hks 272s with adjustable cam gears

[white90gsx]

I did some reading and they say that using adjustable cam gears serve no purpose because there supposed to be zeroed anyways...Well I love the idle loop that the cams give you I just aint hearing it so heres my question. I bought the car and the previous owner had it professionally tuned and the exhaust cam is almost all the way retarded is this right and is this the reason im not getting the loop?


Thanks Everyone.

 

[Boost92awd]

First off what is your idle set at? Also depending on how your cam gears are adjusted could make a difference. Which you cause less valve overlap. This is how your valve overlap works.

I'm just using this as a number I'm not exactly sure what the exact specs are. Your stock cams will have very little valve overlap. Valve overlap is how long both the intake and exhaust valve are open at the same time. So lets say that stock valve over lap is 55 degreez. Which means that both valves are open for 55 degreez of a full rotation of the crankshaft. With that little of valve overlap, your car will idle great and will pull hard in the low to middle RPMS and die off in the high RPMS. Now with your 272 cams, you will have a much bigger valve overlap, lets say 130 degreez overlap. Now both valves are open 130 degreez of a full rotation of the crankshaft. With the valves being open this long during idle is what causes the lumpy idle, because its not able to build optimal pressure in the cylinder. Which will cause your lumpy idle, not much power in the low RPMS and much better mid-high RPM power.

 

[white90gsx]

Yea now that you mention my idle could be too high to hear it..I'm not sure but I have it ripped apart already because I just bought it and its my turn to do it right..Needs a good cleaning..

 

[chrisAWD]

retarding the exhaust cam would result in more overlap. Your idle is just too high.