RE: Beginners question sorry

["Dennis C." <dennis.2914@xxxxxxxxx>]

OK,

I had plans for someday in the future to remove the 318 Poly from my 64 
and put a big block in - I think you just screwed up my plans.

You have me thinking really hard about stroking the old 318, rebuilding 
the old automatic and having some fun with it.  I knew the poly was a 
nice engine but I guess I never really knew how nice.

Thanks for the great information.

Dennis C.


Gary Pavlovich wrote:
> 
> Dave,
> 
> The  318A "Poly" engine that many refer to is nicknamed a "Poly" because 
> the 
> head design is a Polyspherical combustion chamber with canted valves 
> (angled 
> intake & offset from the exhaust - not in the same plane and side by 
> side as 
> the Wedge chamber) as opposed to a HEMIspherical chamber.
> 
> The Plymouth Poly was produced from 1956-66 as a 277, 301, 303, 313, 
> 318, 
> and 326 (1959 Dodge only) and shares many of the same parts as the later 
> 
> 273/318/340/360LA Wedge-head engines.  Sometimes the aforementioned 
> Wedge-head engines are mistakenly called "A" engines which can be 
> confusing.
> 
> Interestingly, the modern 4.7 Chrysler engines are a Polyspherical 
> chamber 
> design and not a wedge design; even the new HEMI's are not true 90degree 
> 
> Hemispherical valve layout.
> 
> The BMEP, brake-mean-effective-pressure of a Poly engine is far superior 
> to 
> the Wedge chamber and slightly behind the HEMI;
> 
> "...the poly engine had one absolutely unique feature: its volumetric 
> efficiency. If the Mopar figures as found in the Plymouth factory manual 
> are 
> to be believed, torque of the poly 318 was 345 lb.ft. Now, take torque 
> and 
> divide it by cubes, then multiply this by 151, and you get brake mean 
> effective pressure (bmep). Try it for your self: bmep for the poly 318 
> is 
> 164 psi. (Again, that's the figure Plymouth gives). That is near to the 
> theoretical limit for an unsupercharged engine (and that's with the old 
> log-type exhaust manifolds too) and is very close to the 426 hemi's bmep 
> of 
> 173psi, which had all those performance-designed components. The bmep 
> figure 
> purely reflects breathing efficiency (proportional use of the charge 
> coming 
> into the engine), and is a product of the head, as opposed to the block, 
> 
> which just needs to suck/blow as rapidly as possible without flying into 
> 
> little pieces..."
> 
> Gary Pavlovich
> ----- Original Message ----- 
> From: "Dave Isle" <mnwildpunk@xxxxxxxxx>
> To: <1962to1965mopars@xxxxxxxxxx>
> Sent: Thursday, December 10, 2009 8:56 PM
> Subject: Beginners question sorry
> 
> 
> >
> > I see a lot of you guys saying you have a poly this or a poly that. I 
> > know 
> > it is a type of engine but which one is it and what makes it a poly.
> >
> >                Thank you for being patient and answering this probably 
> > silly question.     Dave
> > Sent via BlackBerry by AT&T
> >
> >
> > ----
> > Please address private mail -- mail of interest to only one person --  
> > directly to that person.  I.e., send parts/car transactions and 
> > negotiations as well as other personal messages only to the intended 
> > recipient, not to the Clubhouse public address. This practice will 
> > protect 
> > your privacy, reduce the total volume of mail and fine tune the content 
> > signal to Mopar topic.  Thanks!
> >
> > '62 to '65 Mopar Clubhouse Discussion Guidelines:
> > http://www.1962to1965mopar.ornocar.org/mletiq.html.
> >
> >
> > 
> 
> 



1996 Dodge Ram 3500 Van Conversion
1964 Plymouth Belvedere 318 Auto
1963 Plymouth Sport Fury 383 4-speed
1949 Dodge Pickup 289/C4 soon to be changed
1998 Honda Valkyrie Standard


----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.