403 SBO?
- Thread starter TROUBLED215
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403 SBO!
The 403 has the largest bore size of any Olds engine at 4.351" and the small block's standard stroke of 3.385", and it used the same crank/rod combination of the 330/350. Unfortunately, it is a true thin wall cast block and contains the "windows" found in the 260, 307, and late 350's. A main/crank girdle will help, contact J & S Machine for that.
Consider this block unique because of it's siamesed bores, but you may swap intake manifolds, cranks, heads (the 403 uses a 455 intake and 350 exhaust valve and a big block sized combustion chamber), and cams from the earlier small blocks to wake the motor up. Do need to keep the revs under 6200 though (it will rev way past that) to prevent main journal flex and crank walk, a deadly combo!
if you want that Olds engine to fly, it's no problem!! Here is what i recommend meanwhile you get engine.
Front Suspension: go with TRZ.
Aluminum Radiator: Either Modine 951, or #433918 $95-autozone
On transmission, go with the 200-4R, just like what came on the Hurst, and 442's, so you'll have overdrive for hwy driving. Add a Hayden 514 Transmission Cooler! Then contact Lonnie Diers, he owns Extreme Automatics and it's the real deal. Check his references/recommendations on the TurboBuick forum and you will not find one disappointed customer. billet drum, billet input shaft, billet servo, and deep sheetmetal pan. Little spendy, but you get what ya pay for! Do it once, do it right!
Rearend: You have the 7.5" 10-bolt rear, so pick up a 3-series posi, and either 3.73, or 4.11 gears, you usually find them complete on ebay for under $275, and roughly $250-install them. Upgrade to Moser axles, Girdle covers are a good idea but you MUST weld the tubes. Also you'll want to grab the rear lower control arms with sway bar from any 78-84 G-body. You're going to have to get the speedo recalibrated after you switch gears.
The 403 has the largest bore size of any Olds engine at 4.351" and the small block's standard stroke of 3.385", and it used the same crank/rod combination of the 330/350. Unfortunately, it is a true thin wall cast block and contains the "windows" found in the 260, 307, and late 350's. A main/crank girdle will help, contact J & S Machine for that.
Consider this block unique because of it's siamesed bores, but you may swap intake manifolds, cranks, heads (the 403 uses a 455 intake and 350 exhaust valve and a big block sized combustion chamber), and cams from the earlier small blocks to wake the motor up. Do need to keep the revs under 6200 though (it will rev way past that) to prevent main journal flex and crank walk, a deadly combo!
if you want that Olds engine to fly, it's no problem!! Here is what i recommend meanwhile you get engine.
Front Suspension: go with TRZ.
Aluminum Radiator: Either Modine 951, or #433918 $95-autozone
On transmission, go with the 200-4R, just like what came on the Hurst, and 442's, so you'll have overdrive for hwy driving. Add a Hayden 514 Transmission Cooler! Then contact Lonnie Diers, he owns Extreme Automatics and it's the real deal. Check his references/recommendations on the TurboBuick forum and you will not find one disappointed customer. billet drum, billet input shaft, billet servo, and deep sheetmetal pan. Little spendy, but you get what ya pay for! Do it once, do it right!
Rearend: You have the 7.5" 10-bolt rear, so pick up a 3-series posi, and either 3.73, or 4.11 gears, you usually find them complete on ebay for under $275, and roughly $250-install them. Upgrade to Moser axles, Girdle covers are a good idea but you MUST weld the tubes. Also you'll want to grab the rear lower control arms with sway bar from any 78-84 G-body. You're going to have to get the speedo recalibrated after you switch gears.
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