I am trying to find the base timing for an 87 IROC 350 TPI. Does anyone know what it is and if its anywhere on the site? I couldn't find it, and it would make a good article if someone knew it.

Note: I am looking for the factory base timing.

 

I am not sure what the factory timing is, but anywhere from 6-10 should be good. make sure that you disconnect the EST wire before you set it as well. Once set, plug the EST back in and reset the ECM by pulling the fuse.

 

I would be almost certain it's 6*. Apparently it's written on your emissions sticker on your hood (you know, the one that's most likely not there anymore lol).

Even the factory service manuals tell you to check this sticker without telling you what the timing is. Seems kind of lame they wouldn't write it down anywhere else.

edit: Oh and my understanding of how our timing works is the base is just like a default that your computer bases it's adjustments off of. The ecm can't tell what you set the base timing too but it operates under the assumption that its at what it's supposed to be. Advancing it past where it should be just causes the computer to unknowingly advance it too far during operation, causing a possible ping which causes it to retard when if it was set at the proper base timing, it would most likely not have "knocked" and had to retard. So performance wise, you are better off leaving it right at spec (which if you can't find it, 6* is typical base small block timing).

Of course every car is different, yours may actually run better or worse if you change it outside of spec. I may also be completely wrong about what I wrote above but Im pretty sure it's accurate

 

hmm, i will try that, but since I reinstalled my dizzy, the only place it seems to idle is around 14 advanced. Am I 180 off ?

 

You can't really install a distributor 180* off and have it run at all. Cylinder #1 on the cap should be a little right of 6 oclock when youre looking at the engine. As long as that's around there, it's not installed incorrectly. Double check your firing order too.

Are you unplugging your est wire when you set the timing?

edit:correcting my info, getting a little mixed up now that Im thinking about it lol

 

Ok, I must be doing something right because I can get it to idle, it just idle's like crap with the EST wire disconnected. My Concern is that i cannot turn the dizzy far enough to get it to 6 degree's for base timing. It wants to idle at something around 20.

On a side note, perhaps this is relevant: I have an autoxray scanner connected to it and i am reading the spark advance from their. I know that is coming from the ECM, so would guessing it would be better to read this from the base timing from the Harmonic Balancer instead ?

Today i am going to TDC, and pull the dizzy one more time, and mark 6 degree's on the HB and try to time it from the balancer.

 

Ya, for your base timing you HAVE TO set it according to the balancer, that's what base timing is. You also have to disconnect your est wire when you set it from the balancer, its a little brown and white wire (correct me if im wrong someone) that pops out of your wiring harness on the passenger side of the engine, goes to a quick connector and goes back into the harness.

If youre trying to set it to 6* according to the computer, that's way off, if the scanner is showing 20* advanced, youre probably atleast 10* retarded on your base timing.

 

I don't know how far you've gotten on this but as was said unless you know what the ECM's base timing is you can't use the scanner to set mechanical base timing.

You don't need to mark the HB 6° from TDC you need to set it 6° (or whatever it's suppose to be) BDTC with a timing light.

If you can't time it with a light by just turning the Dizzy a little bit then most likely the chain has jumped a tooth, or 2 assuming you stabbed the Dizzy with the rotor close to the #1 wire tower on the the compression stroke when the HB TDC mark was aligned with the timing tab zero mark.