Re: 318 Poly Stroker
[Re: Cab_Burge]
#1783693
03/19/15 03:55 PM
03/19/15 03:55 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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There are several major impediments:
1. You will need custom pistons, as AFAIK there are no stroker Poly pistons out there. The intake valve needs a relief pretty close to the edge of the piston. 2. Camshafts are quite hard to come by. Camcraft has some new cores, but their hydraulic flat tappet grinds start at about 242 degrees at 50 lift. The other alternative is regrinding, and you are limited by what the lobes look like on the cam. 3. Intake manifolds are very high priced. There are only a couple of aftermarket manifolds, the Weiand 7503 and Edelbrock P-600. Weiand 7503s are selling for around $500. The P-600 is an antique design that for the most part runs Stromberg 97s, although a few were made that used a Rochester two-barrel. Neither intake is available new. There is a factory four-barrel, found on 1962 and older. This is also selling at about $500. The factory dual four barrel intake is currently the lowest priced, running around $250 last I checked. There is SUPPOSED to be a new intake that looks superb, but I don't believe it's hit the streets yet. It is around $600. 4. Then there are the heads, which flow quite equivalent to a 360 smog head, around 200 cfm at max. They also have the same problems as LA motors, with short installed height making spring selection more difficult. 5. Exhaust will also be problematic. All Poly exhaust manifolds are logs, definitely low performance, and there are no headers readily available for the Poly exhaust port layout. Cleveland Ford comes closest.
Now put this together with an engine assembly weighing around 60 lb more than an LA motor and you will see why it's not a solution to your problem. Also, like the Hemi, the Poly stroker will take a lot of $$$$$$ to make a horsepower.
Pavlovich's Poly stroker made 400 hp, not exceptional.
I say all this and I like Polys, ran one for years.
If I was going to start a new engine family it would be GIII Hemi. Makes no sense to go anywhere else.
R.
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Re: 318 Poly Stroker
[Re: Rob C]
#1783698
03/20/15 04:18 PM
03/20/15 04:18 PM
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Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
master
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master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
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I gave some thought to that idea years ago, and by the time I had crunched the numbers, I realized I would be cheaper to build a nice 440 and do the entire big block swap. And of course, you can build a 500 horse 440 with your eyes closed.
That being said, I would enjoy the heck out of seeing a stroker poly come together.
2 kids and a dog
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Re: 318 Poly Stroker
[Re: TonyS451]
#1783699
03/20/15 07:54 PM
03/20/15 07:54 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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I am a Poly kind of guy, I own a Weiand 7503 and have been all through the Poly stuff. I can rattle off part numbers for pistons etc with the best of them. Years ago my little brother told me the Poly 318 was stouter than an LA 318 and stock for stock, 2-barrel against 2-barrel, the Poly wins. It has much better heads than the 318 and its cam is about the same as a 360. So it runs pretty well. BUT, building a stroker that maxes out at 405 horsepower? You can build a nearly stock 360 that will make that kind of power, and a lot more. Torque? that wasn't a boatload of torque. So you take the expensive intake and the custom pistons and the stroker crank and the $1000 or much more for headwork and paying more for headers and you have an engine that any carbureted 5.7 Hemi will beat and weigh 150 lb less, be much easier on fuel, and cost less to boot.
What really pi$$es me off is all this ignorant hot air being blown around by people who are fooled that the engine really compares with a Hemi, because someone called it a semi-hemi. This kind of horse crap has caused these giveaway engines to all of a sudden be advertised for $500 for a core.
Now let's get into the wonderful CNC heads referenced above. Big honkin deal. So it's a CNC program. Read the writeup. Every intake port has a pushrod tube in it. They broke through one intake port in another place but that's okay, because it isn't an exhaust port so you can stuff some epoxy into it. What this tells me is that those heads are max ported and thus: a. They are really expensive, and b. They are about as durable as a potato chip.
It just doesn't add up. Years ago I corresponded with E-berg about this subject, and he said don't waste your time. I didn't want to believe him back then, but he was right. And that was way before the new Hemi. At that time the Mag motor was the way to go.
So guys, let's not fool ourselves into thinking the Poly is some kind of hidden gem that's been ignored for 55 years because everybody was just too stupid.
People will do what they want, it's a free country. I may still build a Poly stroker, but it'll be because I want to be different. Heck, I might just decide to build a 273 stroker! But I won't be kidding myself about how totally gnarly my motor is, it'll just be something I did for myself.
And, if I didn't have enough money to contemplate a GII Hemi, I for sure wouldn't go back in time to the Poly when the GIII Hemi rolls out of the factory door with a roller cam and heads that flow as well as those max-ported Poly heads. No way you can't build equivalent horsepower with the new Hemi for less than the stroker Poly motor.
R.
Anybody want some flathead Ford stuff? It's just a little bit older.
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Re: 318 Poly Stroker
[Re: Jeff_383]
#1783703
03/21/15 01:13 AM
03/21/15 01:13 AM
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Joined: Aug 2003
Posts: 43,129 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,129
Bend,OR USA
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Quote:
As much as the above is right, I would much rather look under the hood and see the old poly as opposed to any new gen hemi engine. Just looks more at home.
Why Did you ever own or drive one of those antiques? If not maybe you should I owned and drove a 1959 Dodge Coronet for several years that had a 326 C.I. Poly motor(one year only motors made by Dodge, same as a 318 C.I. Plymouth ), it had a 2 speed Powerflyte in it and it got decent mileage, it was a dog at WOT until about 30 MPH and then it would start to pull okay That was after changing the single exhaust to duals and removing the stock 2 barrel intake and carb. and putting on a stock 4 barrel carb. and manifold from a 1959 Plymouth Fury station wagon 318 Poly motor I think the wagon had a early 3 speed cast iron torkflyte in it also, I should have go that tranny and shifter to put in my car Chrysler Corp. quit making them motors for reasons that made since to them back then, the L.A. 318 was better,more power, less emmisions and cheaper to make probally Chrysler and Dodge had thier own versions of the Poly motors also, different C.I. for each brand and nothing interchanged between them that I can remember now except the carbs. maybe IHTHs
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 318 Poly Stroker
[Re: Jeff_383]
#1783706
03/21/15 03:58 PM
03/21/15 03:58 PM
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Joined: May 2003
Posts: 6,561 Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
Posts: 6,561
Downtown Roebuck Ont
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The price of a custom poly piston notwithstanding, it won't cost a nickel more to stroke this out to 426 than an LA. Of course as others have pointed out a stone stock 440 swap will get you the same results for less $$, but where is the sport in that? I have a 65 C-body wagon with a poly and an extra 100 cubes of bottom end torque would be most welcome. Will the heads limit horsepower? Absolutely! With the heads cleaned up with bigger valves and a good valve job I would expect it to be completely out of breath at 45-4800 or less but guess what, it's a 5000 lb cruiser that never sees the high side of that rpm anyway. 340 ft/lbs to 450-475 will cause tires to protest. As for those CNC heads $2800?? Most shops that I see advertise CNC ports are around $1000 +/-. I realize these are max ported because they have to install tubes etc but does that really add $1800 to the job? I suppose cast iron causes more wear and tear on the equipment than aluminum but the price seems to be a tad extravagant. Kevin
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