315 318 Semi-Hemi or what ?

[Dougofthenorth]

Greetings,

I just came across your web site. & I'm currious.
I have an all OEM 1960 Dodge ½ ton D100 straight-side shortbox with pushbutton (truck) auto trany, with 13,000 original miles (no winters).

I have a letter from Dodge Canada in Windsor ON verifying there were only 146 of these built, but could not break it down further as to how many with the V8 & auto - most were 6cyl with 3 in the tree (column shift).

I have never seen another with these options.
I was told my motor is known as a “Wedge” because of its width & that after 1963 they closed/upswept the V & the blocks were then narrower.

I was further told this is called a polyspherical 318 or semi-hemi.

It also has what were called Power Pack heads, as found on the 1958 Regent.
Unfortunately, I do not have the Ram fuel intake set up with the dual 650 Carters (the Octopus).
Is this a Hemi motor? Possibly the 315 (not 318)?

I had it balanced & blueprinted & run straight pipes with resonators no mufflers. It is incredibly fast & powerful, I once did a brake stand at a stop light in 1974 & snapped the frame. It took a 340 sixpac car to beat it back then. Its got a 4:10 Suregrip rear end.

Thanks for your help.

I sent this to Scott in an email.

[centerline]

The following Poly tutorial is pretty much a transcript from my web site and explains the Chrysler Corporation "Poly" motor history.

In 1950 Chrysler consisted of four divisions; Chrysler, DeSoto, Dodge, and Plymouth. The pecking order or hierarchy between divisions being just about in that order. Of the four divisions, lowly Plymouth was the only one never to produce the early hemi. Their V8 production consisted of the "Poly" head (twisted wedge head) design. This is significant because the '55 and '56 Plymouth Poly head engines were based on the Dodge hemi block and these motors can be a very good source of parts for the early hemi enthusiast. Chrysler and Dodge produced poly head engines as well. Chrysler's 301, 331, and 354 polys and Dodge's 270, 315 and 325 polys can easily be converted to hemis by adding the proper heads, intake and exhaust manifolds. It is important to understand that polys can be converted to hemis only within an engine family. Chrysler polys accept Chrysler hemi heads, Dodge and early Plymouth polys will accept Dodge hemi heads. DeSoto never produced a poly head motor so DeSoto hemi heads won't work on anything but a DeSoto hemi. (The 325 ci. Firesweep Poly head motor installed in some 1957 DeSotos were actually Dodge motors built in the Dodge engine plant.)

In 1956 Plymouth began production of a new series of wedge head motors. Although still referred to as Polys or new generation Polys these "A" series motors are actually more closely related to the later "LA" series. The "A" and "LA" motors share many parts between them but have little in common with the earlier version.

In 1959 Dodge began production of 318 and 326 ci versions of the "A" series Chrysler Polysphyre engine design. The 326 ci. being produced for only one year. "A" series motors should not be confused with the earlier Plymouth and Dodge poly head engines or the Chrysler Polys of similar displacement. Parts between the early Poly/Hemi design and new "A" series Poly generally will not interchange.

All Polys can be easily recognized by the scalloped lower edge of the rocker covers, however in the new generation "A" series Polys the scalloping is much less dramatic. More like a wavy line than a true scallop.

In the Hemi design the valve positions are at opposite sides of a hemispherical shaped combustion chamber. The early Poly design still had the valves more or less placed that way with a generally hemispherically shaped combustion chamber, hence the "semi hemi" moniker, however the position of the valves were moved much closer to the centerline of the cylinder. On the "A" series Poly head the valves are positioned on one side of the cylinder the same as the later "LA" series and the combustion chamber is "wedge" shaped very similar to what you would see on a small block Chevy or a Chrysler 340.

From the date of your truck I believe you have one of the later Dodge "A" series Poly 318’s, which is more closely related to today’s V8's than the hemi design.

[Dougofthenorth]

Thank you very much for the fast & thorough response it is obviously a 318 Poly A type.

Do you have the horsepower & torque specs?

Also, what would the "Power Pack" heads be from the Dodge Regent?

[centerline]

I don't have that info since the "A" series poly isn't related to the early hemis. Just do a search on the web, I'm sure the info is out there.