318 A Poly Head Engine Resources Page

318 poly head

The A Series 318 Poly Head Engine:

The A-series 318 Poly Head V8 engine gets its name because the combustion chambers are Polyspherical in design. The hemi designed engine was complex, expensive to build and heavy. To address these issues and concerns Chrysler designed and used a polyspherical shaped cumbustion chamber. What this did was allow the Poly head engine to use a single rocker shaft to operate the valves on either side. The rocker shaft was centered between the valves with the exhaust valve on a vertical plane and the intake valve canted toward the carburetor, like its larger hemi brother. This design positioned the spark plug in a prime location in the combustion chamber and allowed for larger valves and more efficient breathing. The Poly head engine is easily identified by its valve covers scalloped design to fit around the exhaust valve springs on the exhaust sides of the engine. The 318 A series Poly head engine was produced from 57 through 67 when it was replaced with the LA series 318 engine. The engine displaces 318 CI with a 3.91″ bore and the 3.31″ stroke.This head & engine design was coined Semi Hemi by Mopar enthusiasts.   

By adding a performance cam, 4-bbl, 2-4bbl or 3-2bbl induction, and headers to a 318 poly head engine you have a respectable small block Mopar engine powering your truck.  A rare truck deserves a rare power plant.

I wanted to include a list of 318 poly head engine resources for anybody considering using a 318 A poly head engine in their sweptline truck project.

Here goes:

• Dual quad Carter carburetor set-up for poly engine

http://carburetorsandmore.com/toppage1.htm

• 4-bbl install on poly engine with part numbers

http://www.mascotgraphics.com/4_barrel.htm

• poly engine upgrades and interchangeable parts

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0109_chryslers_poly_head_engine/viewall.html

• Poly engine facebook page

http://www.facebook.com/pages/Mopar-Polyspherical-engine/181327685230564

• Poly engine headers

http://t137.com/dtapoly.bak/addpoly.php

• Poly engine association

http://www.webring.org/l/rd?ring=plybelvedere;id=1;url=http%3A%2F%2Fwebspace%2Ewebring%2Ecom%2Fpeople%2Fcu%2Fum_4409%2F

• Poly engine ID information

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0109_chryslers_poly_head_engine/viewall.html

• Poly engine article

http://www.streetrodderweb.com/tech/0805sr_vintage_engines/viewall.html

• 318 LA & 318 A engine interchangeable parts

http://www.1962to1965mopar.ornocar.com/poly318_1.html

• 318 poly forum

http://autos.groups.yahoo.com/group/318poly/messages

• Poly engine transmission information

http://www.moparfins.com/repairs/Transmissions/Difference_in_Poly_Transmissions.htm

• Adding tri-power to a V8 engine information

http://www.thecarburetorshop.com/Aftermarkettripowersetups.htm

• Tri-power set-up forum discussion

http://www.forwardlook.net/forums/forums/thread-view.asp?tid=44887&posts=53&start=1

• Poly engine book

http://victorylibrary.com/POLY.htm

• Tri-power carburetor set-ups

http://www.vintagespeed.com/

• Custom camshafts

http://www.camcraftcams.com/index.php?page=contact

• Decode poly engine numbers

http://www.townwagon.com/pgpws/pgengines/318v8.htm

• Rochester 2GC carb rebuild article

http://www.hotrod.com/pitstop/hrdp_1102_rochester_2gc_carbs_rebuild/viewall.html

• Progressive linkage set-up information

http://static.speedwaymotors.com/pdf/560-6271.pdf

• Tuning progressive linkage article

http://www.stromberg-97.com/tech_center/pdfs/stromberg-progressive-linkage-tune.pdf

• progressive linkage set-up information

http://static.speedwaymotors.com/pdf/135-6720.pdf

If you know of any other helpful sites for truck owners considering a 318 A poly head engine swap please let me know and I will add them to the list.

Click here to go to the next post: 71 Power Wagon Build-Up – No Turning Back!

Mark Polk

RV Education 101

RV Consumer

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