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Stroking a 318 poly?
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muddy
Posted 2015-03-26 1:58 AM (#473477)
Subject: Stroking a 318 poly?


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I have for some time been considering building a stroker 318 poly for my Plymouth, if ever time allows, that is!
I have also been reading of Chuck's adventure's with his stroker, and must say i feel very sorry for his continuing troubles in getting the old girl to run, hassel free...best of luck mate, i hope you get it sorted.
I'm not sure if the information i'm after was covered in Chuck's thread or even if it might have been covered else where on the forum?

In reading that thread and the "Victory Labrary-Poly Performance" book, i am just trying to get a couple of things straight on what i need to parts-wise to stroke my 318.
So basicly (i'm not a mechanic, just an armature, so bear with me!) i'd like to go with the 318 to 402ci route, and from what i gather i'll need to bore my 318 out to 90 thou over, then buy a 340 LA crank and 6.30 inch (possibly Oliver?) rods.
I take it the crank flange difference from my '58 poly motor to the later post '64 motors (and the LA 340 crank), is only an issue if you intend to use the original '58 trans? I will probably be using a different trans.
Also, is there an over the counter piston for this conversion, or do i require a custom made piston?
That's basicly it to start with, and if i have missed anything please feel free to point it out.
Cheers Muddy.
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ttotired
Posted 2015-03-26 4:47 AM (#473480 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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I want to put a 671 on one, but no help on the stroker except I believe there is a recipe for doing it by a guy named Pavelich (sommething like that)

Chuck refers to him in his thread and Chuck would be the most knowlegable one on this forum

There is a 318 poly forum I believe that will have more info on it about stroking the engine as well

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mstrug
Posted 2015-03-26 7:51 AM (#473488 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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See if this link works:

https://groups.yahoo.com/neo/groups/318poly/info
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Rodger
Posted 2015-03-26 12:39 PM (#473503 - in reply to #473477)
Subject: Re: Stroking a 318 poly?


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Hola Grant and Mick

In the later years when they started making The LA-273 and The LA-340 ---- MoPar used The A-318's Crank Shaft -- Rod's --- Every Bearing ---- The Oil Pump ----- The Water
Pump ------ The Distributor ------ The Oil Pan ------- Oil Pan. The 2 bbl LA-273 and LA-318 got the 1962 - 1966 A-318's Carburetor ... for a bit.

When The LA-360 started its production life, The Oil Pump --- Cam Shaft Bearings an some other items from a 1958 A-318 were used.

For MoPar's Slant Six's The Adjustable Rocker Arm's from a 1958 A-318 were used.

----------------------------------------
The 1956 - 1961 Bell Housing Design and its corresponding Torque Convertor Assembly or Fly Wheel Assembly - Starter Motor and Crank Shaft all match.

The 1962 - 1992 same items match.

One can use a 1962 and newer complete item package to a 1958 - 1961 A-318's Block. The Bell Housing to Engine Block Locating Dowel Pins do not match
at a 100% rate. This is OK if it is used in a vehicle that is driven respectfully.

------------------------------------------------
If The Rear Main Bearing Surface of a LA-360 Crank Shaft is machined to a 318's size ( and then re-hardened ) ----one can have any 318 "stroked". This is The Max Length
available if you use "off the shelf items".

---------------------------------------------------------
To remove metal from The Cylinder Walls is to remove metal that is always to be gone. If you go past a 0.040 Over-Bore, then you are getting to the area of "always running
a Hot Temperature".

-----------------------------------------------------------------
The best "Bang for The Buck" Stroking of a 318 is The 360 Crank Shaft and 0.040 Over.

This will still perform respectfully with it's same 2 bbl Carb Assembly in a vehicle that is used for a Land Speed Record --- In The 2bbl Class.

----------------------------------------------------------------------------
There are no after market headers made for The A-318 Engine and your car.

To use 2 inch Exhaust Piping from your Exhaust Manifolds to a Duel in-let / Single out-let Muffler that is spec'd for a early 90's car is Dyno Wise the same as
using Grand-Pa's Duel Muffler's and Duel Tail Pipe's.

-------------------------------------------------------------------------------------
In 1959 MoPar started using a Silicone Fan Drive with all Senior Division Cars that had Factory A/C. By 1975 it was used in every 318 ( even w/o A/C ) --- in every
division because it was an item that used less power from the engine. To a Dyno it is a boost in The Power to Engine Size Ratio. If you do not want this - then one
can go "backwards" in the Power to Engine Size Ratio and use any flex fan.



Rodger & Gabby
COS
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VAN HELSING
Posted 2015-03-27 6:14 PM (#473603 - in reply to #473480)
Subject: Re: Stroking a 318 poly?



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..........

You were close Mick , Gary Pavlovich is a good source of info for poly engines ......................... and I'm sure Chuck here has a lot of experience now from his stroked poly build .

Gary's contact email is glpavlovich@coxnet.com if you want to contact him, he usually replies in a day or two.

..........
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60 dart
Posted 2015-03-28 12:12 AM (#473635 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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you'll need a 4" stroke la crank . if older than 62 block the rear bearing journal will have to be extended back toward the hub . bore needs to be .040 along with the 4" stroke to give you a 402 . mine is .030
over bore at 390ci. . rods need to be 6.123" long . custom pistons from AUTO TEC . they were the most economical and are a street side of RACE TEC ----------------------------------later
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muddy
Posted 2015-03-28 6:37 AM (#473647 - in reply to #473477)
Subject: Re: Stroking a 318 poly?


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Location: South Australia
Onya Mick,love to see a poly with a huffer on it,let us know how it goes...
Will be checking out that forum too Marc, cheers.
Great information folks, i appreciate that no end, it's very handy to know what inter-changes with the LA motors...
So Chuck, i think the 340 crank has a 4" stroke, and 6.123"rods... i think i'll see if i can get hold of a post '62 block for ease of build (mine's currently a '58).
According to the "Victory Library" book, using a 360 crank is doable,but gives an odd rod length / stroke ratio that i take it is not good for engine harmonics?, otherwise i would have thought of using a 360 stroker crank to go bigger again?
Thanks heaps again for the info.
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fenix
Posted 2015-03-28 9:59 AM (#473652 - in reply to #473647)
Subject: Re: Stroking a 318 poly?



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Doesn't DLI ( Dick Landy Inc.) offer a roots blower setup for the Poly?
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DepsilonD
Posted 2015-03-28 1:11 PM (#473675 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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fenix,

DLI did, but they are no longer in business.
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ttotired
Posted 2015-03-28 7:52 PM (#473714 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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I didnt know that

The only blown poly pictures I found were shaft drives (pointing backwards, in front of the engine) or the blowers that are just belt driven turbos

But I can see a massive thread derail here

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fenix
Posted 2015-03-28 7:54 PM (#473715 - in reply to #473714)
Subject: Re: Stroking a 318 poly?



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Thread derail? yep, sorry Muddy, guilty as charged. :-)
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60 dart
Posted 2015-03-29 4:19 AM (#473737 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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when and if you get custom pistons make sure you get exactly the compression ratio you want . just another piece i haven't conveyed yet is , i ordered 10:1 . when i took the motor down
to check things out , math put em at 11.24:1 and go the extra yard by gettin the entire rotating mass balanced . you'll be tickled pink you did ------------------------------------------later
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58coupe
Posted 2015-03-29 10:33 AM (#473767 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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FYI, the LA 340 stock stroke is 3.3125" same as LA and poly 318. It has a 4.040 bore and 6.123 rods. The LA 360 has a 3.58" stroke and a 4.00" bore, haven't measured rod length. The 360 crank will not fit the smaller engines unless its mains and rear seal area are ground smaller.
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Mopar1
Posted 2015-03-29 11:19 AM (#473769 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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Best to use the '62 & later block, with the turned down mains the 360 crank fits right for bolting up to a '62 & later tranny. A 392 adaptor fixes the bell pattern difference on the '61 & earlier engines, but are set up for the OEM length cranks where the 360 crank is different length.
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fenix
Posted 2015-03-29 11:25 AM (#473771 - in reply to #473767)
Subject: Re: Stroking a 318 poly?



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If Your using bushed full floating wrist pins, make sure the tops of the rods have an oil hole through them, and that it's all the way through the bushing also, I didn't notice mine were not drilled till I was ready to put the motor together, that woulda been a disaster when they seized!
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Mopar1
Posted 2015-03-29 11:30 AM (#473772 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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There is @ least 1 Thread here....http://www.moparmarketforum.com/forum/index.php
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muddy
Posted 2015-04-01 6:49 AM (#474080 - in reply to #473477)
Subject: Re: Stroking a 318 poly?


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Sorry on the slow response, am at work with limited access...

OK, like i said, i am an armature, and i think it's starting to show...
So, Chuck your combo is a 0.30" bored over 318 block, with a 4" stroke crank, and 6.123" inch rods, to give you 390ci displacement...and a 0.40" overbore will take that same combo out to 402ci?

58coupe is saying that the 340LA has a 3.3125" stroke, and the 360LA has a 3.58" stroke. I'm not sure if this is a silly question, but which crank will give me the 4.00" stroke that i think i need?

From other material i had read i was under the impression that the 340 crank was the one i needed, but that doesn't make sense if it's .6875" short on stroke??.
....now my head is spinning!!

Thanks heaps for everyone's input too, much appreciated.
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58coupe
Posted 2015-04-01 9:22 AM (#474083 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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Grant, here's your confusion, you cannot use a factory crank. You have to use an aftermarket stroker crank. The best way to go is a complete balanced assembly, (crank, rods pistons rings) to fit the 318-340 block but the problem is the pistons for a 318 poly are different.
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60 dart
Posted 2015-04-01 2:10 PM (#474099 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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stroke and bore work together to give total stroker CI. . 4 inch stroke is what you need-------------------------------------------------later

http://www.jegs.com/p/Mopar-Performance/Mopar-Performance-Cast-Cran...
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muddy
Posted 2015-04-02 5:30 AM (#474145 - in reply to #473477)
Subject: Re: Stroking a 318 poly?


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Location: South Australia
Ahh!

Right on the money men, i thought that the 340 crank would give me the increase in stroke that i needed!

Thanks for the link Chuck, and so the money starts....
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Mopar1
Posted 2015-04-02 10:15 AM (#474161 - in reply to #474145)
Subject: Re: Stroking a 318 poly?



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In Australia they had mostly 318s, very few 340s & nothing bigger. They found that putting a 360 crank with a .030 overbore in a LA (or A) 318 would give them a 349 that had a chance to compete with the 351 Clevelands. Here there is no real need for it, it's just something that some want to do.
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ttotired
Posted 2015-04-02 7:18 PM (#474182 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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I am a bit unclear about the crank

If you use a 340 crank, how does the trans all bolt up again?

Do you have to go to the later trans?

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muddy
Posted 2015-04-04 7:22 AM (#474304 - in reply to #473769)
Subject: Re: Stroking a 318 poly?


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Mopar1 - 2015-03-29 11:19 AM

Best to use the '62 & later block, with the turned down mains the 360 crank fits right for bolting up to a '62 & later tranny. A 392 adaptor fixes the bell pattern difference on the '61 & earlier engines, but are set up for the OEM length cranks where the 360 crank is different length.


From what i have picked-up Mick, yeah you will have to use a different / later tranny with the stroker / LA crank.

Edited by muddy 2015-04-04 7:26 AM
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Mopar1
Posted 2015-04-19 10:36 AM (#475962 - in reply to #474182)
Subject: Re: Stroking a 318 poly?



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ttotired - 2015-04-02 6:18 PM

I am a bit unclear about the crank

If you use a 340 crank, how does the trans all bolt up again?

Do you have to go to the later trans?

With the '61 & earlier block you have 8 nutted studs on the torque converter going threw the crank flange, so, yes, you'd need a 62 & up tranny with the early A Poly. 62 & up A & LA, including the 340, you have 6 flywheel bolts. The 340 crank is the same as the 273-318, you only increase stroke with a 360 crank with the mains cut down.
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Mopar1
Posted 2015-04-19 10:39 AM (#475963 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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One poster on the HAMB was fairly adamant that stroking the m to 390-400 CID area wasn't productive because he believes the heads cant breath well enough to utilize that much CID.
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muddy
Posted 2015-04-24 9:16 PM (#476559 - in reply to #473477)
Subject: Re: Stroking a 318 poly?


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That sounds a little odd, as i though that the Poly heads were supposed to be well known for being good breathers??
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mstrug
Posted 2015-04-25 3:48 AM (#476566 - in reply to #473477)
Subject: Re: Stroking a 318 poly?



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POLY GROUP:

https://www.facebook.com/polysuperpac

https://www.facebook.com/ChryslerPower

http://www.chryslerpower.com/

Edited by mstrug 2015-04-25 3:50 AM
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