Anybody want to take a stab at whether a 4.10 is too much for the strip? Mostly 1/8. Occasionally a 1/4. Current combo is 3.42 with a 28” tire (455/TH350) leaving at ~2200-2500 foot brake

 

Go to Wallace Calculator. It will have formula to see max rpm with normal converter slippage. My guess your safe.

 

Calculator says ok, but was looking for real world. Those calculators sure are handy and pretty amazing what you can get out of them.

 

For what it's worth 4.30 gear 30 tall tire and 7% converter slip I went 6800 rpm. Pretty accurate info as I have a data logger on race car.

 

For final drive gear ratio you really need to look at your MPH and RPM.

 

Current 1/8 is 7.96@85.5mph but I haven’t looked at trap RPM. Still getting used to the strip process. Used to circle track.

 

You need to figure what MPH and RPM you want/expecting to cross the finish line. Since you want to race both 1/4 and 1/8 4.10 will most likely work out well with a typical 455. If anything the 4.10 is not enough for 1/8. I would look at what the 1/4 mile combination is and use that gear. Since I don't know anything about your combo it's a guess.

 

I think you are right Duh. Without knowing more about combo this is a guess. And most likely it should be okay.

 

Thanks for the input. I have decided to stick with the 3.42s and keep my streetability since I drive this car every chance I get (have had it 20yrs, since high school). I will go with 4.10s when I can drop some more change on the motor.

Currently it’s:
’71 Cutlass (3,750 pounds)
fiberglass hood
455 swapped in
.030 369P pistons already in it when I found it at Pick-n-Pull
thumpr cam kit (springs, timing chain, etc)
‘68 Toro C heads (not ported that I know of, but were on motor)
torker intake
nice 750HP double pumper
hei ignition
flowtech headers
Single chamber off-brand mufflers turned out ahead of axle with cutouts installed just after collectors
th350 w/shift kit of some sort
10-inch “3,000” rpm stall Summit converter (gone over by Atlantic Coast Converters to up the quality some)
3.42 w/ welded spiders

went 7.962@85.57 1/8 mile (275/60-15 drag radials) with some left to gain, I’m sure

 

Very important.

Great story. Maybe she will be with you for the rest of your life or at least deep into your golden years. I managed 18 years with my first Old's.

Great performance !

 

I'd go 3.90's
Any more and you'll be floating valves for the 1/4
-peter

 

Update:
Went a 7.85@86.5 mph with a 1.69 60’ today.