I was referred to this forum from another site and hopefully learn more about my TPI. I've searched and haven't found what i am looking for. Sorry if i'm in the wrong forum.

I am getting ready to fire up my 383 TPI in my Jeep. I need to know the proper procedure for setting the base timing for the initial start up and the adjustments after start up.

I had the ECM programmed for my cam, 30lb injectors, and ordered a custom harness. I'll try to provide any other info you guys may need.

Please start schooling me on TPI's.

 

6* is a good place to start, this is the factory setpoint for the TPI.

 

Plus ask who ever did your chip what they based the base timing on. As already said, 6* BTDC is the "standard".

 

I'm still searching trying to learn a little more about the TPI timing.

Like said earleir.........6* BTDC is the factory. Right now I have #1 at TDC.

I was reading earlier about disconnecting a wire when setting timing. Which wire do ya disconnect?

Anybody ever delt with this guy


custom efi

 

If it's anything like tha factory harness, you should have a connector that looks like this. It must be disconnected to set the timing. Thne you'll have to pull the battery negative cable for a few minutes to reset the error code/check engine light that running with the ESC disconnected causes.

It will be a round barrel single wire connector, brown and tan if I remember correctly.

 

Thanks vernw.

I have a barrel connector that is wired with the 4 wire connector on the distributor. I think that is the one.

I feel like i need to be in a newbie section.

Thanks for the help.......I'll keep searching for more info.

 

I believe the factory manual also calls for jumping the A and B terminals at the ALDL port while setting timing. Not sure why. I have tried it with the pins jumped, and without. Never really noticed a difference in anything.

You should have your base timing set to whatever it was set to in your chip. If you set it to something else, it might idle a little better depending on what is programmed in your spark table, but it will also move your timing throught the rpm range. For example, if its set to 6 in your chip and you move the distributor to 10, then there is a difference of 4 degrees. You timing will be 4 degrees more than it is supposed to be everywhere. If your chip was well done, thats not a good thing.

 

With my 383 its weird. I have to set it at like -2*. Anything 0 and above gives me valve chatter on a hard takeoff.

 

If you do things the right way and have a chip setup for your application, you set the timing at the base reference angle, usually 6 degrees, as already has been mentioned. Messing with base timing was for back in the day when DIY prom tuning was not available.

 

What would changing the base timing on the car and changing it in the .bin, too do anyway? I mean, if you left all the spark advance tables and everything alone, would it change anything?
I'm just curious because I'm about to check and set my timing and was wondering if there are any advantages to changing that?

 

Think about it -- No. The only reason the base reference timing is not zero degrees is because an engine will probably not idle w/ the throttle body at the minimum idle setting at zero degrees. This would make setting the base timing very difficult. Some advance is necessary to keep the engine running with a closed throttle -- 6 degrees BTDC allows this. If you set your base timing to 10 degrees BTDC and changed the base reference angle in your bin editor to 10 degrees, nothing has changed -- the computer only needs to know the correct base timing to calculate total timing relative to TDC off of. The only way you could find an "advantage" to running base timing other than 6 degrees (and properly reflecting this in your bin) is if you had a really cammed up engine that would not idle steady enough to set base timing at 6 BTDC. You could bump base timing up to like 15 or 20 BTDC and then change the bin to reflect that.

 

OK, makes sense now that I read your reply twice. I thought you were talking about it idling with the ESC connected, but I realize you mean with the ESC disconnected. I have had my motor set at 20* base timing, but just recently installed my prominator, and still have been running the factor .bin setting of 6*. I'll see how far I can turn it back and see if it will even run steady at 6* with my cam. And if not, I'll just set it accordingly in my .bin. I wonder how my engine liked being 14* advanced on all my values all this time. Thanks for the insight!