318 value

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1Badcolt said:
MANY !!!!
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Thanks Captain Obvious....

Captain Obvious A01.png



I found my answer.... 67 - 75....


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My first notch came with a 74 318 in it. I got a mancini stroker kit 390ci and put it in my buddies a-100. The way I see it, it’s a good starting point one way or another.
 
I have family in Warrenton! And we are coming up to visit the end of May. I can drag a short block 318 up if you want it. Forgot what year but I can check if it matters
 
MOPAROFFICIAL said:
Casting dates are '66-72 I believe.
There are many out there for those years but not all are that casting.
Same 318 'smaller' main cap and saddles though.
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I looked it up on mymopar and the castings were used from 67 - 75

318 Castings.png
 
RAT ROD AL said:
I have family in Warrenton! And we are coming up to visit the end of May. I can drag a short block 318 up if you want it. Forgot what year but In can check if it matters
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No I don't, but I thank you for the offer though. Warrenton is a peaceful place. Who knows, with you having family in the area one day I might be able to meet you that would be cool
 
RAT ROD AL said:
I have family in Warrenton! And we are coming up to visit the end of May. I can drag a short block 318 up if you want it. Forgot what year but I can check if it matters
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I think that is awesome that someone is willing to help out a person that they don't even know. I respect you sir, thanks again. If things change before you come this way in may I'll let you know
 
RAT ROD AL said:
I have 1 on the scrap trailer and another just pulled from a parts car. It's a 67 318. I think the going price is about 29 cents a ton. How many you want ?
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A 67 will be a 9.2:1 motor.

Those and the mid 80's 9.2:1 motors might be worth a couple bucks extra.

Seems like 9.2-9.5 is the new 87 octane "pump gas friendly" ratio these days.
 
YY1 said:
A 67 will be a 9.2:1 motor.

Those and the mid 80's 9.2:1 motors might be worth a couple bucks extra.

Seems like 9.2-9.5 is the new 87 octane "pump gas friendly" ratio these days.
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How can the compression be that good when the pistons are usually 0.080" in the bore and mopar cylinder heads have big chambers, like 65cc plus. I don't think that a 0.028" head gasket alone would do it.
 
Dan the man said:
I think that is awesome that someone is willing to help out a person that they don't even know. I respect you sir, thanks again. If things change before you come this way in may I'll let you know
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Let me know if you would want this 318, as it is on my scrap pile !If you want it, I'll not scrap it.
 
Dan the man said:
How can the compression be that good when the pistons are usually 0.080" in the bore and mopar cylinder heads have big chambers, like 65cc plus. I don't think that a 0.028" head gasket alone would do it.
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the early pistons were not that far down, and the heads were smaller chambers, and the metal gaskets were .020. By the math it often comes to 9.2 or thereabouts
To get to 9.2, the total chamber size needs to be 79.5cc, which is pretty big actually.
Pistons .057 down is 11.2, the gasket is about 4.0, the pistons are flat tops and the heads could be up to 64.3 to still make the 9.2
 
Dan the man said:
How can the compression be that good when the pistons are usually 0.080" in the bore and mopar cylinder heads have big chambers, like 65cc plus. I don't think that a 0.028" head gasket alone would do it.
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The early LA 318 was built as a 9.2:1 engine.
It may or may not actually measure out to that.
I think they were 67-69.

Most "mid production" LA 318 engines were built to 8.8:1.
Again, they may or may not actually spec out to that.

Then, the mid 80's to early 90's LA "roller" engines were again built to 9.2:1.
We had a member a few years ago tear one down and measure. IIRC he got 9.18:1.
Close enough for me to be a believer that they got better with their math and tolerances on the roller LA engines.

Not sure why hardly anyone seems to know, care, or factor this.
Almost half a point of "free compression" has got to be a good thing.
 
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According to the Wallace Calculator;
With no other changes, and stock cam, at 800ft elevation;
here is what the different iron headed-318 compression ratios bring to the party:
@8.0 =136psi / 113 P/V(abysmal), burns any gas all the time
@8.8 =154psi / 128 P/V still on 87gas, most of the time
@9.2 =163psi / 136 P/V now requires 91gas at WOT, and 136 is getting peppy
@10.1=184psi /154 P/V only works with alloy heads and burns 87 again
read about P/V here; V/P Index Calculation
Now theoretically speaking, assigning a value of 100% to P/V of 113, here is how much stronger each engine will be, in the critical bottom end, for street-use;
113/113 =100%
128/113= plus 13.3%
136/113= plus 20.35%
154/113 =plus 36.63%
If your 318 makes 50hp at 2000 rpm, you might expect the power to increase by these percentages so; 13.3%=6.5hp, 20.35%=10.2hp, 36.63%=18.35hp.. This is how you get back the bottom-end that is usually lost when you up-cam, and neglect compression ratio, which then requires a higher stall to overcome.

These higher P/Vs allow you to run lower stalls, lower rear gears and the engine will gain fuel-economyFuel economy can be expected to increase but I don't have estimates for that.
As to gearing, you can decrease your gear easily by half the P/V percentage increase. Assigning 3.55s to the 113P/V this means that;
pv of 128 can run 13.30/2% less gear so 3.32s; and
pv of 136 can run 20.35/2% less gear so 3.19s, and
pv of 154 can run 36.63/2% less gear so 2.90s
with no loss of low-rpm performance........

each stronger P/V allows you to decrease your cruise rpm by at least half the percentage difference, with no loss in low-rpm performance .
If I assign 3.55s to P/V of 113, then the others, with 27"tires and 3% cruise slip; come out like this
with 113, 3.55s, 65=2960
with 128, 3.32s, 65=2770
with 136, 3.19s, 65=2660
-and 154, 2.90s, 65=2420
and that reduced cruise-rpm is another boost to the mpgs, and;
NONE of this requires an overdrive.
================================
Check out what those alloy heads can do for you; going from 3.55s to 2.90s, the cruise rpm drops 540 rpm or the same as a .82 overdrive. Maybe not .69 like the A500, but cruising at 2420 instead of 2960, I have a formula for that which says an rpm reduction of 1.00 less 81.2%= 18% which should yield an increase in fuel-economy of half that, so 9%; which takes a 20mpg combo to 21.8mpgs . If you buy 600gallons of fuel per year at 20mpg, but at 21.8 only 488 , how much money will you save? Now, factor in burning 87 with the alloys versus 91 ( see note 1) with iron, and I get an annual savings of about $660 at last weeks pre gas-gouging prices.
How many years will it take to pay for those alloy heads just in the fuel-economy difference, at those prices?
Since my car was, in those days, a DD, I estimate that it took between two and three years. Over the life of the body, about 16/18 years, I saved a lotta lotta money.

EDIT
note-1
What I mean to say is that 91 is best pump-gas that you can buy and limits the pressure you can run with iron heads to around 160/165psi.. Whereas 87 will support alloy heads to at least 185psi, and I have successfully run a tic over 190 still on 87. Thanks to YY1 for calling attention to this seeming error
 
Last edited:
I don't remember 9.2 318's to requite 91 octane.
 
AJ/FormS said:
According to the Wallace Calculator;
With no other changes, and stock cam, at 800ft elevation;
here is what the different iron headed-318 compression ratios bring to the party:
@8.0 =136psi / 113 P/V(abysmal), burns any gas all the time
@8.8 =154psi / 128 P/V still on 87gas, most of the time
@9.2 =163psi / 136 P/V now requires 91gas at WOT, and 136 is getting peppy
@10.1=184psi /154 P/V only works with alloy heads and burns 87 again
read about P/V here; V/P Index Calculation
Now theoretically speaking, assigning a value of 100% to P/V of 113, here is how much stronger each engine will be, in the critical bottom end, for street-use;
113/113 =100%
128/113= plus 13.3%
136/113= plus 20.35%
154/113 =plus 36.63%
If your 318 makes 50hp at 2000 rpm, you might expect the power to increase by these percentages so; 13.3%=6.5hp, 20.35%=10.2hp, 36.63%=18.35hp.. This is how you get back the bottom-end that is usually lost when you up-cam, and neglect compression ratio, which then requires a higher stall to overcome.

These higher P/Vs allow you to run lower stalls, lower rear gears and the engine will gain fuel-economyFuel economy can be expected to increase but I don't have estimates for that.
As to gearing, you can decrease your gear easily by half the P/V percentage increase. Assigning 3.55s to the 113P/V this means that;
pv of 128 can run 13.30/2% less gear so 3.32s; and
pv of 136 can run 20.35/2% less gear so 3.19s, and
pv of 154 can run 36.63/2% less gear so 2.90s
with no loss of low-rpm performance........

each stronger P/V allows you to decrease your cruise rpm by at least half the percentage difference, with no loss in low-rpm performance .
If I assign 3.55s to P/V of 113, then the others, with 27"tires and 3% cruise slip; come out like this
with 113, 3.55s, 65=2960
with 128, 3.32s, 65=2770
with 136, 3.19s, 65=2660
-and 154, 2.90s, 65=2420
and that reduced cruise-rpm is another boost to the mpgs, and;
NONE of this requires an overdrive.
================================
Check out what those alloy heads can do for you; going from 3.55s to 2.90s, the cruise rpm drops 540 rpm or the same as a .82 overdrive. Maybe not .69 like the A500, but cruising at 2420 instead of 2960, I have a formula for that which says an rpm reduction of 1.00 less 81.2%= 18% which should yield an increase in fuel-economy of half that, so 9%; which takes a 20mpg combo to 21.8mpgs . If you buy 600gallons of fuel per year at 20mpg, but at 21.8 only 488 , how much money will you save? Now, factor in burning 87 with the alloys versus 91 ( see note 1) with iron, and I get an annual savings of about $660 at last weeks pre gas-gouging prices.
How many years will it take to pay for those alloy heads just in the fuel-economy difference, at those prices?
Since my car was, in those days, a DD, I estimate that it took between two and three years. Over the life of the body, about 16/18 years, I saved a lotta lotta money.

EDIT
note-1
What I mean to say is that 91 is best pump-gas that you can buy and limits the pressure you can run with iron heads to around 160/165psi.. Whereas 87 will support alloy heads to at least 185psi, and I have successfully run a tic over 190 still on 87. Thanks to YY1 for calling attention to this seeming error
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All of this is way over my head. Can I get decent performance from a 8.25:1- 9.0:1 compression ratio? The reason why I was looking at closed chamber heads is for the compression, flame travel. From what I've read on the magnum / 302 heads concerning them cracking it's not a matter of if but when they will crack. Seems they are prone to cracking between the seats and naturally the crack only gets worse. I can't see putting money into cracked cylinder heads. One guy claimed that the exhaust seat came loose due to severe cracking. Is it possible to run a decent torque cam with a 8.5:1 compression ratio? I'm wanting good throttle response and strong low to midrange torque, engine speed will probably never exceed 4,800 rpm's as that's what the cam pulls to that I looked into.
 
RAT ROD AL said:
I have 1 on the scrap trailer and another just pulled from a parts car. It's a 67 318. I think the going price is about 29 cents a ton. How many you want ?
Click to expand...
Next time you come up my way I'll take a couple. 67 318s were good blocks.
 
well if its any consolation and if you can use this info and adjust prices to "todays money" I bought a 318 and a 904 for $40 dollars about 15 years ago, then turned around and sold it for $ 100 about 8 years ago...I sold it to my wifes uncle who wanted it for a 39 Plymouth so I figured why not he's family and Its scrap prices anyway...it sat ion my garage 7 years so I wasn't doing anything with it but I have two 340s and a 318 to play with so why hoard it?
 
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