found a used 318 with 70000 miles on it.beleive he said its a 1968. has a 340 purple cam in it with j heads. hes keeping the heads but the stock heads come with it also throw in a set of rebuilt never been on an engine 360 heads. has receipts for close to 600 in head rebuild. wants 300 for everything. can the 360 heads be run on the 318 or would i be better off using the stock heads. its going in my 70 d100. its just a driver not going to be raced.im thinking the 360 heads will run but maybe lower compression. thanks
360 heads on a 318. will it work?
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caferacerx
BAND MEMBER
how low can you go?
compression wise that is
318's left the factory as low compression workhorse's with small chamber heads they are only 8:1 - 8.5:1
if you put large chamber 340 or 360 heads on one you will lower the already minimal compression possibly down into the 7's, great for cheap gas, bad for everything else
also the larger ports of the 340, 360 heads will lower intake velocity with a resulting loss of low end torque
compression wise that is
318's left the factory as low compression workhorse's with small chamber heads they are only 8:1 - 8.5:1
if you put large chamber 340 or 360 heads on one you will lower the already minimal compression possibly down into the 7's, great for cheap gas, bad for everything else
also the larger ports of the 340, 360 heads will lower intake velocity with a resulting loss of low end torque
ive been doing some reading and seems if i have the 360 heads shaved .040 off they should do ok with the 340 cam and i will add a performer intake and carb. im also ok getting the stock heads checked out and run them if the 360 heads will totally kill it.
mullinax95
Well-Known Member
Also I believe the intake ports are larger on the 360 heads. If you have a 318 intake the ports will not match the 360 head ports.
mullinax95
Well-Known Member
You don't by chance have the "302" heads do you on your 318?
If you mill the heads that much, you will end up milling the intake also to match.
I have run "J" heads on a fresh 71 318 for years using a stock 340 six-pac cam.
Used a performer intake and a 600 holley. Did not like it. wrong combination. When it started pulling good, the intake and carb just would not flow.
Put a weidan single plane on it with a 750 vacuum secondary and the engine come alive on top end but still not much bottem end, pulled really good after 3K rpms.
Your truck should have 3.91 gears, at least my last two d100's had them.
I would buy the motor with both set of heads, and figure out what you want to do with it for the price you were offered.
I have run "J" heads on a fresh 71 318 for years using a stock 340 six-pac cam.
Used a performer intake and a 600 holley. Did not like it. wrong combination. When it started pulling good, the intake and carb just would not flow.
Put a weidan single plane on it with a 750 vacuum secondary and the engine come alive on top end but still not much bottem end, pulled really good after 3K rpms.
Your truck should have 3.91 gears, at least my last two d100's had them.
I would buy the motor with both set of heads, and figure out what you want to do with it for the price you were offered.
the trucks geared 3.23 with 3 speed manual. the guys gonna remove the j heads and keep them. havent seen any of it yet dont know about what stock heads he had on it. if i get it all whats a good set of 360 heads worth? doesnt sound like i want to use them.
In the late 70's early 80's I build a 1973 318 with 360 J heads, steel 340 crank, 471 lift purple shaft cam and 430 rear gears. This engine make killer horse-power and was one of the fast cars in the York, Pa area!
j5dart
Well-Known Member
I built A 72 318 and used 360 heads. At the time I was told it couldnt be done. I put it in A 73 challenger with 727 manual valvebody 2500 stall converter and a 391 gear. It ran a very respectful 13.60 quarter mile. Not bad for the late eighties!
mullinax95
Well-Known Member
Any idea what compression you was running? KP, J5dart
It really depends on the casting numbers, I sold my last set for $150 but they were 587.
This can help you determine what they are, but for $300 for everything, I cannot forsee you getting hurt unless something is really broken in the short block.
http://www.mymopar.com/headcastnumb.htm
That manual trans is really close, deep first and second with a wide 1.1 in third.
You will have plenty of bottom end with the 3.23 trans.
I drove the same trans with a 225 and 3.91 as a daily driver for years. It was geared to low but the drum brakes and straight axle it ran what it was designed for.
You will have plenty of bottom end with the 3.23 trans.
I drove the same trans with a 225 and 3.91 as a daily driver for years. It was geared to low but the drum brakes and straight axle it ran what it was designed for.
mr.318
Well-Known Member
My 318 ran good with the 360 heads, i had the 302 heads and changed to the 360 heads, and went from a 9 flat to an 8 68 in the 1/8 mile, But my block was zerodecked and had K,B. pistons, It's just who you talk to some say no to the 360 heads others have had good results, If it's just a streeter i stick with the 318 heads the 360 heads, killed my gas mileage
j5dart
Well-Known Member
The pistons and bore were not changed. I cant remember what cam i used but i did remove a crane fireball because the car fell on it's face for the first part of the quarter.
Somewhere around 8.5 to 1
Chrysler did it from the factory on all the police motors in the 1980s. They were 318s with 360 heads. They used the same pistons as the earlier motors too.
Supershafts
Well-Known Member
Mill the heads 40 to 50 and have the intake face done also so you can use any intake you want with no other issues....
needsaresto
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I had a 1983 Plymouth Caravelle rwd cop car with the 318 4bbl motor. It had 360 heads and a super low 7.5:1 or so compression ratio. The bottom end torque was real soft,mid range tq was great. Takes a big cam to use all that port on a 318 with 360 heads. I'd not reccomend it unless you cut those 360 heads 40 or 50 thou and the intake face to match.Thinking the 318 head would be much better. With a clean up of the ports/bowls and 360 valves,the 318 head becomes a great match to a mild to mid performance 318. Keeping things reasonably cammed for the street is important,you wont like having a cam with more than 235 deg of duration for the street.Those 360 heads a re a good price though. I'd buy em anyways,and trade or sell for what you really need.
zakimodo
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X2. Look at my sig.
oldrookie
New Member
I also have been researching what heads for a ‘18. I’m concluding there are different replies because of different goals.
I also notice the post that discourage the 360 heads don’t mention what they are running but the posts favoring the 360 heads are running 360 heads. I’m concluding 360 heads work and work well when the engine is tuned (geared, carbed, cammed, manifold etc) for them. You didn’t mention an intake but the head and intake I believe need to match. If you go the ‘18 route then get a ‘18 port size intake, and likewise if you go the 360 head route get a 360 port size intake.
I’m guessing you want economy and a smooth cruising low / mid rpm performance. That may be what others recommending the stock ‘18 heads want.
I want maximum quarter mile acceleration; don’t mind pulling 6200+ rpm and so I am leaning toward putting some milled 360 heads on my ’18 even though I have perfectly good stock ‘18 heads.
Look at what your goal is and what the rest of the package is and then make a decision and be ready to adapt if it doesn’t perform the way you planned.
When I get ready to step up my ‘18 to the next level I hope to find some fresh 360 heads for $300.
I say buy the package, put the combination together that is consistent with your goals and let us know how it worked or didn’t work.
I also notice the post that discourage the 360 heads don’t mention what they are running but the posts favoring the 360 heads are running 360 heads. I’m concluding 360 heads work and work well when the engine is tuned (geared, carbed, cammed, manifold etc) for them. You didn’t mention an intake but the head and intake I believe need to match. If you go the ‘18 route then get a ‘18 port size intake, and likewise if you go the 360 head route get a 360 port size intake.
I’m guessing you want economy and a smooth cruising low / mid rpm performance. That may be what others recommending the stock ‘18 heads want.
I want maximum quarter mile acceleration; don’t mind pulling 6200+ rpm and so I am leaning toward putting some milled 360 heads on my ’18 even though I have perfectly good stock ‘18 heads.
Look at what your goal is and what the rest of the package is and then make a decision and be ready to adapt if it doesn’t perform the way you planned.
When I get ready to step up my ‘18 to the next level I hope to find some fresh 360 heads for $300.
I say buy the package, put the combination together that is consistent with your goals and let us know how it worked or didn’t work.
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