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318 w/ 360 heads?

Discussion in 'The Hokey Ass Message Board' started by 19vegas56, Jun 25, 2012.

  1. 19vegas56
    Joined: Apr 4, 2004
    Posts: 30

    19vegas56
    Member

    Hi, I need some assistance from the mopar gurus. I just picked up a reman 318 shortblock for a good price. I have a 360 w/ a nasty rap in it out of my 48 plymouth. Will there be a problem using the 360 heads on the 318?
    Thanks, Jerry.
     
  2. 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.
     
  3. Low buck? if you shave .050 off the heads, just shim under the rocker shafts .025 and let er rip - no need to find 273 rockers or aftermarket.
     
  4. 41plym
    Joined: Jan 11, 2009
    Posts: 184

    41plym
    Member


  5. daliant
    Joined: Nov 25, 2009
    Posts: 685

    daliant
    Member

    Its not worth the loss of compression ratio to run 360 heads on a 318, any airflow gains will be offset by the low compression. Keep in mind the 360 is externally balanced and the 318 is internal so don't put the 360 flywheel, converter or damper on the 318.
     
  6. 50dodge4x4
    Joined: Aug 7, 2004
    Posts: 3,535

    50dodge4x4
    Member

    Since he has a short block, they come without heads, no?

    What you want to do with the engine determines what to do with your heads. If it is a street driver that will see little or no track time, be sure the heads, valves, and valve guides are good and bolt them on. Milling will bring the compression back to the 318 level, but you probably wouldn't notice the difference, short of a time slip over a stock 318.

    A 318, even where a wore out 360 was, will be down on power from the start. The 318 would need the heads milled, a bigger cam, a good 4bbl intake & carb, and a set of headers to be on par with the pulled 360, unless it was really junk. Gene
     
  7. dgg-dt1948
    Joined: Oct 14, 2010
    Posts: 74

    dgg-dt1948
    Member

  8. 19vegas56
    Joined: Apr 4, 2004
    Posts: 30

    19vegas56
    Member

    Thanks for all the info guys. This site is the best for that.
     
  9. Streight8
    Joined: Jun 12, 2012
    Posts: 125

    Streight8
    Member

    Note their comments on adding the larger valve. The 360 head is pretty much the same as the 340 heads except for the smaller valves. So a pretty cheap gain.

    This is a link I used to design my build. http://www.mopar1.us/dyno.html
    I used basically package two with package three heads and 9.5 to one compression and the 270 comp cam.
     
  10. If you are talking 340 X heads and 360 J heads, then yes they are pretty much the same and putting a set of 2.02s and doing a bowl cut to match the bigger valve gets you the same flow. Later 360 smog heads don't flow as well without some extensive porting.
     

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