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318 and 360 pistons #1256549
06/24/12 04:46 PM
06/24/12 04:46 PM
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Missouri
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Clayton Offline OP
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Missouri
I have a stock 318 and a set of 30 over 360 pistons, can I safely bore a 318 to the 30 over 360 pistons? 318 is 3.91 bore and the 360 pistons are 4.030. Can it be done and what does the 318 need to be bored to? Thanks, Clay

Re: 318 and 360 pistons [Re: Clayton] #1256550
06/24/12 05:28 PM
06/24/12 05:28 PM
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Alton, IL
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Dakota_Don Offline
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ummm no

Re: 318 and 360 pistons [Re: Dakota_Don] #1256551
06/24/12 05:33 PM
06/24/12 05:33 PM
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dennismopar73 Offline
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Quote:

ummm no




some one may say yes,, BUT I WONT!!

HI DON!

Re: 318 and 360 pistons [Re: Clayton] #1256552
06/24/12 05:39 PM
06/24/12 05:39 PM
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Glendale, AZ
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69L78Nova Offline
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Quote:

what does the 318 need




360 casting numbers


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Re: 318 and 360 pistons [Re: 69L78Nova] #1256553
06/24/12 06:24 PM
06/24/12 06:24 PM
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Missouri
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Clayton Offline OP
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If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?

Re: 318 and 360 pistons [Re: Clayton] #1256554
06/24/12 06:52 PM
06/24/12 06:52 PM
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las vegas
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Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?




360 .030 is 4.030
318 is 3.91

you will need to bore the 318 .120...good luck on that...


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)
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Re: 318 and 360 pistons [Re: 70AARcuda] #1256555
06/24/12 06:55 PM
06/24/12 06:55 PM
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Missouri
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Clayton Offline OP
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Duh...now I see where I calculated wrong:)

Re: 318 and 360 pistons [Re: Clayton] #1256556
06/24/12 06:55 PM
06/24/12 06:55 PM
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Lincoln Nebraska
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RapidRobert Offline
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Not likely a 318 would take that much oversize plus the compression height of the 318 and 360 pistons is different & will not interchange


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Re: 318 and 360 pistons [Re: RapidRobert] #1256557
06/24/12 07:08 PM
06/24/12 07:08 PM
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Oregon City, OR
Baxter61 Offline
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Have it checked, then you will know. And as stated the 360 pistons wont directly work, youll either need to find an old 3.58 crank with 318/340 mains or have a 360 crank turned down.

Re: 318 and 360 pistons [Re: Baxter61] #1256558
06/24/12 08:06 PM
06/24/12 08:06 PM
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Bowie, MD
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Reggie Offline
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Comparison pic with 360 piston in the middle. It will probably be a low compression dog...

Last edited by Reggie; 06/24/12 08:06 PM.
Re: 318 and 360 pistons [Re: Reggie] #1256559
06/24/12 09:11 PM
06/24/12 09:11 PM
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Supercuda Offline
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Some have taken the old POLY 318 out that far and put a 3.58" stroke crank in them too.

But an LA 318? I would say no.


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.
Re: 318 and 360 pistons [Re: Supercuda] #1256560
06/25/12 08:52 AM
06/25/12 08:52 AM
Joined: May 2003
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Florida
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Quote:

Some have taken the old POLY 318 out that far and put a 3.58" stroke crank in them too. But an LA 318? I would say no.




I have an old magazine artical that did this with a poly block 318,.120 over bore,3.58 stroke crank. forgot what pistons,I will dig it up and re-read it.

seems I have saw LA 318s bored for sleeves to go to .120 overbore at my local machine shop,said it was the only way unless a LA 318 was sonic checked to see if it was thick enuff for a large bore. very few but a couple have been found from what he said.

a few have said you can cut a 360 crank to fit the LA 318,then use early lopo 318 pistons with some clearceing on the piston pin boss and skirts, which will also help on the balanceing. makes a 346 stroker IIRC.

what I am doing is a cut down 3.58 stroke crank,.030 318 roller cam block, 349 stroker pistons, should be plenty torque for my truck and I had all of it exept pistons.


Last edited by scratchnfotraction; 06/25/12 08:57 AM.
Re: 318 and 360 pistons [Re: scratchnfotraction] #1256561
06/25/12 09:15 PM
06/25/12 09:15 PM
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dogdays Offline
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So how much are you paying to get the crank mains turned down?
I wanna know.
R.

Re: 318 and 360 pistons [Re: Clayton] #1256562
06/27/12 12:43 AM
06/27/12 12:43 AM
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waco tx
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gogo318 Offline
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Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?


i have a 83 318 i went 40 over with trws and you never seen an engine like 7 grand so much


67 charger fastback 318 stock 67 belvedere II 4dr soft top built 318 68 newport 2dr hard top 318 84 b150 440/727 84 d150 short wheel step side 4x4 lifted 87 omnitruck (you just have to see it ) new addition 63 dart wagon !!!
Re: 318 and 360 pistons [Re: gogo318] #1256563
06/27/12 10:10 AM
06/27/12 10:10 AM
Joined: Aug 2003
Posts: 12,291
Kent, Wa
340SHORTY Offline
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Quote:

Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?


i have a 83 318 i went 40 over with trws and you never seen an engine like 7 grand so much




what are you useing to verify 7000 RPM?


I am truckless..
Re: 318 and 360 pistons [Re: Clayton] #1256564
06/27/12 10:14 AM
06/27/12 10:14 AM
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Grand Haven, MI
patrick Offline
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Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?




stock 318 bore is 3.91. .030 over 360 is 4.030....re-do your math. I get .120" over (or about 1/8")

then you have the compression height problem. a 318 has a 3.31 stroke, with pistons about 1.72" compression height stock. a 360 has a 3.58" stroke with ~1.6" compression height pistons, so if you used the stock 318 crank, you'd be like .2" down in the hole, and have no compression....


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Re: 318 and 360 pistons [Re: 340SHORTY] #1256565
06/27/12 10:17 AM
06/27/12 10:17 AM
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Bloomington, Illernoise
cptn60 Offline
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Quote:

Quote:

Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?


i have a 83 318 i went 40 over with trws and you never seen an engine like 7 grand so much




what are you useing to verify 7000 RPM?



Probably the size of the hole in the side of the block where the rod went


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Re: 318 and 360 pistons [Re: cptn60] #1256566
06/27/12 10:26 AM
06/27/12 10:26 AM
Joined: Sep 2007
Posts: 14,889
up yours
Supercuda Offline
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Quote:

Quote:

Quote:

Quote:

If my math is right I would only have to bore the 318 to 40 over, a 318 won't take a 40 overbore?


i have a 83 318 i went 40 over with trws and you never seen an engine like 7 grand so much




what are you useing to verify 7000 RPM?



Probably the size of the hole in the side of the block where the rod went




Or a tach in 4 cylinder mode


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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