I need to replace my drive belt on my '89 Formula 305 TPI, and I'm having trouble determining the length. I'm using a March underdrive crank pulley only, no water pump or alternator pulley. First, I looked in my Parts & Illustration Manual, printed 1989, for 1982-89 Firebirds. It shows a stock belt length of 97.8 in. According to Autozone and March, the stock length is 94.5 in. March couldn't tell me exactly what belt to use for my crank pulley, since they size their belts for their kits, and I only have the single pulley. They thought it would be around 91.5 inches, though.

I don't remember where I bought the pulley, but it wasn't directly from March. They included a belt, but I can't find an invoice showing what length it was. I know I can just take my belt off and measure it, but I'd like to have a new belt in hand before I take it off.

Anyone know what the stock size belt is for 1989 305/350? Anyone else have the single pulley setup and know what size to use? Any help would be appreciated.

Thanks!


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1989 Formula WS6 M5
SLP cold air induction, K&N filter, TPIS modified MAF, TPIS 52mm TB w/ airfoil, Random Tech cats, SLP cat-back, TPIS AFPR, March underdrive pulley, Accel 300+ coil & 8.8mm wires, Bosch Platinum+4 plugs, Hypertech 160°F t-stat & fan switch, Hypertech Streetrunner chip, Centerforce dual-friction clutch, PST front suspension kit, PowerStop cross-drilled rotors, Porterfield Carbon Kevlar pads, Russell SS brake lines, Firehawk SZ50 EP P255/50ZR16.

G-Tech Pro measurements:
0-60 mph: 6.0 sec
212 RWHP

1/8 mile results: 9.74 sec @ 74.5 mph; 0-60 ft @ 2.35 sec; +0.46 reaction

2001 Trans Am WS6 A4
Stock

More info at website:
www.fbody.com/members/stevenmh

 

When I installed my underdrive crank pulley (don't remember the make, it was over 7 years ago), I went to a local Goodyear dealership and they let me try a couple of belts. I also just installed the crank pulley.

With A/C, my stock belt was a Goodyear 4060922, with the underdrive pulley try 4060915. That was the next step down and it fit like a charm, right in the middle of the adjustment indicator for the serpentine system.

 

I did the same thing when I had my 88 GTA and took off my air pump. I just went to a NAPA and got the next size down. It took me two or three tries but I just exchanged the belts when they didn't fit. Changing belts is pretty easy.

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1998 Z28 - 6-Speed
12.79 @ 110.29 (1.975 60ft) - With no muffler, Drag Radials, and free mods (That's all!)
SAE Corrected 346rwhp 354rwtq with Mac Headers, UD Pulleys, B&B Triflow Catback, and Direct Flo Airlid

89 Taurus SHO

 

Thanks for the input guys. I had the bright idea today of going out to my car and looking to see if there were any numbers printed on the belt. There were, and it's a 92.3 inch belt. Went to autozone and got a 92.2 inch belt. I'll put it on tomorrow evening and see how it fits.