i have a 67 old 98 and it's all original i have always assumed it was a 455 but now thinking about it i don't know where i got that information from and i may be totally wrong. i have to replace the oil pan, need to order it ASAP and i don't to order the incorrect one. i have the VIN and the cars outside so i can easily go looking around under the hood if i just knew what to look for to find out what my motor is. thanks!

 

If it's never been changed, it's a 365 hp 425.
The only engine offered in the '67 Ninety Eight.

 

It could also be the 375HP Sfire engine if it has dual exhaust.

 

The 455 was not offered by Oldsmobile until the 1968 model year. As has been said, if your car really is original, it would have a 425.

There's good information here about identifying big block engines of that era:

http://tech.classicoldsmobile.com/36.shtml


I have a '67 Delta 88 with the 425, and it has the casting code shown next to the letter "D" in the table of information in the above link. Specifically, mine has the code 389244D, with the "D" about twice the size as the numbers.

Go take a look at your engine, and I'll bet it has the same number. It should be on a little shelf right under the little coolant hose that comes out of the thermostat housing and enters the top of the water pump.

 

This is not written in stone. For example you could have an F block up to 76. So the list should say: F '68 - '76 455 396021 - Fa '72 - '76 455 396021. I know a few cases where this is so. Don't have any experience with other blocks however.

 

thanks guys, idk why i always thought it was a 455. but now i wish it was. keep it numbers matching or do a 455 swap?

 

Why take your original and correct engine out for a mere 30 ci's? You are not building a racer and the 425 had a shorter stroke than the 455 which can be good for quicker RPM buildup. My pop had a 68 Delta 455 and I had a 66 Delta with 425. The 425 felt snappier to me than the 455.

 

But the oil pan should be the same on all the rear wheel drive cars, wouldn't it?