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Early 318 maximum bore? #60722
05/21/08 12:15 AM
05/21/08 12:15 AM
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Nevada
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dezduster Offline OP
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I have an early 318 block and I have heard somewhere they can be bored to 4.080 any truth to this? I believe its 68 or 69.

Re: Early 318 maximum bore? [Re: dezduster] #60723
05/21/08 12:53 AM
05/21/08 12:53 AM
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Kalispell Mt.
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HotRodDave Offline
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I had one sonic tested, was suposed to be good up to 4.060 I had it bored to 4.000 and 2 bores cracked the first time I stood on it. I busted through and measured with calipers and some places were plenty thick and some were .090.

Get it cleaned real good in the water jacket and then get a real good sonic test job and watch them do it, I suspect the guy testing mine only checked a couple cyls while I was there then stopped when I left and just asumed they were all good.


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Re: Early 318 maximum bore? [Re: HotRodDave] #60724
05/21/08 09:55 AM
05/21/08 09:55 AM
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dogdays Offline
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I'd say you are skating on thin ice at that size. This is another case of "I've heard that..." coming before information that is either wrong or dangerous.

With Mopar casting quality a sonic check should be mandatory before spending big bucks on block preparation, especially at crazy overbores. 318 blocks are cheap, if you're at 30 over right now get another block.

R.

Re: Early 318 maximum bore? [Re: dezduster] #60725
05/21/08 10:24 AM
05/21/08 10:24 AM
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Alton, IL
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Dakota_Don Offline
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my 68 is .040, thats as far as i would go..

Re: Early 318 maximum bore? [Re: dezduster] #60726
05/21/08 06:24 PM
05/21/08 06:24 PM

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Quote:

I have an early 318 block and I have heard somewhere they can be bored to 4.080 any truth to this? I believe its 68 or 69.




An early 318 would be a 57 or 58. They or any of the poly 318's might go to 4.08.

Wedge 318's are thin-wall castings, 4.08 bore ain't gonna happen.

Re: Early 318 maximum bore? #60727
05/21/08 06:39 PM
05/21/08 06:39 PM
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Eastern Ohio
mopowergtx Offline
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Look at this chart closely and you'll see you aint boring this 1967 318 of mine anywhere evan close to the number you quoted. Oh that test was done when it was still the stock bore of 3.91 also.




Notice on this chart I figured what it would do to cut it to stock 340 bore. Subtract that number from some of those test numbers and you are under .100 thick in alot of places if you did.But I do know of guys with Max Wedge 13 to 1 piston motors that have over bore 413's and left .100 of meat in spots but not on any thrust sides and they are running low 10 ET's and still alive after a year of action. But like I said its only in a few spots not all the way around by any means. I do have a 66 Poly 318 I'd like to check myself and see if its any better as far as core shift and sidewall thickness compared to my 67 LA 318.


Re: Early 318 maximum bore? [Re: mopowergtx] #60728
05/21/08 11:55 PM
05/21/08 11:55 PM
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Nevada
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dezduster Offline OP
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Well C-rap. I asked so that I could get info like you all gave. Good solid #s of what you have actually seen. Thanks to all reply s.
So now I guess its a MOPAR block or nothing.

Re: Early 318 maximum bore? [Re: HotRodDave] #60729
05/22/08 01:03 AM
05/22/08 01:03 AM
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Not2farfromNashville, TN
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Doesn't the LA heads etc swap to the 318 Poly blocks?


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"NUNQUAM NON PARATUS!"
Re: Early 318 maximum bore? [Re: Rug_Trucker] #60730
05/22/08 07:27 AM
05/22/08 07:27 AM
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Posts: 16,122
Grand Haven, MI
patrick Offline
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Quote:

Doesn't the LA heads etc swap to the 318 Poly blocks?




yup, block is essentially the same.


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1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Early 318 maximum bore? [Re: patrick] #60731
05/22/08 08:29 AM
05/22/08 08:29 AM
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Not2farfromNashville, TN
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Quote:

Quote:

Doesn't the LA heads etc swap to the 318 Poly blocks?




yup, block is essentially the same.




And they can take a bigger over bore?

Henslee is building 318 based 402's


"The only thing to do for triumph of evil is for good men to do nothing"

"NUNQUAM NON PARATUS!"
Re: Early 318 maximum bore? [Re: Rug_Trucker] #60732
05/22/08 09:47 AM
05/22/08 09:47 AM
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Alton, IL
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Dakota_Don Offline
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a poly block is the same as an la block? but the valve timing is different from the poly to the La right?

Re: Early 318 maximum bore? [Re: Rug_Trucker] #60733
05/22/08 09:54 AM
05/22/08 09:54 AM
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Posts: 16,122
Grand Haven, MI
patrick Offline
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Quote:

Quote:

Quote:

Doesn't the LA heads etc swap to the 318 Poly blocks?




yup, block is essentially the same.




And they can take a bigger over bore?

Henslee is building 318 based 402's




sonic check to be sure....

cams are different because of the difference in valve/rocker layout.


1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Early 318 maximum bore? [Re: dezduster] #60734
05/22/08 09:56 AM
05/22/08 09:56 AM

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Quote:

I have an early 318 block and I have heard somewhere they can be bored to 4.080 any truth to this? I believe its 68 or 69.





Re: Early 318 maximum bore? [Re: Rug_Trucker] #60735
05/22/08 10:56 AM
05/22/08 10:56 AM
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Posts: 4,920
Joplin, MO USA
Robbins Offline
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Quote:

Doesn't the LA heads etc swap to the 318 Poly blocks?




I never new that, so I can get a poly motor (318 that is) and put E-brock heads on it? If so, then will you need a custom intake or will the regular LA intake work? Wow, that some cool info right there.


Moparlee
Re: Early 318 maximum bore? [Re: Robbins] #60736
05/22/08 11:21 AM
05/22/08 11:21 AM
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dogdays Offline
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Well I took out a new poly head gasket and laid it on top of a used 318 LA gasket and there are differences. they will bolt up and use the LA intake but there may be some coolant holes that are not covered.

R.

Re: Early 318 maximum bore? [Re: dogdays] #60737
05/22/08 04:21 PM
05/22/08 04:21 PM
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Eastern Ohio
mopowergtx Offline
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