You guys with large cams please post what cam you have, engine size and driveability and idle rpm. Also post torqe and hp curve.

 

Thats asking a lot...

But at one point I had an isky 270 mega flat tappet (221/.465/108 LSA) with a victor-e and 1000 CFM 4bbl TB, vortec SFI, etc.. Pulled around 10 inches at idle, drivability was ok with the proper amount of part throttle spark and throttle follower. Those really help to make the loss in torque more "transparent" to the driver under normal driving conditions. The car is a stick with a curb idle speed of 725 RPM with the old cam, which is the lowest my TB can do with the IAC closed. The only other thing that would lower it is reducing the SA at idle, but that makes things like the stall saver action a little more tricky to handle.

Fuel economy was terrible. Only 12-14 in the city. The overlap kills the fuel economy as it bleeds off cylinder pressure at lower RPMs where it matters the most. My next cam was a small "xtreme" energy 256 4x4 roller. Power down low was much better, and fuel economy was around 22-24 in the city, so it does make a big difference. Current cam thats soon to be in is an XE 270 roller so Im going back to more overlap, and worse economy.

As for how it will impact your setup, what will you be running around the cam? That also matters. Its not "buy a nice cam" and stuff it in a pukey LO3 with a stock exhaust. Its all gotta match for everything to work well all over.

 

Mine isn't big, but it might help you decide. LT4 hot cam with an Accel single plane 1000cfm 4bbl throttle body. Idles perfectly at 700-800 with a slight lope. Not sure what the vacuum is but my idle specs are 700-800 with about 20* advance and it has a MAP reading of 30-35 kPa. I cant drive it to well below 1300, but I only go that slow when I am crawling through a parking lot...

 

I have the Comp Cam 294 and it's terrible on gas, but the setup will snap your neck back with my 383. That's all was shooting for anyways. I probably only get 10mpg running on 93 octane, but it's not a daily driver so no big deal.

It idles around 1200 and in drives around 900, any lower than that it doesn't want to run right - I assume not enough vacuum. Don't know the numbers or the power curve, all I know is what it does at the drag strip......no dyno tuning needed here.

Camshaft Part # 12-443-8 Grind # XR294HR-10
Duration @ 0.006": 294° / 300°
Duration @ 0.050": 242° / 248°
Max Lift w/ 1.5RR: .540" / .562"
Lobe Separation: 110°
Lobe ID#'s: 3317 / 3318
Intake Centerline: 106°

 

i have a comp cams xr274r solid roller, my idle is around 675, cant remember how much vacuum at idle but have no problem with breaking and still has a real lumpy idle, its in my 406 sbc with 11:1 comp and a holley 750 with a vic jr and afr heads heres the specs

intake exhaust
Duration- 274 280
@.050 236 242
Valve Lift 564 570
Lobe Lift 377 381
Lobe sep-110*
rpm range-2200-6200