</font><blockquote><font size="1" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">quote:</font><hr /><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Originally posted by DerekM:
<strong>----Sorry for the hijack Brown----</strong></font><hr /></blockquote><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">No worries, man-- we're all hanging out talking about timing and stuff! <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" />

I did retard mine to 2.5* BTDC this morning, and there was MUCH less pre-ignition. It's very driveable up hills now, and really-- all I have to do is not lug the engine up a hill, and I won't get the pebbles in a can sound. Still, I want to try going back to 5* with 89 octane gas. I'll drive it like this for ahile though and then switch, so that I can compare any mileage difference between the two scenarios in dollars per mile. <img border="0" alt="[Nerd]" title="" src="graemlins/nerd.gif" /> <img border="0" alt="[Nerd]" title="" src="graemlins/nerd.gif" />

All right, I still seem to be having some minor problems. After everything else mentioned above that I have done, here is what followed:

1- My initial impressions of driving with the timing at 2.5* BTDC were not as good as I originally stated. It seemed to help some, but not that much.

2- I filled up with 89 octane fuel several days ago. The spark knock is almost completely gone, but then again, the timing is still set at 2.5* BTDC. I still get some spark knock when the engine is under a load when I am accelerating.

If I set the timing to stock spec of 5* BTDC, it's gonna be worse. Seems to me that there is still something not totally right. So that's where I am right now. Any other advice?

Is it possible that you thought the chain had jumped a tooth so you moved your new chain accordingly, and now your vavles are closing too soon?

I don't really know how it would run with the chain 1 tooth off. Maybe this is a possibility...

Something else to think about: maybe your TPS needs to be adjusted since it does affect timing.

There are 2 things that made me realize that the timing had jumped suddenly. The first was that the timing was all of a sudden waaay retarded and therefore running very roughly. This is what caused me to tear into it initially after all the other ignition components checked out okay. The second thing, and this is what verified it for me, was that when I lined the new chain up, it would not match up with the marks on the sprockets-- it was exactly one tooth off. So, I had to slightly rotate the crank to get everything to line up-- and then made sure that the driver's side part of the chain was in tension, and the passenger side had slack. Anyhow, I'm pretty sure it's not that, because when I fired it up the first time after replacing the chain, it was only about 1 or 2 degrees off on the timing light (I had marked the distributor and put it back in in the same spot).

I've never adjusted the TPS-- I'll look into that to see how it affects things. Thanks for the advice. <img src="/forums/images/graemlins/kewl.gif" alt="" />