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Hey you MOPAR guys...

Discussion in 'The Hokey Ass Message Board' started by Tim Rocheford, Mar 31, 2010.

  1. Tim Rocheford
    Joined: Oct 24, 2007
    Posts: 28

    Tim Rocheford

    This spring I was going to try and freshen up the heads on the 318 in my dad's '57 pickup. The plan was to get a spare set of heads and have them gone through so the truck's engine wouldn't have to lay open for a week while I wait for the machinist to get done. A friend, who has a pile of 318's laying around, said I could pull a set of heads and have them. I pulled a set and dropped them off only to get a call from the machinist saying that the heads I left with him, which were in beautiful shape (his words), are 273 heads. I have never heard of a 273. He said he's never come across a 273 either. He also told me that these heads will not work on my dad's 318. Is there a way to make them work or am I back to square one?
  2. Retro Jim
    Joined: May 27, 2007
    Posts: 3,860

    Retro Jim

    Don't you have a Poly 318 engine ?

  3. Tim Rocheford
    Joined: Oct 24, 2007
    Posts: 28

    Tim Rocheford

    Whats a Poly 318? I don't usually mess with mopar stuff. The motor came out of a '76 Plymouth Fury. This truck was my dad's pride and joy, he's been gone five years today. I could put a Chevy in it, but then he'd haunt my ass, not to mention the MOPAR guy that'd probably string me up from the nearest telephone pole
  4. you have an LA 318 same familly as a 273 , 273 cameout in 64 or 65 ...i think....

    i had one in a 65 belvedere good engine when you pulled the heads off the 273 did it have a 4 factory 4bbl on it? or did it have black wrinkle coated valve covers with little aluminum finned squares on them ?

    if it did then its a commando 273 very good engine the original high performane mopar small block

    the 273 heads will bolt to a later 318 but the ports are alot smaller

    a poly 318 was usede from like 58 -67 it is some times called a "big block" 318 which it isnt it has very unusuall valve covers on it they were good decent performance engines hard to find parts for
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  5. SteadyT
    Joined: Sep 11, 2007
    Posts: 483


    273's are awesome. 8 grand rev if built well.

    Do you want to put 273 heads on your 318? No.

    Find out what heads you pulled off the 318. They might not be the factory ones for that motor. If they are X or J casting hang on to them (they SELL easy).

    My opinion, put some 360 heads on that sucker.
  6. The 273 is the original LA motor. In it's solid cammed 4 barrel incarnation in a light a-cuda or dart it was a good performer, but when the 340 came out and started giving the big block guys a fit, it was forgotten about.

    The heads off the 273, while they are a bolt on to the 76 318 have a different angle on the intake faces and a different bolt pattern. It looks close, but it won't fit. Just find some 318 heads (not at all hard to come by!) and save yourself a headache.
  7. 360 heads flow a bit better, but you take a hit in compression by about a half a point with the bigger chamber. Considering the 318 is under 8:1 real compression, that is 2 steps back. I have pocket ported 318 heads and had great results with a 340 cam, a good dual plane intake and some small tube headers on an otherwise stock 318 in a heavy car.
  8. The Poly 318 is the older MoPar design before the LA (Lightweight “A” Engine) motors, if your dads motor is a ’76 motor; it’s likely an LA 318.

    The 273 CI motors were the first of the LA castings that came out in 1964. They were common in the Darts Valiant’s and Barracudas of that era. The early 273 heads were beveled at a different angle intake manifold than 318/340 LA motors. If you use them you may need to find a new intake to go with it.

    If you get Magnum 318 (after 1992) heads you will get a better breathing design and there all over the junk yards in van & trucks. The guys on the “For A Body’s only’ web board will be glad to give you lots of good advice.

    Attached Files:

  9. 340Fish
    Joined: Nov 10, 2008
    Posts: 101


    273, 318, 340, 360 LA engines will all accept the same heads. The 273 items have smaller ports and therefore small intake manifold runners. Find any set of LA heads with hard valve seats and you're well on your way. If you get stuck and need a contact, message me. I can direct you to a guy in NY that will send you a set at a very fair price... 99% sure he'll have a couple sets. He may also have some of the 308 swirl port heads but they are getting harder to come by.

    from forabodiesonly;

    The casting numbers for most LA heads are found in two places. On the underside of the head on an intake runner, and under the valve cover on an intake runner.

    Casting Number Under Valve Cover on Intake Runner. Casting Number on the Underside of Head on Intake Runner.

    LA Engine Cylinder Heads Casting Numbers

    Casting Number Engine CID Year Intake Exhaust
    2465315 273 1964-65 1.78 1.50
    2536178 273 1966 1.78 1.50
    2658920 273 1967 1.78 1.50
    2843675 273 1968-69 1.78 1.50
    2658920 318 1967 1.78 1.50
    2658234 318 1967 1.78 1.50
    2843675 318 1968-74 1.78 1.50
    3769973 318 1975-83 1.78 1.50
    4027163 318 1977-86 1.78 1.50
    4027593 318 1977-84 1.78 1.50
    4323302 318 Fast Burn 1985-86 1.78 1.50
    4323345 318 Police 1983-86 1.78 1.50
    2531894 340 1968-70 2.02 1.60
    3418915 340TA 1970 2.02 1.60
    3418915 340 1971-72 1.88 1.60
    3671587 340 1973 1.88 1.60
    3418915 360 1970-72 1.88 1.60
    3671587 360 1973-74 1.88 1.60
    3769974 360 1975-76 1.88 1.60
    3671587 360 1976 1.88 1.60
    4027569 360 1977-86 1.88 1.60

    as well as;

    51 318/360 1977-83
    308 360 Swirl? 1989-93
    596 318/360 1977-83​
  10. Tim Rocheford
    Joined: Oct 24, 2007
    Posts: 28

    Tim Rocheford

    Thanks guys. The 318 in the truck has regular old valve covers, nothing unusual that would indicate anything out of the ordinary. I'll just hunt up another set of heads. Maybe I can sell the 273 heads and recover a little of the investment I've already made in this project.
  11. Tim Rocheford
    Joined: Oct 24, 2007
    Posts: 28

    Tim Rocheford

    I knew if I posted a question here I'd have an answer before my luch break was over. You guys are the best around.
  12. SteadyT
    Joined: Sep 11, 2007
    Posts: 483


    Agreed. If this is a driver truck, and not a HOT ROD truck, the 360 heads would be a sufficient and cheap move.
  13. HotRodChassis
    Joined: Jan 23, 2005
    Posts: 2,283

    Alliance Vendor

    And breath better. 318 head aren't the best for flow, and really, neither are the 340 heads.

    I love the HAMB. Almost as much a nice MoPar thread. :D

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