Re-gearing rear end (update)

Surfinhurf · April 13, 2013, 12:09 PM

I have a 1977 Winnebago Brave. I recently put a rebuilt Olds 455 / TH400 combo into it. At 60 mph it runs about 3300 rpm. I would like to be under 3000 rpms at 60 mph. I am considering a ring and pinion swap from 4:56 to 4:10. I do tow a Jeep CJ7.

I believe the stock engine for this camper was a Dodge 360, which would explain the 4:56 gearing. Although I have seen a few units on this site with 440's.

Do you think the Olds 455 (G heads, rv cam, .60 over, W-30 W & Z exhaust manifolds) has enough torque to run the 4:10 gear. Compared to the stock Dodge 360/ 4:56 set-up.

HURF

ClydesdaleKevin · April 13, 2013, 07:45 PM

Olds 455 is going to have about the same output (and fuel economy) as the 454...so you shouldn't have any problem with that gearing. We run a 454 on our 35 foot Holiday Rambler towing a YJ, and average about 2700 RPM at 55mph.

Kev

Surfinhurf · April 14, 2013, 11:55 AM

Thanks ClydesdaleKevin,

Is your 454 fuel injected? That helps a bunch.

Do you have a 3 speed or 4 speed trans?

The 455's (Olds, Pont, Buick) are known for their torque. I just don't want to spend $1,xxx to re-gear and not be happy with it. I would feel better if I knew for sure that the Brave originally had a 360/4:56 combo,Then the 455/4:10 combo seems do-able. If it was originally a 440/4:56 combo, then the 455/4:10 combo seems more risky.

HURF

ClydesdaleKevin · April 14, 2013, 12:04 PM

Carburated (Edlebrock 1411), 3 speed transmission. I'm light on the pedal and rarely drive over 55...and again, RPMs at that speed are right around 2700, or a tad under that. I get about 8 mpg at 55, closer to 9.5 at 45, and it drops WAY down to 6 or less at 65+.

Kev

Surfinhurf · April 14, 2013, 12:33 PM

Thanks again,

Your input has helped to" calm my nerves". I have a Edelbrock performer intake and a 1406 (600 cfm) carb. I like to cruise along at 60 mpg, anything more than that and my MPG also drops substantially.

Do you know what trans/gears you are running?

HURF

ClydesdaleKevin · April 14, 2013, 08:07 PM

You might want to think about getting a bigger carburetor. 600 cfm is barely adequate for a Chevy 350...a 454 or 455, and your fuel economy and performance is going to really suffer (small carbs with low cfm will have to run with the secondaries open all the time at highway speeds or if you need to accelerate). You need a 700-750 cfm for a big bore big block like the 455.

Kev

Wantawinnie · April 14, 2013, 11:54 PM

My '73 Chieftain is 28' and had a 440 with 4.56 gears standard. It also has 19.5" rims with 33.6" tall tires. Not sure what your tire size is but a 4.10 gear with 30" tires has about the same effective gear ratio.

Surfinhurf · April 23, 2013, 11:55 AM

I looked at the carb today, Its a 750 cfm Edelbrock 1411 not 1406

HURF

Surfinhurf · July 10, 2013, 10:17 AM

Got the Winne back with a new Ring and Pinion. Went from 3200 rpms at 60 mph to 2600 rpms at 60 mph. Man what a difference. Seems to cruise effortlessly. Still plenty of power up to cruising speed. More power from 60 to 65 mph. The Olds 455 makes the most power at 2700-3000 rpms. I only drove it 65 miles, rolling hills, expressway. Ive got 2nd stage jets in the Edelbrock and its running rich. The 455 only has 600 miles on it after a full rebuild and I like to break them in rich. I will be driving it up to Michigan Tech (10 hrs about 550 miles one way) in a couple of weeks towing Grants Jeep YJ7 and all his stuff. On the way back I may step down the jets. No idea on fuel economy yet, but it has to get a bit better. Im just happy that she is running strong and not screaming at 3200 rpms, should be alot easier on the engine/mpg's.

HURF