Owning an Arnolt Bristol is a privilege, but keeping it running smoothly requires specific knowledge. This guide, based on expert advice from Jim McQuay, provides essential car tuning tips for Arnolt Bristol owners, especially those in the Bristol area. Whether you’re a seasoned mechanic or a passionate enthusiast, understanding the nuances of this classic car is crucial for optimal performance.
Ignition Timing and Spark Plugs: The Foundation of Performance
Proper ignition timing is paramount for any engine, and the Arnolt Bristol is no exception. The owner’s manual specifies setting the static ignition timing at 5 degrees before top dead center (BTDC) with the ignition fully retarded. Contact breaker gap should be between .010 and .012 inches. This might be slightly narrower than what’s common in other vehicles, highlighting the Arnolt Bristol’s unique requirements.
Original spark plugs were KLG P10L80 single-piece units. Suitable substitutes include Champion Z9 or Z10, and NGK C6E or C7E. Remember that a “6” heat range is hotter than a “7.” These alternatives are all 10mm plugs with a 5/8-inch head size and 3/4-inch reach. Crucially, the manual recommends a spark plug gap of .018 to .020 inches, again narrower than many other vehicles.
Carburetor Adjustments: Fine-Tuning for Optimal Performance in Bristol
Carburetor adjustments should be minimal for altitudes below 3000 feet if the original jetting remains unchanged. The Arnolt Bristol utilizes three carburetors, each with two idle screws. One screw controls engine speed at idle, aiming for 750 to 900 RPM. All three carburetors should be synchronized to draw equal amounts of air. This can be achieved using a unisyn or manometer. Alternatively, a mechanic can listen to each carburetor intake with a hose.
The slow-running adjustment speed screws should be adjusted until slight resistance is felt when removing a piece of paper placed underneath, then turned in one additional turn. The idle mixture is controlled by the mixture control screw, initially turned out one full turn. Turning it clockwise leans the mixture, while counterclockwise richens it—opposite of Amal motorcycle screws. Altitude significantly impacts jetting. For every 3000 feet of elevation increase, reduce the main jet by one size. Ensure the engine reaches 70 degrees Celsius before adjusting carburetors. Proper valve seating and minimal wear in valve guides are also crucial.
Troubleshooting: Prioritizing Ignition Issues
Experience suggests that poor engine performance often stems from ignition problems. While not always the culprit, the ignition system is the logical starting point for troubleshooting unless a different problem area is definitively known.
Car Tuning in Bristol: Finding Expert Help
Finding a specialist in Bristol familiar with the Arnolt Bristol’s intricacies is essential. These tuning tips offer a foundation, but professional expertise ensures accurate adjustments and optimal performance for your classic car. Consult with experienced mechanics in the Bristol area specializing in vintage car maintenance and tuning. Their knowledge will prove invaluable in preserving your Arnolt Bristol’s legacy.
In conclusion, maintaining an Arnolt Bristol requires attention to detail and adherence to specific guidelines. By understanding these tuning principles and seeking expert assistance in Bristol, you can ensure your classic car continues to perform at its best. Remember, proper maintenance and tuning are crucial investments in preserving the legacy of this iconic vehicle.
