"Poly", "polyhemi", "semihemi", "big block 318". Call it whatever you want, its a 318 CID motor made by mopar in the late 50s and 60s. If you wanna get your ******* in a wad over names, there are much better arguments to be had. I recommend ignoring the *****s who think they know more than you, instead of trying to explain to them why they are wrong. A good definition of intelligence is "awareness of ignorance", and letting them flap their gums about stuff they aren't aware of is just letting them broadcast their absence of intelligence to the world. The Dodge brand RVs of that era that I have seen had removable crossmembers and the motor kinda dropped out the front. I've thrown out maybe a half dozen of those motors, because I couldn't give them away. It seems like kind of a shame to part out a cool motorhome for a less than sought after motor.
If it looks like this one, the mtrs drop out the bottom. I put a mtr in one yrs ago & had to slide the mtr under the mtrhome & had a small A-Frame set up inside the RV. Talk about a royal PITA.....joe
Four Thirteen as well as Defarm are correct. The semihemi does exist. The difference is in the combustion chamber not on the outside, it doesnt look like a hemi. Anyone who says it doesnt exist is wrong. To the average joe all 318's are polyspheric. They made all kinds of stuff in the 50's and 60's and just because you havent heard of it doesnt mean it didnt exist. Everyone on here speeks to quick without really doing any kind of research.
Thanks four-thirteen for being a voice of reason; getting ****ered into a never ending ******* match isn't what I was after; simple advice without having to totally destroy the motorhome, not having a manual for this type of vehicle. It was given to me, in trade for a job, it's not in great shape except for the engine/trans, which is the only reason it came home with me. I hadn't seen a lot of interest in other parts for a vehicle like this on Ebay or elsewhere before, but then haven't tried looking for awhile.
No problem , The SemiHemi will be cool I hope you get that thing out of that motor home and in to your hot rod, so you can show up at a car show to prove everyone wrong.
Hi,I've owned a few of each over the years and I understand where the confusion arises. Dodge's Poly 315(325?) and Chryslers 354 windsor Poly were Hemi's with poly heads .(and pistons to suit etc ) . Then there were the arguments over the 318 Poly and the 318 LA engine. What really throws people is that one or two bits interchange a****st the range. I wouldn't bag Defarm over this, because i've come across this plenty of times. I would be wary of an ex Motor home unit though. It will be worn pretty badly and speed gear is a little hard to find. That being said the Poly makes great power with a cam change and the Weiand 4BBL intake. The heads flow so well you don't need to work them over and the ignition ius upgradeed by simply bolting in an electronic unit from the LA . If you want to see real confusion,read up on how Bristol cars in the UK had a "hemi". It wasn't,it was a 313 Poly. An engine sold only in Canada and Australia and nothing from any other poly fits them. Buy the mopar perfomance engine manual for real performance advice on the Poly V8.
How many of you guys claiming that the 318 Poly was/is a "semi-Hemi" are actually Mopar guys? Probably the same guys that call the Poly 318 a "big-block 318" (no such thing!), or worse, calling it a "Y-block" 318 (no Ford anywhere!)...it is a small-block "A" Polyspheric-head engine. Yes, there IS some interchange between an A-block and the later LA-block 318 engines; specifically the timing set, distributor, and water pump, but not a lot else. One question to you guys that insist the Poly-head 318 is something other than a Poly-head-318...Do the spark plugs come out through the valve covers? No? Need I say more? There IS a difference between a Hemispherical head and a Polyspheric head. Look at one each and you will fully understand why they are NOT the same thing. The term "semi-Hemi" is just a cutesy name for the Poly head by those that do not know any better or different.
Yeah,isn't that amazing!. 55 year old technology that is still being used today in the latest engines! . There were even race heads being offered 10 years ago for the generic brands called "twisted wedge " heads. The combustion chamber was really a copy of the poly thinking . Poly= many Sphere = round shaped ball . = many rounded shaped combustion chamber.
If it's a van ch***is, the motor can come out the side door while the trans drops out the bottom. Motor homes are a great source for low mileage and usually well cared for power-trains. And while we've got the pop corn poppin'; that new "HEMI" ain't a true hemi either!
They're not saying "Y block 318" they say "wide block 318" because the A intake looks wider than the LA intake.
But isn't it the heads (combustion chambers to be exact) that determine what is and wha isn't a hemi? If they aren't hemispherical combustion chambers it ain't no hemi right? or do I not know what I'm talking about... <!-- / message --><!-- sig --> __________________ You know what you're talking about
Yeah, sure looks like a hemi to me. the resemblance is stunning. And here are some more "facts" I came across checking on this topic. So far, still no 318's: http://cl***ichemi.com/index1.shtml. Still could be something off the charts out there, who knows. So, if you want to believe it's some kind of hemi or possibly could be made into a hemi and want to go through the effort to get this out of an old RV, that's cool with me. I am not knocking you for that, just would like to get the terminology correct. Regardless, it is probably not a bad engine to use for something. But, it's still not a hemi. An almost hemi is just like being almost pregnant. It either is or it isn't. All kinds of engines from all over the place have sort of sphere-ish combustion chamber tops in the heads. That doesn't make them hemis. When was the last sharp edged head you saw? I am not really a hemi snob, just sort of wrong to try to pretend it is something it is not. Nothing wrong with just being what it is. Calling it a "semi-hemi" is just kind of lame. My original point was to suggest that to you incase you had your heart on this somehow being some kind of hemi which is just isn't. I am not sure going through all that effort with the RV just for a 318 would be worth it, but that part is up to you to decided. Good luck with it either way.
So is this the Poly version of the Red Ram Hemi? Or is it based on a different block? And what does the word Poly stand for? ( many?) That it has several spheres combined into one combustion chamber? ( I guess I can kinda see that...) This is turning into a cool History lesson...
Not a point of being a "never ending ******* match". Its the subject!! IT NOT TRADITIONAL , Its not even a ****ing car!! Jeez, is that hard to understand, go to another Forum!! We shouldn't even be wasting space on this site for this ****. Wheres germ??? JimV
Grab both yer 'nards with half stickin out. Polyspherical. Grab one nut, half stickin' out. Hemi. One rocker shaft = poly Two rocker shafts = Hemi
It wouldn't be traditional if the subject was the motorhome. The subject is the engine, so it is Traditional.
No the 318 isn't a Poly version of a red ram hemi. It's an "A" block. They simular but different than the early hemi block. The "A" Poly(polyshereic) came in 277, 301, & 318(plus some 303, 313, & 326) CID. The earlier hemi were made as Polys also as Chryslers, DeSotos, Dodges & Plymouths. There were Chrysler 301 polys made in '55 that are totaly different from the '57 301 Plymouth polys. For a couple years both hemi based polys & "A" polys were being made @ the same time!
Sometimes, you just want to sit one out. For those who are curious about the A engines, check out the Polyspherical Engine ***ociation here: http://www.geocities.com/polyman64/ Join the Yahoo Group here: http://autos.groups.yahoo.com/group/318poly/ And check the forum out here: http://www.diamondbackengines.com/forums/index.php/board,6.0.html ALL your answers are a few clicks away. As for this "poly hemi" stuff... whoo-wee... I'm gonna be smart and just take the bench on this one. If you guys have any questions about these motors, feel free to PM or email me. I'd be more than glad to answer anything you throw at me. "Poly hemi", huh? Hoo boy... ~Jason
The subject wasn't the ENGINE.It was how to get the motor out of a motorhome!!!NOT TRADITIONAL!! Read the beginning first! Or better yet read the post ***le!! JimV
Are you guys talking about the 318 we used to call the "318 marine engine"? Not the 273 base engine, the big block with the bolts in the center of the valve cover? Weighed a ton not much HP?
Yep. Although I'd argue the HP deal... but not with a stock motor. Here is some ****, courtesy of 29Jay: ~Jason
Well, I tried to stay quiet, but this just doesn't want to go away... Marine, truck, and OMG, p*** cars ! Weight? maybe 30 lbs over an LA. Gary Pavlovich will argue the hp issue while he counts more than 400 on a recent dyno run. Looks like we need a scootermcrad clone to do an index on the A series, Hey Jason, maybe you know someone... .
I guess we'll have to ban threads about guys pulling Hemis out of air raid sirens where this isn't an air raid siren Forum.
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