not having either a poly nor magnum valve cover to look at, i once took an original 54 [?] oldsmobile valve cover with the two attaching holes in the middle, and welded two studs to the top of a pair of small block chevy valve covers.
the olds covers fit down over the small block covers, and were bolted fast.
gaskets were glued to the olds covers, so it appeared the engine was an olds instead of a small block chevy.
this engine was in a 1928 ford roadster pickup i had a hand in building for my one cousin.
as it was run sans hood, it had a 3 two intake, and was painted the oldsmobile green color, and used a pair of exaggerated "ram horn" exhaust manifolds that speedway motors sold.
fooled almost 99% of the people who saw it.
maybe it's possible to do something similar with the poly valve covers ?

I don’t have a 318 Poly valve cover handy to get any measurements from.
Probably the largest early Poly valve cover would be the 55-57 301/331/354 Poly…..I do have one of those.


Z PV 1 by M Patterson, on Flickr


I took some measurements if that helps.


Z PV 2 by M Patterson, on Flickr

that would be a cool valve cover to see fitted to a magnum or la cover if it were possible.
if i remember correctly, the la cover is somewhere around 16-17" long, and 3" and change wide, so it's conceivable the covers you show could be relatively easy to be attached over top of.
of course the breather and oil fill caps, as well as the pvc provision would have to be removed from the la covers, and somehow incorporated into the la intake or the back of the poly covers, but that doesn't seem like a particularly difficult thing to accomplish.

That Poly valve cover looks close to the covers on the Poly V8 currently in my 56 C3. Except the early Poly V8 valve covers only had two mount studs through the cover. Those I could just weld up or put some short bolts into the hole with a nut on the underside, maybe just a C-clip to hold a fake stud head onto the cover. Those dimensions of the Poly covers is pretty close to the Magnum covers, though the overall length of the Poly covers (not including the flange) is almost as long as the Magnum covers with the flange. I'm thinking I could take the stock Magnum valve covers and cut them off just above the mount flange. Likewise cut the mount flange off the Poly valve covers. Then have a buddy TIG weld the Poly valve covers to the Magnum mount flange, along with some pieces welded in to fill the wavy areas back to the Magnum mount flange. Would have to make some recessed access to the Magnum mount holes on the exhaust side of the covers. With a good clean small bead TIG weld, especially on the exhaust side of the heads, it may be tough to even notice the TIG welds. Would be a lot of work, but could look really cool.

It would make for a great vintage look, with the Poly valve covers painted silver with some Mopar orange lettering on them. Plus, I scored an original 50's Cadillac complete batwing air cleaner assembly that fits directly onto the throttle body on top of the 5.2 Magnum (very little mod needed) and visually covers a bit of that big ol' Kegger. Paint that Caddy Batwing air cleaner Mopar orange with the silver valve covers, should lood pretty good. Put a round MOPAR sticker on top of the air cleaner housing Yeah the pic below is on a GM engine (cough, cough) but it is a cool look to see under the hood of a vintage pickup, and the replacement filter element should be easy to find near anywhere.

in the twisted sense of humor i possess, i always thought "faked up" valve covers were kinda neat to do, making people scratch their head wondering what they are looking at.
i have a pair of "international" script valve covers waiting for the right time to make the "scene"............

Don't take this as to criticize, its merely the welder guy forward thinking about the possible obstacles that might cause a problem. Its something my mind automatically does.

What will you do to get a place to add oil, have a PVC valve, and provide air for the PVC valve, on the poly valve covers? The next tissue I see is how are you planning on holding the poly cover on the Magnum head, pretty obvious the bottom isn't going to match worth a darned.

I'm thinking it might be easier to somehow mount the poly cover over the top of the complete magnum cover (hopefully its tall enough to cover everything), and hold it to the top of the magnum cover by adding provisions for using the poly mounting screws to hold it to the magnum covers. One cover over the top of the other, bottom one still works on the motor. Still would have to deal with the PVC stuff, but at least you could pull a few bolts and still have the magnum oil fill intact. Wouldn't have to worry about sealing the poly cover to the magnum head either. I have to wonder if the magnum covers are taller then the poly covers.

The old poly motors had a separate tube to add oil and didn't have a PVC system.

I like the concept.
A couple pictures of a 5.2 Magnum valve covers in a real live 49 Dodge truck (the best views I have of the covers).

Aww c'mon Gene, you had to go and simplify the whole idea. Not like me (an engineer by trade) to over think this whole idea and make it tougher to do than need be.

In other words, you're thinking this through better than I am. I like the idea of cosmetic valve covers to make the Magnum look more like an old Poly V8. I could weld threaded bungs into the Magnum valve covers so the Poly covers would mount with their original shortened hardware. Doing the PCV and oil fill could be more easily done too. Hmm,....the PCV would not necessarliy "have" to be on the top of the valve cover right? Could be off the back end of the Magnum cover, so the Poly cover slides over it, and a clearance "slot" for the PCV would only be visible between the rear end of the Poly/Magnum valve cover and the firewall.

Putting the PVC at the back end of the magnum covers would depend on how much space exists between the back of the cover and the firewall. Nothing much would fit on my 49 at all, there is maybe an inch and a quarter between the cover and the firewall. I would also be concerned about baffling the PVC, so it wouldn't suck the oil off that rear cylinder's valve train. Don't know how much space is available inside the magnum valve cover.

The logical location to run the PVC stuff would be at the bottom lower edge of the magnum cover, and run the hoses under the bottom edges of the poly cover, but I'm not so sure that would be the best location to put a PVC or the PVC's fresh air intake on the magnum covers. Maybe you could get high enough on the lower side of the magnum cover (under one of the poly lower scalps?) wouldn't necessarily need to have the PVC valve there, but an inlet and outlet hose nipple (1/2" OD hose for the PVC?) at a 90 degree angle, run towards the rear of the motor and put the PVC in the hose? Have the PVC inlet on one side and the PVC itself on the other side, run up around the back of the motor, and be under the air cleaner housing.

See what you started?

I like the ideas though. Logical approach to a potential solution.

I thought it may make for an interesting way to create a vintage look and not just go the uaual way of the die cast aluminum Mopar valve covers. Not saying I don't like that look, because it does look really good. But almost everyone does it, and a decent set of cast valve covers is well over $200 or so I've seen so far. Take the idea of cosmetic valve covers a bit further and really mess with people's head when they open the hood and see Packard valve covers:

lots of options to re-route the pcv, breather, and oil fill cap, providing one thinks outside box [as everyone is so fond of saying] and carefully considers the baffling needed to prevent sucking oil and excessive vapors into the combustion chamber.
poor boy has a couple of good suggestions. also look the intake over closely to see if an oil fill location could possibly be installed in it. [obviously not in the runners to the heads. ]
doing so may/will probably, involve good welding and fabrication skills, but the quizzical expressions of onlookers will definitely be worth it !

The stock intake for the magnum 5.2 is the "beer barrow" intake, and it doesn't leave much space on top of the motor for anything else.

The last I heard, Andy is looking into alternative intakes, so a possibility for an intake mounted oil fill may exist (you just need a space on the intake that is open to the valley between the heads, big enough for a fill tube, could be epoxied in place, maybe). If a guy went that direction, he could add a breather as the cap for the oil fill, and then you only need to plumb into the valve cover would be the PVC valve. A guy could weld a bung onto the cover at a location where a baffle could be added in the magnum cover and install the PVC in a hose between the cover and the hole in the cover with a baffle for the PVC. For that matter, if the poly cover fits tight to the top of the magnum cover, one could just cut a hole for the PVC into the top of the poly cover for the PVC to pass through it (It not like there will be an oil leak there in the poly cover, its just a bolt on imposter cover.

Would be fun at car shows to have the hood uo and have people asking how much power were you able to get out of that 273 Poly V8?

But then, anyone smart enough to know what a 273 Poly V8 looks like would probably pick up on the PCV and other "not quite right" visuals. Still would be different than the typical Magnum covers.

its almost always fun to listen to some guys tell other people what they think you have done to your old ride. You have to learn not to take any of their comments seriously. Most know it all guys have no clue, just nod and smile at their open stupidity. IIs wasted energy to point out their mistakes, they won't believe you anyway.

Kind of brings back a fun memory.
My GM buddy and I was at a big car show many years ago. He had installed a set of door poppers on his chopped and freshly painted S10. We were sitting a ways back, in the shade,but close enough we could hear and see people by our rides, and he was having fun popping the door open when ever he thought it might be amusing. This one teenage guy came by with his buddies and was standing there looking inside the S10, so my buddy hit the door popper. The kid thought his pecker was something special and had caused the door to open. When he walked away, my buddy jumped up and shut the door again. The guy came by with some more friends and he stood in front of the door and did a hula dance, facing the now closed truck door, so my buddy hit the popper and opened the door again. The kid was so proud!. He took off and gathered more friends to show off his talent, so while he was away, my buddy closed the door again. He came back with 3 or 4 more friends, and did his hula dance. This time, my buddy didn't open the door. The kid scratched his head, and did the hula dance again, this time with more movement, but my buddy didn't open the door. Now thew kid was putting great effort into his hula dance, with lots of hip movement, and thrusting himself much closer to the door with his tool. We were about dying laughing at this fool, so my buddy rewarded this huge effort on his part by popping the door open again. This kid entertained us for better then a 1/2 hour before he couldn't drag any more friends over to witness his moves. My buddy won a trophy (it was a really nice truck), but I kept telling him I think the hula dance kid stuffed the ballet box.

ya do know, that when your private "part" stands at "attention", something is REALLY good...............

The older I get, the better I understand that statement.

its almost always fun to listen to some guys tell other people what they think you have done to your old ride. You have to learn not to take any of their comments seriously. Most know it all guys have no clue, just nod and smile at their open stupidity. IIs wasted energy to point out their mistakes, they won't believe you anyway.

Yea it’s a hoot listening to the so call experts at car shows. Was at a show couple months ago and seen what looked like a survivor 69 Cornet. Walked up it and looked under the hood expecting to see a 318 or slant six. To my surprise there was a LS tucked in there. Two guys were standing there admiring the Hemi engine swap. I told them it’s not a Hemi it’s a LS. They told me I did know what I was talk about that is was intact a Hemi in there. I just shook my head and walked away.

HA! Y'know, I am in no way a trained mechanic. What I know, what I have done is by actually doing it and learning it, and a lot of non-tool work studying. One thing though, I know my vehicles deeply, even the ones I've not wrenched my way into and through them, and I am always open to learning more about them. So the claims of the unknowing are always humorous and entertaining, and most often best left to the ignorance of those unknowing.

I've been deeply involved in motorcycles for over 50 years, so most of these types of comments are two wheeled based. Like the claim "I was clocked doing 160 on my CBR600RR", ya sure, nope. A bone stock BMW S1000RR, 1000cc, making near 200hp at 14,000 rpm WILL do 185mph during the right conditions. That BMW makes about 50hp more than a CBR600RR, so the physics itself does not work as the aero drag of a CBR600RR and a BMW S1000RR are very similar, weight and tires are similar, rider exposure in the airstream, etc, etc. However, a rider here in WI does have some bragging rights as he was recently clocked by WI State Police in an airplane, while he was doing 175 mph on I43 north of Milwaukee. Bet that was an expensive claim.

the best way to learn things, is to screw something up, spend untold amounts of time and money to fix it, then not REPEAT the "learning experience".
that is why i'm so "smart" these days...........er, uh...... what did i do wrong THIS time ? ...............[i forgot......... ]