tranny and rear end questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Green72GMC · 08-09-2003, 04:15 PM

Would your truck have a ton of power in first and second if say you took a 250 6 cylinder 3 speed transmission and changed the bellhousing to fit a smallblock V8(If possible?) and put a 305 on it with a rear gear ratio of between say 3.73 and 4.11?

Reason I am asking is Im trying to figure out what kind of tranny and rear end the last owner put in it. My dad said it is probably a 6 cylinder tranny, and I looked up what the truck came with and it was a 250 6. The truck can lift the front tires off the ground about 6-10 inches in first and tops out at around 90-100 (what my friend said when he was in his, I got no speedo).

PS: What would 3.07 gears do to the top speed? Make it go faster?

fast71 · 08-09-2003, 05:27 PM

1st of all the six cyl trans bell housing would bolt to a v8. second
I cant believe it pulls the front wheels off the ground with a 305.I have a lightly build 307 and it wont pull the wheels. 3rd my truck was orginally a 6 cyl straight shift truck and it has a 373 gear . I know that 50 mph I'm turng around 2800 rpms so if I went to 90 there is no telling what I would be turning it but Iwouldnt hold it there long. if you put a 308 gear in the rear it would help on top end and gas but hurt on take off.

lukecp · 08-09-2003, 09:00 PM

I highly doubt your 305 will pull the front wheels of the ground....my 325hp 350 won't do that....i would imagine it would take drag slicks and over 400 horsepower to pull the front wheels off the ground.

Anyway, 3.07 gears will make it go faster. I have 3.07's in my truck, and i pull 2000rpms @ 50mph, 3000rpms @75mph, 4000rpms @100mph, and so on. So, if my truck had enough horsepower (which it dosen't), it would pull 150mph @ 6000 rpms, with 3.07 gears. You would have better gas mileage with the 3.07 gears, and they would allow you to comfortably crusie at 75mph all day long on the interstate. If all you want them for is to get a higher top speed, you need to get a different vehicle. These trucks aren't aerodynamic, and it takes alot of horsepower to push them over 100 mph. Plus, the handling and braking in a 30 year old truck, even if all the suspension and brakes are fresh, can be just plain dangerous over 100 mph. If you want triple digit speeds, get a rear wheel drive, V8 powered sports car (Camaro, Firebird, ect.)

FRENCHBLUE72 · 08-10-2003, 01:15 AM

Can we see pic's of the wheel's off the ground???? The only way I could get the wheel's to come off the ground on my old blk 72, was to put in in 1st and pump the gas pedal on /off real quick... That got the front tire's to kinda bounce like a low rider...

Green72GMC · 08-10-2003, 05:04 PM

Quote:

Originally posted by FRENCHBLUE72
Can we see pic's of the wheel's off the ground???? The only way I could get the wheel's to come off the ground on my old blk 72, was to put in in 1st and pump the gas pedal on /off real quick... That got the front tire's to kinda bounce like a low rider...

Thats the way I do it on mine. I dont just press it to the floor and hold it. I shouldn't have said lift, I should have more said bounce them off the ground. And believe me if I knew someone with a digital camera, the day I found out about it being able to do that I would have pics on here.

08-09-2003, 04:15 PM	#1
Green72GMC Registered User Join Date: Apr 2003 Location: Deville, Louisiana Posts: 293	tranny and rear end questions Would your truck have a ton of power in first and second if say you took a 250 6 cylinder 3 speed transmission and changed the bellhousing to fit a smallblock V8(If possible?) and put a 305 on it with a rear gear ratio of between say 3.73 and 4.11? Reason I am asking is Im trying to figure out what kind of tranny and rear end the last owner put in it. My dad said it is probably a 6 cylinder tranny, and I looked up what the truck came with and it was a 250 6. The truck can lift the front tires off the ground about 6-10 inches in first and tops out at around 90-100 (what my friend said when he was in his, I got no speedo). PS: What would 3.07 gears do to the top speed? Make it go faster? __________________ 1972 GMC SWB, 305 powered 1980 diesel VW pickup, Needs a Heart Transplant 1997 Toyota Taco The Second Amendment is in place incase they ignore the others.

08-09-2003, 05:27 PM	#2
fast71 Drive it like U stole it Join Date: Mar 2000 Location: tunnel hill ,GA /Chatt,TN Posts: 956	1st of all the six cyl trans bell housing would bolt to a v8. second I cant believe it pulls the front wheels off the ground with a 305.I have a lightly build 307 and it wont pull the wheels. 3rd my truck was orginally a 6 cyl straight shift truck and it has a 373 gear . I know that 50 mph I'm turng around 2800 rpms so if I went to 90 there is no telling what I would be turning it but Iwouldnt hold it there long. if you put a 308 gear in the rear it would help on top end and gas but hurt on take off. __________________ 71 custom 10 swb 72 nova ss 72 nova custom 87 s10 96 burb 94 camry 53 5 window 3100

08-09-2003, 09:00 PM	#3
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I highly doubt your 305 will pull the front wheels of the ground....my 325hp 350 won't do that....i would imagine it would take drag slicks and over 400 horsepower to pull the front wheels off the ground. Anyway, 3.07 gears will make it go faster. I have 3.07's in my truck, and i pull 2000rpms @ 50mph, 3000rpms @75mph, 4000rpms @100mph, and so on. So, if my truck had enough horsepower (which it dosen't), it would pull 150mph @ 6000 rpms, with 3.07 gears. You would have better gas mileage with the 3.07 gears, and they would allow you to comfortably crusie at 75mph all day long on the interstate. If all you want them for is to get a higher top speed, you need to get a different vehicle. These trucks aren't aerodynamic, and it takes alot of horsepower to push them over 100 mph. Plus, the handling and braking in a 30 year old truck, even if all the suspension and brakes are fresh, can be just plain dangerous over 100 mph. If you want triple digit speeds, get a rear wheel drive, V8 powered sports car (Camaro, Firebird, ect.) __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

08-10-2003, 01:15 AM	#4
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,606	Can we see pic's of the wheel's off the ground???? The only way I could get the wheel's to come off the ground on my old blk 72, was to put in in 1st and pump the gas pedal on /off real quick... That got the front tire's to kinda bounce like a low rider... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..



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