Well it has been a while since I last played with burning my own chips. Back then I had an 86 irocz and played with it a lot.

Anyway I still have some of my eprom gear and I have been asked to help out with a chip burn.

I would like to know where to change the setting for setting overdrive speed? basically we want to set the chip to allow for OD at 50mph and higher.

The only settings for the Automatic I can see are for the Torque converter. But I don't think these are the settings I should be playing with.

I don't recall changing this setting for myself so am now wondering if this is possible at all?

Maybe that is why I used to shift manually into OD once over 50mph.

 

OD is hydraulically controlled in the 700-R4.

 

Thanks JMD, so basically a mod to the transmission is the only way. Probably one of the reasons why I used to do it manually because there was no way. Even though this is for 88 vette they used the 700r4 also in the 4 speed automatic version.

 

The prom on my vette was made by Brian Van Schoiack,.............does anyone know what happened to him ?

may be a terminology thing here

Torque converter lock up at 50 mph NOT 35 mph

 

May be able to change the 3-4 up-shift valve and/or springs to get this to occur. I've never tried it so don't know how well it would work. In general need to counteract the governor out pressure.

As for selecting OD position, same here, I don't use it until the vehicle speed is over 45 MPH or so. Although with the stick in the D (3rd) position the overrun clutches are engaged. And not engaged in the OD position. So putting around with the stick in the OD position can provide for less jerkiness in the vehicle speed.

RBob.