h/c motor 10.1-1, hot cam. msd, STILL running like crap

[Guest sweething_2_5]

Hey all wow havent posted here in a while, heres the prob i have a 77 280z, bored .030. flat tops, hot cam .475 274, MSD 6AL, 60mm tb, cold air, no coldstart, headers, 2.5" exhaust.. umm i think thats about it. Its runnign rather rough at idle still even with the msd, i know with a cam my size it will run rough but theres more to it than that. I have little vac like 5hg and i cant find the leak anywhere, sprayed starting fluid everywhere cant find it. Should vac be this low at idle with a big cam? Timming is set at 10 degrees advanced. It also takes a long time to rev down the hammer in the afm isnt snapping back like it should it hangs there and lets down really slow. im so confused any help would be great!!

 

thanks

 

jason

[datsunlover]

My thought would be the AFM needs some adjustment... IMO, with that kind of work done to the motor, the stock AFM would not be very good.. You could try to tighten up the spring tension on the wheel inside the AFM.. or maybe play with the air bypass screw (I believe thats what it is..) in front of the throttle body? Thats all I can think about right now..

[Z-Gad]

Double check your oil pump drive spindle to make sure it is aligned properly. I have run into 2 motors which have been rebuilt (by others) in the last month where the oil pump spindle was a tooth off. It really screws up the performance.