Mustang MonthlyHow To Tech Qa
1967 Ford Mustang 289 C-code & 1970 Mustang Boss 302 - Beyond The Basics
Vintage Mustang Tech Advice From Bob Aliberto
Intermittent Brake LightsMy question is about the brake lights in my '67 289 C-code, C4 auto Mustang. Last spring, I replaced the entire four-wheel manual-drum system from the master cylinder back, including new drums, wheel cylinders, and even stainless steel lines. Initially, my brake lights didn't work, so I replaced the brake-light switch. The lights now work, but only intermittently on the road. They're fine when the car is stopped and work with the engine both running and off, but they come on sometimes when stopping on the road. Could this be a short? I am uncomfortable not knowing if my brake lights work.Barry RutmanApple Valley, MN
I believe your brake lights work all the time as long as enough pressure is applied to the brake pedal to activate the switch. Some brake-liquid switches require a lot of pressure in order to work and do not function with the light pedal application typically used during low-speed, around-town driving. Apply the brakes hard while sitting still. Repeated applications should illuminate the brake lights every time.
Brake-light switches for power-brake-equipped vehicles require less pressure to operate, so a different switch may help cure your problem. I have removed the plastic bushing from the master cylinder's pushrod to the brake-pedal pivot to create more movement of the brake light; however, the installation of a power-brake switch is a better fix.
Looking For A MasterMy wife and I have a '66 coupe that needs some brake work. I think the master cylinder is going bad. I get a decent pedal when I pump the brakes, but the longer I sit in Drive with my foot on the pedal, the pedal gets soft and slowly sinks to the floor. There are no visible leaks at the calipers or wheel cylinders, so I'm figuring that leaves the master as the culprit.
My problem is I can't order a new master cylinder without knowing the build date of the car. We are at least the fourth owners, and the car has been in several accidents and minor restorations; therefore, I have no buildsheets. The doors have also been replaced, so I don't have a correct data plate either. The VIN is 6T07C195493. The car has a single reservoir with manual-disc brakes. Any help you could give in locating a new master cylinder would be greatly appreciated.Rich and Barbara WozencroftMedford, NY
Your diagnosis is correct. If there aren't leaks in the calipers, wheel cylinders, or the rest of the hydraulic circuit, there is an internal leak in the master cylinder causing the sinking brake pedal. The master cylinder is available from Cobra Automotive (203/284-3863). Early-car disc-brake master cylinders are the same, with small differences in the fitting area. Call Cobra Automotive with a description of the fitting, and your situation will be resolved.
Racer BossI have a '70 Boss 302 that I'm preparing for nostalgic road racing. I'm going to stroke the motor to 347 ci, which I know will increase torque. I was thinking about using Hooker Super Comp headers with 151/48-inch primaries. Would tri-Y headers for that dealer-installed look reduce performance much in conjunction with 211/42-inch pipes, X-crossover, and Flowmaster 50 Series three-chamber mufflers with 3-inch tailpipes? I will be adding roller-tipped rockers with needle-bearing fulcrums to use with the stock mechanical cam. The 780-cfm Holley has been replaced with a 735 of the same type, which should be sufficient.
I originally purchased a Hi-Po 289 clutch assembly from Ford before I thought about stroking. What do you suggest? I'll be keeping the 3.50:1 rear gear.
I lowered the upper control arms two inches and installed caster correction wedges and 429 springs with 111/42 coils removed. I intend to install five-leaf performance springs out back, which will lower the rear 111/42 inches. The shocks are KYB all around with Midolyne bushings throughout the suspension. The stock front sway bar is 151/416 inch, and the rear is 11/42 inch. Will increasing the front to 1 inch and the rear to 31/44 inch make a big difference? I will also add subframe connectors and possibly rear discs down the road.Steve SlutzkerPittsburgh, PA
I agree with most of your proposed modifications, assuming you're building a vehicle for both limited street and road racing purposes.
The stock Boss 302 will certainly benefit from increased displacement, as the large ports and valves can easily handle 347 cubes. The stock camshaft should be replaced with a modern computer-aid designed unit, as much has changed in camshaft technology since 1970. The Hooker four-tube headers will work better on a race-prepared engine than the tri-Y design because the long, equal-length runners will be necessary to handle the exhaust flow from a high-rpm engine. Race-designed tri-Ys are available and make good power; however, they are quite expensive compared to off-the-shelf Hooker headers.
I suggest a new blow-proof racing clutch, as the stock Ford units were never designed for track use and are prone to explosion at high rpm. Racing clutches are still quite streetable, inexpensive, and readily available for your application. Use of a scattershield for extra insurance, even with the racing clutch, is highly recommended.
Your suspension modifications are OK and will be complete with the addition of the lowered leaf springs. You may find the front spring rates are a bit much and the stock sway bar a little too small. However, fine-tuning the suspension must be accomplished at the racetrack. Small changes in sway-bar diameter can affect the car's handling considerably, so wait until you run the car before making a sway-bar change. Because any improvement in body stiffness and overall braking enhances track performance, subframe connectors and rear-disc brakes are also good ideas. Try to make small changes, and remember streetability will suffer with each race-only modification.
Send your questions to: Beyond the Basics, c/o Bob Aliberto, P.O. Box 205, Salt Point, NY 12578. E-mail us at email@example.com.
Back IssuesTo order back issues, write to:
Back Issues2100 E. Howell Ave., Suite 209Anaheim, CA 92806
Toll-free mail-order phone: 866/601-51998:30 a.m. to 5:00 p.m. PST Mon.-Fri.
Back issues are $5.99 plus $2.00 shipping and handling.