LA blocks

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rumblefish360 said:
I can’t remember the place, but they are sonic chexking 318 blocks (stock bore at 3.91) and boring them out safely to 4.00 and popping in 4.00 stroke cranks. Yep! That’s right! Safely removing .090 of cylinder wall! YIKES!

There was a time I’d call a person a lier for that statement.
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I mentioned the same thing in my post regarding the Engine Masters poly builder that used a 318 LA block. I about fainted when I saw .090" or .100" over, but according to him, they're pretty common.
 
63SplitWindow said:
That is a pretty badass '318' then!
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Yeah, especially with 402 cubic inches!

...'course if I had that stroker under the hood of a factory Poly car, I might just lie and say it's "just a 318" anyhow. Much like the Spanish Inquisition, nobody expects a stompin' Poly. :p
 
I built a 416 from a 77 360 block in about 1999. I just dropped it off and let um bore it .070" and never looked back. In fact, the engine is still running in a Ram Charger, as far as I know.
 
Demonic said:
I've been looking for a source for quite a few years now, of something I read a long time ago. In the late 80's, early 90's there was an article or book about someone sonic checking 318's and boring them .090" over. Might have been Bob Mullen. They were doing that and welding up cranks for a 4" stroke. Obviously much easier nowadays.

Tha answer to your question - is it depends. Most any block can go .030 with no worries. A very rare few blocks have bad core shift and .060 can be a problem. And the opposite is also true, some have perfect cores and you can go .070. A 318 is 3.91 bore, and would need careful checking to go .090" over by someone who knows what they're doing. A 360 is 4" bore. Rumors have persisted for years about early blocks w thicker jackets.
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Hensley Performance bored alotta 318s .090 over!!
 
Cudafever said:
The story goes that the early 360 had more cyl wall thickness because the early 360 was a 340 mold with 360 mains?????
What i do know is that my 68 340 block was bored .060 over and my stupid arss shove a intake valve thew the cyl wall.............the hole reviled a paper thin........ok ok maybe .010 to .015 thow thick.
Eng over headed easy
new block bored over 30 and all else the same (Different head, but both 360 heads) and no over heating issue anymore.......coincident?
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The probability is that the early 360 water jackets weren’t cored on just 340 water jacket coring, but the 340 TA water jacket coring. Unfortunately not the webbing, though. But the extra thick cylinder walls are for sure nice. I can confirm later 318 industrial blocks (Big capital “I” cast into the side), also have very heavy cylinders. They almost touch each other in the top third and only have an 1/8 inch between them on the bottom two thirds. I have yet to see any later year industrial 360s, though.
 
NoCar340 said:
.040" should be fine, but I always sonic-check a block these days.
I had a standard-bore 318 that wouldn't have safely withstood .020" halfway down #2 in the 9 o'clock position. Otherwise, it would've gone .060" easily. A few years ago, one of the Engine Masters Vintage class entries was a Poly 318 that used an LA block (he couldn't find a proper Poly) and the builder claimed .090" was rarely an issue on 318s through '76 or so. Would I do it? No. I agree with the others that have stated keep the walls as thick and rigid as possible. A couple of cubes will not make up for wall flex. The 340 for my Challenger is only .020" over because it was clean there.

If you're hanging around the kind of people that refer to their 350 and 400 Chevrolets as "355" and "406" just because it's been bored .030", find smarter friends (or more confident in their manhood). I've never heard a Mopar guy say he's got a "four-forty six" unless it was immediately followed by "pack". :p A .040"-over 360 is still a 360 to me.
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a Mopar 408 or 416 is recognized as a stroked 360 or 340 small block, a 400 is a smog B block 400. I dont know anyone that's gonna still call his 4" stroked 360 a '360'.
Cudafever said:
The story goes that the early 360 had more cyl wall thickness because the early 360 was a 340 mold with 360 mains?????
What i do know is that my 68 340 block was bored .060 over and my stupid arss shove a intake valve thew the cyl wall.............the hole reviled a paper thin........ok ok maybe .010 to .015 thow thick.
Eng over headed easy
new block bored over 30 and all else the same (Different head, but both 360 heads) and no over heating issue anymore.......coincident?
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I sold a .060 over 340 to someone. He bought it. Bores looked good to me and it ran fine. But in knew it was on its last life.
 
pishta said:
a Mopar 408 or 416 is recognized as a stroked 360 or 340 small block, a 400 is a smog B block 400. I dont know anyone that's gonna still call his 4" stroked 360 a '360'.
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You didn't read my follow-up post. I had originally addressed it in the one you quoted, but apparently somehow deleted that part while editing the length of it.
 
Dartswinger70 said:
I would like to point out(not trying to start a pissing match) that a 318 technically cant be bored that big.
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Sure they can, I've seen a handful of 318s with a 4" bore. But just because you can doesn't mean you should - always go with the smallest overbore you can get away with so it doesnt flex. Plus they aren't making these things any more and you might get another rebuild out of it.
My 318 is 0.060" over, thinnest cylinder is 0.167" on the trust side.
 
This is just a thought not based on fact but I would think or recall that the early engines possibly had more metal cast in them. it would make sense from the mid 70s on the block would be cast with less material to save money. I seem to remember Chrysler always going bankrupt and being bailed out by the govt so they would have cut costs everywhere especially after the govt. got involved. We know now when the govt gives you money they essentially tell you where to trim fat. I would think the magnum engines are even lighter and thinner also. Just a though though I can't back any of this up.
 
Ted265 said:
Sure they can, I've seen a handful of 318s with a 4" bore. But just because you can doesn't mean you should - always go with the smallest overbore you can get away with so it doesnt flex. Plus they aren't making these things any more and you might get another rebuild out of it.
My 318 is 0.060" over, thinnest cylinder is 0.167" on the trust side.
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For clarity 4.00" in a 318 is .090" over? and you've seen this? I personally would go over just enough to clean it up .010" at a time. But I am conservative and would want to get another rebuild also.
 
RustyRatRod said:
I built a 416 from a 77 360 block in about 1999. I just dropped it off and let um bore it .070" and never looked back. In fact, the engine is still running in a Ram Charger, as far as I know.
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Is that where ya got the old name strokerscamp?
 
mopardude318 said:
Is that where ya got the old name strokerscamp?
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Naw. That engine went into a 67 Dart GT. I had a 73 Scamp sometime after that I had planned to build a 451 for....but as with a lot of my projects, I had to sell due to finances. I wasn't happy with it, but I was happy I was able to get us out of the tight.
 
Dartswinger70 said:
For clarity 4.00" in a 318 is .090" over? and you've seen this? I personally would go over just enough to clean it up .010" at a time. But I am conservative and would want to get another rebuild also.
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Yep .090" over. My brother bought a 318 powered valiant around 10 years ago that developed a knock after about a year of driving, we pulled it down a found a worn 4" bore and bearings down to the copper. That block was a Brazilian casting and was sent to scrap and a replacement motor sourced for the car. I also saw 2 more built on our Aussie forums before they shut down - one was an industrial 318-3 block and the other was a very early casting if I remember correctly.
Also ran Into a guy at a car show also with a 318-3 that claimed to have a 4" bore.
Dartswinger70 said:
This is just a thought not based on fact but I would think or recall that the early engines possibly had more metal cast in them.
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Ive heard this before also, mine is a '73 block so there may be some truth to that?
 
I wouldn't worry about .040 over. I have a 1980 block at .060 with several problem free years.
 
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