Jolly_John Posted March 22, 2010 Share Posted March 22, 2010 I'm looking at a never-run since rebuilt, 1966 425 nailhead engine. It has been bored .040 over. Should I be concerned about this much of an overbore on a 425? Thanks. John Link to comment Share on other sites More sharing options...
Guest ahhh65riv Posted March 22, 2010 Share Posted March 22, 2010 John,I would be if I were you. I have heard others state "never bore more than .030 over on a 425." My own experience agrees with that due to my own findings. There are/were core shift issues, allong with the "thin wall casting" schenario that does not bode well in your favor. Without sonic testing of the bores you will never know for sure, so I would do that before you got too deep in it. There are ways to do a partial hardblock fill to help re-inforce low in the bores as well. On the other hand, I wouldn't throw the baby out with the bath water either. Sleeving IS a viable option!Erik Link to comment Share on other sites More sharing options...
Guest wildcat465 Posted March 23, 2010 Share Posted March 23, 2010 I have put together a couple of 425's that were overbored 0.040", both run fine. Unless you are doing a serious hop up, it should be OK.How much is it? What is the code on the block? (KT, KX, LT, LX, MT, MX) I may be interested if you pass. Link to comment Share on other sites More sharing options...
tim63riv Posted March 24, 2010 Share Posted March 24, 2010 Hi John!I would want the block sonically tested at .040 overbore. It might be OK, but it is taking a chance. I think 401's are just fine and personally wouldn't pay a premium for a 425. Dan said you were looking for a project, let me know if you are!Thanks,Tim Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now