jcdynamic88

hey guys, not very familiar with the 394 olds engine,will a 63 and 64 394 interchange? i thought i remembered some changes to this engine between 58 and 64 that would prevent some years not working in another .thanks for any help.jc

Tedd Thompson

There should be no problem swapping a 63 into a 64 or the other way around , same engine, same mounts, same transmission. There are many differences if you try and use the early 303 324 371 engines though... Tedd

67 Cutlass Freak

I believe there may be some differences in the timing cover, water pump, fuel pump, depending on wheather the car came with AC or other options. You may also want to look closely at the oil pan. Some had a large extra oil capacity round protrusion.

jcdynamic88

thanks for the info and prompt replies.jc

Oldskeeper

The 63 and 64 engine are the same, both have aluminium timing chain cover/water pump housing. The motor mounts are the same and all of the linkages match up, vacuum ports are the same and the choke tube is the same. The only difference is the casting numbers on the transmission flange showing casting month and year.
Internally the difference is in piston compression and cam design. The water pump is a/c or non a/c and it is a bolt on. If you are going from non a/c to a/c you will need the carb to match and vice versa.
Steve

64Rocket

The Olds 394 was in groups. '59/60 , '61/62 , '63/64
Alot of internals are different, '63/64 font cover is the total different.
But the external measurement are all the same.
the other problem is the exhaust manifold bolt pattern.

Gene

cutlassefi

Hey Gene,

Do you know if the 394 and 64-90 blocks have the same bore spacing?

Thanks.

Tedd Thompson

I don't know for sure but 394 heads will ( fit but not work) on a 350 block so they are close for what it is worth....Tedd

64Rocket

Mark, as far as I know it is the same. But nothing interchanges.

The best blocks are the '63/64's. Also the #23 heads.
Ross racing has a bunch of stuff.

Gene

59-59-59

And why is that?

D. Yaros

Am hazarding a guess, but suspect 63-64 would be favored as Olds squeezed more h.p. out of the 394 by then. Certainly a lot more than when the block debuted in 1959.

64Rocket

Well, not so much in the horse power rating, for all that changes when you rebuild, the cams used,different intake manifold,
I like the front cover arrangement better, lighter. The main brg set up, uses later style oil pump. The early ones use a 3 bolt oil pump with a funky oil pick up & screen. I believe the late ones use the same pan gask for oil pan. Just IMO

Gene

Tedd Thompson

Earlier heads had a problem with cracking if they once got hot also...Tedd

lazy394

X2 Tedd....mine has had both heads cracked and repaired