Mopar Action On-line – Tech Questions


Tech Question

Ray Peters, Spokane Valley, WA, 1973 Plymouth Gold Duster 225cid

I’ve been a big Mopar fan for years, this Duster being my third A-Body.However, this is my first project car and, being somewhat new to all this,could use your expert opinion.

Currently, the car is totally stock with the 225, A904 Torqueflite, and 71/4″ rear end. I have recently purchased an open 8 1/4″ rear end (out of a’73 Duster – how convenient!) with 2.45 gearing and intend to swap it underthe car along with your front disc brake conversion in advance of a newengine and transmission.

My question is this: I’m hoping to eventually replace the bulletproof butboring Slant Six with either a 318 or 360 with a SB 904 or 727 tranny aswell as limited slip for the rear end. What gear ratio would you recommend?And what sort of performance I should shoot for out of the small blockwithout overwhelming the new drive train?

The car will be used as a Sunday driver and drive-in cruiser, but thethought of embarrassing those unfortunate and misguided souls who stilldrive Brands C and F is intriguing.

Any insight you could provide would be greatly appreciated.

Thanks for your time.
Ray Peters


Since you’ve already got the 2.45: 1 gearset, here’s my suggestion: Use anA-999 trans, suitably beefed. This has the 2.74:1 low gear set (as oppesedto the 904 and 727’s 2.45:1). This will give improved low gear acceleration,while the tall axle ratio will be close to overdrive – quiet andeconomical.

I’d go with a semi-built 360, something partway betweent the specs for theMP 300 and 390 HP crate engines, in a lightweight Duster this should be aneasy low-14-second ride. Be sure, however, to start with a Magnum 360″core”). The 8.25″ axle will live indefinitely with this setup as long asyou don’t bolt on any drag slicks!



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