Anyone put "gears" behind a 3.8?

Just curious, looking at a 86 with a V6. If GM held true this will have some horrible ratio like 2.29 or something.

Anyone try a set of 3.73z behind a stockish motor?
 

malibu795

Pro Stocker
Apr 17, 2005
1,496
4
38
spgfd ohio
wouldnt hurt anything...

any adition gearing would help the anemic little engine
 

JuniorJ

Frequent Racer
I just put 3.73 in my wagon with a stock 231, but I am also building a 200-4r for it. Should be fun or atleast better than the 2.29's I pulled out.... :lol:
 

bukweet

Top Fueler
Mar 22, 2005
2,803
0
0
Mississippi Gulf Coast
My buick 231 has a set of 3:42's behind it.
Woke it up (had 2:73's) but I wouldn't keep it out for long at highway speeds without a overdrive or lock up convertor.
Don't have a tach on it but it winds up a bit tighter.
Put a pair of 255/60 15's on it and it helped pull the RPM down a bit from the 225/60/14's that were there before.



bukweet
 

tiedyemike8

Frequent Racer
Oct 28, 2009
658
0
0
Naperville, IL
Doober said:
Actually I think 2.14 would be even better for me... I'd like to have 1800RPM or lower @ 70, and even with a 28" tire and 2.29s I turn about 2000RPM right now. With the 275/40/17s it'll be up around 2100...

Jeez Doober, why don't you just make it 1:1 already and be done with it! :D
 

cttandy

Pro Stocker
Mar 9, 2009
1,458
0
0
Springfield, Tn
I think doober wants a landspeed car, HAHA!

My favorite combination was in my 96 GMC JIMMY. 4.3L/4l60E/3.08/30 inch tall tires. After a few performance tweaks, I was getting 28 mpg out of it consistently, and it pulled pretty hard for what it was. Later on, I changed it to 3.42 rear. Didn't feel all that much peppier, but it would pull sideways on the 1-2 shift at full throttle. Mileage dropped down big time, never topped 21 after the 3.42s.

I sold a 87 C10 with a TBI 305/700r4/2.73/28 inch tires. It as well would get some 26 MPG on the hwy, but it liked to eat transmissions (you didnt worry about MPG, you worried about MPT- miles per transmission) . It was an absolute dog.

I don't know what the final numbers work out to, but my current pickup is TBI 350/700r4/3.42/35.5 inch tall tires. 40MPH sounds like it is idling. I was getting 19 MPG with the stock 30 inch tires and no topper.

Before you say anything, I know how to figure mileage, and I don't inflate numbers. I am that weird guy that can drive your car and get way better mileage than you most of the time. I had a guy bring is GPS and computer in my 87 C10 to verify the speedo, and filled the tanks at the same exact pump. I have also had a hand full of vehicles that never got better then 6 MPG.
 

Doober

Moderator
Jun 2, 2003
14,704
1
38
Catalina, AZ
www.cardomain.com
You guys give me a chuckle ;) My ideal rpm is about 1700 at 70, but with the current trans that would require a 1.8:1 rearend ratio, but that's just silly. Here's the math (tires taken out of the equation):
Saginaw 4-speed, 3-line input shaft (3.50:1 1st gear) with 2.29s:
3.50*2.29=8.015
2.47*2.29=5.666
1.65*2.29=3.779
1.00*2.29=2.29

2004R with 3.42s:
2.74*3.42=9.371
1.57*3.42=5.369
1.00*3.42=3.42
0.67*3.42=2.291

See where I'm goin'? 1st to 2nd is a bigger drop with the 2004R, but the final drive ratios are fairly close. If I stepped up to the 2.73 that's bolted to the 78's frame right now, it would be like going to a 4.10 with the 2004R.
 

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