Posted By: Scott Carl
Here we go again; More cam questions - 05/03/10 04:10 PM
I thought I had this resolved in my mind until I read the article on AllPar.com about performance upgrades for the 318. They claim that anything more than a .430-.455 lift will kill low end power. Here's my delema. I'm currently running 2.76 gears behind a 904. My 318 will have a 600 cfm Carter AVS on a stock cast iron intake. I was going to go with Cam #1, but was told I will require at least 3.31 gears and better with 3.55 to make it work.
Given the claim of the allpar article, would I be better off with something like Cam #2? Could I maintain my 2.76 gears with this cam? The car (sig photo; '74 Challenger) will mainly be driven on the street on week-ends through the local Sonic and such, but I'd also like to take a road trip or two without breaking the bank at the gas pumps on the way. Will the bigger cam with the lower gears really kill my mileage? Or am I splitting hairs on these to cams? I want to maintain decent low-end power but I don't want 3rd gear wound up so tight that I can watch the gas gauge fall as I drive on the interstate.
Specs:
Cam #1 CCA-K20-223-3
Basic Operating RPM Range: 1,600-5,800
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Duration: 268 int./280 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh. lift
Lobe Separation (degrees): 110
Cam #2 CCA-K20-221-3
Basic Operating RPM Range: 1,000-5,200
Duration at 050 inch Lift: 212 int./218 exh.
Advertised Duration 256: int./268 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.447 int./0.455 exh. lift
Lobe Separation (degrees): 110
I know the mileage will suffer a bit due to the upgrades anyway and there are a lot of factors I haven't included here, but I'm just trying to get some informed opinions. Thanks for taking the time.
Scott
Given the claim of the allpar article, would I be better off with something like Cam #2? Could I maintain my 2.76 gears with this cam? The car (sig photo; '74 Challenger) will mainly be driven on the street on week-ends through the local Sonic and such, but I'd also like to take a road trip or two without breaking the bank at the gas pumps on the way. Will the bigger cam with the lower gears really kill my mileage? Or am I splitting hairs on these to cams? I want to maintain decent low-end power but I don't want 3rd gear wound up so tight that I can watch the gas gauge fall as I drive on the interstate.
Specs:
Cam #1 CCA-K20-223-3
Basic Operating RPM Range: 1,600-5,800
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Duration: 268 int./280 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh. lift
Lobe Separation (degrees): 110
Cam #2 CCA-K20-221-3
Basic Operating RPM Range: 1,000-5,200
Duration at 050 inch Lift: 212 int./218 exh.
Advertised Duration 256: int./268 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.447 int./0.455 exh. lift
Lobe Separation (degrees): 110
I know the mileage will suffer a bit due to the upgrades anyway and there are a lot of factors I haven't included here, but I'm just trying to get some informed opinions. Thanks for taking the time.
Scott