low first gear 727

[440rb]

This is a follow on from my carb thread. I now have some more info on what were doing next year, the car>
'69 Roadrunner approx 3850@the line...brkt car
Motor 589 wedge, 10:1CR, 694hp@5500, 724ftlbs@4400, 4.500 crank, we won't talk about bore size, thats another complete topic on its own.
herbert solid roller, .625/.625", 260/270@.050
Jesel, 572-13's (CNC365's), 950DP, 440-2 intake
2.1/4" hdrs, 4"collectors.
probably will be run with all ancillaries (mechanical) and 3.5" exhaust so some hp loss there
caltracs/mono's, QA1's
converter is the only thing I don't know yet but am assuming it will be in 4k+ stall range.
built 727, low first gear
4.10's, 10x29 bias slicks.
SLR will be in the 11's
What do you racers who run or have run a low 1st think it will work like on our combo, personally I think thats gonna be somewhat pushing things for slr, perhaps good to get the weight moving and the 60 (hit 2nd before it) but with such a short max rpm range?.....your thoughts gents?

 

[AndersonTommy]

Have been doing it for years.
Low gear sets work especially on a heavy car which gets you out of the beams quicker.
Better reaction times and better 60 foots equal better 1/8th mile but your 1/4 et Will be the same regardless.

 

[440rb]

Well if you 60ft better you are reducing the time you cover the distance, your on the track for less time so how does it not lower the 1/4et, not heard that before.
I ran 10.53@124.98 with a 1.51 60, then ran 10.21@129 with a 1.48 60, still got the tickets from 1990.

 

[Badvert65]

Keep in mind that it will be a low first and second gear. You will go through the gears faster and be in 'third' (sooner) longer. With that much motor, I wouldn't think you would really benefit much from lower first.

 

[Lefty71]

With that much motor, I wouldn't think you would really benefit much from lower first.

I would think you may be right. Thats a heavy car, but thats a lot of motor too. I would think the determining factor would be just how high are the RPM's down track on the 1/4??
That's a few bucks to spend to find out, for sure.

 

[dvw]

I've tried them. Did nothing if you have the correct converter. Back when I ran my low 10 second car we tried 4.56, 4.30, and 4.10. Also tried the low gear set. The result? They all ran about the same. The 4.10 was the quickest (10.1×). Car was 3450# with a 498. To be honest the combo seems mismatched. Big heads, big primary headers, low comp, small cam, small carb, 4k converter. My current car runs a 572 with a 4.30, 2.45 first gear. Has been quickest (9.00@150) with 6100-6300 flash. However it runs way more duration 285/292@.050" and compression 15-1. But smaller heads , -1s, smaller headers, 2 1/8". Foot brake 60ft in the 1.2x, been 1.240 best. It's been 9.03@149 with a 4.10
Doug

 

[440rb]

Well it should certainly launch/60ft better which is fine, its just the motor only makes power to around 5500 so our shift points will be 6k max and that ain't a lot, 3rd gear will be in early!.....Yes it is a strange combo, it was built as a street not race engine, this suits my mate well though as he will be doing a lot of short street trips. Got a lot of paperwork for it so it will get the treatment at a later date.

 

[malex]

I switched to the low gear set and have no regrets. It gets you out there quicker, that's for sure.

 

[AndersonTommy]

Your 1/8th if you hook up will be better but overall 1:1 ratio will net you the same 1/4 mile ET.
BEST ET IS 8.57@160

1.19 60 foot.

 

[Darter6]

I ran both when I was racing my Dart.Only raced 1/4 mile. I really didn't find one was better than the other in my overall ET.

 

[biomedtechguy]

To be honest the combo seems mismatched. Big heads, big primary headers, low comp, small cam, small carb, 4k converter.

This...
But on another note, Mike Gaines is looking for comments on a 2 speed Powerglide because his RPMs are going to high, too quickly w/a 3 speed 727.
FWIW

 

[dvw]

This...
But on another note, Mike Gaines is looking for comments on a 2 speed Powerglide because his RPMs are going to high, too quickly w/a 3 speed 727.
FWIW

If its not spinning, the quicker it picks up RPM the quicker the car is accelerating.
Doug

 

[AndersonTommy]

Mike's RPMs are too high because his converter is probably wrong for his car or possibly his high gear clutches might be going away.
A 32 inch tall tire with 4.56 gears, his trap speed should be around 7300-7400 rpms

 

[Mike Gaines]

Mike's RPMs are too high because his converter is probably wrong for his car or possibly his high gear clutches might be going away.
A 32 inch tall tire with 4.56 gears, his trap speed should be around 7300-7400 rpms

Wow....thanks DVW and Tommy...but this is getting way above my paygrade (and knowledge) and check book (LOL). I now have the tranny out of the car to check all of the internals...will have the results of the checkout of the tranny parts, clutches, etc next week.
Going to get it all back together and run it Feb 22/23 at the test and tune weekend and whatever it runs will be what it is.
I am getting my NHRA Competition License at that test&tune so I can run in the 9s with no problem with the track officials.
I will be running it wide open with the adjustable restrictor plates set at full open. I will trying different shift points, different launch rpm's off the brake, etc, etc....and see what it does...
Again...thanks for the input and I will be sticking with the Torqueflite with standard low gear set and my current converter, 4.56 gear and 105" rollout slicks and the wheels on my wheelie bars set at 8" off the track.

 

[AndersonTommy]

Perfect Mike.... But I think you'll find that your shift point will be around 7300 with your combo.
Set shift light at 7100.
By the time you shift you should be right where you want to be.
I find short shifting 1st gear usually nets me the best ET.
I shift 7200 in 1st and 7400 in 2nd and 3rd.
I think your Hemi should be very similar to mine.
Good luck and report back!

 

[stage3]

hey mike,,i thought u got rid of that hood scoop!

 

[malex]

hey mike,,i thought u got rid of that hood scoop!

----
I got one you can borrow. LOLOL

 

[biomedtechguy]

This...
But on another note, Mike Gaines is looking for comments on a 2 speed Powerglide because his RPMs are going to high, too quickly w/a 3 speed 727.
FWIW

Wow....thanks DVW and Tommy

Hey Mike, I was "spreading the word" in someone else's thread to try to get as much attention and advice to you as possible, since I muddied up your Powerglide thread so badly.
Now I have another apology to make to the OP of this thread...

 

[440rb]

Yes it has gone a bit off thread, never mind no big deal I got an idea of what its gonna be like on the hit, just hope we don't have to put w/bars on the rear, he won't like that driving with them on the street!!!!

 

[33 IMP]

Wheelie bars on a street car is cool, but only if you can PROVE you NEED em ! There was a guy locally that drove his 63 around with wheelie bars. The only way he was getting the front end off the ground was with a floor jack.