Boring a 360 block

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Demonracer

Demonracer

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I have a 73 360 block and am curious as to whether or not you can bore these blocks .060 over. I can't remember if the 73 and later blocks will take that much over without the cylinders being to thin and splitting. I plan on doing a full fill with HardBlok once it has been bored. Any info will be greatly appreciated.
 
After decking to specs, fill first, one side at a time, with torque plates or heads & mains installed. THEN bore & hone with torque plates & mains. Use a head gasket like the one to be used in final assembly.

You should be able to go 1/2-1" below a "full fill" to help with cooling. I've run them at .060", but sonic checking is always a good idea. They can vary.

Follow the instructions carefully.
 
Our 71 Dart has a .060 over 360....and it is a early block ...could not see the exact casting date on it...headers in way....Been like that since 2006.....

But .....as said...never know ...only by sonic testing it...
 
It's going to be a race only motor, and I'm going .060 over because I have .060 pistons handy.
 
Sonic test is the only way to know but .060 is only .030 per side. Pistons are cheaper than paying the machine shop to machine your block and everything else that is required in a rebuild, just to find boring it .060 to have cooling issues. Roll the dice. You said it would be race only. Hard block it. You can cool it down between passes. You made find it'll idle for hours.
 
Back in April I had a 360 ..bored...honed...decked...block baked...and cam bearing installed...470 dollars..

Find me a set of forged racing pistons for 470 dollars?....

The bore and hone was 125 dollars...
 
I'm just wondering how many 360 actually fail sonic check?
Anyone have a 360 that fail to go .060" ?
 
I've never bored a 360 past .030, only because I haven't had one to need it. Never had a cooling issue on a big block or small block that couldn't be fixed with a good cooling system. They will bore farther than you think. I had 68 383 block one time that was bored .070 over with standard bore low compression 440 pistons. Worked great for a low budget build. Pistons were only about .010 in the hole. Never had a cooling issue. Mopar has better piston wall thickness over all than most. A lot of people go by the numbers on the block when picking one for a build. The number that tells how many cores were corrected or something like that. I've always heard the lower the number the better. I don't know how important that is but a seasoned block is. How many cycles it heats up and cools down. You can season a new one in a furnace or find one that has a lot of miles on it that was taken care. A daily driver that was someones ride. My last 360 was out of a church van with over 100,000 miles on it. Clean cylinders that you could hardly feel a ridge of even carbon at the top. Bearings were good too. Lots of duty cycles. I built my 408 with it. Look the block over good. Look at things like freeze plugs holes, dose the block look like it was a sloppy day casting blocks for mopar or not. You'll probably be fine.
 
in 73 they were still using the 340 sand casting for 360's and stock bore was 4.04 so your only boring it .020 over a stock 340 .And I have gone to .100 on these blocks with out problems until about 76.
 
273 said:
I'm just wondering how many 360 actually fail sonic check?
Anyone have a 360 that fail to go .060" ?
Click to expand...

I had a 340 that "failed" to go .020" and had to put a sleeve in it. Since 340's are made out of (fools) gold, we had to save it for the customer.

I have seen a few 360 block that I sonic tested that had so much core shift in them, they were down to .070" thick on one side(cant remember if it was the top side or bottom).
 
MRL Performance said:
I had a 340 that "failed" to go .020" and had to put a sleeve in it. Since 340's are made out of (fools) gold, we had to save it for the customer.

I have seen a few 360 block that I sonic tested that had so much core shift in them, they were down to .070" thick on one side(cant remember if it was the top side or bottom).
Click to expand...

Not one of my 340s sonics worth a ****. Bad core shift and thin castings. Best left to the numbers match resto guys, or class racers that have to use them.
The best blocks for me have been the later roller LA 360s. Much better casting quality, machining, and material IMO.
 
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