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Re: 318 Poly question [Re: 6PakBee] #2977585
10/23/21 12:56 PM
10/23/21 12:56 PM
Joined: Jan 2003
Posts: 17,264
So Near, Yet So Far
topside Offline
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So Near, Yet So Far
Anyone contemplating building a Poly should pick up Victory Library's "Chrysler Poly Performance" - I think a member here wrote it but can't recall his name.
It's a great resource & delves into a lot of stuff.
I've had a few - '63, '64 & '65 318s - and they didn't seem very octane-sensitive to me, they'd run on anything. Not sure I'd worry much about improving quench.
Then again, they were stockers, never pushed the CR, just drove them. Decent street motors, and not everything needs to make 600HP.
They used heavier castings than LA is what I've heard, and metal costs money. Chrysler would do anything to save a buck.
It's tempting to think "BBC" when looking at the valve arrangement, but ported Poly heads seem to max out at around 250/200 CFM I/E.
Subtract about 50CFM each side for stock.

Re: 318 Poly question [Re: topside] #2977602
10/23/21 01:45 PM
10/23/21 01:45 PM
Joined: Aug 2003
Posts: 38,343
Bend,OR USA
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Cab_Burge Offline
I Win
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Bend,OR USA
For those that don't know why Mopar designed and built the Poly motors was for using a single rocker arm shaft to save money over using the hemi motors heads with dual rocker shafts and rocker arm spacers and spring on the same designed blocks on the Chrysler, De Soto and Dodge cars scope shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: 318 Poly question [Re: topside] #2977608
10/23/21 02:13 PM
10/23/21 02:13 PM
Joined: Jan 2003
Posts: 8,729
North Dakota
6PakBee Online content OP
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North Dakota
Originally Posted by topside
Anyone contemplating building a Poly should pick up Victory Library's "Chrysler Poly Performance" - I think a member here wrote it but can't recall his name.
It's a great resource & delves into a lot of stuff.
I've had a few - '63, '64 & '65 318s - and they didn't seem very octane-sensitive to me, they'd run on anything. Not sure I'd worry much about improving quench.
Then again, they were stockers, never pushed the CR, just drove them. Decent street motors, and not everything needs to make 600HP.
They used heavier castings than LA is what I've heard, and metal costs money. Chrysler would do anything to save a buck.
It's tempting to think "BBC" when looking at the valve arrangement, but ported Poly heads seem to max out at around 250/200 CFM I/E.
Subtract about 50CFM each side for stock.


Thanks for the tip, just ordered the booklet. up


Wife says too many cars, liquidation coming soon......
Re: 318 Poly question [Re: 6PakBee] #2977682
10/23/21 05:37 PM
10/23/21 05:37 PM
Joined: Jan 2003
Posts: 41,055
Round Lake Beach, Illinoisy
Rhinodart Offline
Rhinotruck
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Posts: 41,055
Round Lake Beach, Illinoisy
I just picked up a low mile 66 318 poly and 727 trans, my first ride was a 66 Satellite with a poly and I was always intrigued with it...


The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!
Re: 318 Poly question [Re: Rhinodart] #2977774
10/24/21 05:21 AM
10/24/21 05:21 AM
Joined: Nov 2020
Posts: 343
Isle of Sheeps
Gtxxjon Offline
enthusiast
Gtxxjon  Offline
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Joined: Nov 2020
Posts: 343
Isle of Sheeps
Huge commitment building a stroker Poly!

A few (pre 66) friends have started and baled out, but one fine Moparmate has carried on through 'thick and thin'...
Divorce, baliffs, forced to move house and no money for beer and Mopar Mags... spank

Once you begin the POLY Project its for life, not just for Christmas...(10 years and counting)
He laughs in the face of WEDGE heads now... realcrazy

But a trip to San Diego to see 'Gary Pavlovich' in person and he was struck dumb, with POLY POWER!!! drive

It was a revelation and Epiphany all in one moment!

He couldn't believe how folks has dissed the lowly Poly and how the head design was being used in modern V8 engines...

Its like Betamax and VHS, the best product doesn't always win out?

Its all about 'supply and demand'... drumhit

400 cfm Chev-head, can't be bad... ozbbq

400 cfm.jpg
Last edited by Gtxxjon; 10/24/21 05:45 AM.

Carpe diem, quam minimum credula postero, thanx Horace!

There’s no point trying to fix stuff that ain’t broke,,, 'but if ain’t broke',,, you is not trying hard enough...
Re: 318 Poly question [Re: Gtxxjon] #2977864
10/24/21 11:46 AM
10/24/21 11:46 AM
Joined: Sep 2003
Posts: 15,330
north of coder
moparx Offline
"Butt Crack Bob"
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north of coder
Bruce Toth from down around Emlenton Pa. has been working with poly engines over the last several years, and has had several articles published in Chrysler Power magazine.
pretty impressive hp and torque numbers from these engines.
they are worthwhile reading if one wants to build a poly. just be aware, these non mainstream engines cost way more than the typical small block chebby, but can be a real surprise to a lot of them if built right ! drive
beer

Re: 318 Poly question [Re: moparx] #2978106
10/25/21 06:54 AM
10/25/21 06:54 AM
Joined: Jan 2003
Posts: 1,221
Oregon
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earlymopar Offline
pro stock
earlymopar  Offline
pro stock
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Posts: 1,221
Oregon
I didn't find the cost of building a poly to be any different than building an LA. The only problems are part availability / fewer options which often forces the builder to get creative on adapting other parts. As usual, it really depends on what the build is.

Re: 318 Poly question [Re: earlymopar] #2979292
10/28/21 02:54 PM
10/28/21 02:54 PM
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Posts: 11,144
Kalispell Mt.
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HotRodDave Offline
I Live Here
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Kalispell Mt.
318 poly head is much better than a 318 2bbl head any day of the week, they flowed more and everything, the engine were just bigger, heavier and more expensive to make, the wedge design was a compromise. Boring away .100 in 8 cylinders took out a lot of weight...


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: 318 Poly question [Re: HotRodDave] #2979492
10/29/21 06:50 AM
10/29/21 06:50 AM
Joined: Jan 2003
Posts: 1,221
Oregon
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earlymopar Offline
pro stock
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Oregon
Agreed on all points Dave. A comparison of the Poly head to the current generation Hemi head underscores the Poly head design is sound. They called the Poly a "semi-hemi" for a reason.

Re: 318 Poly question [Re: earlymopar] #2979525
10/29/21 08:53 AM
10/29/21 08:53 AM
Joined: Jan 2003
Posts: 8,729
North Dakota
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North Dakota
Thanks to topside up for the tip about Victory Library's "Chrysler Poly Performance". I ordered a copy and it is an excellent read. Going through it the only problem I foresee is getting a hydraulic roller camshaft. Everything else seems to be doable....at least at this point. grin


Wife says too many cars, liquidation coming soon......
Re: 318 Poly question [Re: 6PakBee] #2979818
10/30/21 08:31 AM
10/30/21 08:31 AM
Joined: Jan 2003
Posts: 8,729
North Dakota
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Have read the entire "Poly Performance" booklet over three times and there is one dimension I can't find. Is the center-center lifter bore spacing for a cylinder the same for the 318 poly as it is for an LA engine? Thanks!


Wife says too many cars, liquidation coming soon......
Re: 318 Poly question [Re: 6PakBee] #2979849
10/30/21 10:25 AM
10/30/21 10:25 AM
Joined: May 2003
Posts: 6,165
Downtown Roebuck Ont
Twostick Offline
Still wishing...
Twostick  Offline
Still wishing...

Joined: May 2003
Posts: 6,165
Downtown Roebuck Ont
Originally Posted by 6PakBee
Have read the entire "Poly Performance" booklet over three times and there is one dimension I can't find. Is the center-center lifter bore spacing for a cylinder the same for the 318 poly as it is for an LA engine? Thanks!


Yes.

The reason the push rod angle for an LA is less than ideal is because the lifter location and angle was not changed.

A Poly head can be run on an LA block with some minor modifications, external oil drains from the heads and pushrod clearancing the block.

Kevin

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