I have a garage find 66 fury III its 100% stock I have done a few things to spice it up like putting new wheels and cleaning up the poly 318 but as it runs great it is quite gutless so I'm on the fence on if I should swap a 360 in because it's pretty much bolt right in or should I go for big block I have a 383 from my grandpa's 72 roadrunner but seems like it would be a lot more work... Any advice
Engine swap should I go 360 or 383
- Thread starter bigfury3
- Start date
commando1
Old Man with a Hat
Welcome.
Slide the Fury under the crane and the SB will literally fall in.
Going with BB is gonna get your hands dirtier.
I vote a built and stroked SB to 400 inches.
Slide the Fury under the crane and the SB will literally fall in.
Going with BB is gonna get your hands dirtier.
I vote a built and stroked SB to 400 inches.
You can also opt for a mild build of the poly. Aftermarket 4BBL manifold, mild cam and a set of headers will get you to about 300hp.
Dave
Dave
Yea had also thought of that but the parts are so hard to find and anyone that has them near me thinks they are made of gold for what they are asking. That's why I figured a 360 would be a good build because of the ease of installing and parts being readily available, as I said I also have a 383 but would need to get a trans for it. That's why I'm on the fence not sure on what to do.
Considering the Poly's heritage, a 392-style Gen I "double rocker shaft" (i.e., early Hemi) might be an option, but would require a good bit of parts to make it work, I suspect.
A stroker LA 408 would be ideal, plus a slightly looser torque converter and otherwise beefed LA904. Nick has a video on a stroker 408 on the dyno, which is quite amazing, but we don't know what was in the engine. Still, it proves the capabilities of such an engine.
CBODY67
A stroker LA 408 would be ideal, plus a slightly looser torque converter and otherwise beefed LA904. Nick has a video on a stroker 408 on the dyno, which is quite amazing, but we don't know what was in the engine. Still, it proves the capabilities of such an engine.
CBODY67
Nice looking 66!
Both are great engines and have been used for years. If you’re looking for the easiest and can be worked on almost anywhere you go, I recommend going with a 360. The LA 360 would be a drop in as long as you get a weighted torque converter or if you’re trans and converter are good you can get a special flex plate. I would take it a step further and use the magnum 5.9 360. You would need some adapter motor mounts and an intake to use a 4 barrel carb but the magnum gives you lots of advantages like better heads, and roller camshaft. Plus you can find them all day in good running condition for cheap. They are designed for torque because they were designed for trucks so it will have no problem moving a big c body.
That being said it is hard to beat a good running 383 and would look more correct in your car. Your car being a 66 means you will have a rod not a cable shift so finding the big block 727 will be easy. You can find big block 727’s on MP for less than $500. As long as the trans behind the poly is a 727 it is an easy swap. The cross member, drive shaft, linkage and speedo hook up will all work.
If it were my car and I already had a known good 383 I would go that way. The up side is if you ever want to go to a 440 it would be an easy swap.
Both are great engines and have been used for years. If you’re looking for the easiest and can be worked on almost anywhere you go, I recommend going with a 360. The LA 360 would be a drop in as long as you get a weighted torque converter or if you’re trans and converter are good you can get a special flex plate. I would take it a step further and use the magnum 5.9 360. You would need some adapter motor mounts and an intake to use a 4 barrel carb but the magnum gives you lots of advantages like better heads, and roller camshaft. Plus you can find them all day in good running condition for cheap. They are designed for torque because they were designed for trucks so it will have no problem moving a big c body.
That being said it is hard to beat a good running 383 and would look more correct in your car. Your car being a 66 means you will have a rod not a cable shift so finding the big block 727 will be easy. You can find big block 727’s on MP for less than $500. As long as the trans behind the poly is a 727 it is an easy swap. The cross member, drive shaft, linkage and speedo hook up will all work.
If it were my car and I already had a known good 383 I would go that way. The up side is if you ever want to go to a 440 it would be an easy swap.
REGARDLESS of which engine you decide on, if the car does not have a (optional on 318 cars, std on 383s) front sway bar, GET ONE from the salvage yard. In reality, it should have been standard on 318 cars, but was not, usually.
Might need to upgrade the brakes with the heavier 383, too. Remember, too, that less weight and more torque make for faster acceleration. Which makes the 408 stroker motor very attractive. Price it both ways.
Enjoy!
CBODY67
Might need to upgrade the brakes with the heavier 383, too. Remember, too, that less weight and more torque make for faster acceleration. Which makes the 408 stroker motor very attractive. Price it both ways.
Enjoy!
CBODY67
Timmayy
Member
I had the same dilemma with my 65 Belvedere wagon. 273 ran great but didn't have any get up and go. I went with a 360 and glad I did. Added an 8 3/4 SG with 3.23s. Much easier than doing a full big block conversion. I drive it everywhere.
cbarge
World Famous Barge in a Budget
Go 360.
Lighter in wieght, can make the same or more power as a big block for less money.
Even if you get a later 5.9L Magnum engine and convert it to carburetor you stil gain over the Poly.
MAke sure you use a B&M flex plate as 360's are externally balanced.
That way you can use any torque convertor of your choice in a 727.
Lighter in wieght, can make the same or more power as a big block for less money.
Even if you get a later 5.9L Magnum engine and convert it to carburetor you stil gain over the Poly.
MAke sure you use a B&M flex plate as 360's are externally balanced.
That way you can use any torque convertor of your choice in a 727.
57fury440
Well-Known Member
Poly 318s can be made to run well. How fast are you looking to make it. A good intake and carb, along with a good cam and lifters will wake that motor up. Put in a good set of gears and it will perform like a different car. Even if the parts cost a little more it will still be less than a complete engine swap. Back in 1964 when I got my car it had the 290 HP poly in it. It had the two four barrels on it. I added an Isky cam, Hedman headers and 3:91 gears and it ran great.
Ripinator
Old Man with a Hat
I'm all in for the Poly. Although the 360 and 383 engines are great, they are rather pedestrian when compared to the Poly. With very little effort and a 3.23 gear, you can make that Poly run like a raped ape. Here is some food for thought: “Chrysler Poly Performance”, Illustrated
I don’t know about 1966, but 1968, a Plymouth fury with a 318 used the same torsion bars as a 440 car. My 1968 Plymouth sport Fury with a 520 drives and handles fine without a front sway bar. A 1966 parts book should be consulted to see what torsion bar was used with a 318. For what it’s worth, at one time I had a 1968 Plymouth sport fury with a 383, which had the front sway bar and in terms of ride and handling I did not notice much difference between the two cars.
IMHO, of the 360/383 options, I'd go with the 360. The 360 will be lighter, make the same power and be easier to swap in. I'd also look at some of those stroked 318 crate engines.
If it was my car, I'd look seriously at keeping and building the poly. Open the hood of about any old Mopar and 99 out of 100 times, it's got some form of small or big block. That poly is different.... and has a ton of potential.
Just my 8 bucks (2 cents adjusted for inflation).
If it was my car, I'd look seriously at keeping and building the poly. Open the hood of about any old Mopar and 99 out of 100 times, it's got some form of small or big block. That poly is different.... and has a ton of potential.
Just my 8 bucks (2 cents adjusted for inflation).
Thanks for the advice I would build the poly as it runs great but the issue is finding parts they're not really out there and when you do find them the are very overpriced. But from the feedback I'm getting I might go for the 360 and save my 383 for later if I want to go that route
In our current world of 1000 horsepower HellCats with factory a/c and a factory warranty, 230 gross-rated horsepower seems more like a lawn tractor engine, by comparison. Yet when the 1966s were new, about 500 real dyno horsepower meant factory a/c was not available (especially with the RV-2 compressor) for many reasons.
Although the Poly 318s could have had a factory "power pack" 4bbl and dual exhausts in 1958, by the middle 1960s, with the larger 383s and RB motors as "power options", the Poly motor was relegated to normal "drive around car" status. With a small 2bbl carb, too. Yet it was also the first engine in the Travco motor homes (with truck-style rear axle ratios and such).
When I saw my first 301 (Plymouth) V-8 block at a machine shop, I was amazed at how much stronger it was in the main web area than the beloved small block Chevy V-8! But with its heritage including the Gen I Hemi motors, not a real surprise.
Camshafts, back then, were more like "bumps on a log", compared to modern engines. Similar with exhaust manifolding. We've learned a lot since back then! At this point in time, cam choices can be more limited than for a later LA motor, though. Same with better exh manifolds, too.
I'm not sure if a later LA cam will work in a Poly A motor, considering the architecture similarities. Even with the stock exh manifolds, a good 2.25" dual exhaust system with Street Hemi mufflers (or thereabouts) can help that side of things. Add a 4bbl intake with a 600cfm-style AVS2 and that could help things a bit on the total rpm spectrum, even with the stock cam. Then a one-notch-looser torque converter, similar to the old '68 Road Runner converter, for "the icing". The car should already have a 2.93 rear axle ratio. Might head over to the Hot Heads website?
Front sway bar? In 1968, CAR LIFE magazine did a comparison test of "standard V-8 full-size 4dr sedans", which included a Fury III 318 2bbl car. As was their practice back then, they did a full-on shot of the cars in a corner at the same speeds. That Furi III was leaning in the corner and the front wheels were leaning, too. NOT what I wanted to see, but they also mentioned it was the ONLY car without a factory front sway bar in the group. That's when I discovered the 318 cars didn't have one, but the B/RB cars did, as standard equipment. Compared to the later 1969 tests of B and RB C-bodies, that '68 Fury III looked more like a '54 car than a 1968 car, to me. Many might not notice the difference in their normal driving patterns where ultimate handling is not a consideration.
If you look at modern engines of the past 10 years or so, you'll discover that a bore size of about 4" is where most of them are, with the CID increases being related to "stroke" dimensions. Something about the speed of the flame front being more efficient with the 4" bore sizes. Guess where the Poly and LA motors are. Which, once again, meaning power production is "in the heads, intake, and exhaust systems". Having valves which open away from the cyl bore walls is better, too! Guess where the Poly or "single rocker shaft" motors are?
MANY things to recommend a Poly 318 over the LA 318, just that those advantages were over-shadowed as they were not fully understood back than and the bigger B/RB motors were where all of the emphasis was. By that time, production costs were also a consideration!
Path of least resistance? Carb, intake, exhaust system. Cam? Aim for something close to the LA340 cam. Then do the one-notch-looser torque converter if desired. You might be surprised.
Just some thoughts,
CBODY67
Although the Poly 318s could have had a factory "power pack" 4bbl and dual exhausts in 1958, by the middle 1960s, with the larger 383s and RB motors as "power options", the Poly motor was relegated to normal "drive around car" status. With a small 2bbl carb, too. Yet it was also the first engine in the Travco motor homes (with truck-style rear axle ratios and such).
When I saw my first 301 (Plymouth) V-8 block at a machine shop, I was amazed at how much stronger it was in the main web area than the beloved small block Chevy V-8! But with its heritage including the Gen I Hemi motors, not a real surprise.
Camshafts, back then, were more like "bumps on a log", compared to modern engines. Similar with exhaust manifolding. We've learned a lot since back then! At this point in time, cam choices can be more limited than for a later LA motor, though. Same with better exh manifolds, too.
I'm not sure if a later LA cam will work in a Poly A motor, considering the architecture similarities. Even with the stock exh manifolds, a good 2.25" dual exhaust system with Street Hemi mufflers (or thereabouts) can help that side of things. Add a 4bbl intake with a 600cfm-style AVS2 and that could help things a bit on the total rpm spectrum, even with the stock cam. Then a one-notch-looser torque converter, similar to the old '68 Road Runner converter, for "the icing". The car should already have a 2.93 rear axle ratio. Might head over to the Hot Heads website?
Front sway bar? In 1968, CAR LIFE magazine did a comparison test of "standard V-8 full-size 4dr sedans", which included a Fury III 318 2bbl car. As was their practice back then, they did a full-on shot of the cars in a corner at the same speeds. That Furi III was leaning in the corner and the front wheels were leaning, too. NOT what I wanted to see, but they also mentioned it was the ONLY car without a factory front sway bar in the group. That's when I discovered the 318 cars didn't have one, but the B/RB cars did, as standard equipment. Compared to the later 1969 tests of B and RB C-bodies, that '68 Fury III looked more like a '54 car than a 1968 car, to me. Many might not notice the difference in their normal driving patterns where ultimate handling is not a consideration.
If you look at modern engines of the past 10 years or so, you'll discover that a bore size of about 4" is where most of them are, with the CID increases being related to "stroke" dimensions. Something about the speed of the flame front being more efficient with the 4" bore sizes. Guess where the Poly and LA motors are. Which, once again, meaning power production is "in the heads, intake, and exhaust systems". Having valves which open away from the cyl bore walls is better, too! Guess where the Poly or "single rocker shaft" motors are?
MANY things to recommend a Poly 318 over the LA 318, just that those advantages were over-shadowed as they were not fully understood back than and the bigger B/RB motors were where all of the emphasis was. By that time, production costs were also a consideration!
Path of least resistance? Carb, intake, exhaust system. Cam? Aim for something close to the LA340 cam. Then do the one-notch-looser torque converter if desired. You might be surprised.
Just some thoughts,
CBODY67
66Phury
New Member
Great looking ride!!! I dropped a modified '68 318 in my '66 Sport Fury Convertible and have had no complaints. Easy drop-in, bolt-up conversion. I won't win any races but its a fun drive, plenty of get-up and go.
I understand completely. Some guys think this stuff is made of gold.
Just for the sake of discussion with anyone else contemplating swapping, here is a decent list of interchangeable parts with the LA and the Poly. Poly 318 Polyspherical Parts Interchange - Poly318.com
I would keep the Poly
Similar threads
