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???
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67a 100 pickup
6 posters
273 vs. 318
67a 100 pickup- Number of posts : 1319
Location : ann arbor, mi
Registration date : 2009-01-29
- Post n°1
273 vs. 318
SIN BIN- Number of posts : 68
Location : Vancouver, BC
Registration date : 2010-07-05
- Post n°2
Re: 273 vs. 318
My vote is the one with more HP & Torque...but that's always my vote
jkr- Number of posts : 1148
Location : prince edward island canada
Age : 65
Registration date : 2008-05-29
- Post n°3
Re: 273 vs. 318
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- Number of posts : 1319
Location : ann arbor, mi
Registration date : 2009-01-29
- Post n°4
Re: 273 vs. 318
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- Number of posts : 1148
Location : prince edward island canada
Age : 65
Registration date : 2008-05-29
- Post n°5
Re: 273 vs. 318
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- Number of posts : 1319
Location : ann arbor, mi
Registration date : 2009-01-29
- Post n°6
Re: 273 vs. 318
What rear gear do you have in yours?? And what rpm are you pulling at 60??
RodStRace- Number of posts : 3046
Location : Chino Valley
Registration date : 2010-01-21
- Post n°7
Re: 273 vs. 318
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
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- Number of posts : 1319
Location : ann arbor, mi
Registration date : 2009-01-29
- Post n°8
Re: 273 vs. 318
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- Number of posts : 3046
Location : Chino Valley
Registration date : 2010-01-21
- Post n°9
Re: 273 vs. 318
<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
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- Number of posts : 956
Location : GA
Age : 54
Registration date : 2010-07-29
- Post n°10
Re: 273 vs. 318
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 ). 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
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.
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 ). 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
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- Number of posts : 1319
Location : ann arbor, mi
Registration date : 2009-01-29
- Post n°11
Re: 273 vs. 318
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- Number of posts : 1148
Location : prince edward island canada
Age : 65
Registration date : 2008-05-29
- Post n°12
Re: 273 vs. 318
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
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
Guest- Guest
- Post n°13
Re: 273 vs. 318
Is the 273 similar to the 318 Poly....or more like the 318 La.
Is it "wide"...or narrow? ARe the intakes the same?
Is it "wide"...or narrow? ARe the intakes the same?
benwah- Number of posts : 1135
Location : the land of broken dreams and shattered hopes CT
Registration date : 2008-07-05
- Post n°14
Re: 273 vs. 318
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- Number of posts : 956
Location : GA
Age : 54
Registration date : 2010-07-29
- Post n°15
Re: 273 vs. 318
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
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- Number of posts : 1148
Location : prince edward island canada
Age : 65
Registration date : 2008-05-29
- Post n°16
Re: 273 vs. 318
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.!!
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- Number of posts : 1135
Location : the land of broken dreams and shattered hopes CT
Registration date : 2008-07-05
- Post n°17
Re: 273 vs. 318
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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