340 .060 bored

[Risko1]

I'm looking at a 71 340 long block that has been bored .060.
Can someone give me pros and cons for this bore size.
I assume there is no room left for error since bore is maxed out.
How much increase in HP can this engine supply using standard rebuild parts relative to the .060 vs 340 that has not been bored.

I'm learning, so please indulge me.

[dodge freak 2]

I believe the block needs to be sonic check. Its the only way to know for sure. Some are fine @ .060 over and can even be bore more. Some are cast thiner and should not even be taken out .060. Sonic checking will tell you the thinest part of the wall. I believe they like too see .100 but I could be wrong on the part.

How much does it cost, IDK

[MEK-Dangerfield]

Since it's bored 60 over, you would be at about 351 cubic inches right now if you stay stock. The block would have to be check out as was suggested. You don't want to be buying a cracked one.


  Mike

[Risko1]

Price as a short block is offered to me at $400. 
I was told from someone else that with that bore size, I would be forced to use at LEAST 93 octane to get everything moving smoothly?

[MEK-Dangerfield]

Price as a short block is offered to me at $400. 
I was told from someone else that with that bore size, I would be forced to use at LEAST 93 octane to get everything moving smoothly?

Here's where it gets tricky. How do intend to use the engine? Casual street driving, or drag racing, or something in between? If you go to 10:1 compression when you have it rebuilt, 93 octane should be fine. For what it's worth, I think all of us have to use 93 octane, or 93 octane + an octane booster to keep from pinging. Back in the day, the leaded gas was of higher octane than the unleaded stuff we have now.

The price of the block sounds good, IF it isn't cracked. 


  Mike

[Chryco Psycho]

minimum wall thickness is .125 on the thrust side , outside wall of the cylinder , cylinder wall flex is the big concern if the wall flexes under power the rings lose their seal & power is lost . Octane has Nothing to do with wall thickness octane is resistance to the fuel igniting from heat , the extra CI will make a very nominal increase in power , anyone boring a block to increase power is going the wrong way

[Risko1]

Thanks for the feedback guys, I think I will pass on this one and stick to finding a standard bore or .030 at most.