jacobcartmill

iTrader: (6)

i borrowed a timing light from my friend and checked the timing on the FC (91 gxl) with the intent of running 6 or 7 degrees more timing. so i turned the CAS clockwise and the mark on the crank pulley (only one mark.. ?) moved towards the passenger side about 6 or 7mm's (just making sure that i'm advancing it instead of retarding it).

1. how many degrees is 6-7 mm's on the crank? i was thinking that a 1cm advance is about 9 or 10 degrees.

2. how much advance can i run on stock fuel?

3. can i turn the CAS as far as it will go? it looks like it will only advance the timing 10-12 degrees at full lock.

4. is it a problem that i only have one mark on my crank pulley?

jacobcartmill

iTrader: (6)

13 views and no replies. come on people

Turblown

iTrader: (12)

On the stock pulley there s/b 1 red and 1 yellow mark. On my rx7.com underdrive pulley, 1 inch is like 10 degrees on the pulley. I don't know if they are the same diameter.

jacobcartmill

iTrader: (6)

so can i turn the CAS clockwise to full lock? how many degrees would that advance me?

Project84

What color mark do you see? There should be a whitish yellow one for the lead timing, then about 1/4 inch behind that (to the left, or counterclockwise, how ever you want to call it) should be a red one for the trailing timing.

dr0x

Yes... when you want to advance more than what twisting the CAS allows you have to pull it out and restab it to offset the gear. You have another, you just cant see it. Run your finger nail around the pulley (when the car is off...) starting from the mark you do see. You should feel a second indent, throw a little paint on it

Henrik

360 in one rotation, IIRC the dia of the pulley is about 3.5", mult by pi to give circumference ~10" so 1" is about 36 deg.

Verify the dia though as I'm not sure if its 3.5" and recalc.

Henrik
87TII

jon88se

too much advance = pop goes the motor, i learned the hard way

jon88se

too much advance = pop goes the motor, i learned the hard way

Project84

It is possible to set the timing to where it could ignite the air/fuel in the pocket while the apex seal is below the trailing plug and above the leading plug. The trailing plug igniting the oncoming air/fuel mixture will try to spin the rotor backwards.

jacobcartmill

iTrader: (6)

hey drox i found the other timing mark on the crank. i just turned the timing back down and lined up the leading mark then the trailing mark. i'm gonna leave it at the stock -5 btdc until i can get a non-ghetto timing gun.