Carbs N Cams
Guide To Proper Cam Selection
Taking it away from stock isn’t a hard job but one that’s going to take a little time for thought. You have to ask yourself just what you want to accomplish: Are you building for the street, the strip or towing? If your build up calls for 2×1; 3×1; 2×2; or 4 barrel carb (keep in the 390-500 CFM range,) then the following chart should help. This information is a compilation of input from Stovebolt and Clifford Performance.
Performance & Economy
Stage 0 Tuning
For absolute best idle quality and torque below 3000 RPM the factory cam is the best. Improved intake is recommended and will result in improved performance throughout the RPM range. When installing improved intake, make sure either exhaust heat or water heat is provided to the floor of the manifold. This may be your best choice for heavy duty towing.
Stage 1 Tuning
Good mileage can be retained by using a camshaft of 254 ° to 264° of duration. These camshafts will idle well and produce very smooth low R.P.M. torque but represent a slight loss of torque below 3000 for a very significant power gain above 3000 RPM. We usually suggest using a hydraulic cam when possible in this type of application. Stick or automatic transmissions OK. Improved intake highly recommended to fully complement the camshaft. When installing improved intake, make sure either exhaust heat or water heat is provided to the floor of the manifold.
Stage 2 Tuning
A good overall combination of performance and mileage is attained by using a cam of 260° to 272° of duration. We recommend using exhaust headers and an improved intake system. Hydraulic grinds are best. Stick or automatic transmissions as noted. Agressive axle ratioand 5 speed.
Camshafts 280° of duration and larger are considered high RPM cams and require a correct combination of modifications to perform properly. Manual transmissions only. This is not for street use and should not be used for 235 and 261 street engines.
Stage 3 Tuning
1) Oval Track
All 1/5, 1/4 and 3/8 mile short flat tracks with engines that have limited carburetion (i.e. 1,2 or 4 barrel carburetion) and have less then 250 cid should use camshaft grinds of 270°-280° or 280°-290°. The larger engines 290 cid and more can use grinds of 280°-290° or 290°-300° depending on track and carburetion used. Headers and head work a must!
All 1/2 to 5/8 mile large fast tracks with engine displacements of 250 or more can use 290°-300° or 300°-310° grinds. Carburetion of large 2 or 4 barrel or multi-carburetion is best. Headers and head work a must!
2) Drag Racing
All limited carburetion engines with 4 barrel carbs should use moderate grinds of 290 to 310 duration. Automatic transmissions can be used ONLY if stall speed is increased to 2800-3000 RPM.
All unlimited carbureted engines with multi-carburetion (Webers, 4 barrels, etc.) can use large cams. Most engines of 250 id or more work best with 320°-330° dual pattern grinds. Lighter chassis cars of 1500 lbs. or less can use 330°-340° grinds. Headers and full head work a must!
A big thanks to Clifford for the use of this information!
If you need further help give us a call at 1-586-739-9601.
We would be glad to sit down and help you with your cam spec.