Ad Radar
Car Craft
Click here to find out more!

Mass Airflow Sensor to Direct Bolt-on Air Filter - Ask Marlan

What's The Diff?
I have a '72 Olds Cutlass fastback with a 350 Rocket backed up by a TH350. I am almost done with this project except for the rearend. I want to replace the open diff and 3.23 gears with a posi and 3.73s, but I am having a very hard time finding parts. If I use a rearend out of another GM A-body, will it be a basic bolt-on part except for the U-joint? If not, what modifications are needed? If it won't work, who has parts for the 10-bolt that's under it now?
Glenn Ardolino
Kansas City, MO

Any '68-'72 GM A-body rearend bolts in as a complete assembly, although a conversion U-joint may be required. However, there shouldn't be any problem finding parts for your car's existing rearend if it's the original factory-installed item: Unlike other A-bodies of the same vintage, the '71-'72 Buick Special (includes Skylark) and Olds F-85 (includes Cutlass) came with the 8.5-inch ring-gear "corporate" 10-bolt rearend. Ring-and-pinions and differential cases from many other trucks and passenger cars (including the '71-'81 Camaro/Firebird and '73-'77 A-bodies) fit, plus there's a huge selection of aftermarket parts available.

Performance With A Price
I drive a '79 Volvo 262 Bertone with a '90 Mustang H.O. 302, AOD trans, and all computer functions intact. I'm running cast-iron manifolds to 2-inch pipes to a single three-way cat. From there back, it's Volvo 1 7/8-inch pipe with a muffler from a six-cylinder Camaro. I drive the car a lot and really appreciate the quietness. What do you feel is the minimum-size exhaust that I should use, and will a freer-flowing exhaust really help my gas mileage?
Bob Price
Drexel Hill, PA

Up to a point, reducing exhaust restriction generally helps gas mileage. But going too large can overscavenge the engine and result in a mileage reduction. Proper exhaust size is a function of both engine output and displacement. Ford used a full 2 1/4-inch dual exhaust system on the Mustang, complete with dual cats and mufflers. Assuming the engine is stock, in theory, 2-inch dual pipes should be adequate, as indicated by the accompanying exhaust system recommendation chart courtesy of Flowmaster Mufflers. Specifically, it's the 1 7/8-inch single-pipe and weak, little, single six-cylinder muffler that's holding you back. If there's insufficient room for dual pipes and mufflers after the converter, use a single 2 1/2-inch pipe and corresponding low-restriction aftermarket muffler. The converter inlet and outlet should likewise correspond to the inlet pipe sizes.

Source:
Flowmaster Inc.

Dept. CC
2975 Dutton Ave.
Santa Rosa, CA 95407-7800
800/544-4761
www.flowmastermufflers.com

Manual Labor
I have a '68 Ford Ranchero that I have been wanting to upgrade to an overdrive Tremec 3550 five-speed in place of my current four-speed Top Loader. Will it bolt to my bellhousing and allow me to use my stock clutch and linkage? I know I may have to modify the driveshaft and other things.
Pat Crittenden
Minneapolis, MN

The Tremec five-speed uses the Top Loader trans-to-bellhousing mounting-bolt pattern, but its standard input shaft length is the same as an '83-'93 Ford V-8 T5-about 5/8-inch longer than the small-block V-8-type Top Loader. Spacer plates are available from Dark Horse Performance, McLeod Industries, and Total Performance that let you bolt a Tremec up to a stock-type Top Loader bellhousing or equivalent aftermarket scattershield. Alternatively, the correct-length (shorter) input shaft and required corresponding shorter bearing retainer is available from Tremec distributor Dark Horse Performance. Either way, the stock clutch and clutch linkage remain unaffected.

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
0 comments
Car Craft