Have F.E.D. sbc/pg shift @6200 fallback to 5200 is this to much.How would I change this? Using dextronVI. This old stack injection on alky Runs 5.60s 118-120 mph

I prefer about 800 but 1000 I wouldn't call TOO much. JMO

It is probably too much - do you have any dyno information or idea where peak torque and horsepower are?

I prefer to see 6-700

quote:

Originally posted by Al Alguire:
I prefer to see 6-700

Keeps it happy!

^^^^^ X3. SLR can make it change as well. Make sure you’re geared for the desired finish line rpm.

That converter is way too tight for a small block, IMHO. If you tried to shift it at 7000 does it still fall back to 5200? I suspect it would. IMHO that converter needs to be loosened up 1000 rpm.

Good topic!

I need to address our convertor sometime in the near future. ProCharged SBC with glide/1.76, 3.89 gear & 30" dia. tire.

It is shifted at 6,900 rpm & falls back to 5,900-6,000. I would like to see around 600 drop. The convertor flashes to about 5,600, lower than the intended target of 6,000 but we took a wag at it with no dyno numbers.

2BKING

With out knowing anything about your engine combination it sure seems like converter is too tight and shifting at 6200 is very low RPM.

On most cars especially and FED you are better off being on the loose side with a converter than too tight. My opinion.

I commend you for running a Front Engine Dragster, nothing quite like it and a blast to drive. They are very critical with weight distribution, converter, gear ratio and tires but once you get them working right what a blast to drive. Until you do get it right some of your most memorable passes will be in it!

I had to stiffen my chassis, move weight around a lot and tried 5 different tire combinations before I go it really like I wanted it. But it Won me 2 Championships and was a blast. Main reason I got rid of it was because with long, low chassis it was a pain to load and unload in trailer.

Way too tight for bracket racing, especially a light car, in my opinion.

I'm spragless 8", flash 5700-5900 depending on the DA, shift 6450-6500, ALWAYS falls back to 5950, no matter what.

quote:

Originally posted by Al Alguire:
I prefer to see 6-700

THIS!!

Thanks for help No dyno info,but having 9" stacks power all in at lower RPM Shifting at higher rpm [7000] good for ,02,fallback the same.How to loosen? IT is a spragless

Mine falls back 1600+ rpm.....gonna fix that....car still pulls it though

quote:

Originally posted by spookie:
Thanks for help No dyno info,but having 9" stacks power all in at lower RPM Shifting at higher rpm [7000] good for ,02,fallback the same.How to loosen? IT is a spragless

You’re going to have to pull the converter and send it back to be cut open and loosened by the builder.

Pretty much the only thing that affects the fallback rpm/converter stall is horsepower. Changing the shift rpm won’t change the fallback.

Once you get it loosened I think you’ll see a pretty good performance improvement too.

Why are you only shifting at 6200 RPM? Is that a misprint?

I shift at 6200, shifting at 7000 good for .02-.05 not worth blowing stuff up just to bracket race.Just like making it as good as it should be by fixing what I have.

quote:

Just like making it as good as it should be by fixing what I have.

First, what are you trying to fix? Just because shift fall back is 1k rpm, what problem is it causing that you have identified? Do you use a log book and weather recording to show a pattern of what you presently have? Where is/ are the inconsistency in incrementals? Prior to spending money consider getting some data showing what you have and where you want it to go imho.

Just because ones racing program runs much different than others doesn’t make it wrong or less effective.

In general for a bracket combo, 600-800rpm fall back is ideal for consistency. 800-1200 for headsup type racing where consistency isn't a concern.

Generally the RPM you fall back to is within a couple hundred RPM of the true stall of the converter and you normally want the converter to fall back to right at or right above peak torque.

quote:

Generally the RPM you fall back to is within a couple hundred RPM of the true stall of the converter and you normally want the converter to fall back to right at or right above peak torque.

Following this advice, the OP (first post) may presently have a converter that is very close to optimal for 6200 rpm shifting. The dyno sheets that I’ve received with my engines show peak torque at 5200 -5300 rpm (5252)

quote:

Originally posted by markemark:

quote:

Generally the RPM you fall back to is within a couple hundred RPM of the true stall of the converter and you normally want the converter to fall back to right at or right above peak torque.

Following this advice, the OP (first post) may presently have a converter that is very close to optimal for 6200 rpm shifting. The dyno sheets that I’ve received with my engines show peak torque at 5200 -5300 rpm (5252)

Agreed for the 6200rpm shift. However if peak torque is higher for the OP a looser converter and higher shift RPM would be an improvement but is not required.