Well i just got a 87 iroc and found that the harmonic balancer had slipped.

so i replaced the balancer and turns out the old one was actually aftermarket and had built in total timing marks.

now with my new oem style balncer in i forgot to check where the mark was initall for base timing but i set it to 10btdc.

is this to high? i know 6 is stock

im not 100% but it almost feels a little bit more sluggish now that ive messed with the timing.

and i honestly dont know how it was timed before beings it had total timing marks.

What makes you think the old balancer had slipped?

it had slipped. the inner ring was showing it had slid back.

anyways it has the new one now which is the same weight as the aftermarket one that was on it.

but what im getting at is that now that i set the timing to 10*btdc and now i just brought it back to 6*btdc

its just not turning tires like it was before i touched the timing.

the thing is it didnt idle any higher before and if the timing was advanced beyond 10*btdc the idle would have been high but its the same idle speed as it was before and how it is now.

What replacement balancer did you use? It may not have the timing mark in the right location for your timing comb.

http://www.napaonline.com/MasterPage...+Balancer+Assy

i bought it through napa. matches up with my year and engine 5.7 tpi vin 8

but that link is the p/n of the exact on i put on.

sorry to double post but i also just relized that the balnacer i tought had slipped actually didnt. aparently thats how its made with a lip showing. i just lookat at the same one on summit... humm well crap. at least it wasent any lighter then the one i put on.

still im puzzled as to why my power is now suffering from setting the timing and im 99.9% sure that the timing mark is in the right spot. like i said the idle speed is the exact same as it was before. but my performance. is deffinatly kicked down a noctch.

Did you find out what the problem was . My car has the same problem

Aftermarket balancers don't always have the timing marks printed on them correctly. To check you will need to find true TDC using a piston stop through the #1 spark plug hole and ensure that the zero mark is EXACTLY half-way between your piston stop points when approaching TDC from either direction. No this is not a fun job but there's really no other way to check it if you suspect the balancer is incorrect. Ruling it out is a must.

Also in regards to the 2008 comment about the idle speed changing with added timing - this is incorrect. On a TPI the ECU will adjust the idle speed back to where it wants it in the software.

GD