The "Throw Away 318"

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Bret Tschacher said:
My first real hot rod was a 318 powered E body and I can assure you that I had many times I had to work hard to stay out of fights on account of being called a liar when either I or my younger brother raced it in street races out in south San J valley Calif. We had built quite a reputation in and around Bakersfield with that 70 Barracuda and that 318, it wasn't even bored over and I used the factory cast pistons in the rebuild. I was luck enough to get an engine that had been assembled from the factory with the heavier 360 forged rods with less than 35k miles on it from 72 to 78 when I got it. I wish I had never traded it off. Personally if it came to making a choice it would be real hard for me to decide on another 18 or 60. The one thing that would seal the deal is a forged crank for the 318. Now I could opt for a welded stroker steel crank in a 360 block. I truly love the way those 318 spin compared to a longer stroked motor.
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True about the crank strokes. The short strokes(273, 318 and 340)(stock) are better for street performance, while the longer 360 should give you a better top end and a better working motor, is why I believe they came in trucks and vans first.
 
I think you meant better low end. big swing cranks dont normally rev high.
 
Bret Tschacher said:
My first real hot rod was a 318 powered E body and I can assure you that I had many times I had to work hard to stay out of fights on account of being called a liar when either I or my younger brother raced it in street races out in south San J valley Calif. We had built quite a reputation in and around Bakersfield with that 70 Barracuda and that 318, it wasn't even bored over and I used the factory cast pistons in the rebuild. I was luck enough to get an engine that had been assembled from the factory with the heavier 360 forged rods with less than 35k miles on it from 72 to 78 when I got it. I wish I had never traded it off. Personally if it came to making a choice it would be real hard for me to decide on another 18 or 60. The one thing that would seal the deal is a forged crank for the 318. Now I could opt for a welded stroker steel crank in a 360 block. I truly love the way those 318 spin compared to a longer stroked motor.
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I don't doubt the early 318s were pretty stout. I also seem to recall there was an early truck version with forged crank. Its the 70s ones that are most remembered, the smogger engines, which I think the 360 was a major smogger motor. It stands to reason an early 318 may perform just as well or better than a smogger 360.
 
I have a virgin '68 318 that will get used hopefully some day in something? Guess I can figure out then what's what! with the early teeners. Yes I have seen truck teeners with steel cranks. Aren't poly 318 steel crank and interchangable with the LA?
 
Many teens ended up with forged cranks. 318-3 truck motor is a common forged teen. Poly is a drop in but your better off finding a 273 forged crank. When's the last time you saw a poly crank for sale?
Both the 318 and the smogger 360 had pitiful compression ratios, first thing they did to to reduce NOx along with EGR. Flat top a 360 or dome a 318 (KB399 piston) and they are back up again on power.
 
I want your little virgin ! So here's the deal with old verses newer. I left the world of SB's in the mid 80's and grew my inches to 440. The 68 engines used the same rods they put in the 273's which are good, nothing wrong here. Sometime around late 71 or early 72 the rods in the 18ers grew some muscle so for those of you that are familiar with LY rods in 440s and 6 pack rods, it's about the same thing comparing the 2 SB rods. I had the big boy SB's and I've had LY's, 6 packs and hemi rods. My last build of a 440 I was working a set of hemi rods over to fit in the W. The early 18ers had higher compression then the late 71 up builds. I eventually wound up with an older 18er after I had already assembled my later 18er. If I had been more am motivated, I would have taken the build back down and started over to use the higher CR pistons from the older block with the later rods. This would have entailed a lot more work rebalancing everything which would not have settled with Grandpa since he was helping with most of the machine work at that time. I could've managed on my own, but it was his tooling and his shop. Anyway, early 18ers were around 230 HP with a 2 bbl. and later they were de rated to less then 200 with reduced compression. The earlier engines would have been ok with low octane but barely. Timing and fuel control at that time were simply not up to the task as they are now with electronic systems. I've learned that bigger rods can be a hinderance with RPM's just take SBC as and example. Obviously they aren't going to live for ever but big rods slow things down and can abuse cranks. Big rods need bigger bolts! That why 6packs blew up, the bolts just weren't up to the task like the hemi bolts were. Everyone knows 7/16 bolts are better then 3/8's. Chevy and ford all learned eventually by going from 11/32 to 3/8. There were 3 crank options offered over the life of the 318 from the beginning to the end from memory. And as far as I can remember they would all interchange with proper balancing, might need some working on the clutch pilot part. 273 and 318 both have the same stroke, 340 was so slightly different, barely worth considering. Old racers used de stroked cranks in 340's to build the TA's at 305 C.I.D.. Those engines were totally good to 10k RPM. They used longer rods to get the piston up where it belonged I think, it's been too long since I was there. The 18er did well enough in trucks all the way up in the 1 ton and over and in small motorhomes but the 60 did better for sure. As far as guzzlers. don't say 60's were guzzlers any more than any other, it all depended on how heavily loaded they were. Emissions hurt mileage for sure until Detroit learned how to do it right. Transmissions needed lots of help with more gears and better axle ratios to go with the better gears. One thing never changes, it take a specific A/R and displacement is what it is, bigger will take more, no way around that. Even a little 2.3L turbo will make as much power as a 5.8 or even bigger but to do it you MUST put more A/F in there which means it will guzzle under high boost. It also won't last as long as a bigger plant if you demand power all the time. Aircraft engines are a perfect example as are boat motors. 360's are meant for higher torque and lower RPM. I have known a few guys pushing 360's to 8k+ but they don't last long even with forged cranks and aluminum rods, of course alloy rods are limited to begin with. That rule is never going to change, there's no replacement for displacement but don't confuse engine displacement for air displacement. We all should know how it works by now. OEM's have know for a long time now, which is why they did modular displacement back then and are doing it now.
 
It's my opinion that the SB's were capable of making more HP per cubic inch with less work then the BB's could do. But as I have said before, HP is nothing more than a calculation based upon Torque at a given RPM. Take into account that back when Emissions came around in the early 70's, the output of the 440 was dropped under 300 factory while the output of the 360 stayed closer to what the BB was rated at when compared to the highest ratings of either. 360's always were close to what old 383's were at anytime There were more head casting option available for the SB's then for the BB's and even with what was out there for the BB's the power potential in them was not all that much different. At least with the SB's you could swap on a set of 318 heads on a 273 and see a noticeable boost in flow. Of course putting a set of 202 340 heads on a 273 was out. Putting them on 318 was marginal unless you were using the later heads with the 188 intakes. Some people used to install 392 hemi intake valve in the both the poly and LA SB heads on 18ers because they didn't require dangerous bore notching. You could put the 188's in the 18er heads and have better flow and response with the smaller ports and bigger valves. Math will tell this if you know how to use it. It's all about cross sectional area, in ports and around raised valves. There were the original 340 TA heads with the offset rockers but the heads still have the restricted ports of the standard heads. They could be modified to make use of the extra area for more flow but the flow wasn't all that much better. MOPAR heads of any app. needed to be designed the same way heads for any other engine, raise the floors and straighten out the ports. Enter HEMI's. If I could find an old poly head I would work with it. They used those in early Factory backed circles in the early 60's because it was all they had and they did well. The valve and rocker design gave decent results. There is enough block for stoking and they were thick enough to overbore and not over heat. If anyone has one I may be interested. MOPAR even had a dual quad intake out for it from the factory at one time.
 
Finally found the info on what I did on my 318 on another website. I was very happy with how this engine performed in a '72 Charger, 904, and 8.25 w/2.94 gears. I drove this car everyday 30 miles to work. No, it wasn't going to outrun anyone but it was a very fun and reliable setup. In a lighter A body, the right gearing, and a decent chassis setup, this would have been extremely fun on the street.

Below, excerpted from an article that originally appeared in Hot Rod Magazine, are the dyno results from a baseline test of a stock 318 engine, and the horsepower gains recorded after various modifications.

  • 186 HP at 4000 RPM (Base Platform):
    • 318 non-roller 8:1 compression cop car short block
    • Production 318 cam with 240* adv. dur. .390"/.400" lift
    • Heads were the 4323302 casting (302s) high swirl mileage/emissions heads with the heart shaped chamber (9.0:1 compression installed)
    • 4BBL cast iron cop car intake manifold
    • Thermoquad carburetor
    • Stock exhaust manifolds
    • Factory stock (non lean burn) electronic ignition system
  • 217 HP at 4200 RPM:
    • Added a 360 2BBL cam (252* adv. dur. .410" lift)
    • Mopar Performance Electronic Ignition conversion kit
    • Cam and MP Electronic Ignition swap was good for a 31 HP increase.
  • 225 HP at 4500 RPM:
    • Added stock 1.88" intake/1.60" exhaust 360 heads with stock springs, retainers and keepers
    • Gave the heads a performance valve job
    • Head swap was only good for an 8 HP increase.
    • Power was weaker than the swirl head combo below 3500 RPM.
  • 251 HP at 5000 RPM:
    • Added Mopar Performance P4120249 valve springs to the 360 heads
    • Added Mopar Performance P4286669 cam (260* adv. dur. .430" lift)
    • Holley 0-3310 750CFM vacuum secondary carburetor
    • Edelbrock 2176 Performer aluminum intake manifold
    • Mopar Performance P4286437 headers (1 5/8" primary tubes with 3" collectors)
    • The above items added 26 HP.
  • 290 HP at 5250 RPM:
    • Ported and polished the heads
    • Upgraded heads to 2.02" intake and 1.60" exhaust valves
    • Added Mopar Performance P4452033 chrome-moly valve spring retainers with 8* keeper grooves
    • Mopar Performance P4120620 8* hardened valve stem locks
    • Added Mopar Performance P4286671cam (272* adv. dur. .455" lift)
    • Mopar P4120600 Gold Box competition ignition control unit
    • This combo added 39 HP
  • 331 HP at 5750 RPM:
    • Swapped the 360 heads for ported and polished 302 heads modified with 1.88" intake/1.60" exhaust valves
    • Mopar Performance P4120249 valve springs
    • This combo produced a 41 HP increase over the previous combination, netting 1.12 HP per cubic inch!
    • This combo also produced more power than all of the other combinations from the lowest RPM on up

Notes:

  • All tests were conducted on an engine dyno stand with an unrestricted exhaust system.
  • 4323302 casting heads (302s), 4343646 castings and similar castings are 1.78" intake/1.50" exhaust high swirl mileage/emissions heads that were used on all civilian duty M-bodies from late-1985 to 1989.
  • Actual cop car engine compression per the 1987 Factory Service Manual was 8.4:1 due to the open-chambered 360 heads. Compression for civilian model 318s with closed-chambered factory 302 heads was 9.0:1.
  • The base HP for civilian model 2BBL 318s was about 140, so expect HP numbers a bit less than the above baseline test if you add a 4BBL intake/carburetor and convert to electronic ignition.
  • Modifications usually work together to produce results. The 41 HP increase recorded in the last dyno test was achieved because the camshaft was much stouter than a production cam, and it was designed to take advantage of superior breathing heads. A similar increase should not be expected with the same heads and a stock cam.
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I edited out some nonessential crap from the quote.
 
It's my opinion that the SB's were capable of making more HP per cubic inch with less work then the BB's could do. But as I have said before, HP is nothing more than a calculation based upon Torque at a given RPM. Take into account that back when Emissions came around in the early 70's, the output of the 440 was dropped under 300 factory while the output of the 360 stayed closer to what the BB was rated at when compared to the highest ratings of either. 360's always were close to what old 383's were at anytime There were more head casting option available for the SB's then for the BB's and even with what was out there for the BB's the power potential in them was not all that much different. At least with the SB's you could swap on a set of 318 heads on a 273 and see a noticeable boost in flow. Of course putting a set of 202 340 heads on a 273 was out. Putting them on 318 was marginal unless you were using the later heads with the 188 intakes. Some people used to install 392 hemi intake valve in the both the poly and LA SB heads on 18ers because they didn't require dangerous bore notching. You could put the 188's in the 18er heads and have better flow and response with the smaller ports and bigger valves. Math will tell this if you know how to use it. It's all about cross sectional area, in ports and around raised valves. There were the original 340 TA heads with the offset rockers but the heads still have the restricted ports of the standard heads. They could be modified to make use of the extra area for more flow but the flow wasn't all that much better. MOPAR heads of any app. needed to be designed the same way heads for any other engine, raise the floors and straighten out the ports. Enter HEMI's. If I could find an old poly head I would work with it. They used those in early Factory backed circles in the early 60's because it was all they had and they did well. The valve and rocker design gave decent results. There is enough block for stoking and they were thick enough to overbore and not over heat. If anyone has one I may be interested. MOPAR even had a dual quad intake out for it from the factory at one time.
 
Never knew there was so much interest in the poly engines.
This time last year my uncle was begging me to come up to his house and get a free running poly.
All I had to do was show up with my truck, and he would have loaded it up.
Oh well, I already have enough crap.
 
The first LA was the 273 like we all know.
But Chrysler used so many items off the Poly 318 shelves to save money. Even the lifter angles are the same (STUPID) angles

The first run 273 cranks are Poly teen forged cranks. But the smaller 273 piston was a HUGE mismatch balance to that heavy crank so Chrysler added a very heavy thick wall wrist pin to the light 273 piston. Equal Bob Weights BABY!

Can you imagine taking that huge slug wrist pin out and putting a custom super light one in and then remove weight from the forged crank? I bet you can take 5-8 pounds out of the crank.
Well the 318 has a smaller piston than the 340 and again they used a heavy wrist pin. I was told the 340 did use used a lighter wrist pin in the heaver piston... Again, what were the Bob Weights? I know there is a difference due to 'Pressed Pin' and 'Full Floating'.

So use the same light wrist pin on the Teen and re-balance the teens crank.
 
With what we are forced to live with these days? We may be in an age of High tech in some ways but in others, we have take several steps backwards. We started out with singles, then twins and eventually 4's and the L6's to advance to V8 and there were bold engineers making L8's V12's and all sorts of other designs of infernal combustion plants. Just look for Arden Hemi conversions for FHV8 Fords. Then Arias Hemi conversions for BBC's. Personally I love a big engine, the bigger the better. Then when you can sqquezze 400+ from a small block and read numbers from a dyno that make a muscle era BB hang its head in shame, well that just gives me a woody. Since engine engineers started making parts to build inches and still stay under 540 lbs of iron, that just makes all the sense in the world because weight has always been a factor. I admit a decked out BB of any brand is tough to not look at and say what a beast or drool over. I wish someone had come out with a real head turning FAT valve covered relocated distributor arrangement for the famous LA...So what's left in that department return to the poly headed block. Those engines didn't have much for port size but it didn't seem to make a lot of difference as they still performed pretty good. At least well enough to race in high level ranks of the time and work with 8 bbls. These days if anyone built a poly and installed it in a later model such as an A or any other model, it would be left up to the old guys to teach kids about how it was done when it was first being done. Getting beat down by a FAT block with over 500 inches is not that bad but being walked on by a SB with over 400 when you're the guy with the FAT block is.
 
Bret Tschacher said:
With what we are forced to live with these days? We may be in an age of High tech in some ways but in others, we have take several steps backwards. We started out with singles, then twins and eventually 4's and the L6's to advance to V8 and there were bold engineers making L8's V12's and all sorts of other designs of infernal combustion plants. Just look for Arden Hemi conversions for FHV8 Fords. Then Arias Hemi conversions for BBC's. Personally I love a big engine, the bigger the better. Then when you can sqquezze 400+ from a small block and read numbers from a dyno that make a muscle era BB hang its head in shame, well that just gives me a woody. Since engine engineers started making parts to build inches and still stay under 540 lbs of iron, that just makes all the sense in the world because weight has always been a factor. I admit a decked out BB of any brand is tough to not look at and say what a beast or drool over. I wish someone had come out with a real head turning FAT valve covered relocated distributor arrangement for the famous LA...So what's left in that department return to the poly headed block. Those engines didn't have much for port size but it didn't seem to make a lot of difference as they still performed pretty good. At least well enough to race in high level ranks of the time and work with 8 bbls. These days if anyone built a poly and installed it in a later model such as an A or any other model, it would be left up to the old guys to teach kids about how it was done when it was first being done. Getting beat down by a FAT block with over 500 inches is not that bad but being walked on by a SB with over 400 when you're the guy with the FAT block is.
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Now... Imagine a Harley rider that gets its butt handed to him by a SCOOTER.
My Suzuki Burgman 650 scooter runs a 15.7 1/4 mile and top speed is 122 MPH (GPS).
 
Dave_J said:
Now... Imagine a Harley rider that gets its butt handed to him by a SCOOTER.
My Suzuki Burgman 650 scooter runs a 15.7 1/4 mile and top speed is 122 MPH (GPS).
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Might wanna think twice about a VROD there Chico..
 
Heywodja said:
Might wanna think twice about a VROD there Chico..
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I pick my fights well. Won't win a race with most S&S Harleys too. Ain't stooopid. ;)

But I can out corner about 95% of all Harelys and I can run 100 MPH for hours in desert heat without over heating. Gas mileage suffers at 100 MPH, about 38 MPG

How much does a used V Rod cost? My scooter cost me $2000 used and has 62,000 miles on it now.
 
Bret Tschacher said:
I truly love the way those 318 spin compared to a longer stroked motor.
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Not to pick on you Bret;
KB107s are like 502 grams. My cast crank equipped 367 has, since 1999, has made hundreds and hundreds maybe thousands of runs to 7000/7200, in a streeter with a manual trans.
And
it has over 100,000 miles on it today.
And
I could, and have,told you guys that on one certain day-trip, to the 2004 CarCraft Nationals, it pulled over 30mpgs(USg) from point to point.
318 lovers keep painting 360s as evil,gas-sucking, slo-reving,useless piles of iron junk; but it just ain't so. Don't blame a slo-azz cammed, low-compression, 360 for what the 727 chains it to.
BTW; the 340 had forged slugs that weighed in at 745 grams IIRC, and I don't recall hearing anybody ever talk about how slow-revving their first-gen 340 was. Well, the factory cam wasn't good for much over 5500 anyway, and the factory springs barely made it that far..... Oh but don't diss the mighty 340! somebody will want to kick yerazz.
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Consider this;
>The factory 318s had about 135 psi of CCP on a good day. That translates to a possible 1621 pounds of force to the rod. By the time that gets to the flywheel it might be 224 ftlbs with the crank at 90* to the rod.
>And the lowly 360, might pump 145psi, and so the force translates to 1822 pounds and to the flywheel; wait for it, 272 ftlbs ............... which, you guessed it is about 21% stronger than the 318.
>The factory 10.5 340 pumped about 175 psi,which maths to 2243 pounds of force, and to the flywheel might be 310 ftlbs.

All these are math numbers only
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Buttum pump the CCP of the 360, to 185 with alloy heads, and watch the force go to 2325, and at the flywheel to 347 ftlbs.
But I can hear the 318-lovers screaming unfair! unfair!
Ok so lemmee say this; the 360 falls together with 63cc alloy heads, and KB107s; at right around 10.7 with no milling of any kind. So you just slap it together about as cheap an engine as you can build.
Ok so on the same budget, how high can you get the pressure in your 318. Your total chamber volume will come in around 82cc with the FellPro .039s, and 57cc heads. That makes about a 9/1 engine.
Ok so you get the bright idea to install the 340 cam, and instantly the pressure falls to 140psi, the force to 1681, yipee! and to the flywheel; 232ftlbs.
Unfair! Unfair! Yeah but that's what you guys brag on.
Ok so for the small % of you 318guys that might realize that mistake, you put a solid cam in there and pump the pressure to 185psi about the maximum you can run on pumpgas with closed chamber alloy heads. Great idea. So now, the force comes to 2221, and at the flywheel.... 307; good job! congratulations you just unseated the "king". So,
>2221/307 is about as good as it gets for a 318....
Speaking of which; the king-340 is already at 175psi so has almost nowhere to go. So the
>2243/310 is already almost maxed out.
And the lowly 360, at
>2325/347 is also nearly maxed out.

But you say, how is it that the 360 has so much more to the flywheel? Well because of it's 3.58 stroke, versus the 3.315 of the junior engines.

Now, to finish the exercise; what will you have to do to the 318 to make 185psi?
Answer; everything will have to be machined. It will cost you a fortune, versus the 360 with 63ccheads and KB107s just falls together there.
 
AJ/FormS said:
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BTW; the 340 had forged slugs that weighed in at 745 grams IIRC, and I don't recall hearing anybody ever talk about how slow-revving their first-gen 340 was. Well, the factory cam wasn't good for much over 5500 anyway, and the factory springs barely made it that far..... Oh but don't diss the mighty 340! somebody will want to kick yerazz...
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Actually, 340's had cast pistons, and with stock cam and springs will pull to 6,500 easy. Horsepower for any engine is air flow through the carb, intake and heads and out through the exhaust.
 
Bret Tschacher said:
... At least with the SB's you could swap on a set of 318 heads on a 273 and see a noticeable boost in flow. Of course putting a set of 202 340 heads on a 273 was out...
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318 heads are a power loss compared to 273 heads, both in compression and air flow. I've run 1.88 intake J heads on a 273 with good result.
 
AJ/FormS said:
... Consider this;
>The factory 318s had about 135 psi of CCP on a good day. That translates to a possible 1621 pounds of force to the rod. By the time that gets to the flywheel it might be 224 ftlbs with the crank at 90* to the rod.
>And the lowly 360, might pump 145psi, and so the force translates to 1822 pounds and to the flywheel; wait for it, 272 ftlbs ............... which, you guessed it is about 21% stronger than the 318.
>The factory 10.5 340 pumped about 175 psi,which maths to 2243 pounds of force, and to the flywheel might be 310 ftlbs.

All these are math numbers only...
Click to expand...

What is the math you are using?
 
66fs said:
318 OPEN CHAMBER heads are a HUGE power loss compared to 273 CLOSED CHAMBER heads, both in compression and air flow. I've run 1.88 intake J heads on a 273 with good result.
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I fixed that in BOLD for ya. ;)

We put some 1.88's and 1.60" in a set of closed chamber 273 heads and did just a little unshrouding. Using a SP2P 318 intake and a 500 AVS made a mild RV cam'ed 318 real responsive down low for a small Airstream's Fury wagon tow rig.
Later 273 open chambers were not any better than 318 open that we could see. The 1.78" and 1.50" valves were not up to power.
 
Dave_J said:
I fixed that in BOLD for ya. ;)

We put some 1.88's and 1.60" in a set of closed chamber 273 heads and did just a little unshrouding. Using a SP2P 318 intake and a 500 AVS made a mild RV cam'ed 318 real responsive down low for a small Airstream's Fury wagon tow rig.
Later 273 open chambers were not any better than 318 open that we could see. The 1.78" and 1.50" valves were not up to power.
Click to expand...

68 and 69 273 heads are just 318 heads, same casting number. I don't consider them 273 heads ;-) Now, if you take a 68 or 69 273 and put closed chambered heads on them, you will have something since the pistons are about .030 higher in the block.
 
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