engine "bore"

charliepickup22 · 10-17-2009, 07:50 AM

i dont know if anybody has asked this before but here goes trying to understand engine bore. i guess if your engine block is standard thats good.
but is it better when the engine bore is at 20,30,40 or 60? or is that a way of saying that the engine has been worked-on too much?

wayfastwhitey · 10-17-2009, 08:09 AM

The overbore on the block is a result of rebuilds. It is caused by the cylinder having either too much taper, or the size being worn beyond the recommended tolerance. At that point, new pistons are ordered and the bore is increased to match the piston plus the piston to cylinder clearance specification provided by the piston manufacturer. Some overbore is ok, but each block has a limit. Once that limit is reached, you either get a new block or sleeve back down to standard. Absolutely nothing wrong with a sleeved block if it is done properly.

charliepickup22 · 10-17-2009, 08:25 AM

so then standard is the best, if its resleeved its ok as long as its done right, what is the safest bore to work with?

wayfastwhitey · 10-17-2009, 09:02 AM

Safest bore to work with is whatever bore retains cylinder integrity. Too thin of a cylinder wall makes for a really bad day. On most Chevy 350 blocks, that limit is +.060 though I like to sleeve after +.040

Maverick2664 · 10-17-2009, 02:59 PM

its fairly rare that you find an engine thats .060 over, most of the ones you find will be between .020 and .040, the most common being .030 over, everytime you see someone say "its a 355" all that means is its a 350 bored .030 over to get those extra 5 cubes

an overbore is not a bad thing, so dont think it is, if youre trying to sqeeze as much performance out of an engine, then having it bored out is a necessity... theres no replacement for displacement

so dont be discouraged from buying an engine with an overbore

charliepickup22 · 10-17-2009, 03:29 PM

i'm not sure the engine is in the car so i'm almost sure its "std" i'l have to waite and open it up to see what is looks like. thanks for the info i'l keep you posted on engine specs.

10-17-2009, 07:50 AM	#1
charliepickup22 Registered User Join Date: Dec 2007 Posts: 389 Location: User is: OffLine	engine "bore" i dont know if anybody has asked this before but here goes trying to understand engine bore. i guess if your engine block is standard thats good. but is it better when the engine bore is at 20,30,40 or 60? or is that a way of saying that the engine has been worked-on too much?
	[Reply w/Quote]

10-17-2009, 08:09 AM	#2
wayfastwhitey Ross Racing Engines Age: 33 Join Date: Oct 2005 Posts: 1,380 Location: Aggieland, College Station, Tx User is: OffLine	Re: engine "bore" The overbore on the block is a result of rebuilds. It is caused by the cylinder having either too much taper, or the size being worn beyond the recommended tolerance. At that point, new pistons are ordered and the bore is increased to match the piston plus the piston to cylinder clearance specification provided by the piston manufacturer. Some overbore is ok, but each block has a limit. Once that limit is reached, you either get a new block or sleeve back down to standard. Absolutely nothing wrong with a sleeved block if it is done properly.
	[Reply w/Quote]

10-17-2009, 08:25 AM	#3
charliepickup22 Registered User Join Date: Dec 2007 Posts: 389 Location: User is: OffLine	Re: engine "bore" so then standard is the best, if its resleeved its ok as long as its done right, what is the safest bore to work with?
	[Reply w/Quote]

10-17-2009, 09:02 AM	#4
wayfastwhitey Ross Racing Engines Age: 33 Join Date: Oct 2005 Posts: 1,380 Location: Aggieland, College Station, Tx User is: OffLine	Re: engine "bore" Safest bore to work with is whatever bore retains cylinder integrity. Too thin of a cylinder wall makes for a really bad day. On most Chevy 350 blocks, that limit is +.060 though I like to sleeve after +.040
	[Reply w/Quote]

10-17-2009, 02:59 PM	#5
Maverick2664 Heavy Metal Body Man Age: 25 Join Date: Jun 2007 Posts: 2,846 Location: Erie PA User is: OffLine	Re: engine "bore" its fairly rare that you find an engine thats .060 over, most of the ones you find will be between .020 and .040, the most common being .030 over, everytime you see someone say "its a 355" all that means is its a 350 bored .030 over to get those extra 5 cubes an overbore is not a bad thing, so dont think it is, if youre trying to sqeeze as much performance out of an engine, then having it bored out is a necessity... theres no replacement for displacement so dont be discouraged from buying an engine with an overbore
	[Reply w/Quote]

10-17-2009, 03:29 PM	#6
charliepickup22 Registered User Join Date: Dec 2007 Posts: 389 Location: User is: OffLine	Re: engine "bore" i'm not sure the engine is in the car so i'm almost sure its "std" i'l have to waite and open it up to see what is looks like. thanks for the info i'l keep you posted on engine specs.
	[Reply w/Quote]