JR, just don't go overboard. Our SC is not designed to spin much over 15,000rpm. My 178/70 spins it at 15,750 right near redline. That is where I run a bit lean but I gave in and ordered a set of NEW BOSCH 550cc injectors and jerry will be doing the tune soon. I do not go to the track but I love the extra bottom and midrange power the pulleys I have give. The 70 is smaller than stock and the 178 crank pulley just enhances that 70 giving the motor more power in the range I want it, passing. Right now, staying in a good AFR range and that is partial throttle 100mph comes very quick. I should have the 550's and the tune in by mid October. I am hoping Rob has something on those headers by the end of october.
Let's face it. These cars do not have the potential to be especially quick. many new cars are much quicker off the showroom floor, however whether you have a Crossfire or an SLK you have a unique car. For me if I get into the 11's I will be happy as that is about all they will do. Remember the 178/70 is about the same as a 62mm SC pulley and Rob said that guys with the 62 pulley probably run lean or they don't have a wideband so they don't know. Running a 65mm SC pulley with whatever crank pulley that is larger than stock requires a lot of mods and patience.
If I can get the n550's to give me an AFR of 11.5-11.9:1 I will be pleased and then concentrate on the exhaust. maybe the headers will allow a few to get to the 11.5et which is over 120mph in the 1/4 mile. My track days ended back when big block muscle cars were sold as used cars that got terrible mileage when we had the oil embargo. Could have bought a '67 Dodge R/T with a 426 HEMI for $1300. I got my first muscle car, a '66 buick gran Sport for $450. from the original owner. back to the future. We are limited by the SC. If these cars had a turbo the power would be limited only by the short block's strength.
Stay with the 178 crank and the stock SC pulley or go for that extra part throttle power that I enjoy, choice is yours. I know you have been wrestling with this for some time, make a decision and stick with it. For me it is to get the 178/70 to run at it's full potential. Mark