Not quite ready to pull the trigger on EFI? Still not convinced those throttle bodies look like a carburetor? If so, now is the time to super-tune your engine with these analog tuning kits from Speedway Motors. Improve horsepower, torque, and acceleration, while learning how to get the most out of your engine...the old fashioned way (just like Mickey, Smokey and Grumpy used to do...the mechanics, not the dwarfs). All Holley 4160 Series carbs are shipped with a “base” tune designed to get you up and running. The “base” tune is for an average combination, resulting in average performance. Our DIY super-tuning kits help you optimize your Holley vacuum secondary carburetor (and ignition...in stages) to unlock the full potential of your unique parts combination. Super-tuning a carbureted engine typically involves adjusting 3 circuits – the transition circuit (acceleration), power-enrichment circuit (load) and the main circuit (RPM). This tuning kit includes everything you need to activate all of those circuits, but on the secondary side. Tuning the open-rate of the secondaries can make your vehicle more responsive and enjoyable to drive. Kit Contents: Holley 20-59 Cover-Diaphragm Housing 1 x 4 BBL Allows you to change the secondary diaphragm spring without disturbing the diaphragm Cover-Diaphragm Housing (Quick Change) Expedites Changing Of Vacuum Spring. Holley 20-13 Secondary Diaphragm Spring Kit Allows changing the rate of the secondary operating ranges Holley 135-4 Secondary Diaphragm Secondary diaphragm replacement for vacuum secondary 4160 series carbs.
