piston size
Thread Starter
Heel & Toe
Joined: May 2011
Posts: 15
Likes: 0
From: Strongsville Ohio
piston size
Well we finally got all the pieces that we wanted shipped to the shop for the rebuild but now find that the pistons won't "fit" the 30 over that it's been bored... "Piston's" is becoming a dirty word in my vocabulary! Long story!
Anyway...what is your collective opinion of going with 60 over pistons (have had trouble finding 40 over that will fit our configuration and give the outcome we are looking for (10:1). Machine shop says using the 60 over that we just sent to replace the 30 overs will cause problems with the walls thinning...engine has never been bored previously... Our understanding is that you could actually go 100 even 120 over...what do you think??? ('74 454 Corvette)
Anyway...what is your collective opinion of going with 60 over pistons (have had trouble finding 40 over that will fit our configuration and give the outcome we are looking for (10:1). Machine shop says using the 60 over that we just sent to replace the 30 overs will cause problems with the walls thinning...engine has never been bored previously... Our understanding is that you could actually go 100 even 120 over...what do you think??? ('74 454 Corvette)
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Are you saying that the pistons you purchased are too big for the bores? And the machinist bored your precious 454 block without having the pistons beforehand? If that's the case then the bores should just need to be finish-honed up to the correct size, which is standard procedure for an overbore. If your machinist is unaware of this I would highly advise considering another machinist...
As far as boring this block more than +.030", you would just be removing additional material unnecessarily. I'm no big-block guy ( there are plenty here though) but I do know that going past +.040" with a 'mouse motor' is not advisable without having the cylinders sonic mapped to check for thin walls, ESPECIALLY when said motor is going into a car that is known with heating issues like a C3 Corvette...my $1.380
As far as boring this block more than +.030", you would just be removing additional material unnecessarily. I'm no big-block guy ( there are plenty here though) but I do know that going past +.040" with a 'mouse motor' is not advisable without having the cylinders sonic mapped to check for thin walls, ESPECIALLY when said motor is going into a car that is known with heating issues like a C3 Corvette...my $1.380
Last edited by birdsmith; Feb 6, 2013 at 08:02 AM.
