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BRINGING IT ALL TOGETHER.... A's, G's & E's


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SIN BIN
67a 100 pickup
6 posters

    273 vs. 318

    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

    273 vs. 318 Empty 273 vs. 318

    Post by 67a 100 pickup Mon Sep 06, 2010 4:51 pm

    Looks like I am going to have one of each to put in the '67 pickup. I know there is about 20 ft lbs difference in torque and 30 hp, but which one would you put in???
    SIN BIN
    SIN BIN


    Number of posts : 68
    Location : Vancouver, BC
    Registration date : 2010-07-05

    273 vs. 318 Empty Re: 273 vs. 318

    Post by SIN BIN Mon Sep 06, 2010 4:55 pm

    My vote is the one with more HP & Torque...but that's always my vote Laughing
    jkr
    jkr


    Number of posts : 1148
    Location : prince edward island canada
    Age : 65
    Registration date : 2008-05-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by jkr Mon Sep 06, 2010 5:22 pm

    wish i could get my hands on all the 273's out there. if your 273 has a mechanical camshaft go with it. ( adjustable rockers ) it should be about 230 hp. the best the 318 had was 210 hp. there are about the same aftermarket internal engine parts available for both but the 273 will rev higher and faster. the 273 commando engine was and still is a great drag race engine in stock classes for its ability to rev high and make great hp across the tachometer. one thing of note is the 273 needs a better torque converter than stock to get the power from the engine, about a 3000 stall converter. still very streetable though.
    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by 67a 100 pickup Mon Sep 06, 2010 5:26 pm

    Thanks jkr... I'll get the serial # off the block when I get it home. To pull more out of the 273 should I go with a 3.55 or 3.91 posi??
    jkr
    jkr


    Number of posts : 1148
    Location : prince edward island canada
    Age : 65
    Registration date : 2008-05-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by jkr Mon Sep 06, 2010 5:33 pm

    the 3:91 will spin the engine about 400 to 500 more rpm at 60 miles per hour than the 3:55's
    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by 67a 100 pickup Mon Sep 06, 2010 5:36 pm

    What rear gear do you have in yours?? And what rpm are you pulling at 60??
    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

    273 vs. 318 Empty Re: 273 vs. 318

    Post by RodStRace Mon Sep 06, 2010 6:48 pm

    unless they are free and run well, I'd hold out for a magnum motor and put the carb intake on.
    The magnums have better breathing, will probably have fewer miles (no rebuild) and be just as easy to bolt in.
    You can grab one for ~200 here in the yards. Grab a newer starter while you are there. You might even want to grab all the serp belt stuff, although it may require some work to get it working with just a WP and alt.
    The intake is ~330, so it's not cheap, but you would still be cheaper than rebuilding the others.

    http://chucker54.stores.yahoo.net/inman.html
    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by 67a 100 pickup Mon Sep 06, 2010 6:59 pm

    Both of these "old dogs" run and don't burn oil, so it's add electronic distributer for now and a newer power plant is down the list right now.
    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

    273 vs. 318 Empty Re: 273 vs. 318

    Post by RodStRace Tue Sep 07, 2010 5:43 am

    <thumbs up!>
    No sense spending chrome money on an engine if you have a good one (or 2)!

    The starter might be a good idea anyway, and you want to convert to an electronic voltage regulator for the EI to be happy and bypass the AMP gauge.

    http://www.madelectrical.com/electricaltech/amp-gauges.shtml
    slowflapper
    slowflapper


    Number of posts : 956
    Location : GA
    Age : 54
    Registration date : 2010-07-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by slowflapper Tue Sep 07, 2010 10:26 am

    I've thought about this myself as I have a 273 in my van.

    In your situation I would go with the 318, mainly because parts are cheaper and/or more readily available (intakes, heads etc) if you want to build it up for horsepower. An aftermarket 273 intake for example is going to cost a lot more than it's 318 cousin (in my experience) and they aren't interchangeable (different bolt angles). I don't get too exotic on my engines anyway as good street performance is enough for me (I don't plan on racing the van Wink ). A standard build out for me is carb/cam/intake, aftermarket e-ignition (mallory), headers, Edelbrock carb and that pretty much wraps it up. Just looking at the Offenhouser 4 barrel intakes for the 273 makes my wallet hurt Smile

    My own plan is to just get my 273 "running right" and to make it as reliable as possible and keep it as stock as possible (I am doing some things for heat control though). Down the road, after everything else is done, I plan on building a 318/360 with some stones and doing a remove/replace on the 273 and bagging/saving the OEM motor.
    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by 67a 100 pickup Tue Sep 07, 2010 5:34 pm

    I'm with you on the big HP. The plan after getting the truck complete is to get a mancini stroker kit for the 318 and take it to 390, but that is at least 2 years off right now.
    jkr
    jkr


    Number of posts : 1148
    Location : prince edward island canada
    Age : 65
    Registration date : 2008-05-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by jkr Wed Sep 08, 2010 2:49 pm

    while working for a machine shop here we did a comparison on magnum and stock heads for flow. both from 318's or 5.2 engines. worked out to about 6% more for the magnum heads. that is not enough of a gain to see it on a dyno sheet. the newer magnum heads oil different so care must be taken when interchanging old and new parts. it get EXPENSIVE............

    slow flapper ; some of the casting numbers from 273 heads are the same as 318 and i personally don't remember there being a difference in the intakes but i am as old as dirt and getting forgetfull. poly heads were definatly different and wont work
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    273 vs. 318 Empty Re: 273 vs. 318

    Post by Guest Thu Sep 09, 2010 9:23 am

    Is the 273 similar to the 318 Poly....or more like the 318 La.
    Is it "wide"...or narrow? ARe the intakes the same?
    benwah
    benwah


    Number of posts : 1135
    Location : the land of broken dreams and shattered hopes CT
    Registration date : 2008-07-05

    273 vs. 318 Empty Re: 273 vs. 318

    Post by benwah Thu Sep 09, 2010 11:06 am

    The 318 poly is a whole diffrent animal. 318 la has a wider spread than a 273 for intakes. The bottom ends are interchangeable.
    slowflapper
    slowflapper


    Number of posts : 956
    Location : GA
    Age : 54
    Registration date : 2010-07-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by slowflapper Thu Sep 09, 2010 12:12 pm

    benwah wrote:The 318 poly is a whole diffrent animal. 318 la has a wider spread than a 273 for intakes. The bottom ends are interchangeable.

    On a side, the 273 is actually an LA series engine as well, just the smallest of them in a v8 (you know that already thought). As far as I know (from searching the WWW) the intake bolt angles are different (273 vs 318/340/360) but I haven't personally tried to swap one out so try find out for certain. I'd love to get a cheap Summit/Edlebrock dual plane 4BBL intake for my motor but all the ones I've seen are far from cheap rabbit

    Offenhauser seems to be the only one's Ive found for 273's and they run >$200 each.

    eta: this might help:
    link to allpar

    The intake manifold was special hybrid single/dual plane design that incorporated two plenums, one for each side of the engine. They were joined by a specially sized rectangular passage that solved lean/rich problems that occurred with the initial, purely dual plenum design that dedicated one barrel of the BBD to each bank. This was done to reduce the overall height of the engine and allow installation in the (originally /6 designed) Valiant engine compartment. (Thanks, Jim Deane.)

    Since the bolt angle on the intake changed in 1966, the 1964-65 heads and intake are unique and cannot be interchanged with other LA engines or with the later 273.

    So maybe they are interchangeable after '66?
    jkr
    jkr


    Number of posts : 1148
    Location : prince edward island canada
    Age : 65
    Registration date : 2008-05-29

    273 vs. 318 Empty Re: 273 vs. 318

    Post by jkr Thu Sep 09, 2010 4:02 pm

    poly or polyspherical as they were offically known used the same block as la engines but the intake, heads and valvetrain were completely different.

    wieand intakes used to make a four barrell intake for 273's but they are hard to find. if you use the thick paper intake gaskets from a 360 and a four barrell from a 318 i am sure it will work on a 273. most of the ones i experimented on were late build engines 67 68 69 .
    the last generation 4 barrell intakes used on dodge cars were fitted with g-m quadrajet spreadbore carbs.!!
    benwah
    benwah


    Number of posts : 1135
    Location : the land of broken dreams and shattered hopes CT
    Registration date : 2008-07-05

    273 vs. 318 Empty Re: 273 vs. 318

    Post by benwah Fri Sep 10, 2010 7:32 am

    Actually 318 heads will bolt on your 273. Its fitting the 340/360 heads on a 273/318 that you will run into some issues. I believe the pushrods are at a diffrent angle. You can do a little head work to make them fit.

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