Block Core-Shift Question
Thread Starter
Bud2
Joined: Jul 2005
Posts: 1,237
Likes: 4
From: Warrnambool Victoria
Block Core-Shift Question
I usually reside in the C2 section but you guys are more into the advance tech side so I'll ask the question here to.
I'm looking for a seasoned block to build a new powerplant for the vette and in looking at the blocks on offer, most display the cam opening off-center to the upper left of the boss. I thought this was an indication of core-shift. Is it worth the time/$ to have one of these sonic tested or should I keep looking? Another question how much over 30 can you safely go?
Thanks in advance.
Bud.
I'm looking for a seasoned block to build a new powerplant for the vette and in looking at the blocks on offer, most display the cam opening off-center to the upper left of the boss. I thought this was an indication of core-shift. Is it worth the time/$ to have one of these sonic tested or should I keep looking? Another question how much over 30 can you safely go?
Thanks in advance.
Bud.
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
Sonic test it. Really that should be done on any rebuild. Blocks that core shift do so on the final casting. If I remember correctly there are six or maybe eight parts to a block when the final cast takes place. Any shift takes place then. Those holes commonly called freeze out holes are really casting holes.
If enough shift took place to scrap a block, during final casting, the block would be scrapped. When I sonic test one, there may be .015 to .025 more cylinder on one side or the other. Not enough to be concerned, unless a large amount is to be bored out of the cylinder.
I would be more concerned with a bone yard block who has been setting around with water in the coolant passages, and rusted the cylinders from the inside. Sometime sonic testing can catch it.
Back on point, if a cylinder is heavy on one side or the other, some boring bars can offset bore and leave a little more material on the light side of the cylinder. Often saving a block at .030 instead of boring to .040 or larger. Leaving more metal in the walls. Common feeling is thicker walls builds more power, I haven't seen anything that prooves that to me, but it is common theory.
If enough shift took place to scrap a block, during final casting, the block would be scrapped. When I sonic test one, there may be .015 to .025 more cylinder on one side or the other. Not enough to be concerned, unless a large amount is to be bored out of the cylinder.
I would be more concerned with a bone yard block who has been setting around with water in the coolant passages, and rusted the cylinders from the inside. Sometime sonic testing can catch it.
Back on point, if a cylinder is heavy on one side or the other, some boring bars can offset bore and leave a little more material on the light side of the cylinder. Often saving a block at .030 instead of boring to .040 or larger. Leaving more metal in the walls. Common feeling is thicker walls builds more power, I haven't seen anything that prooves that to me, but it is common theory.
