sabrooks

Hey, folks. I finally got my 91 back from having a 383 installed and a fresh paint job. Can anyone give me some direction on timing this TPI? I am running about 10.5:1 with 219/219, .560/.560 cam. 30# injectors, Edelbrock heads, Edelbrock intake and runners, custom tune, long tubes, etc. Could someone please get me started on timing? I know to unplug the ecm and I have a light. What would be a good starting point, as far as advance goes? Do I initially set at idle or at a certain rpm range (I.e. 2500)? Any advice would be greatly appreciated. Thanks in advance.

Shaun

l98tpi

Since you have invested in a 383, my advice would be to set the timeing at 8 degrees and take it to the dyno to get it tuned right. A custom burnt chip can get you close but to get the most out of your build it is best to do a dyno tune so the tuner can see what is going on through out the rpm range and adjust the maps accordingly.

sabrooks

Thanks a lot for the reply. I agree. I don't have anyone local, but there is one about an hour away. Is that 8* set at idle? Again, thanks for the response.

Shaun

l98tpi

Yes at idle in neutral.

sabrooks

thank you so much. I'm trying to find a tuner nearby.

aklim

Why 8 degrees? When I had mine dyno tuned, it was mistakenly set at 0 but he wrote it in the chip and it didn't matter according to him.

Edit. Wasn't his fault, I set it and didn't tell him.

aklim

I had that cam with the Superram system. With the 30pph injectors, when we started it up, it ran pig rich. Got enough to move it onto the trailer and shut it down.

In your post you said "custom tune". Why are you trying to do this if you have a custom tune? If you do, why not ask the tuner what he wrote the program for? If not, 30pph was a little large and smoked like crazy for my setup so I wouldn't drive it there. Tow would be better.

sabrooks

I had the chip built, based on the 30# injectors. That stopped it from dumping too much fuel, as it did before the injector reflash. After the engine was built, I had a leak at the distributor. When I pulled it out to replace the gasket, I got the timing screwed up and to start all over again. It is obvious that the car liked the advanced timing. Just a few minutes ago, I found out that the builder originally timed it at 38 degrees at 3500RPMs, which ran great. I have also emailed the tuner to see what was written into the program. I definitely need to have the tune customized with the help of a dyno, but in the meantime, I want to get the best performance possible.

aklim

Based on what did you come to that conclusion? Did you check for knocking under all the conditions under the curve? I would at least datalog it before being so sure. It might be good at one point and not the other, IDK.

Is that 38 degrees base or 38 degrees total advance? That sounds extremely high for a base timing. My car never ran right when the idiot mechanic gave it 19 base. Ran good at WOT only because I couldn't see what the ECM was doing to pull out timing when it saw knock. Lingenfelter was uncomfortable with what it was doing when he was adjusting it so he threw a timing light and found it was way out of line. As he explained to me, it would advance the timing to what was programmed and when it saw knock (engine damage possible), it would retard it a little and see if the knock went away. If so, fine. If not, it would pull another little bit away and see. IIRC it is at 2 degrees a time so knock can still hurt the engine till it gets to what it wants. Other tuning experts can chime in.

I wouldn't. I'd get it dyno tuned before worrying about best performance. A tune via email usually has a lot of safety written into it last time I investigated it. If they datalogged, they can go more aggressive than if they just guessed at the program based on some specs you gave them.

l98tpi

I am not sure why 8 degrees but my tuner told me to set base timing at 8 degrees so that is what I did. I would have put it at the factory 6, but he said it was best to set at 8. He is the pro at the tuning so I listen to him.

aklim

But that is for how he set up YOUR chip. Mine was set to 0 and he wrote the program around it so it is set for MY chip. OP thought it was set to 38 but that might be wrong. Just curious why you told the OP to set to 8 since factory is 6 and we don't know what the OP's tuner set it to. Not sure I would go with a SOTP setting since we don't know what the program was set up for. Many tuners go off 6 and others go off whatever they like. I'd probably see what the tuner wants, set it and then find a dyno tuner. 8, in my case would be too much.