Anybody done this to thier nailhead. If so can you tell me whats involved and what kind of results you got.
bigger bigger bigger I am with doug, check it out first. But I would bet that it can be done. When Buick recored to jump from 364 to 401 I would think that they planned for it because the factories know 10 yrs ahead what they plan to do with engineering.
NO WAY!!!!!! Buick started with the thin wall castng method in '57. As time came closer to the demise of the ole Nail the core shift was TERRIBLE!!!!! I would not even think about going .030" over without sonic testing for some kind of a race engine. Even in the Chassis manual for a 425 it only recommends a .010" overbore. On my friend's engine & many others I have sonic tested with an overbore as small as .030" some cylinder walls were only .090" thick. On a stock rebuild .030" is questionable never mind .125" or an 1/8th. inch. Just my thoughts & experience speaking.
question I beleive I said that I am with doug, he said to sonic test first and then bore. I have bored several .030 with no problems and currently have one in my car that is bored .040. but I had the block tested first. This is the very first time I have ever heard any one say that the nails had a core shift problem.
a few years back we tested every casting number buick manufactured and found a few that would consistently bore fine. Turns our Buick used the same casting for the later 401 and 425. The las three digits of your casting number will be 705
The 425's were cast with bigger holes for the cylinders. Some but not all 401's can be bored to a 425 without problems. I agree that sonic testing to assure there is enough meat on the cylinder walls is a good thing to do.
Gotta disagree with Nailheadracer on this one..from personal experience I have found the `64-`66 Nailheads follow a distinct pattern in terms of block casting numbers. I have found the 401 to be the 705 casting number and the 425 to be the 704 casting number.....without exception. Checked maybe 30 or 40 cars over the years, quite possibly more. Tom Mooney
I have 2 401's one is .040 and the other is .060 over. I know that the 425 has less metal for this but testing is always a must over .040.
.060 over and feelin fine Guys, I am currently running a 65 401 that is .060" overbored. I have not had any problems with cooling or any others. It has been in the car for three years and I beat the crap out of it. I spent all three days at the San Bernadino Route 66 Rendezvous the last three years cruising all day and night. not to mention that I drive it daily, and have since I was 16 years old. Not one problem. If you sonic (Ultrasonic) test it, you will find it to be stout enough.
