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360 heads, 302 casting 318 heads, or Magnum heads on a 318

20K views 53 replies 13 participants last post by  SeahawkDodge 
#1 ·
I have a 360 intake and 500CFM carb that'll be going on my stock 318 soon. I'm thinking that it might be a good time to work the heads to my advantage since I'll have the top end cleared out already. I'm thinking on using a set of 360 heads to cure the port and valve size problems.

I've never been this deep into the engine...      ...any engine before, so I need someone to explain this like I'm a beginner.

And I'll need to know ALL the things needed to make this work because once prepared, I'll only have a weekend (20 hours total) to do it.

Will I need new lifters and such? What size?

Most parts will be coming from the pick-n-pull and will be cleaned and maybe polished before use.

I'm building it for fuel economy but I want power when I step on it.
 
#2 ·
Electric Squid said:
I have a 360 intake and 500CFM carb that'll be going on my stock 318 soon. I'm thinking that it might be a good time to work the heads to my advantage since I'll have the top end cleared out already. I'm thinking on using a set of 360 heads to cure the port and valve size problems.

I've never been this deep into the engine... ...any engine before, so I need someone to explain this like I'm a beginner.

And I'll need to know ALL the things needed to make this work because once prepared, I'll only have a weekend (20 hours total) to do it.

Will I need new lifters and such? What size?

Most parts will be coming from the pick-n-pull and will be cleaned and maybe polished before use.

I'm building it for fuel economy but I want power when I step on it.
You are going to lose compression, as the combustion chambers are larger in the 360 heads. I know you can have the heads shaved, as well as the block, but I don't know what they should be shaved to. You can also use a thin head gasket for slightly higher compression.
 
#3 ·
There is another thread that covers this same topic. look under "smog pump problems" . He was also asking about 360 heads on a 318. In your case, like Seahawk said, the 360 heads have a larger combustian chamber so you will lose some compression, but I think in the real world, you may never notice it. Just in case, it wouldn't hurt to shave the heads no more than .030. Unless you are changing cams, there is no need to change lifters. The heads are a direct swap. You unbolt one and bolt the other back in it's place. The only difference between 318 heads and 360 heads are the port size and combustion chamber size. Good luck
 
G
#4 ·
As stated, all the same hardware swaps. With no milling of the heads, the engine will have a true comprtession ratio around 7.8:1, but this will allow maximum ignition advance on regular gas without detonation. I agree that a good .030" mill job on the heads would give a good, but not excessive increase in compression ration. Also, the intake must also be milled to adjust for the head milling. Any decent shop should know how much to remove. It all depends on how much you mill the heads.
However, if you want fuel economy, the cost of the machine work would buy an Edelbrock Performer intake to use with the 318 heads. The Performer more closely matches the 318 ports. I had great results from an old Edelbrock SP2-P intake (see eBay). With the CompCams High Energy 260 grind and headers, I averaged 19mpg in my old '69 Charger. Yours will not do quite that well with the stock cam, but either intake would do more for you than a 360 top-end on a stock-cammed 318. I did the 360 top-end swap on the same engine, and despite the better cam, it was still down in power, and lost about 1.5mpg. I went back to the 318 setup. It ran like stink above 4,000rpm with the 360 parts, but in my package, the 318 heads gave a fuller low rpm power curve, and the car performed better overall (3,800lbs/3-speed auto, stock stall speed/2.76 gears) and Edelbrock 750--overkill, a 600 would have been better....and the mileage came back. Nowadays, with the right stuff, it's no contest. The 360 parts win, but that requires all the latest performance pieces.
 
#5 ·
I don't know where the hell you guys go for machine work...but you guys gotta deal with mickey mouse for machine work, and this would explain alot

Also, the intake must also be milled to adjust for the head milling.
The intake does not get milled, everything is done on the heads if not then leave the mickey mouse machinist and find a real machinist.

With no milling of the heads, the engine will have a true comprtession ratio around 7.8:1
Right now without you doing anything your motor has 7.8 to 1 maybe 8.2 to 1...add those 360 heads without taking off atleast .030 and you can figure on less power.

the 360 heads have a larger combustion chamber so you will lose some compression, but I think in the real world, you may never notice it.
Oh you'll notice it..unless you have no feeling for anything at all...but maybe you won't notice it there are many other mopars running around and don't see the problem either.

Make sure you mill the heads, make sure you use a competent machinist.
 
#7 ·
What are these port and valve size problems you speak of? A stock 318 with stock heads doesn't have port or valve size problems.

My recommendation for you, if you want to make your power/fuel economy dreams come true, is find a set of '302 casting 318 heads in the JY. You will have a swirl-port, closed chamber head that won't hurt (may help) your compression ratio. Economy will be good with the swirl port design and some have claimed as much as 50 hp over stock with these heads. Take that with a grain of salt, but they'll bolt on, and all the stock stuff will work, or use the Performer intake and a 4-v if you want.

Check the '302s carefully for cracks.

More here: http://www.allpar.com/mopar/4bbl.html

BTW Bruce, there was no link.
 
G
#8 ·
Evildriver-3 said:
The intake does not get milled, everything is done on the heads if not then leave the mickey mouse machinist and find a real machinist.
Yes, it does require milling. It'll bolt together without milling the intake, but it will be, as you say, a "Mickey Mouse" fit. Well, actually, it can be done either way. I see what you mean about it all being done "on the head". The head could be refaced to adjust the angle where the intake meets it. So, either way, an adjustment needs to be made to compensate for the head milling.
http://victorylibrary.com/mopar/intake-mill-c.htm

Yeah, the 302's are the best LA heads, and were the last in the evolutionary step to the Magnums, which carried over a lot of the developments in the 302's.
 
#9 ·
GunPilot said:
What an interesting read !! ;D

I got about 1/4 way through it. I'll finish later.

There are two terms I didn't understand and I need someone to explain to me. Here they are:

They said "float the valve", what's that?

And what do they mean by "tulip"?
 
#10 ·
"floating the valves" occurs when you over rev the engine and the springs aren't strong enough to hold the valve close at that rpm, so they actually stay open when they should be closed. I'm not too sure about the "tulip" comment. They are refering to the bowl area which is inside the head behind the valve. I'm sure it's a techique in the porting process. The question above about what is the problem with ports, the problem lies in the difference in intake port size. The 360 has a larger port size than the 318. A 318 manifold won't match up to the 360 heads very well (may have a sealing problem causing a vacuum leak) and will just plain choke it off, restricting the benefits of the larger 360 runners. Hope that helps.
Bill
 
#12 ·
The runners are the passages, from the intake port to the valve. Or the exhaust valve to the exhaust port. Also in the intake manifold from the carb to the ports.
 
#13 ·
so wayne, read anything new , that i didnt tell you in the IM? ;)

as for the "tulip" comment, it is in reference to the valve.

there are two common valve head styles for these engines, tulip head and nail head.

the nail head valve is a flat faced valve, decreases total combustion chamber size 1 or 2 cc's per valve so gives a slight boost in compression

the tulip head valve is the most common stock vavle in these engines and has that lovely little divot in the top of the valve, shaped somewhat like a tulip.

trust me, you arent going full blown race motor on this engine, you dont need the hassle of trying to go to a different set or type of valves.

nor do you really need the headache of trying to find the proper machinist to machine a set of 360 heads to your specs.

just go with the 302 heads like i told you yesterday.

and as soon as these guys post something up that i didnt tell you about, let me know, will ya? ;D

eric

ps: all of the info i gave you yesterday, was gathered over the past 4 or 5 years from talking to the same people that have posted above ;)
 
#14 ·
Not for nothing... buuuuut some of the stuff in that rediculous article is BS....and i even ah forget it....

I could routinely wind this motor up to 7500 rpm without it dropping out, and one time slipped a gear on the highway to move quickly to avoid an accident and hit first doing 55(7500 rpm) and shifted at 75 before I really realized what had happened (panic mode to avoid the accident). I figure I hit 8400 rpm and not only did it not float or bend a valve, but was still picking up rpm and power before I could correct my mistake.
Could you imagine that...with a 444 crane cam and 1.88 valves and it wasn't a W head....someone tell this kid to come see me with that motor let me see it happen again and he has a job here just waiting for his special self to walk thru the door.

Yes, it does require milling. It'll bolt together without milling the intake, but it will be, as you say, a "Mickey Mouse" fit.
Ok let me explain this again....why in the world would you mill the head and then the intake....the head is in the mill having the chamber side done.....hmmmmm remove the head and then do the intake so now the head can never be used on anything else again or you can't use another intake on that head again.....WTF is wrong with the mental patient machinist and owner for even contemplating some stupid shit like that...the head is in the mill...you make your cut...rotate the head and machine the intake face for the difference.....Anything else is retarted...actually super retarted
 
#15 ·
intenseimages said:
so wayne, read anything new , that i didnt tell you in the IM? ;) .....

....just go with the 302 heads like i told you yesterday.....

....ps: all of the info i gave you yesterday, was gathered over the past 4 or 5 years from talking to the same people that have posted above
;)
And with Eric's permission, here is the PM he's talking about.
The quote below is my message to him, followed by his reply:

[quote author="Electric Squid"]
I was wondering these last few days, if I have the intake off, should I just go ahead and replace the heads too?

And will a set of 360 heads w/ lifters and all fit a 318? That would take care of the port/valve size problem wouldn't it?

I was going to post a topic on this to get the details from some that have done it, but you are the guru of all things mechanical, I figured I'd ask you if it was possible first. ;)

Wayne
[/quote]

Reply from: intenseimages

good news and bad news on this. yep, the heads from a 360 would drop right on and bolt up. all stock 4bbl 318's used 360 heads.

now the bad news, how much power would you like to keep? yes, the 360 heads have larger ports and support more air flow, but at the same time they also have larger combustion chambers and you would drop your already anemic 8.5 or so compresion down to about a 7.9 or 8:1 compression ratio.

so in essence, if you swapped to 360 heads and slapped that 4bbl on, you wouldnt notice as much difference in the power improvment. you would still get some, but not as much.

unless you are going full blown all out performance on that motor, i would leave the 318 heads on it. yes, the ports are a bit mismatched (about 1/8 of an inch) in size, but from everything i have read and experienced, you only lose out on the effects of the larger ports at high rpm's. you actually gain a bit in low end torque by keeping the smaller port heads. which, we all know, in a truck, extra low end torque is never a bad thing.

another thing you could do, if you are really worried about the air flow on the motor wit hthe smaller port 318 heads, is to go ahead and get a set of 360 heads, have a good valve job done on them, and then have them milled to boost the compression ratio back up on them. if oyu go this route, make sure the machinist knows to check the intake angle on the heads after you have them milled. you shouldnt have to mill them so much the intake angle is thrown off, but if you do go quite a ways on them then theintake wont line up unless you ahve that side machined as well. i cant remember the exact numbers on this, but if you get ahold of Marty (evildriver-3) he could tell you real quick.

if you really want to change the heads and can locate a set of them, get a set of mid-80's 302 casting heads. they came on alot of mid=80's 318's, have a slightly smaller combustion chamber (58cc's versus 65) and also have a closed chamber swirl port design. this provides much better combustion and quite a bit of improvement in air flow and power. the only better stock heads i have read about are the magnum heads. it would also place the compression ratio real close to a 9:1 ratio.

eric
.
 
#16 ·
I put 360 heads on my rebuilt 318, with a mopar manifold, 600 cfm edelbrock, lower compressions you can run lower octane fuels too, also if you want to supercharge it, you will reap the bennies.

if you take material from a surface, other surfaces will be out of alignment.
 
#17 ·
GunPilot said:
... if you want to make your power/fuel economy dreams come true, is find a set of '302 casting 318 heads in the JY.... Â

...Check the '302s carefully for cracks.Â
How do I identify these 302 casting 318 heads? I'm going to the pick-n-pull tomarrow ;D

And anyone have any info on the Magnum heads Eric mentioned?

Oh, and most of my driving is city/suburbs. I rarely get it over 2600-2700RPM. I have stock 3.21 gears and 31"(actual size) tires.

I'm not sure how much the RPM's will change w/ the 35" BFG A/T's and 4.10 gears that are planned.
 
G
#18 ·
Evildriver-3 said:
Ok let me explain this again....why in the world would you mill the head and then the intake....the head is in the mill having the chamber side done.....hmmmmm remove the head and then do the intake so now the head can never be used on anything else again or you can't use another intake on that head again.....WTF is wrong with the mental patient machinist and owner for even contemplating some stupid shit like that...the head is in the mill...you make your cut...rotate the head and machine the intake face for the difference.....Anything else is retarted...actually super retarted
What is your problem now? Substituting 60 grit for Charmin again? As I said in my response, I could see what you were getting at by machining only the head, and not the intake. Perhaps you should have your reader complete the entire passage before you reply. However, to say it's "retarted" is, well, some might say retarded. Coming from you, it's single-minded ignorance. There's always more than one way to do things. Besides, typically, people build an engine, and run it til it's done. If it gets rebuilt, you're usually gonna need new heads anyway, since the smallblock Mopar heads are usually cracked. After the several years that will have passed, there would no doubt be a better alternative, pretty much negating the loss of a milled intake.

As for putting Magnum heads on, the Magnum heads are all big-port, big valve units a la 360LA, and the higher ratio rockers will kick up your gross valve specs some, but it's more than just a head swap...requiring different pushrods, the Magnum rocker assemblies, and a Magnum-compatable intake.
 
#19 ·
gen1dak said:
What is your problem now? Substituting 60 grit for Charmin again? As I said in my response, I could see what you were getting at by machining only the head, and not the intake. Perhaps you should have your reader complete the entire passage before you reply. However, to say it's "retarted" is, well, some might say retarded. Coming from you, it's single-minded ignorance. There's always more than one way to do things. Besides, typically, people build an engine, and run it til it's done. If it gets rebuilt, you're usually gonna need new heads anyway, since the smallblock Mopar heads are usually cracked. After the several years that will have passed, there would no doubt be a better alternative, pretty much negating the loss of a milled intake.

As for putting Magnum heads on, the Magnum heads are all big-port, big valve units a la 360LA, and the higher ratio rockers will kick up your gross valve specs some, but it's more than just a head swap...requiring different pushrods, the Magnum rocker assemblies, and a Magnum-compatable intake.
There is a right way, a wrong way, and the Marty way ;D
 
#20 ·
    No i make sure and learn the correct way, my way is taught to me by REAL PROFESSIONALS...where alot of people here learn is beyond me.

    G1d  again saying to just mill the head chamber and the intake is RETARDED,  atleast if you are going to tell someone something here tell them the right way and let them know what the right way is so when they run into a halfassed machinist they know and can make there own judgement....then if they also want to be retarted it's all on them

    Oh yeah i read your response in total i don't see "either way"  as saying the correct way is to do it to the head.   

  SH  instead of making dopey comments pay attention you might learn something
 
#21 ·
I have to agree with gen1dak. Based on my experience, machining the manifold is the most common method, and I certainly wouldn't call it "retarded". In fact my small block rebuild book gives the specs for how much to machine the manifold based on how much was removed from the heads/deck.

I would also think that the amount of machining on the head would be very limited, otherwise the corner where the head and block meet wouldn't line up very well leaving a gap that could only be filled with more RTV.
 
#22 ·
Electric Squid said:
How do I identify these 302 casting 318 heads? I'm going to the pick-n-pull tomarrow ;D

And anyone have any info on the Magnum heads Eric mentioned?
same as all mopar cylinder heads, yank a valve cover, clear off the grunge and look at the casting number. the last 3 digits of the casting number are what you are looking for

as for the magnum heads, you will need a mangum specific intake (kind of a waste since you already got yourself an LA intake and carb=-))

magnum specific pushrods and rockers

magnum specific valve covers

and i am sure there is somthing else i am missing here

i would stick with the LA series stuff unless you are going for a lot more horsepower than i think you are

eric
 
#24 ·
KThaxton said:
I have to agree with gen1dak. Based on my experience,
   How many heads and blocks have you  2 machined in your experience?  So you guy's both think that it's smarter and better to mill every damned intake you ever buy and switch to....and have no use for on anything else other than those heads...  So you are telling ES to mill the head only on the chamber side so he has to mill every intake he ever uses also,  this way if you decide on more upgrades later...or you want a different intake because this one doesn't suit your needs that you need to go to a machinist for every intake you buy and have it machined......Do you see the retarted problem now or do you both still think the retarted book/machinist  is telling you the right way to do things....
    If you want a different intake you need to have it machined 1st,  that's smart...right....it's smart to make intake changes just like tuning a intake also may need to be changed for another or different style i have had several motors like a different intake,  but you guy's are saying  before you or i do a trip to the machinist is needed 1st.  Intake changes are much more common when making changes and dialing in to your performance.
    Think again and find another machinist,  not 1 that wants to make more money off you making you make further trips to see them

In fact my small block rebuild book gives the specs
Â
  So does the mopar performance book...but it'll tell you the same thing im telling you...all on the head.
   You can go and write a how to build a sb mopar book too kt  doesn't mean you got it right or you actually know what it is your writing about....throw that book out too while your at it.
     Â
 
#25 ·
chrysler300le said:
ElectricSquid your 85 might already have the '302 heads. 85 was the first year for them but i'm not sure if all 85's have them. Also '302 heads are 63 cc's and not 58.
i dont know what i was thinking. for some reason wayne i keep thinking yours is an 82. lol

doug is right, you may already have them. that would be cool. pop a valve cover off and take a look.

as for the combustion chamber size, i am sure doug is right. sorry if i gave you a touch of bad info, but i could have swore i read someplace they were 58cc's

eric
 
#26 ·
I guess I'm just retarded.

BTW, I've had more heads failures than manifold failures. I'll still go about in my retarded ways. If I hadn't machined my retarded intake years ago, I would have had to take my "new" retarded heads in to the retarded machinist and have him put it on his retarded machine and retardedly machine them.

Since my manifold was machined, I don't have to do anything this time to match up with my new heads.

WOW, look at that, another point of view!  ::)
 
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