Gear & Tire question

Meaney124 · 12-03-2023, 09:09 PM

I have an 70 nova bracket car, looks like it was built around the 90s or so. The car is on 33x10.5 Hoosier slicks, 5:13s in the rear. I’m hitting trap around 63-6500. How would going down to 29s affect my car? Car is running around 7.4-7.5.

Car specs:
12 bolt
Strange axles
5.13 gears
Th400 reverse manual valvebody no brake
60 over 350
Dome top pistons
H beam rods
Solid lift cam
Holley alum heads
Quick fuel 750

1320racer · 12-04-2023, 07:46 AM

1/8th mile?
cam specs?
converter size, flash rpm and fall back rpm
stock suspension?
footbrake?

Meaney124 · 12-04-2023, 08:02 PM

@1320racer 1/8th mile unsure of cam specs haven’t torn apart to get numbers or anything, ladder bar, and footbrake is about all the info I can give you lol

Meaney124 · 12-04-2023, 08:05 PM

Quote:

Originally Posted by 1320racer

1/8th mile?
cam specs?
converter size, flash rpm and fall back rpm
stock suspension?
footbrake?

check my other reply, really wondering how it will affect et and mph in case I decide to do any local index classes

Keith 944 · 12-04-2023, 08:11 PM

Summit has a gear ratio calculator on their site. Plug in the info it should get you close

goinbroke2 · 12-05-2023, 10:54 PM

So, you must be trapping about 118mph at 6500?
33 to 29 inch tire jumps you from 6475rpm to 7367rpm. (approx)

http://wallaceracing.com/calc-gear-tire-rpm-mph.php

Keith 944 · 12-06-2023, 07:45 AM

Quote:

Originally Posted by goinbroke2

So, you must be trapping about 118mph at 6500?
33 to 29 inch tire jumps you from 6475rpm to 7367rpm. (approx)

http://wallaceracing.com/calc-gear-tire-rpm-mph.php

A 7.50 car going 118????
Don’t know if he mentioned it is 1/8 mile. Lol.
I do believe some of these calculators have 1/8 mile data

12-03-2023, 09:09 PM	#1
Meaney124 Junior Member Join Date: Dec 2023 Posts: 3 Likes: 0 Liked 0 Times in 0 Posts	Gear & Tire question I have an 70 nova bracket car, looks like it was built around the 90s or so. The car is on 33x10.5 Hoosier slicks, 5:13s in the rear. I’m hitting trap around 63-6500. How would going down to 29s affect my car? Car is running around 7.4-7.5. Car specs: 12 bolt Strange axles 5.13 gears Th400 reverse manual valvebody no brake 60 over 350 Dome top pistons H beam rods Solid lift cam Holley alum heads Quick fuel 750 Last edited by Meaney124; 12-03-2023 at 09:27 PM.

12-04-2023, 07:46 AM	#2
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 2,167 Likes: 110 Liked 588 Times in 289 Posts	Re: Gear & Tire question 1/8th mile? cam specs? converter size, flash rpm and fall back rpm stock suspension? footbrake? Last edited by 1320racer; 12-04-2023 at 07:48 AM.

12-04-2023, 08:02 PM	#3
Meaney124 Junior Member Join Date: Dec 2023 Posts: 3 Likes: 0 Liked 0 Times in 0 Posts	Re: Gear & Tire question @1320racer 1/8th mile unsure of cam specs haven’t torn apart to get numbers or anything, ladder bar, and footbrake is about all the info I can give you lol

12-04-2023, 08:11 PM	#5
Keith 944 VIP Member Join Date: Feb 2006 Location: Dela-where? Posts: 2,160 Likes: 1,079 Liked 1,766 Times in 556 Posts	Re: Gear & Tire question Summit has a gear ratio calculator on their site. Plug in the info it should get you close __________________ KEITH MAYERS 2 X somebody many X nobody

12-05-2023, 10:54 PM	#6
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 773 Likes: 916 Liked 219 Times in 87 Posts	Re: Gear & Tire question So, you must be trapping about 118mph at 6500? 33 to 29 inch tire jumps you from 6475rpm to 7367rpm. (approx) http://wallaceracing.com/calc-gear-tire-rpm-mph.php