Wasup with this motor. There's 1 for sale around me for $500. Are parts avail? HP ratings? Will it bolt right up to my 86 Cutty Salon with a V8 in it? Heard all bout 350s and 455s, but no 425s.
OLDS 425
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425's are great engines. Better rod/stroke ratio than a 455 so it revs higher and more like a small block.
As long as your current v8 is an Olds engine then it will bolt right in. The best part is that the 425 has a factory forged steel crank. 8)
The only issues I believe are connecting rods and pistons. The rods are only good to the 500HP mark I believe and aftermarket, off the shelf pistons can be tough to come by but custom pistons can be had for not a lot of money.
The flywheel or flexplate bolt pattern is also different than most other Olds engines and only works with the 330/425 so make sure it comes with that. Balancer may be different as well.
Oh, and they could have either had a 39* lifter bank angle (most typical among Olds engines) or the 45* angle. Not a huge deal though because you can get the 45* cams from any of the major camshaft suppliers.
Other than that the 425 is just like any other Olds big block and will accept any corresponding aftermarket parts.
As long as your current v8 is an Olds engine then it will bolt right in. The best part is that the 425 has a factory forged steel crank. 8)
The only issues I believe are connecting rods and pistons. The rods are only good to the 500HP mark I believe and aftermarket, off the shelf pistons can be tough to come by but custom pistons can be had for not a lot of money.
The flywheel or flexplate bolt pattern is also different than most other Olds engines and only works with the 330/425 so make sure it comes with that. Balancer may be different as well.
Oh, and they could have either had a 39* lifter bank angle (most typical among Olds engines) or the 45* angle. Not a huge deal though because you can get the 45* cams from any of the major camshaft suppliers.
Other than that the 425 is just like any other Olds big block and will accept any corresponding aftermarket parts.
The 403 is a good engine as well. It has the largest cylinders of any Olds engine at 4.351" but is still a small block so it will bolt directly in place of any SBO and use all of the original brackets, etc.
They do have windowed main webs which makes the lower end the weak point however for a street engine they are just fine. Plenty of guys running in the 12's with them and a few in the 11's.
They do have windowed main webs which makes the lower end the weak point however for a street engine they are just fine. Plenty of guys running in the 12's with them and a few in the 11's.
Just to add to the previous posts, the 425 was built from 1965-67. As noted, it is externally identical to the 455, but there are a couple of things to be aware of. First, the 64-67 Olds motors use a different crank flange bolt pattern than the 68-90 motors, so you need the correct flexplate that goes with the 425. Second, Olds did some weird things with the lifter diameter and lifter bank angles in the mid 60s. This motor will likely have a 45 deg lifter bank angle (68-90 motors have the more common 39 deg angle) which requires a specially ground cam. Also, the lifters may be 0.842" diameter or they may be 0.921" diameter. Check before buying any cam and lifters.
Thanx for the info guys. Gonna decide this week. Don't think the add mentioned anything bout the flexplate inc.
Will the brackets off my 307 for my powersteering and AC fit on this block? Seen pics of it and it doesn't have either. I'm not trying to search the WWW for them. It also has the flexplate with it.
crucial118 said:
The brackets will fit with some minor mods. The deck height on the big block Olds is about an inch taller than on the small block, so where the brackets bolt to both the block and the head there are some changed needed. On the driver's side, you'll need to use a spacer between the alternator and PS pump brackets and a longer bolt to go with it. On the A/C compressor bracket, you'll need to weld a couple of tabs onto the bottom of the outer bracket where it attaches to the studs on the water pump.
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