What's the good and bad with mopar 318 poly's

Cool, now I don't have to make another Poly thread. My question is I've heard that early hemi heads will bolt up to a 318 Poly. Is this true? I realize that the pistons would have to be changed, along with other things.

 

No way - the 318 Poly is one of the very few Polys that Hemi heads won't bolt up to!

~Jason

 

Damn. What other sizes did mopar make their polys in?

 

Here's a few places to get info:

The Polyspherical Engine Association:
http://www.geocities.com/polyman64/
I just updated the business directory page there - the most complete Poly parts vendor list you'll find in one place!

Allpar:
http://www.allpar.com/mopar/a-engines.html

http://www.allpar.com/mopar/poly.html

http://www.allpar.com/mopar/redram.html

And here's the Poly Yahoo Group:
http://autos.groups.yahoo.com/group/318poly/

And here's the Poly Forum at Diamondback Engines:
http://www.diamondbackengines.com/forums/index.php/board,6.0.html

That should get you started.

~Jason

 

I had this one in my 59 Plymouth with a 3 speed overdrive. It ran pretty hard for such a big car. I think there very dependable and a really cool nostalgic kinda dare to be different motor. We did have some problems finding parts for the re-build, you can't just walk into any parts store and get what you need. Gary

 

Nice dual-quad... and nice alternator!

These days you can get an awful lot of stuff from NAPA, believe it or not. Search their site and see - they have water pumps, timing sets, lifters, distributors and alternators... even gasket sets!

You may have to go to Egge for pistons, but the only problem you may have is finding new rockers. I'm working on that (see link below).

http://www.diamondbackengines.com/forums/index.php?topic=185.0

I also know where to get finned aluminum valve covers - I posted it here last night (that updated business directory I mentioned above).

~Jason

 

A friend of mine had done a mock-up playing with LA and Poly heads. I'll have to check with him and report back later, but I think he was going to put Poly heads on an LA block, and it appeared they would need very minor modifications.
I believe his goal was the lighter LA weight and unique looks of the Poly heads. Since the deck height, bore spacing and many other things are common to both blocks, there should be no significant issues with the intake manifolds.
Mike Bynum

 

Polys are a lot wider up top than the LA 318, and the intakes are totally different. The Poly has evenly spaced ports, like a Hemi, and the LA 318 has one port at each end of the head, and two together in the middle.

The intakes are totally different.

Here'[s a company that makes Poly heads for Big Block Mopars:
http://www.nrcperformance.com/

Here's a copy/paste:

"NRC Performance Products Presents...

An all-new cylinder head design that brings the kind of flow and performance to Mopar big-block motors that had previously only been possible with expensive porting, or Pro Stock-style heads. The NRC Predator cylinder head is a cast-aluminum head with greatly improved
ports and combustion chambers, that gives the kind of performance necessary to stay competitive - and win - in today's world of high-tech drag racing."

"New" technology? I think not - check his pictures out! Those are poly heads.

As for putting poly heads on a LA-style motor, I say no way. Look at this head diagram and see for yourself and say WTF:



Now, there's an $8500 kit to put Hemi heads on a Small Block Mopar if you're interested: http://www.rodandcustommachines.com/smallblockhemiheads.html



They're featured in the August '03 issue of Mopar:



The one with the "Parts Deal Gone Bad... Vendor Beaten To Death With Hammer" on the top of the cover.


~Jason

 

Do you know of anyone with experience using a blower set up on a poly 318?

 

Dick Landy sells 'em.

http://dicklandy.com/Products/index.htm#Supercharger

And there's a discussion about them here:
http://www.diamondbackengines.com/forums/index.php/topic,100.0.html

I agree - they BEG to be blown (don't we all?)!

~Jason

 

What about the early (55) 241 270 engines weren't these polys and hemis?

 

Yep. The heads swap.

~Jason