1978 318 heads? Small port? Or large

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Johnny Mac

Johnny Mac

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This should be simple enough for some of you more versed in 318's than I. Some of you may have seen my other post about picking up a 78 dodge with a 318 and a 2 bbl. Was there a changeover year where all L.A. engines had the same 360 port heads? Despite 2bbl or 4? Or because this hog had a 2 barrel does it automatically have small port intake ports? Reason being im contemplating a 4 bbl intake, and want it port marched. But if its small port heads, im probably yanking it altogether as im not wasting the money on an edelbrock performer to put the planned efi (4150 flange) efi tb on.
Probably an ironic post as im not looking for power, just a cruiser, but I hate the uni-flange spread/square bore non performance intakes that sometimes even require the adapter plate.
 
All 318 heads are small port.

All 360 heads are large port.
 
So...the info I found that either 4bbl, or certain 318's after a certain point are the same port as the 360, or simply even the 318/360 heads were the same pn at a certain point...is incorrect?
 
IMO nothing wrong with small port heads on a near stock teener. Good low end torque. And the port miss match is not too big a deal either on mid performance engines. JMO!
:burnout:MT
 
So every 318 L.A. engine ever produced is small port...until the magnum series? Idk if I believe that based on all the other posts I found. I was more or less expecting a cutoff year...not a blanket...NO 318's were ever large port....but again please correct me if my thoughts are incorrect.
 
I do believe every 318 made was 2bbl. Low performance work horse, no need for large port heads. Slow and steady best describes the factory tuned 318. I might be wrong about all but......
 
All 318's are small port heads except the later year 4 bbl. equipped engines. They use 360 heads. All stock Magnum heads have the same port size, 318 or 360.
 
So unless a "later" 318 had a 4 bbl. It was a small port. Clarified. Thank u.
 
How about a year split on that? For future thread searchers.
 
Nothing wrong with a "Teen" head, upgrades for performance would be larger valves, 1.88 intakes, and 1.6 exhausts, a light chamber cut. Get a LD4B intake and a cam that works well with EFI, there's your cruzer.
 
JBurch said:
Nothing wrong with a "Teen" head, upgrades for performance would be larger valves, 1.88 intakes, and 1.6 exhausts, a light chamber cut. Get a LD4B intake and a cam that works well with EFI, there's your cruzer.
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So invest more $ into some low flowing small port heads and a cam, than a 360 long block should cost. Got it lol
 
1978 offered a 4bbl 318 for California. Do not know if they had large port or small port. Check your cylinder head casting number under the valve cover and then it can be for sure.

All 2bbl 318s had small port heads from '67 to '89. At least some 4bbl motors had 360 heads- same cast #s and all, '84 was the last year for civ cars/trucks/vans to get it, cop cars also had them from '85-'89. For some stupid reason they quit offering the 4bbl on civvy models after the 302 head came out and the pistons changed to up CR, which would've made the 4bbls motors much nicer. '85-91 318s are 302 heads/equivalents unless a 4bbl motor. Magnums are the same 318/360 in ports and valves but may have different cast numbers oddly.

The small port heads are a good weight bare for use as an anchor if you've got a nice sized boat.
 
johnnymac2k6 said:
So invest more $ into some low flowing small port heads and a cam, than a 360 long block should cost. Got it lol
Click to expand...

From your own stated purpose, not a big power just a cruzer, you're not gonna feel the difference......if you think you are...build your self a 408 with a forged crank, H beam rods, forged pistons and max ported Eddies......you'll be happy with nothing less
 
Here we go again. Lets keep this thread informative about 318 heads. tmm
 
Had a 78 D100 with 318 4 barrel...thermobog.....dont remember what heads were on it...
 
There were Police/Highway Patrol Dodge Diplomats (etc.) during the 1980's that used a 318 with a four-barrel carb. Probably used 360 cylinder heads. This can be verified by further internet searching or by one of the fans of the former/older California Highway Patrol vehicles.
 
78, 2bbl has small ports, no need to look at casting #'s.
They also have smog ports that need plugged if you run headers.

LD4B if you can find one is about the best port match you will find.

Weiand makes the only new one that is close to the port size, but at least you have a choice between spread bore and square bore.
 
dibbons said:
There were Police/Highway Patrol Dodge Diplomats (etc.) during the 1980's that used a 318 with a four-barrel carb. Probably used 360 cylinder heads. This can be verified by further internet searching or by one of the fans of the former/older California Highway Patrol vehicles.
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It was an option on all cars and trucks from 1978 until 1984. 1981 Gran Furies and St. Regises also had the 318-4 as the top motor since the E58/car 360's last year was 1980. At least the E48 performance motors had 360 top ends. My recollection's that the E48 performance 318 was offered in '80 as well. (I recall one or more H code E48 '80 cars prior to the VIN character count change of '81)

Most of the 4bbl cars had leanburn, the trucks'd likely be hit or miss.

sireland67 said:
78, 2bbl has small ports, no need to look at casting #'s.
They also have smog ports that need plugged if you run headers.
Click to expand...
I saw that after my post and left that just since all '78s that could have 318s could have 360s, so it's worth checking what the block is under the head surface.
 
johnnymac2k6 said:
So...the info I found that either 4bbl, or certain 318's after a certain point are the same port as the 360, or simply even the 318/360 heads were the same pn at a certain point...is incorrect?
Click to expand...

The 318 4 barrel engines were port mismatched from the factory. There was NEVER a small port 318 4 barrel intake made. They simply slapped the 360 intake on the 318 and called it a day. So......all 318 heads are small port and all 360 heads are large port.
 
rumblefish360 said:
All 318's are small port heads except the later year 4 bbl. equipped engines. They use 360 heads. All stock Magnum heads have the same port size, 318 or 360.
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Negative. Chrysler never used the 360 port size heads on the 318. Not even on 318 police cars. They simply slapped the 360 4 barrel intakes on them.
 
"Since 1978, the big port 360 head has been used on the 318 as part of the E48 high performance four-barrel or police option." Quote by Larry Shepard, author of the How to Hot Rod Small Block Mopar Engines book.
 
toolmanmike said:
"Since 1978, the big port 360 head has been used on the 318 as part of the E48 high performance four-barrel or police option." Quote by Larry Shepard, author of the How to Hot Rod Small Block Mopar Engines book.
Click to expand...

Larry Shepard has made a LOT of mistakes in those books. I think that is one.
 
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