Technical The forbidden mid 50’s mopar poly’s

O/k.......stock style front end with 41-56 upper A arms, 55 Ford coils, narrowed 9" Austin 1800 rack & pinion, 42-56 stub axles with Oz 11" vented discs, 1" adjustable link heim jointed sway bar, Valiant upper steering column on alloy tube lower column, Oz 1992 Ford Falcon wagon rear axle & discs, Oz Leyland P76 front seats, stock rear seat, rear fenders widened 2 inches, Oz Chrysler Mahogany Metallic lacquer painted in 1978, engine oil cooler and remote filter, 16" front mounted fan,.........etc.............andyd

 

There's quite a few sizes of Polys, the point was the two 301s Polys are different engines.

 

@George.......my comment was not a criticism.....only a clarification for others who have indicated their interest in learning more about Polys.......

I knew about the 301 ‘55 Chrysler Poly, had one in my ‘55 Windsor, and I knew about the 2nd gen 301 Plymouth .......but even having been a fan and owner for decades of several MOPAR variants......somehow my pea-brain failed to notice/connect the duplication of displacement of the two different engines. I even mentioned the 277/301 in an earlier post ...............can senility be catching up with me sooner than I’d hoped?

Ray

 

What he's been saying along with some others.....Mopar was trying a lot of combinations from about 1953 to 1959......let's not get started on the late 50's RB-383's.......

 

This is a little off the subject, but lately, in the morning, they have been re-running old episodes of "Highway Patrol" with Broderick Crawford. Lately, there have been a lot of '58 Dodge 2 door post cars. From what I can see, they are sticks. What engine would they have? 361? I know they used real CHP cars on the show, because if you look closely at the 2 door post '56 Buicks they use, they have the "Century" script on them. They were the only Century post cars made.

 

@tubman

IIRC, in late 1957 or 1958 Hot Rod Magazine did a feature article on the CHP testing procedures for selecting their patrol cars. The Dodge was the winner in the competition for the contract. I do not know what month that was featured, but if anyone has a set of HRM issues from that period they can answer the question.

Regular production ‘58 Dodge’s were offered with the B series 350. Possibly the 361 as you suggest, but I don’t remember. I will check other references and see if I can find anything pertinent.

Ray

 

Thanks, Ray. Boy, I would like to find one of those, especially if they were sticks! Plus, I'd like a '55 Century (sorry for the earlier mistake) post car. I bet they had the 6-bolt cover GM selector transmission behind the 322 nailhead. Not the fastest shifting, but plenty strong.

Is my taste in cars getting weird as I age?

 

If so, then we are in the same boat, with one difference.....mine has always been
weird (though I prefer “eclectic”).

 

@tubman

Denny, check this out. Copied from The Standard Catalog of American Cars........



Doesn’t say what the CHP bought, but there obviously were some Hi-Perf 361 choices available.

Ray

 

I'm brand new to this thread and just discovering the vast amount of chatter on the Hemi/Poly subject.
I'm running a 315 Poly turned 325 Hemi. 35K miles as of 2020. Big surprise on assembly was my Poly block would not accommodate the Hemi push rods,....I'll explain if anyone is interested.
Regarding the low deck 241/270 Hemi/Poly comment. I am converting a 270 Poly into a Hemi because the Poly heads were junk. And as previously mentioned, most Hemi stuff can be accommodated on the Poly except the exhaust manifolds. Further what I have learned is, a Hemi cam can be reground for a Poly,...and vise versa. You may want to have the long snout made short at the same time and is a requirement if you plan on the Chevy water pump modification. Replacement pistons, like from Egge, have valve reliefs for the Hemi configuration 'tho they sell them for Poly replacements and they work as long as you don't get aggressive with "valve lift". Intake manifolds, same for either, are out there but used.
Two good sources of parts and info are www.qualityengineeredcomponents.com and hothemiheads.com.
Good luck!

 

I think most of us didn't pay attention to Post #6. Scroll back and see how the poster was enjoying the best of both worlds.

 

No, I didn’t catch that.

Some trivia: when Mopar got back into NASCAR racing a few years ago, their engine was basically a 354 Poly.

 

That's my garage floor soon........have I think 3 - 241 Red Rams one fresh rebuild but cracked block - 1 good - 241 truck motor - 1 -good 270 block and one "spent" 315 D-500 motor....

 

Back in HS there were a few 57 Chebbies that wish they didn’t pick on 57 Dodges. Even with a 318 single 4barrel automatic they were faster/quicker than many gave them credit.
I always thought they were a good looking engine especially with 2-4’s..

 

The Polys were excellent engines, superior in many ways to competitive makes. In road tests done on new cars in the fifties the Poly would run with a hemi of the same size right up to 80 MPH, then the deep breathing hemi pulled ahead.

So why were they so seldom hopped up or used in hot rods? It is because they were always overshadowed by the big brother hemi which did have a performance advantage at higher RPMs especially when souped up. Later the 318 poly was overshadowed by the bigger B and RB motors which were nearly the same overall size and weight but larger displacement, meaning you could have a 383 or 413 in your Plymouth just as easily as a 318.

Why did they even make the poly? Chrysler started out with a line of hemi V8s for Chrysler, DeSoto and Dodge in their premium models and kept the old flathead six for the economy minded. Later they made the poly which was basically a hemi block with simpler, lighter heads to cut costs for the base models. Their idea was to drop the sixes and make all V8s, which they did, except for the cheapest Plymouth and Dodge models.

The only high perf Poly was in the 1956 - 57 - 58 Plymouth Fury and that was only because they did not have a hemi or B motor at the time. They made a 290 HP 318 that would beat any comparable Ford or Chev to a frazzle. But after 1958 no more performance poly, they had the B and RB motors, the poly 318 was relegated to workhorse duty, after 1962 you couldn't even get a 4 barrel on it.

In recent years a few guys have built up polys for the hell of it and been impressed by the performance potential. They have room for bigger valves than a conventional wedge head, and the widely separated valves cool better. The 318 has advantages over competitive makes like larger diameter lifters allowing hotter cams, better rod angularity, strong forged crankshafts etc etc.

 

When I was in high school in 66 my good friends dad sent a message to the school and told him after school to walk over to the Chrysler - Plymouth dealer after school.
Remember a call to the school and a note ,not a cell phone call or text ? Remember walking and not getting picked up at the door ?
He told me what was going on and I walked with him. He got there and was really pissed when he found out his dad had bought a 56 Plymouth for him to drive , he wanted a tri-5 Chevy. The Plymouth was a white with gold trim 2 door hardtop with a V-8 4 barrel automatic.
We didn't know much about the Plymouth and that was a special package . He figured if he would kill it then he could get his sought after tri5 chevy. He wailed on that poor car and was still driving it when he graduated in 67. That car took more abuse than any car I had seen for a long time.

 

That sounds like a 56 Fury. If so it would trim any stock tri 5 Chevy made, with the possible exception of the super rare fuel injection model, and then it would be close. The poor dope had no idea what he had.

 

Looking at old motors manual they don't break down hemis and polys but a 54 dodge 241 was 150 hp as a hemi and a 55 Plymouth 241 was 157 hp as a poly. Both had the same compression ratio rated at the same RPM

 

"Back in HS there were a few 57 Chebbies that wish they didn’t pick on 57 Dodges."

J.D. – You guys all had brand new cars?

 

The first car I rode that impressed me was a 55 Plymouth that had a 341 Desoto hemi swapped in that dads summer farm help had. It was in 1958.

 

I was reading a recent article in HRM about the Christine '58 Plymouth Fury, and it has a dual quad "Golden Commando" or something along that line. Just curious as to how it relates to the rest of the Poly line.

 

the golden commando was the first "B" engine for Chrysler. A low deck big block, later versions was the 361, 383 and 400. It was not a poly head design.

 

In 58 there were 2 dual 4 motors a 290hp 318 and a 305 hp 350 b block.

 

58 was the last year the 290HP 318 was available. It was called the V 800. The same year the first B engine came out, the Golden Commando was a 350 cu in 305HP with 2 4s used in the Fury. The 350 was a one year only version of the new B or big block engine. It was the smallest version made, soon replaced by the 361.

Christine was a 1957 Fury with the V 800, 318 motor with 2 4s.

 

I got mine about ready to drop back in my car, 315 4 barrel poly in a 56 royal

 

If anyone here is interested, a friend of mine is selling a hopped up Poly 318

 

That is beautiful, great to see the early Polys.

 

IMHO the poly is the prettiest engine ever.

 

When I dragged home my 1964 Dodge D-300 in 1987 it had a 318 poly and the first thing everyone said was to just rip out that junk and install a later LA motor.

A compression test showed a good motor. Tuned it up, rebuild the carter BBD and it was hands down the best running 318 I ever had.

4:88 gears and a NP420 this truck would pull hard all the way to 55 mph and that was 4000 rpm’s.

Connecticut to Florida and back, I did that trip 4 times pulling my car trailer and it was a flawless running motor.

That’s it in the back in Florida around 1989 or so.

Cliff Ramsdell

 

Oh, don't forget the DeSoto engines. I so wish Chrysler would have produced a small block and a big block. It might still be producing Hemis if it hadn't built a gillion "different" power plants.