Cadillac Owners Forum banner

1 - 8 of 8 Posts

·
Registered
1979 sdv
Joined
·
27 Posts
Discussion Starter #1
HELLO I hope I ain"t getting hooked on this stuff.however I"ve heard of 425ci.heads going on to 472ci engines, is it at all possible for pre 1974 472ci heads to be installed on to 425ci.pros&cons please
Thanks
 

·
Banned
1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
Joined
·
7,971 Posts
Well, pros would be much better flow and increased compression ratio, just off the top of my head it'd probably be around 10:1. Run the numbers through a calculator though to figure out exact... 425 heads are 96cc and the old 500/472 heads are 76cc.

Cons might be headgasket issues, you'd have to run 4.3"+ gaskets. I'm freakin tired so there are more than likely things I'm forgetting, someone else should chime in soon.
 

·
Banned
1976 Eldorado project
Joined
·
1,631 Posts
425 heads on a 472 would just do a lot of restricting. They don't raise compression that much. 76 cc heads on an engine that came with 120cc heads will yeild 12.5-13:1
 

·
Registered
1979 sdv
Joined
·
27 Posts
Discussion Starter #6
The ? was what happens with pre 1974 472/500 heads installed on 425ci or if at all possible
THANKS
 

·
Banned
1976 Eldorado project
Joined
·
1,631 Posts
davesdeville said:
Well, pros would be much better flow and increased compression ratio, just off the top of my head it'd probably be around 10:1. Run the numbers through a calculator though to figure out exact... 425 heads are 96cc and the old 500/472 heads are 76cc.

Cons might be headgasket issues, you'd have to run 4.3"+ gaskets. I'm freakin tired so there are more than likely things I'm forgetting, someone else should chime in soon.
Looks like your question has already been answered.

4.3 is the bore size
 
1 - 8 of 8 Posts
Top