Have you sonic checked 360 or even 318/340?
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skrews
Well-Known Member
More often then not, blocks bored to .060 over are going to have some thin areas due to core shift and water jacket corrosion. One needs to make a judgement call as to whether the block is usable based on the intended use. I'm currently running a 72 model 360 block that at .040 over is thicker than most all the other 360 blocks I've ever checked. I almost passed it up once I found it was .030, but luckily I hauled it off anyway. There are a lot of second hand myths and wives tales out there on this subject.
To more specifically answer your question. Yes I have seen 360 blocks that would have certainly failed at .060 over. They never got the chance to though, because they were weeded out by sonic checking.
To more specifically answer your question. Yes I have seen 360 blocks that would have certainly failed at .060 over. They never got the chance to though, because they were weeded out by sonic checking.
moper
Well-Known Member
I have several 340 & 360 blocks in service as strokers. 4, actually. All required between 1 and 3 sleeves to be passable by my standards. None have any issues with power or longevity.
Hay Dave, just out of curiosity, what is your accepted minimum limit on the thrust side?
moper
Well-Known Member
I don't like going thinner than .175" on the major and minor thrusts for a street engine. I know others go .150, or even .120 but that makes me nervous. Remember, even doing a good continuous scan you won't test every single spot unless you have a day to do it. I feel .175 allows for some hidden surface features that will be there, but won't present a thin spot for a crack to start.
:cheers:
skrews
Well-Known Member
Aussie Charger
Well-Known Member
I'm curious: were the 360 blocks early castings, ie 3418496 castings produced from 1971-74 and sharing the same metal as the 340s?
My 3418496 360 is already .030" over. Just spoke to a guy last week who has an early 360 block .100" over (equivalent to a .060" over 340), and after sonic testing he still had .150" left on the thinnest side.
I read another of your posts where you believe the 340/360 castings only applied to the 1971 blocks. Did you compare 3418496 castings from different years to discover this?
The reason I'm curious is because I'm planning on taking out my 360 to +.060" and everything I've read - from Shepherd to Szilagyi - all state the early casting 360s are the same as the 340s. That also tends to be our experience with them.
The biggest problem is probably their age and the potential for water-jacket corrosion.
moper
Well-Known Member
Aussie - You're buddy got a good one but I would doubt what he said. Let me clarify that - if he has .150" on the pin axis that's great. Way overkill and the thrusts should be way over .200 - but this would have meant they astarted at almost .300 which is highly doubtful unless it was core shifted to the major thrust side. If he has .150" on the minor thrust, still good. If he had .150" on the major thrust which is what most guys that "know" talk about - I wouldn't brag about it and it would have failed by my opinion depending on his planned use. My impression is he's wording it to make it not a big deal for you. It's not a big deal to him and that is his block. It might be to you on yours. Invest a couple hundred before you commit thousands basing the decision on some authors and a friend's singular result.
I've built using the earlier blocks but that was my pre-sonic tester days. I have tested one for someone - it failed due to core shift in the whole bank - IIRC the even side bank was crooked. Meaning the sand cores were not placed in the core box properly, and the result was castings that were cocked between the deck and main web sections of the block.
You have to read the books with a grain of salt. I own the ones you mention plus a couple others that predate them by decades in the case of Szilagyi. The information in those books is based on published fact. It's a fact that for about a year give or take (cast in 71 and early 72) the first 360s were cast using the 340 block core boxes. But, the reality is the guys casting them were... less than ideal in terms of quality control.
Once I bought a tester and started playing with it - not testing a few spots on each bore but really testing all over and developing a "picture" of the cores in the block - I found that vitually all mopar blocks have core shift. Some in the right direction: the major thrust, most in directions that can potentially cause problems: minor thrust (driver's side of each bore), pin axis (front or back of each bore), or leaned over rather than perpendicular to the deck and main bore. It can be one hole, or the whole bank of cylinders. We are talking the cores here, resulting in the iron being thinner than the engineers specified in particular areas. That's not something the printed records will show because the blocks were production parts that were used and operated fine. The early books almost never mention sonic testing because the technology was not cheap enough to make it worthwhile on an automotive engine. Also - if you don't own a tester and have to pay to have a single block tested - you may swear that what's written is the truth and it's true on your engine. It's my opinon that while it is the truth based on print, reality most times does not reflect the intention of the designers & engineers.
It all comes down to "have every block tested by a competant guy with a good tester". That will seperate "the truth" from your individual "reality".
If your sonic test results have less than 20 readings per hole you cannot accurately determine what the shape and placement of the cylinder casting really is, nor the thickness trends that would indicate possible failure points. If you pay for insurance make damn sure you get a result that lets you make an informed decision. If you chose not to - that's all up to you. I'm sure polls would should a lot of succes with the "just do it" approach but that's little solace to the few that were not successful and spent the same $$.
I've built using the earlier blocks but that was my pre-sonic tester days. I have tested one for someone - it failed due to core shift in the whole bank - IIRC the even side bank was crooked. Meaning the sand cores were not placed in the core box properly, and the result was castings that were cocked between the deck and main web sections of the block.
You have to read the books with a grain of salt. I own the ones you mention plus a couple others that predate them by decades in the case of Szilagyi. The information in those books is based on published fact. It's a fact that for about a year give or take (cast in 71 and early 72) the first 360s were cast using the 340 block core boxes. But, the reality is the guys casting them were... less than ideal in terms of quality control.
Once I bought a tester and started playing with it - not testing a few spots on each bore but really testing all over and developing a "picture" of the cores in the block - I found that vitually all mopar blocks have core shift. Some in the right direction: the major thrust, most in directions that can potentially cause problems: minor thrust (driver's side of each bore), pin axis (front or back of each bore), or leaned over rather than perpendicular to the deck and main bore. It can be one hole, or the whole bank of cylinders. We are talking the cores here, resulting in the iron being thinner than the engineers specified in particular areas. That's not something the printed records will show because the blocks were production parts that were used and operated fine. The early books almost never mention sonic testing because the technology was not cheap enough to make it worthwhile on an automotive engine. Also - if you don't own a tester and have to pay to have a single block tested - you may swear that what's written is the truth and it's true on your engine. It's my opinon that while it is the truth based on print, reality most times does not reflect the intention of the designers & engineers.
It all comes down to "have every block tested by a competant guy with a good tester". That will seperate "the truth" from your individual "reality".
If your sonic test results have less than 20 readings per hole you cannot accurately determine what the shape and placement of the cylinder casting really is, nor the thickness trends that would indicate possible failure points. If you pay for insurance make damn sure you get a result that lets you make an informed decision. If you chose not to - that's all up to you. I'm sure polls would should a lot of succes with the "just do it" approach but that's little solace to the few that were not successful and spent the same $$.
Aussie Charger
Well-Known Member
He mentioned he had over .300" when he sonic tested before boring. Not sure if he offset bored or what the core was like (if the core shifts towards the thrust side it's good), but he's done a couple of them before. This one was a 72 block. I won't be doing anything to my block without sonic testing - a lot of early 360s are old and abused now.
Bloody sonic tester...I have a BHJ and it ALWAYS brings the pain...
30 years ago when cores were abundant it was no big deal, but now the crap we wouldn't have even thought about back then are gold now..
I think that a 340 block at .060 without a spot under .125 is doing pretty good..360's without a .090 or less spot somewhere is doing pretty good..
The days of 185 to 220 are long gone...IMO
I've been jumping over 2 340 blocks that have .185 to 220 wall after .060 since the early 80's.More than likely end up giving them to a customer just to build something neat with them..
30 years ago when cores were abundant it was no big deal, but now the crap we wouldn't have even thought about back then are gold now..
I think that a 340 block at .060 without a spot under .125 is doing pretty good..360's without a .090 or less spot somewhere is doing pretty good..
The days of 185 to 220 are long gone...IMO
I've been jumping over 2 340 blocks that have .185 to 220 wall after .060 since the early 80's.More than likely end up giving them to a customer just to build something neat with them..
moper
Well-Known Member
Agreed. That's why I sleeve now rather then keep testing and looking for better. I've got a couple 408s with pin axis thicknesses of .090 in service too.
I think a lot has to do with intent too. There's people that say they want a 550hp stroker that have no point of reference and will never use it and the sonic test forces them to take a closer look at their ambitions. 340s are not hard on walls. 360s really aren't bad either. It's the 1.5 rod/stroke ratios that start to push it as far as I'm concerned.
You have to sleeve these days because the cores are just not there for a good price...
I have guys trying to sell me cores for 300-500 out of late 70's trucks and they think they have gold.
I tell them $50.00
These days if you have a bad hole ..poke a sleeve in it and down the road it goes..;)
I have guys trying to sell me cores for 300-500 out of late 70's trucks and they think they have gold.
I tell them $50.00
These days if you have a bad hole ..poke a sleeve in it and down the road it goes..;)
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