Is there a simple/easy way to ID a 273 engine vs 318?

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67CBodyGuy

67CBodyGuy

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I'm looking at a '67 Windsor-built car that the VIN says had a 318 (which means it would have been a polysphere).

The current owner (who to me has an unknown level of familiarity with vintage Mopar mech/tech) says the car has a 273. Maybe someone told him that, and he doesn't know any better. I don't know.

I haven't been to the car, it's a bit of a drive for me.

Is there an easy way to know if it's a 273 vs 318? I have an LA318 in one of my cars and I know it's impossible to see any block stampings with the exhaust manifold in the way.
 
Just under the front of the drivers side head, there is a flat place on the block right where the head and block meet. Scrape the paint off that pad and you will see a string of numbers. Somewhere in that string of numbers, you will see either 273 or 318. You will probably need a gasket scraper, a small, stiff wire brush and a can of brake cleaner to get it cleaned off to see.
 
For starters look to see if it has a driver's side exit Cast Iron (thinner) Water pump. Common with the 273, and 68 - 69 318s.
If it has an aluminum water pump then you know it is a later 318.

Timing marks on the passenger side instead of the drivers side like the later 318s.

Just for starters.

Then there is the block casting over the starter on the Drivers side if you can get to it, will show 273 or 318.

Have fun.....


* * * * *
 
The small block demonized numbers just above and slightly forward the strater location are the easy numbers to see and pictured below where the last 3 numbers grouped are the displacement. Sometimes after the displacement number there is a dash and another number. Disregard for CID ID.

image.jpg


image.jpg
 
FWIW - Though to hard to read under the paint but shown below are more ID numbers that contain the displacement of the engine under the drivers cylinder head. If you look hard enough and expand the picture, the numbers “360” are there on the right side.

Normally a bit hard to see due to heavy paint, like below or just years of dirt and grease, it’s just easier to go look above the starter.

image.jpg
 
Vertex_Jeff said:
Arent the valve covers on a Poly completely different looking than an LA?
Click to expand...
YES! But the Poly did come in multiple displacements as well.

277, 301, *I THINK* 315 & 318, I’m sure I’m missing a few.
 
67CBodyGuy said:
I'm looking at a '67 Windsor-built car that the VIN says had a 318 (which means it would have been a polysphere).

The current owner (who to me has an unknown level of familiarity with vintage Mopar mech/tech) says the car has a 273. Maybe someone told him that, and he doesn't know any better. I don't know.

I haven't been to the car, it's a bit of a drive for me.

Is there an easy way to know if it's a 273 vs 318? I have an LA318 in one of my cars and I know it's impossible to see any block stampings with the exhaust manifold in the way.
Click to expand...

Here, this will help you...

www.forabodiesonly.com

How to ID a Small Block Engine Block:

Many people ask how do I find out what a small block engine is? You can find out alot about it if you know where to look.... The first question is: "How do I know what size it is?" That can be easily found out by looking at the driver's...
www.forabodiesonly.com www.forabodiesonly.com


The last year of the poly 318 was 66...

The LA 318 began in 67...

www.forabodiesonly.com

Factory V-8 Engine and Cam Specs by Year 1965-1975

I'm an info guy and like gathering information... I first started a spread sheet on Chrysler factory V-8 engine specs back in the early 2000's but did not have a complete set of service manuals to go year by year, so there were some gaps in my...
www.forabodiesonly.com www.forabodiesonly.com
 
67CBodyGuy said:
I'm looking at a '67 Windsor-built car that the VIN says had a 318 (which means it would have been a polysphere).

The current owner (who to me has an unknown level of familiarity with vintage Mopar mech/tech) says the car has a 273. Maybe someone told him that, and he doesn't know any better. I don't know.

I haven't been to the car, it's a bit of a drive for me.

Is there an easy way to know if it's a 273 vs 318? I have an LA318 in one of my cars and I know it's impossible to see any block stampings with the exhaust manifold in the way.
Click to expand...
NOT MINE - 1967 Monaco convertible $5000 CDN

The owner has posted in that thread and it sounds like the 273 was installed to replace a 318 by a previous owner.
 
krazykuda said:
The last year of the poly 318 was 66...
Click to expand...
Semi-hemi (ie poly) 318 was available in 67 just not in A bodies.


Poly valve cover
Screenshot_20240106-144146.png



LA valve cover

Screenshot_20240106-144226.png



What to look for under the leading edge of the driver's side head. The leading letter is the model year C =67 D = 68 etc.

Screenshot_20240106-144410.png
 
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George Jets said:
For starters look to see if it has a driver's side exit Cast Iron (thinner) Water pump. Common with the 273, and 68 - 69 318s.
If it has an aluminum water pump then you know it is a later 318.

Timing marks on the passenger side instead of the drivers side like the later 318s.

Just for starters.

Then there is the block casting over the starter on the Drivers side if you can get to it, will show 273 or 318.

Have fun.....


* * * * *
Click to expand...
The water pump thing tells you nothing, except that the engine is presently equipped with the earlier pump setup. They made 340s like that as well

I always start with the numbers on the block under the driver side head parting line, as mentioned above. If that does not resolve the issue, then get dirty, get underneath, and look for block casting numbers

I once swapped Commando heads, valve covers, and 273 4bbl intake onto a THREE SIXTY, so you can't tell by looking at the top end!!!! LOLOL
 
My 66 273 doesn't have "273" by the casting number but the casting number tells the story. This # is for 64-66 273 only. There was also a #2806130 for some 65's and up to 69 when 273 production ended. I don't see any LA 318's that share the same casting numbers.

engine 179.jpg
 
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I thought it would have been common knowledge as far back as 30 years ago that Canadian 318's in 1967 were still polysphere's, speculation is that they were the leftovers from the US. If there's an example of a Windsor-made Mopar in 1967 with a small block that is an LA block (not the "A" polysphere) I'd like to know more about that.

So a curbside look under the hood is going to be challenging to ID the block (273 vs 318) other than seeing the scalloped lower edge of the valve covers which will tell you it's a polysphere but not if it's a 273 vs 318.

As to the story of this car, who in their right mind would replace a 318 with a 273 in a C-body? A convert C-body at that? Even if that happened 30 years ago, where would you get a 273 from? It would have been a no-brainer to replace it with an LA318 if anything (but a 383 would naturally been more logical).
 
Well hey.... Though you never said exactly what this car is,
back then, except for the Chrysler and imperial branded ones they did put even /6s in C Bodies
Chryslers and imperials only got big blocks "stock" back then ...
So I have to assume and deduce from the clues you do give that this is a Dodge or Plymouth branded C body... so why not a 273? If the car in question was originally a 318, a 273 would at least bolt up the same where a /6 wouldn't..... We've all been there, need an engine to get a chassis mobile and take what's available at the time just for that sake ....and a 383 wouldn't bolt up to a SB trans either ( using what you said above)
 
I know they put /6 in C-bodies. I had a Canadian '65 Polara 4-dr with a /6 (and a Fury interior and dash).

A US Monaco / Polara in '67 got 383's standard unless maybe you special ordered a 318. In Canada the standard was a 318 unless you upgraded to 383 or maybe special ordered a /6 (it might have been that some 4-dr Polara's had /6 as standard in Canada, I'd have to read the sales brochures really carefully to verify that).

Our family had a '65 Coronet wagon and I think it had a 273 (I think it was originally a US car). My '67 Monaco (2d HT) that my dad bought new had 318 (poly) but I replaced it in '87 with an LA 318.

While I'm here -

I bought a front sub frame at Moparfest last year (it's in really really really good condition) and it turns out it's probably from a Fury. It's got /6 mounts. That sucks. I understand there's really no adapters for mounting a small block. Best course of action is to cut away the entire K member and replace with my old / original K. But I'd still need to get shorter torsion bars (can't re-use mine).
 
67CBodyGuy said:
Is that really the most distinctive difference between the two? (I already know the answer, but I have to ask)
Click to expand...
Yes it is the most distinctive feature. My post 16 has photos of the two distinctly different valve covers.


They are different engines. There might be internal parts that are interchangable?

But it's easy to tell a poly from an LA by the valve covers.
 
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