Recently dis***embled/inspected 3 of these 331 Chryslers, and must say I'm pret-ty damned impressed by the design of these early big Mopar engines- canted valve heads and forged bottom end- how come these were/are not popular at the drags ? The first answer will be "overshadowed by hemi" or "replaced my more modern B/RB engines" but has anyone here hot rodded a Chrysler poly, and if so, what kind of HP and e.t. numbers did you get ? any opinions welcome
The early 301 Polys are anchors. The later 303 is a better platform to start with. Check out the Golden Fin Society website and mailing list, they have some guys with hot rodded motors. Pretty level headed group as well. Hyfire
IMHO...the Spitfire engines are as good as any to be found on this Hamb site and they make gobs of torque which is what a street car needs. The head design is second only to the Hemi and if you want big airflow numbers then they can be ported. Are they expensive to rebuild? Yes, but not any more than alot of other 'old' engines. Even with the 'poly' head you can get 1hp/in without breaking the bank. All of the usual rebuild parts are available and many are the same as their Hemi counterpart. Got any extras ??? I'll take all that I can get.
This has been covered many times before, but here goes. Starting in 1956 Plymouth started the A series (277-301-303-318-326) engines that share little or nothing with the Hemi & Spitfire series engines. The 'poly' engines from Dodge (241-270-315-325), DeSoto(Dodge 325), Chrysler (301-331-354) and 55-56 Plymouth (Dodge 241-259-270) are all based on the Hemi engine design and can be converted to Hemi. The easy way to id the difference is that the 'A' engines have an intake manifold that seals the valley. The other Poly/Spitfire engines have an air-gap style intake with a separate valley cover. The 301 Chrysler is not the same as a 301 Plymouth. ....no wonder that 'new guys' have a hard time with the Mopes...
And there is no such thing as an LA poly, the 273,318, 340, 360 motors have wedge shaped combustion chambers not polysphere shaped.
but has anyone here hot rodded a Chrysler poly, and if so, what kind of HP and e.t. numbers did you get ? I'm Hot Rodding a '64 Plymouth Poly 318. It has a .40 over bore, etc... I am putting a 264/.480 Hot Street cam in it. Headers and 3 deuce intake. Don't know the the HP yet, we are still putting it together... Should make a pretty good amount of thump though for what it is.... And it is going in a Model A.
the yellow car with yellow valve covers is the small block Dodge poly built off the Dodge hemi block- largest being a 325 CID in OEM form. That's the engine family that lacks an OEM harmonic balancer and tends to break crankshafts. Fortunately, HH sells new balancers for them. the second red engine with chrome valve covers, is a poly "A" motor first used by Plymouth in 1956, that eventually grew to a 326 in 1959- and was made until 1966. The 1962-66 is the one to have in that family, as they accept the modern 727 trans- that engine will also accept the Mopar Performance 4" stroker LA crankshaft, and many other bottom end LA parts. So it's pretty easy to grow that "A" poly to 400 CID, 4"bore x 4"stroke. Those are also called a "wide block"- which is a good handle for them- a better description to keep them separate from the big Chrysler poly and Dodge poly. True, a "wide block" A poly, won't accept hemi heads. The one I'm most interested in, is the big Chrysler 354, being it has the best cylinder heads of them all and most CID. That one has 3 hold down bolts per valve cover, and shares the same bottom end as the 331/354 Chrysler hemi engines. Looking at the big Chrysler poly heads, they are similar to the later Chevy 348/409 or Chevy 396/427/454, or Ford 351/400 and 429/460 families. Those Chrysler polys were years ahead of their time, in 1955.
for that matter, there's no such thing as a "poly hemi" series it's either a poly, or a hemi- it can't be both
The "wide block" name is wrong, too, since the block is the same dimensions as the LA. I would love to get a set of A heads with a good 4V manifold and hipo cam, and stuff it all in a 360 block. Might need custom pistons to get the CR right, but it'd be a sleeper! Had a '62 Dart with a 260 horse 318, went pretty good for the day.
Change the pistons, and you can put Hemi heads on the 331 and 354. I'm reasonably sure even the intake manifolds will interchange. -Brad
Poly Hemi is an attempt to keep confusion down about wich Polys can be converted to Hemi & what can't.
The intakes do interchange. Additionally, I have a couple poly's that used pistons that will work with hemi heads (valve reliefs are inline vertically).
That's an Aussie rail from the early 60's. Was built by engineers from the Chrysler plant in South Australia. Pic was taken at an early drag strip at a suburb in Melbourne called Fishermans Bend and was right next to the GM Holden plant. swifty
Exactly, it's just that every time one of these threads comes up someone will be talking about one poly and then someone else will be talking about another. Just trying to clear up confusion. They need better names IMHO.
yep- the 318 poly "A" wide block gets tossed in the mix usually so poly/hemi moniker would make sense, for the Dodge/Chrysler engines that accept hemi heads
I'm surprised panic hasn't been in this thread. This is his specialty. More info? Feel free to check out the Polyspherical Engine ***ociation site: http://www.geocities.com/polyman64 The World's best vendor list is there. Also at the top of the home page are links to: The 318 (and others, but mostly 318) Poly Yahoo Group: http://autos.groups.yahoo.com/group/318poly/ And the 318 (and others) Poly Forum: http://www.diamondbackengines.com/forums/index.php/board,6.0.html Also, as mentioned above, panic (a HAMBer) sells a few books on the poly, and the hot rodding of said motors. Here's a link: http://victorylibrary.com/POLY.htm ~Jason
I think I have a 2x4 poly intake. It has the right temp sender and the water locations are right. The manifold is cast iron and has a choke stove. The carbs would be WCFB by the rectangle bolt pattern (I think). The thing that I dont see is the DPCD or any brand name in the casting. I had a 65 dodge p/u with 318 poly and three speed. I replaced it with a 340. The poly flywheel, motor mounts, pulleys, and oil pan/pickup tube fit right on the 340. I found that the LA series shared the later poly lower end parts. Like a 426 hemi vs R/B. I used dodge dart h/p exhaust manifolds as nobody had headers to fit a truck w/LA at that time. The truck clutch and three speed didn't take well to the 340 and jumped ship within a week. So, I built and installed a 727. A couple of the mechanics ,at the Chrysler dealer I worked at, took an interest in my truck and helped me with tuning and advice. The truck would turn 13.69-13.75 depending on conditions. A fun ride for a high school kid.
Is there any external differences between a Dodge 270 poly and a Chrysler 354 poly? Meaning (mainly) if I pulled my 270 out of my '55 Coronet, would the 354 just slip right in and bolt right up using the stock trans, stock motor mounts, etc?
It'll bolt up to the ******. Top of the 354 is much bigger than the Dodge, ex pipes wouldn't match I'm sure. Not sure, but think the bottom of the block is a bit wider as far as mounts are concerned.
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