318 with 360 heads milling : small valves

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ValerianMagnum

ValerianMagnum

the little car that could
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I have the 318 in my fury ( 71 engine ) and i have a 77 360 on a stand , i was thinking of milling the heads ( 360 ) to put on the 318 to help me out with the choice of big ports 340/360 aluminium intakes... will it bump up the compression to 8-9ishhh compare of loosing some ( 7-ishh ) thx guys , the 68fury is built to be a simple driver with some "umpfff" and still be a good economy and regular car that can keep with traffic and tow small stuff once in a while ( travelling )..thx !
 
2 things:
  1. If you cut the 360 heads about .040, you'll still be lucky to maintain the factory 318 compression. However, I have used cut 360 heads on 318's and always had a good response, but mainly as the RPM's build. My question is why not the whole 360 in the fury?
  2. You can put a 340/360 intake on a 318 and forget the port size difference. Done that more times than I care to remember and always have had a great results.
 
I milled a set of 360 heads .060” off the deck surface and .050” off the intake surface and gained a full point of compression on my 318. 74 motor with pistons near .100” below deck. Chambers went from 68cc to 57cc with 2.02/1.60 valves. Not worth the $$$ or hassle in hindsight.
 

318willrun said:
2 things:
  1. If you cut the 360 heads about .040, you'll still be lucky to maintain the factory 318 compression. However, I have used cut 360 heads on 318's and always had a good response, but mainly as the RPM's build. My question is why not the whole 360 in the fury?
  2. You can put a 340/360 intake on a 318 and forget the port size difference. Done that more times than I care to remember and always have had a great results.
Click to expand...
Hi Tim :) i would love to havea nice cruiser with good mpg , it sounds silly but if i can get the most of it i would be very happy...always heard bad stories with the as mega gas guzzler....
 
The factory in 78/79/80 put the big port intake on the small
port 318 heads from the factory despite the large mismatch and it
worked fine!
 
318willrun said:
You can put a 340/360 intake on a 318 and forget the port size difference. Done that more times than I care to remember and always have had a great results.
Click to expand...
So did Chrysler. On millions of engines.
 
ValerianMagnum said:
I have the 318 in my fury ( 71 engine ) and i have a 77 360 on a stand , i was thinking of milling the heads ( 360 ) to put on the 318 to help me out with the choice of big ports 340/360 aluminium intakes... will it bump up the compression to 8-9ishhh compare of loosing some ( 7-ishh ) thx guys , the 68fury is built to be a simple driver with some "umpfff" and still be a good economy and regular car that can keep with traffic and tow small stuff once in a while ( travelling )..thx !
Click to expand...
A lot of this, “How well will it work”, will be the amount of cc’s each cylinder head has. What exact 360 head cc chamber amount you have and what you can reasonably get it down to will be of your interest.

Now here is the good part even before you get into the first half above. The increased airflow will add power everywhere. Tim (318WR) is right on target. I also believe you’re right on track to be concerned about the compression ratio. Any raise in the ratio will be a benefit.
 
Find a 5.2 magnum if you want to stay "318" and get better mileage or just use a small port Aluminum intake like a Performer and not mill anything.
 
dano said:
Find a 5.2 magnum if you want to stay "318" and get better mileage or just use a small port Aluminum intake like a Performer and not mill anything.
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LOL and no intakes really available. Then you can screw with redrilling the heads for an LA intake
 
Yes. LA intake will not fit without redrilling the heads
 
IIRC the 71 318 is still a 9.2 Scr/ hi-test fuel, engine; which is already running close to max pressure for pumpgas.
I would just install any small-port 4bbl intake on her, and the cam pirated out of the 360, installed with an Ica of 54*, and call it done.
Yes, you'll lose a lil economy due to the bigger cam, but it will be so worth it, especially when you find out that you can likely tune it for 87 gas. And that would pretty much get you back to par as to cost per mile.

But I gotta warn you;
If yur running hiway gears like 2.76s and a lo stall convertor under 2000, NONE of that is gonna make much of a difference at WOT, until about 30 mph/3000 rpm.


Yur best bang for money spent is to increase the stall; and
second best is to increase the torque-multiplication of the rear gears.
then the 4bbl
then dual exhaust
then the cam
or
just install the 360.
 
AJ/FormS said:
IIRC the 71 318 is still a 9.2 Scr/ hi-test fuel, engine; which is already running close to max pressure for pumpgas.
I would just install any small-port 4bbl intake on her, and the cam pirated out of the 360, installed with an Ica of 54*, and call it done.
Yes, you'll lose a lil economy due to the bigger cam, but it will be so worth it, especially when you find out that you can likely tune it for 87 gas. And that would pretty much get you back to par as to cost per mile.

But I gotta warn you;
If yur running hiway gears like 2.76s and a lo stall convertor under 2000, NONE of that is gonna make much of a difference at WOT, until about 30 mph/3000 rpm.


Yur best bang for money spent is to increase the stall; and
second best is to increase the torque-multiplication of the rear gears.
then the 4bbl
then dual exhaust
then the cam
or
just install the 360.
Click to expand...

I did a 5.9 swap as everything AJ said is a ditto.
IMO, 100% accurate.

On the 5.9, the minimum octane it likes is 89. This is a little dicey since not all gas stations have a quality fuel and it would not act well with a sub par fuel. So it is fed 93 octane. While I can re time the distributor for 87 octane, power falls off a lot and mileage isn’t all that great.

The car (‘79 Magnum) has 3.55’s on 245/60/15’s, a 727 w/a 2500 converter. The car weighs 3600+ with me and no fuel.
 
Stock 71 318 heads should be about 68 cc A .040 cut on 360 heads should get you just under 65 cc chambers. I would also mill the intake side of the head .038. Plus you can tighten up the guides, clean up the bowls under the valves, get a good valve job, and use the good Viton valve seals, add valve springs to match your cam while you do the heads. You go from 170 cfm on the intake port to about 200cfm. Now you should add a windage tray, high pressure oil pump relief spring, a 340 distributor, and 3.23 gears. I used to do it all the time. How much it will cost now a days, or will it be worth it, only you can decide.
 
AJ/FormS said:
Yur best bang for money spent is to increase the stall; and
second best is to increase the torque-multiplication of the rear gears.
then the 4bbl
then dual exhaust
then the cam
or
just install the 360.
Click to expand...
Be interesting if someone did a drag and or 0-60 mph comparison.

Of a stock 2bbl 318 with a good tune with optimal performance stall and gears vs stock stall and gears and basic bolt ons 4bbl cam and headers on a low cr 318 vs a stock 2bbl 360 and stock stall and gears.
 
273 said:
Be interesting if someone did a drag and or 0-60 mph comparison.

Of a stock 2bbl 318 with a good tune with optimal performance stall and gears vs stock stall and gears and basic bolt ons 4bbl cam and headers on a low cr 318 vs a stock 2bbl 360 and stock stall and gears.
Click to expand...
I ran my low-compression 318 for a short time with 4.30s, an A998, and a 2800 TC, with just a 4bbl and headers. By the math, Zero-slip at 60 is about 4770 at the top of second. On the tach, that was about 5200. I thought it was pretty peppy. I really enjoyed that Convertor.

at other times, that engine pulled a lotta other gears and usually with a 4-speed/od, and sometimes with a GVOD behind that. As far as smoggers go, that one was pretty good.
My son finally made me an offer I couldn't refuse, and I installed it into his D-100 with 3.55s. In the truck tho, it was pretty hard on gas, so a few weeks later, he traded the 3.55s for 3.23s and it still spun the tires near relentlessly, lol. So, I fabricated a long-armed pinion snubber which ended the wheel-hop, at least.
 
For fuel economy and low-rpm oumph, together, your best bet with a 318 is increasing the cylinder pressure. But the early factory 318s are already pushing the pressure limit for todays pumpgas.
> an optimized ignition curve will pay dividends.
> a free-flowing exhaust is a must.
As to other options;
>A 4bbl will not likely affect hiway fuel economy and with a small-Primary spread-bore like a TQ, could actually better the factory 2bbl.
> the stall-speed will also up the take-off oumph, but may affect the hiway fuel-economy. It sorta depends what you are swapping out.
> Swapping the factory trans out for an A999(with a 2.74 low gear) will better the first-gear oumph, while the Lock-up feature should better fuel economy.
> IMO, for your stated usage,
an overdrive trans, together with a rear gear swap, would be the way to go; together with optimizing the advance curve.
 
AJ/FormS said:
For fuel economy and low-rpm oumph, together, your best bet with a 318 is increasing the cylinder pressure. But the early factory 318s are already pushing the pressure limit for todays pumpgas.
> an optimized ignition curve will pay dividends.
> a free-flowing exhaust is a must.
As to other options;
>A 4bbl will not likely affect hiway fuel economy and with a small-Primary spread-bore like a TQ, could actually better the factory 2bbl.
> the stall-speed will also up the take-off oumph, but may affect the hiway fuel-economy. It sorta depends what you are swapping out.
> Swapping the factory trans out for an A999(with a 2.74 low gear) will better the first-gear oumph, while the Lock-up feature should better fuel economy.
> IMO, for your stated usage,
an overdrive trans, together with a rear gear swap, would be the way to go; together with optimizing the advance curve.
Click to expand...
Unfortunately CR, Stall & gearing (trans/rear) is generally the last, if at all mod they do especially for a 318 :)
 
True and sad but
in the case of the 71 engine, it is already a 9.2 Scr design, and with the factory cam, it's already pushing the pressure limit of pumpgas.
I offered some alternatives to a bigger engine.
 
I don't know. I like spending time and money in the heads more than raising compression and or cylinder pressure. Jim Laroy and company have pretty much proven that head flow has more gains with their low compression builds. Just because Jim doesn't post much anymore, or those threads aren't near the top anymore doesn't make it any less true.
 
RustyRatRod said:
I don't know. I like spending time and money in the heads more than raising compression and or cylinder pressure. Jim Laroy and company have pretty much proven that head flow has more gains with their low compression builds. Just because Jim doesn't post much anymore, or those threads aren't near the top anymore doesn't make it any less true.
Click to expand...
Going up 3-4 cr points is suppose to be about 10% in power gains, you easily do multiplies of that with head flow power gains.
 
273 said:
Going up 3-4 cr points is suppose to be about 10% in power gains, you easily do multiplies of that with head flow power gains.
Click to expand...
I think Jim said for every 1 compression point there's about a 3% power gain......more or less so you're spot on and I agree. I believe head flow is the way to go. It's long been my advice not to risk too high a compression on a street car, but no one ever listens. There are a few exceptions where I would push the limit, as in a quench build or an old school over cammed engine, but that's about it. I can give the 400 in Gladys as an example. It's right at 9:1, maybe a tic less but I am extremely happy with the power and torque output. She's got an 8100 pound GVWR and that old girl will get with it when you crack the loud pedal. The Cleveland style heads flow really well.
 
RustyRatRod said:
I think Jim said for every 1 compression point there's about a 3% power gain......more or less so you're spot on and I agree. I believe head flow is the way to go. It's long been my advice not to risk too high a compression on a street car, but no one ever listens. There are a few exceptions where I would push the limit, as in a quench build or an old school over cammed engine, but that's about it. I can give the 400 in Gladys as an example. It's right at 9:1, maybe a tic less but I am extremely happy with the power and torque output. She's got an 8100 pound GVWR and that old girl will get with it when you crack the loud pedal. The Cleveland style heads flow really well.
Click to expand...
Totally agree most shouldn't push their cr to high, for most a possible pinging mess ain't worth 3% hp to go 10:1 instead of 9:1 and if you got an stock 8.?:1 your only down 3-5% hp.

Airflow is definitely where it's a, 360 with say 235 ish cam is gonna get massive different results with 273/318 head vs 360 head vs everything all the way up to trickflow and beyond. Everyone likes LS and Gen3 hemi cause it's like if 340/360 came factory with edelbrock/trickflow heads, why they can build great power with milder cams.
 
273 said:
Totally agree most shouldn't push their cr to high, for most a possible pinging mess ain't worth 3% hp to go 10:1 instead of 9:1 and if you got an stock 8.?:1 your only down 3-5% hp.

Airflow is definitely where it's a, 360 with say 235 ish cam is gonna get massive different results with 273/318 head vs 360 head vs everything all the way up to trickflow and beyond. Everyone likes LS and Gen3 hemi cause it's like if 340/360 came factory with edelbrock/trickflow heads, why they can build great power with milder cams.
Click to expand...
It's tough to deny the LS platform. They're power makers for sure.
 
People always told me to keep the small ports on a 318 , that smaller ports = more velocity/Torque....i understand performance and mods...but the 318s is a very différent animal :) , especialy when you always had 340s and 360s ! I just wanted à nice 318 in the big fury...if a Ford 302 could move a grand marquis police car that good.. the 318 can move a fury for sure
 
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