School me on the differences between a 318 Wide Block and a Regular 318

Trade ya motors! I have a 360 I'd trade for a running 318 Poly. Seriously.

I have a '66 Fury convertible (same body style as your '65), with an empty engine bay. And I like the Polys. A LOT. Yours is more than welcome under my hood.

Use 273 mounts to put an LA 318 in there, by the way (in answer to your question about putting an LA 318 in).

Why the swap? Other than the heads and valve train, the rest of your 318 Poly is already an LA (the bottom ends are pretty much the same)..

Also, I'd love to have this Fury convertible out of my driveway. I'll make you a HELL of a deal... PM me. You could combine this 'vert and your car and have one smokin' ride...

~Jason

 

ya lost me!!! really!

 

Sorry - I had a lot going on at the time I wrote that, and actuallky stepped away a few times. It didn't help me much for continuity.

I was saying to use 273 mounts to put a 318 in there, and asking out of sheer curiosity about why you were doing the swap. I was also offering to trade you a 360 for that running poly.

Additionally, I was trying to pawn off a car identical to yours, save for color and body (it's a convertible). I traded for it - good car, but bad trade. I hate looking at it in my driveway, and would love to trade/sell it off. I had also mentioned that if you combined your '65 and this '66 you could have one hell of a ride.

~Jason

 

Hello all
I have a wooden boat with a 318 poly, the boat is from late 50' but the poly engine is from 65, when I get the boat, the block was frozen as well as the heads, I decided to found a new engine, and I get a 318 poly from 1958, but the marine transmission will not bolt on...rear of the block is different, my question is , Should I take a 318 LA block and use it as a short block and install the poly heads from 1958? is it possible? as I have all the marine exhaust manifold for it...I would like to keep the poly heads

Thank you for your help

First image is the boat engine, second one is the engine I get

 

The '62 - '66 318 Poly has the same back on the motor as a regular old LA 318, but the '57 - '61 incarnation has the same back on the motor as an early Hemi (and you have to use an Early Hemi transmission adapter to bolt it to later transmissions).

Although it CAN technically be done, I wouldn't advise putting A 318 heads onto an LA block. The amount of work makes it easier to tell people that it's impossible to do, although I'll admit it's possible. Just not for normal people - only crazy Australians, or Dolmetsch.

You're better off finding a replacement '62 - '66 318 Poly, or knocking those slugs out of the block you have, and having a machine shop take a look-see to determine rebuildability.

~Jason

 

Above is a 1955-58 Dodge-based poly motor, using just 2 bolts and having scallops across the lower edge


Above is a 1955-58 Chrysler based Poly Motor, using 3 bolts and having scollops across the lower edge.


The above is 1956-66 "A" Poly motor valve cover, using 3 bolts and having Z-shapped lower edge. (Note, I have seen some of these in cast aluminum with just the two end bolt holes, but the "A" engines have 3 rocker arm mount with the provision to mount a cover stud.)

Now as I understand it, the 1955-58 Dodge-based poly motors used Dodge Hemi blocks and cranks, and the 1955-58 Chrysler-based Poly Motors used Chrysler Hemi blocks and cranks.

The 1956-66 "A" Poly Motors did not use Hemi blocks or cranks, but was based on a new block design.

Have I got this correct? If not, please advise.

 

You can go crazy trying to figure out the welter of engines and transmissions Chrysler used in the fifties and sixties but basically you are right.

The lineup was something like this -

Chrysler Firepower hemi 1951 - 58. Made as a 331, 354 and 392
Chrysler Spitfire polysphere 1954 - 58 301, 331, 354. Basically the hemi engine with different heads

DeSoto Firedome hemi, 1952 - 58. 276, 291, 330, 325, 321. No Poly version

Dodge Red Ram hemi 1953 - 1958. 241, 270, 315, 325.
Dodge polysphere hemi block with poly heads. They made a 326 in 1959 that may have been the only Dodge poly with no hemi counterpart.

Plymouth poly 1956- 66 - no hemi version. 277, 303, 313, 318.

Redesigned into the LA 273, 318, 340, 360 that used basically the same block design with different heads.

Plymouth also used a version of the Dodge poly in cars and trucks, 241, 259, 270 in 55 and 56.

In Canada they made a 303 version of the Plymouth poly that was used in Canadian Dodge and Chrysler cars in 1956. Plymouth US "borrowed" it for the 1956 Fury only.

Some Dodge D-500 used Chrysler 354 hemis "special order" racing models. Dodge used the Plymouth poly 318 as their base V8 1960 - up.

My head is starting to hurt so will stop now. I'm pretty sure there are exceptions, but that is the basic lineup.

 

The '55 Chr 301 Poly is a hemi based Poly, & the '57 Plym 301 is an "A" Poly ( you forgot that one!). The '59 Dodge 326 is a one year only "A" Poly, not a hemi based Poly. The 325 DeSoto Poly was a Dodge hemi based Poly like the early Plym Polys

 

You are correct, they did make a 301 Plym poly in 1957 only. Different from the 303 and different from the Chrysler 301 poly. I told you you could go nuts trying to figure out what they were up to.

 

.....and Chrysler, Desoto, and Dodge hemis each had their own unique bore spacing; so each had unique blocks, cranks, heads, cams, etc.. And they each had blocks with two different deck heights...... And some engines had water in the intake manifolds, others had water outlets in the front of the heads,...... And low-deck Chrysler engines (331 & 354) were used in big Dodge trucks with wet intakes but unique heads with larger cross-over heat ports and sodium valves....... And yeah that 1957 Desoto Firesweep had a 325 Polysphere based on a Dodge Hemi engine but the intake manifold sealed the lifter area....... And now, after about 60 years of guys messing with them, Lord only knows what you might find inside when you take an old Early Hemi or Polymotor apart!

 

[QUOTE="walt460, post: 11066307, member: 267699 And yeah that 1957 Desoto Firesweep had a 325 Polysphere based on a Dodge Hemi engine but the intake manifold sealed the lifter area....... [/QUOTE]No, only on the "A" Polys do the intake seals the valley.

 

Easy to find headers for them, you get flanges and J bends and carry your sorry *** down to the ******s place for a day and some cheese burgers. LOL

Hey what did you ever do with that A you were working on? I know its been at least two floods ago but what ever happened to it?

Other go fast goodies, I think that offy is reproducing some of the old intakes for them and cam shafts can be had if you look around a little bit. if nothing can be found the original can be reground.

 

No, only on the "A" Polys do the intake seals the valley.[/QUOTE]

George, yeah, that is what I thought as well, but in a field in NE PA 2 weeks ago I saw a 1957 Firesweep, 2-door hardtop with push-****on trans, and under the hood was what looked to be a 2V Dodge Polymotor by the valve covers. Except, there did not appear to be a valley cover, the intake manifold was covering that area and there was iron casing between the cylunder runners. There was no oil-fill tube in that area either. It was raining, but we checked the motor pretty well, it was covered in leaves and animal housing, we even tried to turn it over with some hand tools, but we could not get it to move. It started to rain pretty hard, so we left. I will be back there in October and plan to re-visit that Firesweep with more tools and camera before it snows. (I was thinking that we could take the heads off our old 241 Red Ram and make a nice 325 Dodge Hemi!) The owner of the property promised not to junk the Firesweep until we could return.

 

George, yeah, that is what I thought as well, but in a field in NE PA 2 weeks ago I saw a 1957 Firesweep, 2-door hardtop with push-****on trans, and under the hood was what looked to be a 2V Dodge Polymotor by the valve covers. Except, there did not appear to be a valley cover, the intake manifold was covering that area and there was iron casing between the cylunder runners. There was no oil-fill tube in that area either. It was raining, but we checked the motor pretty well, it was covered in leaves and animal housing, we even tried to turn it over with some hand tools, but we could not get it to move. It started to rain pretty hard, so we left. I will be back there in October and plan to re-visit that Firesweep with more tools and camera before it snows. (I was thinking that we could take the heads off our old 241 Red Ram and make a nice 325 Dodge Hemi!) The owner of the property promised not to junk the Firesweep until we could return.[/QUOTE] logic says a pre-62 A Poly was swapped in, ***uming it has the OEM ****** in it. Or possibly a special order, you never know with Ma Mopar!

 

My brother has a 57 Dodge Custom Royal Lancer with a 325 Poly Red Ram 4 barrel, 260 HP.A 4 door sedan with 1st series torqueflite.It's been sitting about 8 years now, which aggravates me.

 

George,
You may be correct. I will take and post pics in October.

 

Well, was in PA in October but did not think to go visit that 1957 Firesweep in the field, but I am back in PA for Christmas and the plan is to go today, raining, and take some pics and get a closer look at the polymotor in that car!
Pics to be posted later today, I hope.

Walt

 

OK, I do stand corrected as the 1957 Firesweep in the field in SE PA does have a valley cover with an open runner intake. So likely this is the stock 1957 325 (Hemi block) Polymotor. Engine has 2-bolt valve covers. Hope the pics post OK.


No carb or distb, but the car has a 1958 PA plate with a 1964 tag and only 38K on ODO, was parked because of collision damage, so base motor might be fine inside if it would have any value. We have a Dodge truck red ram hemi engine, may use the Firesweep's shortblock and put them Dodge Hemi heads on it?

Walt

 

If it's been sitting like it's pictured, it won't be "fine inside" !

 

actually, engine was covered and hood was down, owner claims they pored oil down intake and had been cranking it over with a flex handle on crank a couple times a year until last few years. We fetched some tools and pored Marvel Mystery oil into intake, rocked crank a few times and it turned over so engine is not frozen.

 

change pistons, complete head ***ymbly, push rods, & you got a hemi.

 

I am preatty sure your heads wont fit.
They change the blocks in 56 and made them bigger.

 

They raised the block, but Dodge heads fit all years Dodge hemi blocks

 

George, if they raised the block, then when we put the hemi heads on we will need an intake manifold for a 56 or later Dodge Hemi? Is there such a thing?

 

Yup, a 315/325 intake, can be Hemi or Poly, they are the same.

 

George, Thanks!

 

There's a new intake available that's suppose to outflow any other intake for a wide 318. Chrysler Power Magazine has been dialing in on this for a while. It aint cheap, but it aint old.

 

To get back to the original question of A vs LA 318.... if anybody still cares

This engine family debuted in 1956 Plymouth as a 277 cu in. Quickly grew to 318 cu in. This is the original "wide block" polysphere head engine known as the A engine.

Max hi perf version, the 290HP with 2-4 barrels seen in Christine, 1957 and 1958 only. After that the B and RB big block took over Hi perf duties.

The 318 continued as the base V8 in Plymouth and Dodge, 2 barrel 230HP with a seldom seen 4 barrel option, available only up to 1962.

In 1962 they redesigned the crankshaft's flywheel flange to use cap screws that thread into the crankshaft flange instead of nuts and bolts. This allowed them to shorten the crank, and they had to redesign the back of the block too. This becomes important as engines and transmissions will not interchange. There are 2 separate families, before/after 1962.

Then in 1965 they came out with the new 273 V8 for Barracuda, Valiant and Dart. It was actually a redesigned 318. They couldn't squeeze the 'wide block' Poly into the compact engine compartment. So they changed the heads to conventional wedge type with the valves all in a row. They put the new heads on the old 318 block, and reduced the bore by .285". They made the wrist pins thicker and heavier, so the smaller piston would weigh the same as the 318 piston, and used the 318 crankshaft and rods.

In addition to new heads, intake manifold, exhaust manifolds, and pistons they had to change the cam because the valves were in a different order. They also made the engine with solid lifters and cam to match, and adjustable rocker arms. They kept the wide block 318 for larger cars for one more year.

The 273 engine was revamped into the 318 LA with hydraulics, and became the base V8 for all cars starting in 1966 (1967 in Canada).

In 1968 they bored this engine out to 340 cu in and hopped it up to get the hi perf 340. The reason for this was that the B and RB engines would not fit into the A body Barracuda, Valiant and Dart and they needed a high perf small block to compete against the Chev 350.

I know they did squeeze a few 383s into A body cars but they were a tight squeeze and only a few were hand made.

Eventually the Cuda and Challenger were redesigned on a bigger ch***is to take the B and RB engines.

Final version was the 360. This was a low perf version of the 340 aimed at being a good reliable high torque engine for heavier full size cars. They took the 340, gave it a smaller bore and longer stroke for emissions reasons, put slightly smaller exhaust valves in the heads, and generally tuned it for a workhorse engine in big cars and trucks. But they also made a performance version.

Well that is about it until you get into the Magnum redesign of the 90s which is a little new for this board.

 

I'm currently in the process of adding a small magnusen supercharger to my 65' poly 318 by using an unmodified Edelbrock P600 3-deuce manifold with adapter to mount it. Under boost, the advantage offered by a dual plane manifold is almost nothing but when not under boost should make for a more streetable conversion. The only other dual plane poly 318 manifold is the new one from Chrysler Power but it is much taller than the P-600. I would like to see the P-600 in a head to head (true) comparison to the Chrysler Power Unit. Until now, there has been no other manifold that came close to the performance offered by the P-600.

- EM

 

This is why Im not a mopar guy. Ive got a head ache already just identifying the motor.lol. I will say My 1982 dodge van with a 318 motor runs great but man what a leaker. leaks everywhere. I call it the general leaker.lol, But a great runner, just keep the fluids in her.