ok i have two questions i have a 1991 dodge dakota with a la 318 im doing a 360 swap and want to know if the heads off my 318 will fit to raise the compression ratio if so i also want to put some 340 valves in my heads and port and polish them can anybody point me in the right direction with this im also going to us my tbi intake

 

What year is the 360? If it's a magnum it won't fit at all, if it's also an LA, your wasting your time cause the 318 and 360 heads are exactly the same.

 

the 360 is from an 80's model van and the heads are from a older 318 like early 80's

 

It won't fit...

 

why is that

 

... and what info do you have to back that up?
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If they are both LA blocks, the heads are swappable. I don't know much about LA blocks, cause I have a magnum and am building my 408 stroker out of a magnum, so the magnums are what I've spent my time researching. I know for a fact that the heads on the 318 magnum and 360 magnum are exactly the same, same part number, same cc's. I would assume the old LAs were the same way, but I'm not 100% sure. My guess is if you did the swap you'd be wasting your time. Your best bet is to get the block and heads decked down 0.020" to 0.030" and get a smaller gauge head gasket. That will up the compression ratio.

 

The 318 heads will fit on the 360. But whether or not it will increase the compression I don't know, it depends on what the cc's of both heads are. And I don't know much about the 340. But you can search for the answers at http://www.allpar.com/mopar.html

 

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


The 360 heads and Intake swap will fit on the 318, but the compression will be around 7.2:1, which is not very good for performance, which is not to say that the heads cannot be shaved .050 and intake be rematched to fit, adjustable rockers added to offset the rocker geometry, and away you go.
The book says the 360 to 318 works well, but, take the 318 heads, shave .020 off the head, install 1.88 intakes vice 1.78, port the heads and you would have a better combination, especially on the bottom end response and will still rev as high as you want and float the valves before the power falls off (how can you beat that?). It can be done, but, if you have a 360, which is physically the same dimensions externally as the 318 and 273, why not go the least expensive route? Keep in mind that the 318 runs about 8.5:1 compression and will be about 8:1 or as low as 7.5:1 with the J heads of the 360. This is going to drop the compression pretty low, which is great for cheap gas, but bad for the performance side, thus most 318s are rated at the 185hp, which is a shame


By 1977, 318 heads were only 1.0 c.c. smaller than the 360's. From 1968 through at least 1984, all 'LA' heads, either 318, 340 or 360 were of the 'open' chamber design. The 318 chambers were in the 61-62 c.c. range to 1975 then they slightly increased to about 63 and then to 65 a couple of years later. The 360 heads at that time were mostly 65's. If you mill either the 318 or 360 heads by about .005'', the chamber volume will be reduced by 1.0 c.c. Therefore, a cut of .050'' will reduce the 'c.v.' by 10 c.c.'s. This will in turn raise the C.R. by 3/4's of a point, on average; depending on the piston diameter.

 

If you can find a shop that will machine down the intake. I had tried to get the intake mill down to match the heads but the only was the high performance shop, and cost some BIG bucks for a Little Hp increase. Because none of the other shops had a setup (Jig) to line up the magnum intake. I know yours is not a magnum but it might be the same thing. I wish I could do it at my job. I could make it perfect. Very easy when you know how to do it. But you know how bosses are.

So the max without doing the intake is .030 on the heads. For the magnum so the LA blocks are probably similar. But you can also take off .030 or so on the block. Just need to take it all apart and measure the TDC of the highest piston and see what can be milled down.

 

yes but this is 360 heads on a 318 i want to put 318 heads on a 360 to jump the compression ration up a little like 9-1 or9.5-1 and 340 valves are 2.02 on intake and 1.60 on exhuast