Editing Openai/695c4a9d-28a0-800d-9f93-cab63ec35c09 (section)

=== Assistant: That feeling you’re describing is 100% consistent with a loose converter — and in your case, it’s doing exactly what th… ===
That feeling you’re describing is 100% consistent with a loose converter — and in your case, it’s doing exactly what the data says it’s doing.

Let me explain why it feels faster than you expect, and how to tell if it’s normal loose or too loose.

==== When you stab the throttle: ====
# Engine torque hits instantly (Buick big-block torque)
# The converter allows slip instead of immediate vehicle movement
# RPM “flashes” up to its effective stall almost instantly
# Car then accelerates once the converter starts to couple

That fast RPM jump is called flash stall.

With your combo:
* Big torque motor
* TH400
* 4.10 gear
* 28" tire

The converter is seeing a LOT of load, so it flashes hard and fast.

==== Two reasons: ====

===== Buicks don’t “climb” RPM like small blocks — they hit it. =====

So what feels like:

: 

…is actually the converter reacting to torque, not the engine free-revving.

===== 4.10s multiply torque again. =====

So you’ve got:
* Engine torque
* Converter multiplication
* Rear gear multiplication

All stacking at once.

That makes RPM jump violent.

==== ### ====
* RPM flashes, then stabilizes
* Car accelerates smoothly after the flash
* MPH continues to climb
* No “hanging” RPM that doesn’t pull

From your slips:
✔ Strong 60-ft
✔ Increasing MPH
✔ Consistent ET

This says normal.

===== - RPM flares and stays high with no acceleration =====
* MPH drops pass to pass
* Car feels mushy through mid-track
* Excessive heat in trans fluid

You didn’t report any of this.

==== Based on: ====
* 2,000 rpm footbrake
* Instant RPM jump on throttle
* 6,000 rpm at the stripe
* Slip % we calculated

Your converter is likely flashing to:
👉 3,600–3,800 rpm

That’s loose — but not crazy for a Buick.

==== No — not yet. ====

The converter is:
* Helping launch
* Producing good 60-ft
* Consistent

The gear is amplifying the looseness, not the converter being wrong by itself.

==== ### ====

Going to 3.73 or 3.55 will:
* Reduce how violently RPM flashes
* Improve coupling
* Increase MPH
* Often feel smoother and faster

===== Reduces RPM flare during gear changes. =====

==== On a clean road or track: ====
* Roll at ~30 mph
* Smash the throttle
* Watch RPM

If it:
* Flashes quickly to ~3,600–3,800
* Then steadily climbs with speed

That’s a healthy loose converter.

==== What you’re feeling is not the engine revving uncontrollably — it’s the converter doing its job very aggressively because: ====

👉 Big torque + loose converter + 4.10 gear

Once you tame the gear or control the shifts, that “surprise RPM jump” will feel right instead of alarming.

If you want, tell me:
* Converter brand & rated stall (if known)
* Vehicle weight

I can tell you if the converter is perfect, slightly loose, or worth tightening later.