360 LA sonic test results??

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Val360

Val360

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Hi all,

I've just recently had my 360 block sonic tested to see if I could possibly bore it out to .060" over as it already sits at .040". The results I got from the sonic test showed Cyl 2 and 4 to be just over .100" on the rear of the bores which has me a little worried. Just after some recommendations on what path to go down, I was possibly looking at offset sleeving the two bores and then offset boring (offset towards front of block) the block to hopefully gain a bit in these two areas. I'm open to all opinions and suggestions

Little info on build - Engine I will be assembling will look something like 4.00" stroke, 10.5:1 comp, RHS 'X' heads, mechanical solid cam in a 1450kg (3200lb) car with a 727, 3800 stall and 4.11 gears. Will be mainly for street use. (I'm in AUS so the passenger and driver will be opposite)

sonic1.jpg
 
The front and rear of the bores are not extremely critical. They are not the thrust sides.
 
RustyRatRod said:
The front and rear of the bores are not extremely critical. They are not the thrust sides.
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Certainly aren't major or minor thrust sides but was just worried about taking an extra .010" off the wall may be playing with fire when it comes to high cylinder pressures
 
If your comfort level isn't high, you might want to think about acquiring another block therefore bypassing any angst and additional cost in machining the current block. Perhaps, you can sell it off to someone with a stock/milder build planned. GL.
 
A good machinist can manipulate the bore so as to minimize the effect.
 
GTXperience said:
If your comfort level isn't high, you might want to think about acquiring another block therefore bypassing any angst and additional cost in machining the current block. Perhaps, you can sell it off to someone with a stock/milder build planned. GL.
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Would be the ultimate solution to my worry, trying to find another block over here is ridiculous, rare as hens teeth. I envy the availability of used parts you have in the states
 
I don't think 0.010" will make any appreciable difference. Just reserve full on boggy special events.
 
Val360 said:
Would be the ultimate solution to my worry, trying to find another block over here is ridiculous, rare as hens teeth. I envy the availability of used parts you have in the states
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Well ... lets get a pallet of blocks headed your way. Use one and self the rest. I just need to look up my contacts that have semi regular containers heading out of one of the Southern California ports and headed over there.
 
Hensley Performance has been boring the 318 LA and Magnum blocks to 4" and beyond for well over 20 years. So evidently, they aren't worried very much. lol
 
m880 said:
Are 318/5.2 more plentiful? Stroked 390"+
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Literally bugger all over here, if your into your chryslers/valiants in Australia trying to find engines be it 318/340/360 you won't have much luck or be waiting an eternity for one to be up for sale. Chev on the other hand is in your face where ever you go, I wouldn't be able to look at myself in the mirror if I took that leap ;)
 
GTXperience said:
Well ... lets get a pallet of blocks headed your way. Use one and self the rest. I just need to look up my contacts that have semi regular containers heading out of one of the Southern California ports and headed over there.
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If we are talking pre magnum blocks, virgin bores then I'll definitely be interested in that idea
 
Val360 said:
Literally bugger all over here, if your into your chryslers/valiants in Australia trying to find engines be it 318/340/360 you won't have much luck or be waiting an eternity for one to be up for sale. Chev on the other hand is in your face where ever you go, I wouldn't be able to look at myself in the mirror if I took that leap ;)
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i'm in NZ and same deal here trying to source 360 blocks, sweet FA of them.
 
GTXperience said:
It sounds like 318s would be in demand too. Hmmmm. What's the going rate for virgin 318/360 blocks there?
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If your lucky to find one they tend to go for anywhere from 350-900 for a bare 360 and last 318 I've seen pop up went for 450 with a crank
 
Are the Drivers and Passengers referencing the US orientation, or AU? I identify them as front, major thrust, rear, and minor thrust. Front and back are not as important, but are still important.
Based on the US positions... I would use that block for a lower power level, or plan to have it sleeved on three holes. I'm not a fan of offset boring but it could also be done although looking at the results you really don't have a lot of meat to offset it into. That is what core shift looks like on a LOT of Mopar blocks. BTW - sleeving is perfectly viable. I've got a couple with 4 sleeves in them running just fine years later, and some good power levels.
 
Yeah blocks are hard to get here. Can get a bare 318 block from 80-100 USD but 360 blocks in particular vigin bore early blocks would go for 500 USD upwards.
I sold a later 360 block recently that needed 2 sleeves for 250 USD
The guys building strokers really want to start with a 360 base and unfortunately not many 360s were sold here.
 
moper said:
Are the Drivers and Passengers referencing the US orientation, or AU? I identify them as front, major thrust, rear, and minor thrust. Front and back are not as important, but are still important.
Based on the US positions... I would use that block for a lower power level, or plan to have it sleeved on three holes. I'm not a fan of offset boring but it could also be done although looking at the results you really don't have a lot of meat to offset it into. That is what core shift looks like on a LOT of Mopar blocks. BTW - sleeving is perfectly viable. I've got a couple with 4 sleeves in them running just fine years later, and some good power levels.
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The results are the in AU reference, Drivers side is Major and Passenger is Minor. With the build I will only be looking for close to 500hp with the 4.00" stroke, certainly won't be anything over the top. Planning to sleeve cylinder 2 and 4...in your opinion what would be the third cylinder to sleeve?
 
I had a thought to do one on the driver's side bank (AU handing...lol). But looking again I think I'd just leave well enough alone and do what your test shows as 2 and 4, but are really cylinders 3 and 7 in the factory numbering. IMO it's still a little thin in a few spots. I like to see all the test data from each hole - not just the thinnest because you can get shifting top to bottom, not just side to side. I'm not sure if your tester can do sweeps, but it might be a good idea to do sweeps on any area that shows less than .120". I supply five readings for each compass point in each cylinder: one per inch from top to bottom, and one that records the thinnest sopt along the line of previous test points. It's rare that the thinnest test point is actually the thinnest spot along the bore's length.
 
Here's a bore from a recent test I did. It allows me to see the trend along the cylinder wall. The "thinnest area" could be anywhere. Some places it's potentially a big deal. Some it's not. Both banks of this block have core shift to the minor thrust side, making that wall the thickest.

A result such as the OP put up IMO doesn't tell enough of a story to determine if the block or a given bore is ok or not. Hence my comments. It all boils down to comfort level that the information is completely relevant and accurate, or only partially so.
 

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$80-$100.00 I would give up a litle bit of cubes and buy up 318/5.2's and a good forged stroker crank and go fast and no worry because I would know i had plenty of backups.
 
I have tested about 5 x 318 and 5 x 360 blocks out here in Oz and havent had much luck with finding a decent 318 block. The worst 360 block i sonic tested was better than all of the 318's tested,not sure what everyone else experiences have been.
 
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