture information was invaluable in helping us tune part-throttle operation.

First, we changed the idle transfer circuit's fuel mixture. Both idle and idle transfer mixture are controlled by an air bleed and an idle fuel restriction in the primary metering block. The fuel restriction is the one you want to work with. Do not fool with the air bleed.

That restriction needed to be smaller and an acceptable method is to cut a short length of small diameter wire, bend it into a V and insert into the two IFR passages in the primary metering block. Arriving at the right-sized wire is a trial-and-error proposition. Use a micrometer to measure wire diameter and start at .010-in. A great source of “idle restriction restrictions” is ordinary automotive electrical wire. In the shop, we had a whole box of wire scraps varying from 18 to 10-gauge with strand diameters from .010 up to about .035. Based on feel and what we saw on the K&N Monitor, the car ran best with a .020-in. diameter wire.

Next, we had to lean the main jet. At part-throttle cruise, the main jets are not flowing near their full capacity, so to lean the mixture, a substantial change in jet number is necessary. However, if you make too large a decease, the car may run ok and have better fuel economy cruising on level ground, but when you go to accelerate, but not to the point of power circuit operation, the engine may run lean. In mild cases, the engine may not respond crisply. Still leaner, you may feel the engine surging. If the engine is really lean, it may misfire or go into detonation. Obviously, doing this part-throttle jet stuff using the seat-of-the-pants as a test device is probably not going to work well. However, the K&N Monitor helped us see the effects of incremental changes in part-throttle jetting quite easily. We settled on a #70 jet as best for part throttle cruising. The car felt good and we were seeing about 13-13.5:1 air fuel ratio on the K&N.

Going down five jets had the engine too lean at WOT. Since both the main and power circuits meter fuel at WOT, if we reduced fuel flow though the main jets; we had to increase fuel flow through the power circuit to maintain fuel mixture. The two power valve channel restrictions meter fuel in the power circuit. The Holley 0-4781 has .055-in. power valve channels. Using the Holley jet listing and formulae in Dave Emanuel's, Holley Carburetors, we were able to compute that a diameter increase to .070-in. would be a rough starting point.

Before getting out the drill index, a word about jets. In their catalog, Holley lists the actual diameter of jets so it's easy to buy into the idea you can select them simply by figuring the area of their holes.

Not! Holley jets are categorized by fuel flow not hole size. Each step up in jet number equals about a 3% increase in fuel flow. You have to pay close attention to this because there are blocks of jet numbers that have the same hole diameter but flow different rates.

The same principle applies to the power valve channels, but we had to start somewhere, so we added the difference in area resulting from the main jet decrease to the existing power valve channel area then figured a new diameter from that. The objective is to get additional fuel flow

through the power valve channels that will equal that lost by leaning the main jets. Even though area and flow are not proportional because of flow restrictions inside the carburetor's fuel passages, the diameter we picked would be a good starting point.

You'll need high-quality drills in the .060-.080-in. range. Do not use a drill motor, either. A hand-operated “pin vise” is what you need. Using our jet test procedure to validate each change, we gradually drilled-out the power valve restrictions to .073-in. According to g_analyst data, that brought the Big-Block from Hell's acceleration back to where it was with the 76/86 jet configuration we used to run a drag strip pass. Note that the diameter change necessary to get proper fuel flow did not match our earlier computations. That proves you can't select jets or channel restrictions by area alone.

More testing with the K&N Monitor showed we now had a fuel flow spread between main jets and the power valve channels that was a little too wide during the high part-throttle range, so the engine was running lean just before power valve opening. The stock 850 power valve opens at 6.5-in.hg. manifold pressure. We verified this with the K&N Monitor and a vacuum gauge. The solution was simple–we installed a Holley power valve that opened at 8.5-in. This brought the power circuit in sooner, adding more fuel between 8.5 and 6.5-in. of manifold pressure.

The last calibration change we made was to the accelerator pumps. With the engine idling in the shop, when we whacked the throttle wide open; we could hear the engine hesitate. While driving, if we mashed the gas to the floor, the car lurched a bit. You'd think we need a little more accelerator pump at both ends–not necessarily true, my friends.

With a little more careful operation of the throttle at idle and some driving with the K&N Monitor, we found that we actually had two problems: the primary accelerator pump giving us a little too much fuel and the secondary pump not enough.

Fortunately Holley accelerator pumps are quite adjustable. You can change the volume of the pump shot or the rate of fuel delivery or both. We changed the primary accelerator pump cam (they're made of colored plastic) from a pink unit to a white one. This reduced the amount of fuel fed to the engine and actually improved throttle response slightly. We increased the secondary accelerator pump shot by changing from a 31 pump shooter to a 35.

Now we had crisp response from curb idle. When we stomped the throttle to the floor at 1000 rpm in first gear, the car would take off and, once the camshaft came on at about 2200 rpm, those big 315 Goodyears got up in smoke.

Is this a great country, or what?!

Test Time

Though we always run our published quarter-mile times on 92-octane pump fuel; when we fool with jetting; we add race gas to protect us from detonating the motor if we've jetted lean. As we've done in the past, we called our friends at Trick Enterprises, a major supplier of race gas in the southwest. They provided us with 15 gallons 100-octane (R+M/2 method), Trick unleaded. We mix it 3:1 with pump fuel, because, with 10:1 compression, the resulting 94-octane is sufficient.

Virtually all “super unleaded” gets its octane from exotic chemical additives. Also, depending on where you live and the time of the year, gas is “blended” or “oxygenated”. We suggest, if you run pump gas in an aggressive engine with 9.5:1 or higher compression ratio and you are fooling with WOT fuel moisture, that you add 25% Trick racing fuel. If your c/r is up near 11:1, use at least 50%. For those of you wanting leaded gas; Trick has that, too, including one with 114 octane.

After going through nearly 60 gallons of our Tricked-up, 94-octane brew, we had the jetting squared away. It was finally time head for the drag strip to bottom line the switch to a single four-barrel. We screwed a fresh set of NGK R5674-7s into the Big-Block from Hell's 460 cubic inch rat motor and, with Mobil 92-octane unleaded in the tank, ran three passes. The best of the night was a 12.43/126.3. The e.t. didn't change that much, but we picked up four miles per hour. Obviously the Edelbrock Performer RPM and the Fuel Curve Holley 850 added a few horsepower.

At press time, we had completed 1/4-mile testing. Next month, we'll tell you about a trip we took that finished the evaluation of the Fuel Curve Engineering/Holley 850 carburetor's drivability and its affect on handling.

Shutting the Hood on the Big-Block from Hell

Sometimes, it's the little things in life that can make the Corvette experience downright enjoyable. Numerous times we've gone to cruise nights or Corvette club meetings and wished the BBfH had a light under the hood. Kinda dumb to have this expensive project car and nothing but a cheap little flashlight to show it off at night, eh?

It so happens that Eckler's has just the thing...a hood light (p/n A8289). It's really a stock replacement for '82s, but was simple to add to BBfH by drilling a couple of small holes and and doing a little wiring. Now we can show off all that snazzy Aeroquip plumbing and our trick carburetor at night!

What's really cool is that, when we shut the hood after displaying the fruits of our labor; that cute little light goes off, automatically. My, my...innovation and technology rears its ugly head.

Sources:

Aeroquip Corporation 3000 Strayer Rd. Maumee, Ohio  43537-0700 419 891 7600	Eckler's PO Box 5637 Titusville, FL 32783-5637 800-327-4868	Edelbrock Corporation 2700 California St Torrance, CA 90503 310-781-2222
Fel-Pro, Inc. 7450 N. McCormick Bl. Skokie, IL  60076 708-674-7700	Goodyear Tire and Rubber Co. see your local Goodyear dealer	Holley Performance Box 10360 Bowling Green, KY 42102 502-782-2900
K&N Engineering PO Box 1329 Riverside, CA 92502 909-684-9762	Motorbooks International Box 2 Osceola, WI 54020 800-826-6600	NGK Spark Plugs, USA 22 Mauchly Irvine CA  92618 714-855-8278
SX Performance #6 Sunnen Drive St. Louis  MO  63143 314-644-3000		Paul Oil Co.--Trick Racing Gas Box 248 Oakdale   CA  95361 800 527 6090