Re: how far can a 318 be bored?
[Re: motomatt383]
#619244
02/20/10 10:49 PM
02/20/10 10:49 PM
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Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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there seems to be alot of 318 which are 3.91 bore being bored to 4.00 which is .090...
a 340 is 4.040..you will need another .050 for a total of .130....that is ALOT.
If you want to bore that 318 larger then say .040...you should find a machine shop that can sonic test the thickness of the cylinder walls to determine how much of an overbore you bore can take safely ...
Last edited by 70AARcuda; 02/20/10 10:50 PM.
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: how far can a 318 be bored?
[Re: RapidRobert]
#619247
02/21/10 12:44 AM
02/21/10 12:44 AM
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Joined: Jan 2003
Posts: 931
dulcich
super stock
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super stock
Joined: Jan 2003
Posts: 931
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Quote:
Quote:
As mentioned, have the block sonic checked then you will know just how far of an overbore you can go...
Exactly & I doubt you can go from 3.91" to 4.04"
Let me correct you on this, Robert, it's been done, way back in the days before sonic testers. That said, it is probably a rare 318 block that can go that far. These days, by all means, sonic the block, and prepare to be dissappointed.
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Re: how far can a 318 be bored?
[Re: ademon]
#619251
02/21/10 09:50 AM
02/21/10 09:50 AM
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Joined: May 2003
Posts: 15,487
Florida
scratchnfotraction
I Live Here
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I Live Here
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Posts: 15,487
Florida
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seen lots of the poly 318 bored 90-100+ over bore but its the poly block that is the diff from what I understand cant you use a sleeve in the thin 318 block to get the 340 bore? 4" crank is the ticket with a 318 IMHO anyways 
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Re: how far can a 318 be bored?
[Re: motomatt383]
#619253
02/21/10 02:38 PM
02/21/10 02:38 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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MotoMatt your Q didn't sound vague at all. I think it will depend on what thickness the sonic checker shows you. I am doing a 360 stroker w the 4" crank and some 1.560" badger flat top pistons and some 50 under rod bearings and some .054" felpros' and I am going to destroke it as much as I can w these bearings ALL to reduce my positive deck height deck so I will only have to mill the pistons slightly (plus notches). A bit different but I'm working with what I have (plus on a budget) and I mainly need more torque in my daily driver 65 dart (I'm getting no respect w the stock 318  ). I'd call your shop & see what they want to sonic check it & if it'll go .130" all you need to do is take your choice of pistons in & tell them to go ahead.
live every 24 hour block of time like it's your last day on earth
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Re: how far can a 318 be bored?
[Re: motomatt383]
#619254
02/21/10 02:51 PM
02/21/10 02:51 PM
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Joined: May 2007
Posts: 209
New Zealand
solidcam
enthusiast
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enthusiast
Joined: May 2007
Posts: 209
New Zealand
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I have done it.Would I do it again,....no.That engine failed due to oil starvation,bearing failure.You want the walls as thick as possible on any given block and go for MINIMUM oversize.That block at 130 thou oversize I believe worked but when pushed hard put alot of heat into the walls and jacket water.
Stroker crankshafts have eliminated the need to gain displacement by boring a block not specifically engineered for that purpose.
Last edited by solidcam; 02/21/10 03:00 PM.
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Re: how far can a 318 be bored?
[Re: solidcam]
#619255
02/21/10 03:38 PM
02/21/10 03:38 PM
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Joined: Jan 2003
Posts: 2,111
Bowie, MD
Reggie
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,111
Bowie, MD
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Here is an old Mopar Muscle article about Hensley Performance. They were routinely taking 318s .090" (4" bore - same as a 360) to get 402" with a 4" crank. The 318 cores went through rigorous sonic and pressure testing before being used. Sonic checking is the only way to tell as mentioned, but 4.04" would be pushing it and I would opt for more stroke rather than trying for that much overbore.
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Re: how far can a 318 be bored?
[Re: motomatt383]
#619256
02/21/10 03:52 PM
02/21/10 03:52 PM
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Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
mike s
top fuel
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top fuel
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Posts: 1,668
Mi,U.S.A.
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Quote:
sorry i started this posting kinda vague. i'm researching this, and i keep hearing its been done, but I've yet to hear from someone who HAS done it. I'm putting it in my '70 D-100 pickup, the engine is a 99 Magnum motor, with a dual plane intake & i just ordered my Cam, not huge just a nice improvement over stock. i don't want to get into building a stroker. yea it'd be Kool, but.
I would even more cautious with a Magnum block.Sonic test is a must over .040.
Leave the gun.......take the Cannoli's....Mike
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Re: how far can a 318 be bored?
[Re: motomatt383]
#619258
02/21/10 04:56 PM
02/21/10 04:56 PM
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Joined: May 2007
Posts: 209
New Zealand
solidcam
enthusiast
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enthusiast
Joined: May 2007
Posts: 209
New Zealand
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You don't have to spend a fortune on a teen to get performance.The main thing going against you are the pistons, usually down the hole quite far resulting in low compression.Some KB'S will sort out that problem.Next the cylinder heads, for low bucks I like the the factory J castings(for a non Magnum application) cleaned up with 2.02 or 1.92 valves with new guides,springs,retainers and some machine work(do a bowl port at the minimum),some ARP rod bolts.Find some 273 solid lifter valve gear from a junker or second hand and throw in a nice solid lift cam and you will be enjoying the teen the way it should have been assembled from the factory.
Last edited by solidcam; 02/21/10 04:57 PM.
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Re: how far can a 318 be bored?
[Re: solidcam]
#619259
02/21/10 06:05 PM
02/21/10 06:05 PM
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Joined: Jul 2009
Posts: 525
Durham, NC
motomatt383
OP
mopar
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OP
mopar
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Posts: 525
Durham, NC
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I'm gonna just get a set of .030 pistons, with a zero deck height. i was hoping to get it to 340std. bore specs, mostly because its easier to say its a 340 than it a 318. but I've had a couple of 340 cars & even in there wore out condition. they would run like nobodies business!!
as far as the engine I've got, its a magnum so its got good heads & roller cam!
Last edited by motomatt383; 02/21/10 06:07 PM.
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Re: how far can a 318 be bored?
[Re: solidcam]
#619260
02/21/10 06:07 PM
02/21/10 06:07 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
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Posts: 14,889
up yours
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Apparently, I am the only one that reads CarCraft. They have a stroked and poked 318 article in it RIGHT NOW.
4" bore 318 is not uncommon, but as said t is sonic tested first. BTW, all you recommending a sonic test, what's you minimum wall thickness recommendation?
(funny how everyone hollers sonic test, but no one says what you need, methinks Polly has been around).
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: how far can a 318 be bored?
[Re: Supercuda]
#619262
02/22/10 03:35 PM
02/22/10 03:35 PM
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Joined: Jan 2003
Posts: 2,111
Bowie, MD
Reggie
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top fuel
Joined: Jan 2003
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Bowie, MD
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There is a very good discussion about sonic testing here...
Last edited by Reggie; 02/22/10 03:36 PM.
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