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Hot Rods 318 poly questionss for the guru's

Discussion in 'The Hokey Ass Message Board' started by paintman27, Dec 23, 2018.

  1. paintman27
    Joined: Apr 23, 2011
    Posts: 254

    paintman27
    Member
    from new jersey

    Hey guys, first off let me wish you all a Merry Christmas and Happy New Years.
    I have a lead on 2 poly 318's I am considering for my 46 Dodge pickup project. My question is what parts are still available and what are the ones I am going to have trouble finding. Are most of the parts interchangable with the magnum 318? I thought I read somewhere the lifters are different and not in production anymore.
    Lastly, can you use the same torque plate on the poly as with the magnum 318? My engine man will not touch anything without a plate. Thanks guys!
     
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  2. Oldioron
    Joined: Dec 12, 2018
    Posts: 709

    Oldioron
    Member

    Last edited: Dec 23, 2018
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  3. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,621

    DDDenny
    Member
    from oregon

    @earlymopar please pick up the white courtesy phone please.
     
    Last edited: Dec 23, 2018
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  4. squirrel
    Joined: Sep 23, 2004
    Posts: 42,665

    squirrel
    Member

    a little image manipulation....LA gasket on top, A gasket below. Looks to me like the head bolt holes might be off a little bit?

    318 head gaskets.jpg
     
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  5. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,958

    Rusty O'Toole
    Member

    They made a change in the crankshaft flange about 1962. Older engines use nuts and bolts, the newer ones have the flange closer to the engine and use bolts threaded into the flange. This means the engine/trans interface is different and they will not interchange. However, if you have an older block the newer crankshaft from any 318 will fit.

    The wide block, or polysphere 318 was made from 1957 to 1965 (66 in Canada). In 1964 they came out with a redesigned 318 called a 273, for use in Valiant, Dart, and Barracuda. The original 318 would not fit these cars as they were designed for a slant six. So they took the existing 318 block, gave it a smaller bore, and new heads, manifolds and camshaft. The camshaft had to be changed because the valves were in different order. The new heads had conventional valves all in a row layout.

    The 273 even used the 318 crankshaft and rods, with heavier wrist pins to make the lighter pistons balance.

    The next year they made the LA 318, basically the 273 with a 318 bore for larger cars like Coronet and Belvedere.

    Most parts will interchange other than pistons, heads, manifolds and camshafts. Bearings, timing chain, distributor etc . Pistons have a different shape top.

    You can even use a 360 crankshaft if you turn it down to 318 diameter. And you can bore the cylinders a lot more than newer engines. Guys have taken the old Poly 318 out to 400 cu in and got more than 400HP out of them. The poly head design was better for performance than the wedge head, but not as good as the latest performance heads.
     
  6. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,958

    Rusty O'Toole
    Member

    As for putting them in a 46 Dodge pickup. Mopars of that age have a problem, in being designed for straight six engines. The steering box interferes with the wider V8 engines. Pickups may be different as trucks usually had bigger engine compartments but it is something to think about.

    Guys have swapped V8s into old Mopars but usually have to offset the engine to the right a couple of inches. That is with conventional Chev 350 and Dodge LA 318s. The wide Poly engine may be too wide to fit. Unless you plan to change the steering.

    I think the Poly engine would make a cool swap but may not be practical.
     
  7. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,958

    Rusty O'Toole
    Member

    Looks to me like the LA gasket has larger bores, possibly because it also fits the 360 and 340. If you allow for that the head bolts look the same, although water passages are different as would be expected with the different head configuration.
     
  8. swifty
    Joined: Dec 25, 2005
    Posts: 1,529

    swifty
    Member

    Welcome to another Poly owner. I've got 2 rods running 318 Polys, a 24 T that I built in 62 and a 32-5w that was finished about 5 years ago. Only problem I had getting parts was exhaust valves and I managed to get 4 at $40 each as the other 4 were "just" useable. This is in Australia. I have since got a full NOS set through US Ebay. You should have no problems sourcing parts in the US. I've got lots of consumables from Rock Auto. Good luck with it.
     
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  9. paintman27
    Joined: Apr 23, 2011
    Posts: 254

    paintman27
    Member
    from new jersey

    Sorry guys I forgot to mention both the polys I am looking at are from 1963 and come with their own tranny's. I now I had read somewhere some of the valve train parts are different from the LA's maybe it was the valves and not the lifters as I orginaly thought.
     
  10. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,958

    Rusty O'Toole
    Member

    Heads are completely different, similar to a big block Chevy in layout with staggered valves and related to the Chrysler hemi. Valves are bigger than the LA 318 but smaller than the 340.

    By 1963 the 318 had been supplanted by the 361, 383 and 413 B engines for performance duty and 318s were low perf 2 barrel carb models. Last year for a 4 barrel carb option, 1962. Last year for the 2 - 4 barrel carb, 290HP hi perf models, 1958. The standard 318 230HP should be great for heavy duty use in your truck, although some hop up parts are available if you want them.

    1963 was one of the last years for the pushbutton trans. Try and get the control module that goes on the dash, and the cables that shift the gears.

    They also had the handbrake on the back of the trans, and ball and trunion universal joint.
     
  11. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,044

    sunbeam
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  12. andydodge
    Joined: Sep 28, 2008
    Posts: 858

    andydodge
    Member

    I've been running an Oz 1962 318 Poly since 1973 in my 1940 Dodge.........any LA dissy will fit, I've been using a YL Mallory for 35 yrs tho' any electronic 318/340 dissy will fit straight in, aftermarket intakes are the problem, the Weiand alloy single 4 # 7503 was the last made and available which is what I've had for 35 yrs, US ebay does have these plus the Edelbrock & Offy triples, however Chrysler Power Magazine from Texas was instrumental in getting made about 2 years ago an Air Gap Single Four alloy intake to suit the 277/301/313/318 Plymouth Poly, this is advertised in the magazine and is about $650 US, apparently Hot Heads were involved in suppling a 392 Hemi intake to use as a base to make the new Poly intake, not sure whether hot heads can help with the new intake............Chrysler Power Magazine also have a range of pistons, bearings, cams, headers etc to suit the 318 Poly, also finned alloy rocker covers are available thru them and Allan Fountain in Oz......by far the best engines to use are the 1962/63 onwards which use the alloy Torqueflite due to the change as mentioned in the crank flange, the early cast iron gearbox versions have the studs on the torque converter and don't use a flexplate.........Tex Smiths book on rebuilding the Hemi has a complete chapter on the 318 Poly which is worth getting..........heres a pic of my Poly...........the twin 4 crossram was a pair of Offy adaptors on a 57/58 factory cast iron twin 4 intake with a pair of 600 Holleys, this was back in the 1970's.......then I ran the single Weiand intake and chrome air cleaner for about 25yrs.......then the finned alloy air cleaner for the past 10 yrs........lol.......... andyd
     

    Attached Files:

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  13. VonWegener
    Joined: Nov 19, 2009
    Posts: 781

    VonWegener
    Member

    Some 20 years ago I had a job that needed a long commute. To save gas over my good cars I bought a '65 Dodge Coronet 4-door for $1100. That little poly motor was fun to drive and got 20 mpg. When the job finished I rented the white Dodge out to the studios as a picture car and it made back the money it cost me.
    Many see the poly motor as a curse because it's not a big block but I think they they are wonderful.
     
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  14. earlymopar
    Joined: Feb 26, 2007
    Posts: 980

    earlymopar
    Member

    A lot of parts interchange between the 1962 to 1966 polyspherical A 318 engine and the LA series of Mopar motors (318, 273, 340, 360), including:
    • Thermostat
    • Thermostat housing
    • Internally balanced 273-318-340 harmonic balancers
    • Valve springs, retainers and keepers
    • Main bearings (NOT 360 though)
    • Rod bearings
    • Crankshafts (reground 360's included)
    • Flywheel
    • Starter, both standard and high torque
    • 318 LA ring set
    • timing chain and sprocket
    • fuel pump
    • oil pump
    • oil pan (not 360) “The 360 front and rear seal/front timing cover is bigger than those of the 273/318LA/340 to accommodate the larger main bearings.” ” Bill P.
    • distributor pump drive gear
    • distributor, standard points or electronic
    Though reported as interchangable in several references, the timing covers are not exactly the same.
    The two pictures below show the difference between a poly 318 timing cover and a small block LA cover. The one shown on the right is the poly 318. Notice it has one bolt hole that the other does not, exactly opposite the fuel pump opening. The LA does not have that, and neither do the gaskets that claim to fit all 318's, (poly and LA).

    [​IMG] [​IMG]

    The missing bolt hole in the LA cover is not a problem for the Poly block as that hole in the Poly block is easily plugged. The only problem on Poly to LA timing cover interchange is with the early 1956 to 1961 Poly blocks that use the cast iron timing cover exclusively and have a unique water pump to those years. New Mopar Performance LA timing covers are now available through Mancini Racing and other Mopar Performance vendors for the Mopar LA and would fit on a 1962 to 1965 Mopar 318s. “Fel Pro still makes valve cover gaskets for the Poly 318 Mopar engine (PN Fel Pro VS11828 R ).

    Some of the above are excerpts from information readily available on the web and were just copied to save time (and not forget anything).

    As to modifications and aftermarket parts, there is a boat-load of stuff available like larger valves, forged pistons, headers, intake manifolds (old and some new), connecting rods, piston rings, stoker crankshafts, etc. etc. As one of our Aussy friends stated, Rockauto Auto has quite a few parts available. I may have an Edelbrock 3-duece manifold available and a custom 3-deuce to single 4 barrel adapter I made (show in the attached picture with a supercharger top adapter). Due to height restrictions, I'm going to a slightly lower, custom intake manifold for my small supercharger.

    The poly engine (with heads attached) is actually wider than a big block Mopar and yes, a little heavier than an LA series engine. However the valve arrangement makes for much better airflow as compared to an LA series engine. If looks are impressive, that may count. My engine below is a 110k mile original and is my "test-mule" that I'm using to adapt to my pickup and then plan to swap-in the new engine. I intentionally stayed at a stock stroke and even at that should be right at 500 HP and extremely streetable. By the way, those are Ford headers I'm running with my custom adapters. There is a fellow that makes steel adapters for running the 3rd generation Hemi (shorty style) headers as well.

    What ever you do, have fun. These are surprising engines are great fun to mess with.

    - EM
    Poly with Magnuson.jpg
     
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  15. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,621

    DDDenny
    Member
    from oregon

    I knew EM would have some great input!
     
  16. paintman27
    Joined: Apr 23, 2011
    Posts: 254

    paintman27
    Member
    from new jersey

    Wow thanks guys for all the help here. I guess my biggest concern (and still not confirmed), is the torque plate interchange with the LA 318.
     
  17. George
    Joined: Jan 1, 2005
    Posts: 6,995

    George
    Member

    Poly lifters are solid. Parts....check with Rock Auto, possibly Kanter & Robert's Motor Parts.
     
  18. 73RR
    Joined: Jan 29, 2007
    Posts: 6,198

    73RR
    Member

    How many millions of high performance engines have been built without a deck plate?
    Perhaps they are needed for the hi-zoot 14:1 c/r pro comp cars but for a street engine.....?
     
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  19. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,958

    Rusty O'Toole
    Member

    The weight comparison goes something like this -

    Mopar B block 440 - 650 lbs

    Mopar A block (poly) 318 - 625 lbs

    Mopar LA 318 - 580 lbs

    Chevy 350 small block - 540 lbs
     
  20. earlymopar
    Joined: Feb 26, 2007
    Posts: 980

    earlymopar
    Member

    True almost across the board but there were a very few trucks with factory hydraulic lifter / cam shaft set ups.
    - EM
     
  21. earlymopar
    Joined: Feb 26, 2007
    Posts: 980

    earlymopar
    Member

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  22. earlymopar
    Joined: Feb 26, 2007
    Posts: 980

    earlymopar
    Member

    Also, there are camshafts available from several sources or you can re-grind your stocker to a more aggressive profile. I bought NOS TRW solid lifters through Rock Auto for ~ $3 each (they were being closed out).

    - EM
     
  23. 73RR
    Joined: Jan 29, 2007
    Posts: 6,198

    73RR
    Member

    Bruce is also a head porter for those in need and his prices are tolerable!
     
  24. oldwood
    Joined: Mar 13, 2010
    Posts: 893

    oldwood
    Member
    from arkansas

    Gary and Bruce are the Poly High Tech guys.
     
  25. classiccarjack
    Joined: Jun 30, 2009
    Posts: 1,411

    classiccarjack
    Member

  26. classiccarjack
    Joined: Jun 30, 2009
    Posts: 1,411

    classiccarjack
    Member

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