GCH

Hi,is a little curious if a later 455 is a direct fit instead of
my 425 in my -65 Dynamic ? Same blocks maybe ?

svnt442

Direct swap. Use all of the accessories from the 425....bolt up and go.

joe_padavano

It's a direct swap EXCEPT...

The crankshaft flange bolt pattern is different on the 64-67 motors from the 68-90 motors. You will need a 1968-up RWD flexplate (350, long stroke 400, 455, 307, they are all the same). The 425 flexplate will not bolt up. Otherwise, the two motors are externally identical.

lansing

Rebuild the 425. Sweet engine!

GCH

Ok,thanks.The reason i ask is that my engine had some crankcase ventilation
so i suppose the pistonrings are leaking compression,have removed the pcv valve in the left valvecover and replaced it with a vent tube.

Have also made an oilfillertube cap with 3/4" vent outlet i hope to minimize the crankcase vent to the aircleaner from the right valve cover.

Have an oil leak somewhere behind left cylinder head i must look at,a lot of oil needs to be filled in the engine.Oilpressure are 25-30 psi when driving with engine hot,guess this are ok.My Chevy truck have 30 psi warm also.

But the 425 runs smooth and steady at idle so i should try to fix the oil leak
for now.

Yes Lansing,i like the 425 also.it must been a awesome feeling to drive these cars when they were new from the dealer.

/Glenn.