Big Cam No Vacuum

Dan B. said
The timing is set at 36 degrees total. According to the Dyno this seemed to work best with the NOS. The cam is a roller cam. .288 intake. .292 exhaust duration, and .501/.513 lift. 1.6:1 rockers. 439.5 # Torque and 343 HP at 4100 RPM. and 398.6 # at 5400 RPM and 409 HP. These numbers are without the NOS.

Dan B. said
Here is the engine specs.... 390 hp. Magnum Crate engine. Thermo-block is bored .020 over. Magnum R/T Big Valve cylinder heads. Mopar cast Al. valve covers. High strength SS Valves, 2.02" Int., 1.62" Ex. Heavy duty valve springs. Hydraulic Roller Camshaft- 230'/234' Duration @ .050"/0.513" lift. pistons 9:1 C.R. Double Roller timing chain and sprockets. Single plane manifold w/650 Double pumper. 150 hp. shot of NOS. Line lock. 3000 rpm stall. Hughes racing transmission w/B-M floor shift. All MSD ignition. MSD 6AL Control box w/MSD pro-billet distributor. Blaster 2 coil. 8 3/4" rear with 2.73 gears. (had 4.11 but changed them for better cruising). Dyno: 439.5 ft-lbs at 4100 rpm. 409 hp at 5400 rpm. Fun to drive.

Given all this. There is ABSOLUTELY no reason you should have power braking problems. That cam isn't big by any means. I run 230/236 @50 cam and run power brakes no problemo.

Dan B. said
I had a friend that runs Pro Stock do the tuning for me so i'm pretty sure he set it up to run the best over all. (he owns a shop that specializes in racing engines) Although he probably did not tune it to get the max vacuum. I checked the vacuum and it was about 15" at idol 600 RPM in gear) however it was not in gear.

Your post is a little confusing here. Was it in gear or not in gear? 15" of vacuum at 600 rpm doesn't sound quite right. But that cam should have in the area of 12-15" at idle around 900 rpm I would think. Double check what your vacuum is at idle in gear. Your in gear idle should be 750-850 rpm minimum I would think. Personally I prefer to idle mine at 850-900. I occassionally have even played with it at 1000. Check your initial timing. That cam you should be 18-22 as a starting point. Tune for best vacuum. Then re-time your distributor to get your total back at 36.

Which brake booster are you running? The chrome or the black one? I run a 73-76 k member with power brakes and I get 3 FULL hard brakes out of my booster before it's out of juice.