I am looking to tune my 1985 TPI Camaro with a 305. It has a cam, headers. And all the emissions devices are bypassed or removed. I want to tune the timing curve for the cam i have. Obviously the computer controlled cannot be changed but can i put a vacuum advance distributor in its place? Then i would be able to adjust the curve. The reason i want to adjust is because at wide open throttle it seems like timing is retarding itself. I have verified base timing is correct and i bumped it two degrees to 8. That seemed to help the power a little but i still have a dead spot right at the top. Not really bogging just feels like it looses power. Like it looses about 100 horse but still accelerates.

 

How do you think the computer is going to know when to fire the injectors without the distributor? Hint: It's not.

 

The best mod you can make now is to upgrade from the 870 ecm $1f to the 86-89 1227165 ecm and run $6e mask.
Like drew pointed out the ecm is in control of the timing and you can change the timing table if you have the right hardware. Your ecm is outdated and uses a old 2732 prom. This can be upgraded to a flash eeprom but it’s not worth messing with such a slow baud rate ecm.

 

So the computer controlled distributor acts as an angle sensor for injector timing aswell? If thats the case then im better off going carb because i have a motor swap planned later on and all those parts will fit on basically every sbc.

 

Use your current motor to learn to tune and then after the swap you can take advantage of modern technology

 

dont lie!

 

Lie? Without a distributor reference pulse from the switching side of the HEI module in the distributor, the ECM has no reference for several critical functions, such as when to fire injectors, whether or not to run the in-tank fuel pump, what the engine RPM is at any given time, and a multitude of less critical supporting functions resulting from those data points.

 

Maybe you can figure out what my old man did because I don’t understand it. But I know it’s possible.