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Re: Are 318 Magnum pistons different from 318 LA?
[Re: HotRodDave]
#1071479
09/10/11 12:18 AM
09/10/11 12:18 AM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
OP
Banned. Forever.
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OP
Banned. Forever.
Joined: Apr 2007
Posts: 2,327
Glendale, AZ
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Yeah I'm just going to swap the whole magnum rotating assembly into the LA block. Plus, I already bought the rings and they weren't cheap. Does it matter what year bearings I use since the cranks interchange? Every listing I've seen lists pre-80, and 80-newer for rod/main bearings
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: HotRodDave]
#1071480
09/10/11 12:20 AM
09/10/11 12:20 AM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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I know nothing about the differences but I'll throw this out... Most late model engines have gone to a one piece full circle rear main seal... For that to work the back of the crankshaft is different from an earlier style engine...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: 1_WILD_RT]
#1071481
09/10/11 12:21 AM
09/10/11 12:21 AM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
OP
Banned. Forever.
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OP
Banned. Forever.
Joined: Apr 2007
Posts: 2,327
Glendale, AZ
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They are both 2-piece seal blocks
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: 1_WILD_RT]
#1071483
09/10/11 11:23 AM
09/10/11 11:23 AM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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The only bearings that may make a differance is the thrust bearing, or the rear main bearing, the flange on the thrust bearing may be different (bigger diameter)and I think one bearing fits all but the other will not fit in the other block so if your thrust bearing goes in your block it is good. The rear main bearing one was wider than the other and again I don't remember the year break or witch one is universal.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: HotRodDave]
#1071484
09/10/11 11:37 AM
09/10/11 11:37 AM
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Joined: Mar 2005
Posts: 1,445
Sterling Heights, Michigan 483...
daniel_depetro
pro stock
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pro stock
Joined: Mar 2005
Posts: 1,445
Sterling Heights, Michigan 483...
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Quote:
The differance in piston height is about .080 witch will make a nice bump in compression. However just swapping magnum heads onto a 318 LA with magnum heads will not yield you as much compression as a factory 318 magnum because the 318 magnum had a lower deck height also by about .015.
Interesting...
Is there a difference in deck heights between:
1971-88 LA360
1989-92 roller camshaft LA360
1993-2002 5.9l Magnum
?!?!?!
1969 Dodge Super Bee A12 (440 Six Pack, 4-speed, Dana 60 4.10)
1972 Plymouth Road Runner (400, 4-speed, 8.75" 3.23)
1974 Plymouth Duster 360 (360, 4-speed, 8.75" 3.23)
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: HotRodDave]
#1071485
09/10/11 11:57 AM
09/10/11 11:57 AM
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Joined: May 2003
Posts: 15,487
Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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Quote:
The only bearings that may make a differance is the thrust bearing, or the rear main bearing, the flange on the thrust bearing may be different (bigger diameter)and I think one bearing fits all but the other will not fit in the other block so if your thrust bearing goes in your block it is good. The rear main bearing one was wider than the other and again I don't remember the year break or witch one is universal.
I didnt think of the thrust bearing..but IIRc all the magnum engine used the 360 size rear main bearing or main cap size and 360 oil pan.
not sure if the bearing would have changed or the main cap size for the pan seal
something you might want to look at before the swap starts 
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Re: Are 318 Magnum pistons different from 318 LA?
[Re: scratchnfotraction]
#1071488
09/11/11 02:36 PM
09/11/11 02:36 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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The 318 and 360 magnums both have slightly shorter deck heights than the LAs did. TBI and carb had one deck height and the MPI magnum had the shorter one, I am not sure why they made one ity bity change like that Main bearing diameter on ALL 318 polys, LA, and magnums are the same includeing the rear main. The differance in the magnum and earlier ones is the thickness of the cap, it was changed so you could use one pan for both motors.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Just a thought... 
