HEMI Tech - POLY Tech - early Poly motor info

Okay, so I've had a few requests wanting some info to be gathered up on Poly motors and posted, since they're a close relative to early Hemis. Quite a few blocks are even the same as some of the Hemis which of course means that some can be converted to Hemis. So naturally we need to talk about them.

NOTE! Although 318 Poly motors are very cool as well, I would like to keep this focused on the earlier Poly motors because of their relation to early Mopar Hemis. Thanks!

1) Examples and specs
2) What's a Poly motor anyway?
3) Differences and similaraties between the Hemispherical and Polyspherical style engines
4) What's interchangable?
5) Which Poly motors can be converted to Hemis?
6) What needs to be done to turn a Poly motor into a Hemi motor?
7) Performance parts
8) What vehicles were they planted it?
9) ID information
10) Parts resources

These are great little engines and often get ignored or over-looked and really shouldn't. So let's force the issue and chat about them. Anything you can add would be beneficial.

Alot of this, as you may have guessed, is similar to the early Hemi stuff. Thumb through the Hemi Tech Index for your topic and you just mind find it there.

This thread will be added to the Hemi Tech INDEX for reference as well.

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Current HAMB links on Poly applications:

331 Poly
http://www.jalopyjournal.com/forum/showthread.php?t=323499&highlight=poly

starter info - 325 poly
http://www.jalopyjournal.com/forum/showthread.php?t=323363&highlight=poly

325 poly
http://www.jalopyjournal.com/forum/showthread.php?t=312417&highlight=poly

354 poly
http://www.jalopyjournal.com/forum/showthread.php?t=329798&highlight=poly

315 poly headers
http://www.jalopyjournal.com/forum/showthread.php?t=330231&highlight=poly

270 poly headers
http://www.jalopyjournal.com/forum/showthread.php?t=350235&highlight=poly

241-270 Poly crank breakage
http://www.jalopyjournal.com/forum/showthread.php?t=252892&highlight=poly

301 Poly parts
http://www.jalopyjournal.com/forum/showthread.php?t=241237&highlight=poly

Dodge poly questions 241, 270, 315
http://www.jalopyjournal.com/forum/showthread.php?t=34833&highlight=poly

241 poly info - blown
http://www.jalopyjournal.com/forum/showthread.php?t=230092&highlight=poly

331 poly intake info
http://www.jalopyjournal.com/forum/showthread.php?t=230900&highlight=poly

Chrysler poly info
http://www.jalopyjournal.com/forum/showthread.php?t=228309&highlight=poly

315 poly info
http://www.jalopyjournal.com/forum/showthread.php?t=217830&highlight=poly

301 poly to Hemi conversion
http://www.jalopyjournal.com/forum/showthread.php?t=209283&highlight=poly

325 blower applications
http://www.jalopyjournal.com/forum/showthread.php?t=196428&highlight=poly

331 poly info
http://www.jalopyjournal.com/forum/showthread.php?t=175832&highlight=poly

poly interchange info
http://www.jalopyjournal.com/forum/showthread.php?t=174224&highlight=poly

270 poly transmission adaptation
http://www.jalopyjournal.com/forum/showthread.php?t=102275&highlight=poly

270 poly intake info
http://www.jalopyjournal.com/forum/showthread.php?t=91526&highlight=poly

270 poly info
http://www.jalopyjournal.com/forum/showthread.php?t=88434&highlight=poly

Poly-hemi interchange
http://www.jalopyjournal.com/forum/showthread.php?t=84678&highlight=poly

Chrysler poly info
http://www.jalopyjournal.com/forum/showthread.php?t=59957&highlight=poly

Poly spitfire pics
http://www.jalopyjournal.com/forum/showthread.php?t=40762&highlight=poly

354 poly
http://www.jalopyjournal.com/forum/showthread.php?t=31770&highlight=poly

Poly vs. hemi
http://www.jalopyjournal.com/forum/showthread.php?t=14353&highlight=poly

260 Hyfire
http://www.jalopyjournal.com/forum/showthread.php?t=360864&highlight=poly

 

Damn scooter, when do you have time to work ??? The index is probably the single biggest source of Hemi related info available today.

Thanks for all of your efforts !!

Gary

.

 

That's my goal! Make the HAMB the number one source for Hemi related topics!

Thanks to YOU Gary, as well as everyone else who contributes to this Hemispherical disease...

 

i heard they have shallow.....

 

What 'chu talkin' 'bout Bean? Nevermind... I shouldn't ask.

 

...I thought about asking, but then I became afraid...very afraid...lol


Hey ! save a toke for me...

.

 

sorry that was tall girls...

 

BWAHAHAHAHA!! (sorry guys, inside joke)

 

Getting back on track...

Here's a thread that hotrod hooligan sent to me that I missed. Thanks man!

http://www.jalopyjournal.com/forum/showthread.php?t=318415

 

Sorry, I don't know anything about these "poly" motors. Anybody got a pic?

You're pulling our legs, right? There's no such thing!

~Jason

 

We really DO need more pictures, in all seriousness. They're really neat and detailed looking engines. Not sure who this belongs to, but it's super cool!

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Holy Schmoly's Poly's! Here's the 354 poly in my '57 Windsor:






Engine color is not original. Should be silver.

I have a 4-bbl intake from a 392 Hemi left over.
Having read some topics 'bout these engine I think I'm pretty sure this will be just a simple bolt-on procedure right? (392 intake -> 354 poly.)

 

A 392 intake will not fit on a Poly motor with hemi heads. The poly block has a shorter deck height, same as the 354 hemi.

 

Yup, the 392 manifold bolts on, just be sure to use the 392 gasket.

The 354, Hemi and Spitfire, share the same basic design intake manifold with the 392. The difference caused by the taller deck is accounted for in the cylinder head. That is why mixing heads and block is such a PITA.


.

 

Come on, man - that shit ain't real!

Admit it - you PHOTOSHOPPED that!

~Jason

 

Oh no! Was it that obvious??

 

Totally!

Postin' an SBC "art project" like that should be illegal. Shame on you, sir!



You know, panic's got some pretty great pics...

~Jason

 

Hers' my 354 poly still have to make the motor mounts and get things lined up.

 

Now THAT ^^^^^^^is what we like to see.


.

 

And I can come up with PLENTY of A-engine stuff... but that's not what this thread is about.

You should change the title so it mentions "(Non-A)" or "Early Polys"... The term "Poly" by itself is all-inclusive.

FYI, "Early Poly" is he preferred term, just like "Early Hemi" for the Polys you're looking to showcase.

~Jason

 

This little line finally started knarling at my noggin'... Why and what's difference between the two?

 

poly wants a cracker?......good thread guys....have a 56 D500 that I have to some day open up and figure out why that rod is sticking through the pan...most likley why it was passed up for so long...

 

Herman, the only reason I say to use the 392 gasket is that the 392 exhaust cross-over port is significantly larger than the 354 and some 354 gaskets will not properly seal.
As far as the gasket goes, everything is the same except for the exhaust port.


Gary

 

Ok, thanks. Bit of a releave.
'Cause when I threw the Weiand 'Hemi' dualquad intake on my 354 poly I had just left the old gasket be since it still looked good and was stuck good to the heads.
I just put a thin amount of gasketsealer on it and let it cure for half an hour before putting the intake on.
I did however block-off the heatcross-over ports though with some cut-up spraycan-metal.

 

Looks Good! How does it run with duals?


.

 

I agree, that should be changed - when I think of poly's, I think of the A motor.

 

Not good at the moment.
But I think the motor has other issues which need to be resolved first.

With the original 2-bbl stuff on there, the motor was starved for fuel when driving, which ofcourse I found out during the day I had an appointment with the DMV overhere.
The motor would hold back when you wanted to accelerate, eventhough you would feel the acc.pump deliver it's shot of fuel allright. But it would fall on it's face right after that.
The motor idled nicely, but idle RPM's couldn't be set right and where all over the place because the original carb turned out to be full of dirt and had a well worn throttle-shaft.
The car smelled badly aswell at the exhaust and would smoke badly when revving the motor in Neutral.

So instead of fumbling around with the old carb I decided to go right ahead and install the dual quad intake.
I had it running last week with the dual carbs but it didn't want to idle nicely at first and the smoking out of the exhaust was still there while revving.

I thought this might be build-up oil residue in the exhaust because the previous owner probably didn't really let the motor 'work' a lot.

I went ahead and converted the original ignition to an electronic ignition with a smallblock distributor and new chrome ECU. Also bypassed the ballastresistor for the time being so I was sure the coil would receive the full 12v and put out a good spark, instead of the 4-5volts that were getting to the coil with ballastresistor in the system.
Changed the (new) black plugs aswell for a slightly hotter version but now the motor doesn't want to idle or run right at all anymore, so something is still messed up here.

I also plan on testing both carburators seperatly on another car to confirm they are not the problem. Checked the fuelpump and it delivers 4.5psi while cranking and gives a healthy shot of fuel aswell.

One way or another I have the feeling the motor just has a lousy burn of the fuel-mixture.
Perhaps the timing chain is worn too much. (I can feel about 11/16" 'slop' when turning the motor over left and right at the crank-pulley)

Here's a clip of the motor running with the dual quad just installed, but still with the original ignition;
Notice the motor doesn't react to moving the throttle anymore after I manually turn off the choke's on both carbs...

 

Actually, it DOES refer to early Poly motors in both the title and the big note that I have in the second paragraph. Am I mis-understanding the confusion and/or clarity of this thread verbage??

 

I Grock!

Glad to learn that a 392 Hemi intake will fit a 354 Poly. Just so happens we have one of each laying around.

As an aside; my old Motors Manual calls the Hemi a "double rocker arm motor" and the Poly a "single rocker arm motor".

 

How about some pictures with the valve covers off and some shots of the combustion chambers?