360 heads on a 318 LA

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Brian Hood

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I read a few pages of How To Build HP Chrysler Engines by F. Adkins. He seemed to endorse putting swirlport heads from a 90 ish 360 onto an older 318 LA. He stated that this combo when used with a manifold for a 360 seemed to be a good power house. Has anyone here done this? Does it seem to be a better combo than a stock LA 318 ? Or would it be better off trying to get some Magnum 360 heads and adapting them?
Brian
 
Alot of this depends on what exactly your doing and/or shooting for. Often, (Build dependent) I'll recomend 360 valves in a 318 head with bowl work.
I've had stock 318's run in the low 14's before with stock heads.

Stock 360 heads are a great way to get power from a 318. Buit I would use them as a on the cheap method way to get there if the car/engine combo was track bound. A lack of low end torque is the result. In order to get past this weak area, a higher stall converter and gear ratio need to be installed. Not everyone is happy with this arrangement for a daily driver, a pure street car that grandma can drive.

What is the goal/target?
 
I am building a street engine. I want the most bang for the buck. I have a good 318 an I am trying to get the most I can from it. THe article also mentioned that I would need to get .060 milled from the heads of a 360 to use on a 318 to over come the low compression ratio. Does that seem to help?
 
Yeah but then the heads can not be used on a 340 block if the pistons stick out .018 like stock and kb hypers do. Those later year heads are known to crack between the seats, I would go J heads. Your rear axle ratio plays a part. I had 3.91 gears when I had 360 heads on a 318, was great...who needs low end power if you shift at 6,500 rpm
 
J heads were used on 71 to maybe 73 340 and 360 motors. They have no air port holes in the exhaust ports. Pretty much like the X heads but with 1.88 intakes, not 2.02. Yet its no problem to drop 2.02 intake valves in, just open the seats up.

Ebay would have them, I have a set that needs rebuilding. I'm out in S.E. Michigan, they are heavy to ship. Can do but its two boxes and each box is like $40 to ship-ouch.

I am planing on having my shop guy look at them and get some H.D. boxes from him this week, I'm guessing right now $100 would be a fair price for them. They a semi-clean and all together, a basic valve job MIGHT do it, then again they are 38 years old and look to me the valves have been cut in the past. Why I am going to ask the "man" what he thinks. Valves look not to been leaking-at least baddly.
 
..........Just get the 302 swirl port heads, they r on 85-91 LA, or get a 89-91 318 with roller cam and lifters..............kim........
 
68-69 340s had X heads...
70-71 340 had J heads with 2.02 intakes..
72-73 340 had J heads with .188 intakes

all 360s had what would be basically J heads...1.88 intake valves..all about the same peformance..some had air injector ports...some did not...some had U, Z, O casting but their performance is in line with the J heads..

i have a set of J heads that can milled down to 59 cc....and they fit fine on a domed piston..... with a positive deck piston you adjust the head gasket..

In fact..NHRA blue print spec for a early 340 is 63.3 cc...which means that head has been milled quite a bit...and the pistons blue print spec is +.045 out of the deck....
 
somebody correct me if I'm wrong but aren't the chambers on the 360 heads larger than the 318 heads? I think they are so putting them on a 318 with low compression anyway is only gonna make it lower therefore down on power, something 318's dont make a lot of anyway in stock form. I'm with oldkimmer with the "302" swirl port head.
 
In the early 70 models, yes, chambers run larger. But when you look at late 70, all 80's castings, they are very close cc wise. Only the 302 heads run much smaller. I just milled my 308 heads .030 and stuck them on my 318. Cranking compression was a laugh at 125 psi, yet the darn thing made more power everywhere it seemed.
 
Yes, the 360 heads have larger chambers, so add the cost of milling (decks and intake faces) and shorter pushrods to the swap. The 360 heads also have bigger ports which can be a mixed blessing. They will certainly flow more air and make more horsepower, but low RPM velocity so throttle response suffers. On a street engine, 302 casting heads with 1.88/1.60 valves and mild port work would make for a more flexible and responsive engine. If you were looking for a 350HP screamer, go with the big heads.
 
yes...360 chambers are larger...that is why the talk about milling the heads...

302 head has the same small ports and valves as the 318 head in stock form.
 
dodge freak said:
Yeah but then the heads can not be used on a 340 block if the pistons stick out .018 like stock and kb hypers do.
Click to expand...

He's building a 318. Not a 340. That problem you described dosen't apply. The fix is a thicker head gasket. Cometic!


Those later year heads are known to crack between the seats, I would go J heads.
Click to expand...

Seems to be a on going battle with this cracking issue.
 
rumblefish360 said:
He's building a 318. Not a 340. That problem you described dosen't apply. The fix is a thicker head gasket. Cometic!




Seems to be a on going battle with this cracking issue.
Click to expand...


Yeah but he could end up doing what I did, run the 318 until it breaks and then put in a 340 short block. Cosmetic gaskets weep water when cold, not cool for everybody.

Milling .060 is too much imo, best to stay with .030 max. Why limit your options later on? The "right way" is to replace those low compression pistons with higher compression kb pistons, wasn't an option in the old days.
 
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