I have a 92 RS 305 TBI. Auto. 700-R4 I was wondering what would be the best time to shift. Usually i shift around 4 sometimes 5. Should i go farther or what?

 

i have a 5-speed myself, so i'm no automatic pro, but i'd put a shift kit in the 700r4, and let it shift on it's own in Drive. a shift kit should be around $50, and will definitely make a noticeable improvement in the way your auto shifts. I have a friend with an 88 305TPI auto IROC, and thats what he did. he was very pleased with the results. he just had a local tranny shop install it, its relatively easy for them to do.

 

That's going to depend on your setup. My TBI has the minor bolt ons needed to make power up to 5 grand. Therefore, first gear takes me to about 5100-5200, and the lower gears are about 4800-4900. If your 305 is bone stock, you might find that 4800 across the board is better. A good rule of thumb is to shift about 300 rpm past peak power.

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No guts, no glory.

 

You want to shift right before bad valve float so for a stock it would be about 5200 so shift the tranny manually at like 5000. The idea is that the next gear lands higher in your power curve.

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, Jon (350 TBI!)
91 Red My website

 

I have been shifting mine at 5500 with the mod's below. I might try and shift lower the next time at the track and see what the difference will be.I am using my stock tach and it may be off so....you may not want to go that far past redline but I got 161000 and still running strong.

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Trans Go Kit
Walker 3in Cat-Back (Gutted Cat)
Hypertech Chip
Cowl Induction Hood
Under Drive Pulleys
Open Element Air Filter
1/2 In TBI Spacer and
TBI Injector Spacer
Best E/T 15.442 @ 85.43

 

My friend has the same set-up as you and he says that it starts to breal up at about 4500 rpm. My 87 IROC does the same. I shift on the strip at 4000 rpm. I have tried it higher and it doesn't help in my case...........