[Doug Hopkins]

Originally Posted by Cliff R

Yes, EXACTLY zero decked, and ran flawlessly for several years. The customer was trying to super-fine tune it as it was his "daily driver" at that time. So he bought into the BS that advancing the cam makes the engine more responsive at lower rpms, and improves efficiency, more torque, etc. (He'd have been better off to fine tune the vacuum advance and APT instead, but that didn't happen.)

That's a great theory, but my own testing with moving cams all over the place doesn't follow that logic. The 455 is a HUGE engine, with too much stroke and relatively long rods in it. Piston speed is super-fast, and they are very sensitive to the intake closing point, LSA, and actual seat timing. With tiny heads supporting them (by modern standards) they quickly pinch off a LOT of upper mid-range and top end charge advancing the cams in them. They also very quickly become octane sensitive trying to improve cylinder filling at low rpms.

My own engine has SD"s Old Faithful cam I it, idles nearly smooth at 750rpms, tach barely moves when placed in gear, and ICL is 109.5 degrees. SCR is also 11 to 1, and it EASILY manages 87 octane fuel on a daily basis. I put better fuel in it on my way to the track, but it actually slows the car down about .04-.05, but I do sleep better at night.....Cliff

Here's a clip from Norwalk, with initial timing at 6 degrees (26 total timing), and shifting at 5000rpm's to stay roll bar legal. Notice that it still idles smooth in and out of gear at 750rpm's, and I'm NOT using MVA to run the timing clear off the scale, ported vacuum to the advance instead.....

http://www.youtube.com/watch?v=6zVdoLR-VzM

Hi Cliff, Was wondering what rear gear ratio and tire size you are using to acheive the numbers you are running and what kind of RPM in the traps. My combination that i am building is similiar to yours, only my car is about 200 lbs. heavier right now. Mine has a 3.23 gear in it, and I found a 4.10 Richmond gear for $50, tire is a 28 in QTP Hoosier. Bought the gear and have not installed it yet ,and was thinking it might be too much. I was thinking a 3.90 would be about the max. What are you thoughts on the gear ratio. Not worried about highway use, only over revving on the track on the top end.