[pi71]

i just got the car and it came with a rpm performer, mostly stock cam , 600cfm carb, headers, hei, i prefer cruising and low end power, should i get rid of the rpm performer for a performer? 67 cougar,3.00 gears.

[One Named Fishin']

I cant imagine changing the intake just a level or two would make a huge difference though it would be somewhat better. Your gears are definitely for cruising and will probably not allow your engine to reach the range where the taller intake performs best.

Combinations are the key. If you are looking to make a difference in performance, get a matching cam and lower gears. Otherwise, save your money and keep the intake you have.

[red65mustang]

agree, it won't make a big difference for normal rpms to put on a performer....

this chart attached is from Fletch's 5.0 site from a magazine long ago...the green line would be close to a RPM intake (hi-rise Ford 289)

changing the gears directly "multiples" the torque applied to the rear tires for more push you back in the seat at all/any different rpms....

3.00x300ft/lbs= 900ftlbs of force on the tires
3.50x300ft/lbs= 1050ftlbs of force
-----
150ftlbs diff
????? ever "try" to torque a bolt to 150ft/lbs....it's ALOT of force

you really feel the difference because at 2k rpms, the torque is only roughly half the max but the gears multiply what is there

[pi71]

thanks guys , i was told the bottom end power would suffer and it would bog off the start. i agree with yall. (texas term)

[FEDDO]

smaller carb would give you more port velocity. the original autolite carb would be a good place to start, 480 cfm.