318LA Myth's still being created!

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If I remember correctly, early, till 67, polysphere 318's and 273's use the same forged crank.

I remember that some of the poly cranks has 8 bolt flanges like those in early hemis. You could still swap them into a 273 or 318, just needed the right flex plate.
 
I remember that some of the poly cranks has 8 bolt flanges like those in early hemis. You could still swap them into a 273 or 318, just needed the right flex plate.

Early (pre-62) 318 poly motors with the 8-bolt extended crank flange didn't use a flex plate. The torque converter bolted directly to the crank, with the bolts inserted from the front into the crank flange and then into the converter. Trans had a separate bellhousing and main trans body. So, to put it all together, you bolted the converter to the crank, then bolted the bellhousing to the engine block, then slid the trans into the bellhousing, making sure the input shaft went cleanly into the torque converter, then, once in, you bolted the trans to the bellhousing. And yes, I did all that when I rebuilt the Powerflite trans in my 56 Plymouth.

BTW, Dodge and Chrysler poly motors of the fifties were just early hemi motors with poly heads. But the Plymouth poly (which the 318 originally was) was an all new motor that ultimately developed into the 273-318-340-360 LA wedges. Same bore spacing, same cam to crank distance, timing chains and distributors are interchangeable between A and LA - all years. The 277 in my 56 Plymouth looks just like a 318 poly, but has smaller bore and shorter stroke. 57 was the first year for the 318. There were also the 303, 301, 313, and 326 (59 Dodges only) - all A motors.

Edit: Just to clarify (or confuse) - 55 Plymouths V8's had smaller cubic inch versions of the Dodge poly motor. So did low line 56 Plymouths except those with power pack (4 barrel carb, dual exhaust). And low line 57 DeSotos (i.e. Firesweeps) used the largest version of the Dodge poly motor (325).

56 277 poly

277 with Edelbrock.jpg


The back side of the pre-62 318 poly motors is different than the 62 and later, and the bellhousing bolt pattern is different. Cranks and automatic transmissions are not interchangeable between early and late. Neither are manual transmission bellhousings and flywheels (manual transmissions themselves may be may be with the correct bellhousing and flywheel, not sure). However, ALL Plymouth poly motors, early and late, in all the cubic inch versions, used forged cranks.

pre-62 318 poly rear of the block

318 poly rear view.JPG


62 and later 318 poly rear of the block - notice the lack of ribs in the back of the later block

65 318 poly block rear.jpg
 
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I don't know if it matters but from what I remember reading from the direct connection engine manual the forged 318 crank was always referred to as the truck crank and yes they were forged. I'm sure a few of them found their way into others vehicles My feeling is production 318s at various times got a truck short block or crankshaft as needed cranks were needed and extra truck cranks were available.I also remember reading that they where the strongest of all production crankshafts for the small block .
 
Well, while I agree with the sentiment, it's exactly what the OP did, and on a huge soap box. Love him or Hate him, Tony is a MoPar guy. Seems he's easy pickens though for everyone to rip into, which is funny, cuz I don't thing he gives a rats ***. Though when you come out of the gate claiming someone else is an idiot, well, you sort of get what's comin'....

-=C
Better to hear about [T
I don't know if it matters but from what I remember reading from the direct connection engine manual the forged 318 crank was always referred to as the truck crank and yes they were forged. I'm sure a few of them found their way into others vehicles My feeling is production 318s at various times got a truck short block or crankshaft as needed cranks were needed and extra truck cranks were available.I also remember reading that they where the strongest of all production crankshafts for the small block .

Makes sense
 
Look at all the cast crank strokers making well over 400 horse. Not an issue.
 
In reality the cast cranks are plenty strong, not really a concern.
I totally agree with this statement the only advantages were to a full race application where high compression pistons and maximum output was the theme. My reasoning for the forged 318 truck crank was 318 was the go to engine on every truck application available including military and government work and those trucks were asked to do tasks way beyond their rating or design tortured and punished rinse and repeat rinse is optional. and are legendary in their own rights. And to me there was the beauty of the legendary 318!
 
I totally agree with this statement the only advantages were to a full race application where high compression pistons and maximum output was the theme. My reasoning for the forged 318 truck crank was 318 was the go to engine on every truck application available including military and government work and those trucks were asked to do tasks way beyond their rating or design tortured and punished rinse and repeat rinse is optional. and are legendary in their own rights. And to me there was the beauty of the legendary 318!

Well said , I have a 77 886 Power Wagon ambulance which still has its original 318 with under 50,000 original miles its very heavy , cast iron tranfercase etc , and full time 4WD.
I installed a Isky RV/TOWING cam and vintage Offy dual port intake and it really woke it up.
You would have thought the 360 would have been mandatory in such a heavy vehicle but the old 318 gets the job done bottom-line.
 
Well said , I have a 77 886 Power Wagon ambulance which still has its original 318 with under 50,000 original miles its very heavy , cast iron tranfercase etc , and full time 4WD.
I installed a Isky RV/TOWING cam and vintage Offy dual port intake and it really woke it up.
You would have thought the 360 would have been mandatory in such a heavy vehicle but the old 318 gets the job done bottom-line.
They were a workhorse for sure.
 
I think you're probably just about dead on with perhaps the only exception being 318 truck cranks. They were similar I believe to the 400 cranks used in manual transmission trucks. Those were steel cranks right up until the 400's demise. I traded for a virgin 77 400 years ago that was a truck engine out from in front of an NP435 and it had a factory forged crank.
Yes, I should have explained in more detail about truck 318 cranks. I was mainly referring to heavy duty applications having the forged cranks. Most of the light duty and automatics have the cast cranks. As with all the models I mentioned, sometimes a forged crank was used when a cast crank was unavailable at the time the engine was being assembled. All the trucks I pulled apart that had a 435 or 445 transmission, had a forged crank. The trucks and vans that had the 833 were a mixed bag. Some had forged, some had cast. It may have also has something to do with whether they were a 1/2 ton or 3/4 ton. I didn't pay much attention to that at the time. As for big blocks and specifically the 400, the manual trans applications used a forged crank......basically a 383 forged crank. Just like the 440, Chrysler didn't have a weighted flywheel for the internally balanced BB cast cranks, so they used forged ones so they could use the flywheels they already had on the shelf. The cast cranks in most cases weren't even drilled for a manual trans input shaft, let alone finish machined to accept a bushing.
 
most cast stroker crank's do appear to be cast steel not cast iron though.
Huh? Cast or forged.Cast is poured in a mold. Forged Is pounded and pressed into shape with a forge. The base material is a ingot or billet if you will. Yes, one is iron and one is steel. Cast iron or forged steel. How to Pick a Crankshaft - Car Craft
 
I looked in my 1966 Plymouth parts book and the 273 and 318 Poly are the same crankshaft for that year. Probably sorted out by post #37.
As a replacement crank (2268119) for a manual transmission application, that's true....although I would still rebalance everything. For the automatic 273 with a 904, there is a different part number (2463551), and crank due to the difference in converter hole diameter. 273's in front of a 727, like what was in an A100 van, a police car, or taxi, would have the 318 crank. That doesn't matter on the manual trans applications since the outer diameter of the register hub is the same as 318 flywheels. (and others).
 
they seem to be listed as either cast steel or forged steel, so steel either way not iron. i double checked with 3 different suppliers websites before posting as i thought they were but hate posting without checking.
neil.
 
I also looked up 273 and 318 cranks in my 68 parts manual. New number for both, cast?
Yup, as I mentioned, they started the cast cranks that year for both the 273 and 318 unless there was some reason to use the forged one.
 
I'm always heard that 'mom's cast cranks were a decent piece of iron vs Ford and Chevy and seems like I'm always hearing about someone breaking cast in the 'other' brands but hear it happening in Mopars not so much.

In reality the cast cranks are plenty strong, not really a concern.

Correct , I bet cast cranks would live just fine behind 90 % of forum builds especially street motors where traction is non existent .
Polishing a crank is good but imo, polishing a cast cranks is highly recommended.....
 
When Chrysler came out with the 273 for 1964 they used the 'Off the shelf' parts of the Mid 1960's Poly-Teen. The massive forged steel crank was too heavy for the 273's small piston and the 'Bean Counters' would not let them lighten the forged cranks down to match the pistons. So, their answer was to put a MASSIVE wrist pin in the 273 piston to weight it the same as a 318 Poly piston.
Back when I built my 273 for my 1965 Dart GT 4 speed, I ordered some lighter pistons and lighter wrist pins. The crank was sent out to be balanced to the pistons weight and they took out almost 6 pounds and added 1 pound of Mallory metal.Back in 1975 it cost me big $$$ to balance that pig.
With the stock 9 inch clutch that 273 would go from 800 RPM to 7,000 RPM and back to 800 RPM like a KZ900.

The OP has edited most of the posts removing a lot of stuff. His unedited post was really harsh but the edited one seems calm and all posts after seem to be bashing him for no reason.....

Sorry but Uncle Tony seems to act like a Crack head tweeking. But over the years of reading his posts in Car Mag's, he usually gives straight information. I can only watch his channel if I adjust the playback speeds to 1 3/4 speed. Sorry UT.

Every 273 and 318 I have pulled apart, except my mom's 1978 Dippy 318, were Forged Cranks. Two 273's cranks came out of factory Auto cars that had never been tore down and they had 'Pilot Bushing' pressed in for manual shift trans.

And then there's the 360 Cranks made by Pontiac Motor Division with PMD stamped on them...... Myth or fact???
 
Ha ha, you are a funny guy!

I was in Flagstaff a few years back talking to a Jaguar mechanic in a bar about Mopars, he said “ I know jack **** about Mopar engines, and you guys know jack **** about Jaguars” true I replied.
I know a bit about Mopars and my brother does full restos on Jaguars....over and out
 
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