• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

POLY guys CHECK THIS OUT!!

vanrj1

vanrj1

Well-Known Member
Local time
6:56 PM
Joined
Nov 3, 2009
Messages
657
Reaction score
64
Location
Dixon
I had a guy tell me that early Hemi Heads would fit on a Poly Block.
 
Diecastdeluxe said:
I had a guy tell me that early Hemi Heads would fit on a Poly Block.
Click to expand...

Not the later ones. They have to be the poly engines that were made in the same years as the early Hemi, but that is correct, yes. The later 60s 318 poly is a little different. I kinda wish they'd fit the later polys, cause that's mean they'd fit the small block. lol
 
Why in the world would you put LA heads on a Poly block? Might as well use the whole LA engine. (if its true)
 
vanrj1 said:
Found this while looking for poly parts. The description says this poly has 360 J heads. Has anyone heard of that? I guess anything is possible but first time for me. What cam grind could be in there? 400 HP for a non stroked poly is pretty good!!!
Click to expand...

Something is not right.

First, let me say, that you can pout LA heads on a Poly engine but it will not work. The amount of machining and welding to close the water passages from the block to head would make this un worth the headache in doing so unless your in desperate need to build the engine to get you out of hell or the in-laws house.

the block is basically the same minus some freeze plugs and the in block water passage.

You would need to weld up the water passage from the inside of the block, in the lifter valley and figure out how to re feed the head good enuff to cool.

I have had posted shots of this to dismiss the "Wide block" thing because it isn't a wider block, just a different casting. The intake look wider because of the way the heads are and the way they attach.

This was done at FABO a long time ago.

Wonder if Gary P had any involvement on this? lol
Click to expand...
Some how, I doubt it.


Diecastdeluxe said:
I had a guy tell me that early Hemi Heads would fit on a Poly Block.
Click to expand...

I'm not the best on this, but it is the older engines that can swap heads. If the displacement is the same, in example, 354 HEMI could swap heads with the 354 commando engine of the same time.

Here are a few photo's of "LA" heads on a Poly block with a "LA" Holley Strip Dominator on top just to show that it fits.

First shot is a "LA" head and the problem area of the Poly block. Between the two intake ports is the water passage I mentioned. It is huge and would take a "REAL WELDER" to do the job right.

Next is the Strip Dom and the LA head on the poly block. It fits, wont work.

Third is a comparo of the "LA" head on the Poly. Think about what your looking at. Where exactly is everything located?

$th shot are just the engines on hand to fiddle with.
 

Attachments

  • 100_1930.JPG
    100_1930.JPG
    59.8 KB · Views: 651
  • 100_1925.JPG
    70 KB · Views: 679
  • 100_1935.JPG
    76.5 KB · Views: 666
  • 100_1936.JPG
    100_1936.JPG
    73.4 KB · Views: 659
Then there would be the issue of the camshaft with the different port arrangements.My guess it's an LA engine.
 
rumblefish360 said:
Something is not right.

First, let me say, that you can pout LA heads on a Poly engine but it will not work. The amount of machining and welding to close the water passages from the block to head would make this un worth the headache in doing so unless your in desperate need to build the engine to get you out of hell or the in-laws house.

the block is basically the same minus some freeze plugs and the in block water passage.

You would need to weld up the water passage from the inside of the block, in the lifter valley and figure out how to re feed the head good enuff to cool.

I have had posted shots of this to dismiss the "Wide block" thing because it isn't a wider block, just a different casting. The intake look wider because of the way the heads are and the way they attach.

This was done at FABO a long time ago.


Some how, I doubt it.




I'm not the best on this, but it is the older engines that can swap heads. If the displacement is the same, in example, 354 HEMI could swap heads with the 354 commando engine of the same time.

Here are a few photo's of "LA" heads on a Poly block with a "LA" Holley Strip Dominator on top just to show that it fits.

First shot is a "LA" head and the problem area of the Poly block. Between the two intake ports is the water passage I mentioned. It is huge and would take a "REAL WELDER" to do the job right.

Next is the Strip Dom and the LA head on the poly block. It fits, wont work.

Third is a comparo of the "LA" head on the Poly. Think about what your looking at. Where exactly is everything located?

$th shot are just the engines on hand to fiddle with.
Click to expand...

Well that settles it...B.S.

I think the only advantage to a Poly block is that you can bore 'em .080-.100.
Lot's of potential in the Poly - check this out.

http://www.jalopyjournal.com/forum/showthread.php?t=718677
 
RTSrunner said:
Then there would be the issue of the camshaft with the different port arrangements.My guess it's an LA engine.
Click to expand...

"LA" heads on a Poly block pictured.

Polara Pat said:
I'm no authority but that looks like an LA block.
Click to expand...

That is correct, your not an authority, but you did just call me a liar.
What I would gain from doing so is beyond me.
Oh, by the way, suck a twizzle stick.

theman440 said:
Well that settles it...B.S.

I think the only advantage to a Poly block is that you can bore 'em .080-.100.
Lot's of potential in the Poly - check this out.

http://www.jalopyjournal.com/forum/showthread.php?t=718677
Click to expand...

B.S. on my part?

Good link by the way.
 
Lotsa good info on the Polysphere here:

http://www.1962to1965mopar.ornocar.com/poly318.html

They can be built into a 402 inch fire breather if done correctly. Let's not make this a pissin match. All you have to remember are two things with the Poly families. The early ones have things in common with the early Hemi, the later ones have things in common with the LA.

I don't know what alll of those things are, but I know according to that site I posted, one is the crank between the later poly 318 and the LA, so you can put a 4" arm in the later Poly 318. Nice. I know they will *usually* bore to 4". Of course with anything, sonic testing is advised.

As far as the early motors, here's what I know. Since I *have* a 1956 331 Chrysler Fire Power Hemi sittin out in my shop, I have done a little research on them. They will interchange block for block with the polys from their time period, just as rumblefish pointed out and described. The early Chrysler Hemi heads will bolt right onto the early Poly blocks with the same corresponding cubes, just as Rob said. In fact, My 56 331 has the same casting number as a 354 Hemi AND the 354 Poly of the same year. It is known as an "extended service block", because it was designed to be bored and bored and bored, since it WAS in a 56 D700 OTR truck. It will bore from the standard 331 bore of 3.8125 all the way to 4.00". I know because I've put a sonic tester on it. It's got some MEAT in the bores.
 
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. 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 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 later "LA" motors share many parts between them but have little in common with the earlier version. Plymouth eventually produced 301, 303 and 318 ci. "A" motors while in 1959 Dodge began production of their own 318 and 326 ci versions. The latter 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 generation Poly generally will not interchange. All early Polys can be easily recognized by the rather dramatic scalloped lower edge of the rocker covers, however in the later generation "A" series Polys the scalloping is much less dramatic. More like a wavy line than a true scallop.

Installing "LA" heads on an "A" block is possible with some work but is hardly worth the time, effort or expense. In my opinion the guy selling the car in question is either stupid, lying, or the president of the more money than brains club. If you want to go fast there are many cheaper and better ways to do it than to stick "LA" heads on a poly block.
 
Last edited:
Centerline said:
The '55 and '56 Plymouth Poly head engines were based on the Dodge hemi block
Click to expand...

meh.....almost, but not quite. The blocks are interchangable, not the same. Some of the holes in the deck such as the pushrod holes have a little different shape between the two. So, really.....although they probably should have based the early polys on the early hemi block, they did not. It was indeed its own separate entity. Although WHY, is anyone's guess.
 
RustyRatRod said:
meh.....almost, but not quite. The blocks are interchangable, not the same. Some of the holes in the deck such as the pushrod holes have a little different shape between the two. So, really.....although they probably should have based the early polys on the early hemi block, they did not. It was indeed its own separate entity. Although WHY, is anyone's guess.
Click to expand...
I said they were based on the hemi block, that doesn't mean they were the same.... if they were the same, I would have said so. :grin: There were differences as you have mentioned but not enough to make the interchange of a lot of major (and minor) parts a problem. Back in the day there were a lot of Polys (converted to hemis) on the strips simply because it was a lot cheaper to yank a Poly out of a Chrysler in a wrecking yard and convert it than it was to buy a hemi. That is one reason they're a little hard to find now days. Too bad really, as the Poly did have performance potential but was largely overlooked by the aftermarket for some reason.
 
Last edited:
It's beyond me also why one would want to put Poly heads on an LA engine. If I ever see dyno sheets on a successful project, maybe I would support it. Here's a photo of my 359 cu.in. 392 hp. Poly stroker.

Visit my Yahoo Group website The 318 Poly List, over 600 members.

http://autos.groups.yahoo.com/group/318poly/?tab=s

Nick Tiberio
FuryUs63
 

Attachments

  • Poly Stroker.jpg
    35.6 KB · Views: 470
You must log in or register to reply here.

Similar threads

davek
engine colors 1960-1973
Replies
11
Views
10K
Fm3 Dart
F
ncrobb
‘73 Road Runner 360 stroker?
Replies
18
Views
2K
PRHeads
PRHeads
Slantsixdan
  • Locked
SOLD Service, Parts, Engineering, Promo, & Tech Literature Bonanza
Replies
8
Views
967
Slantsixdan
Slantsixdan
vsandhurst
Update on my GTX
Replies
5
Views
3K
Longknife
Longknife
RJS
  • Locked
SOLD 1972 Satellite Sebring Plus
Replies
4
Views
2K
gibber
gibber
Auto Transport Service
Back
Top