How can I tell a 273 from a 318 from a 340 from a 360?

How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 04:45 PM

I though I already posted this question, but I can't find it. Maybe it got deleted?

Anyway, I simply want to know how I can visually tell the different LA engines from one another (not disassembled)? If someone tells me they have a 340 in their car that I am thinking about buying, how can I tell it is a 340 versus a 318 or 273 or 360?

Also, how can I tell a carburated magnum engine versus the LA engines? All of these questions apply to an engine residing in a car.

Thank you in advance.

Posted By: 1_WILD_RT

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 04:56 PM

Drivers side of block theres a fairly large cast in number... In that number you will see the engine displacement....Also on the front face of the block, just below the drivers cylinder head you'll find a series of stamped numbers... The displacement will be stamped there too...

Posted By: rattler

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 04:58 PM

If you don't mind crawling under the car, the engine size and build date are cast on the side of the block just above the freeze plugs. I forget which side.

Posted By: MoparforLife

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 05:04 PM

340 was always a 4 barrel. 360 2 barrel had a much larger Holley 2 barrel than the small 2 barrel that the 318/273 had. 340 only available in A bodies 68/73 or E bodies 70/73.

Posted By: OzHemi

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 05:08 PM

Quote:

how can I tell a carburated magnum engine versus the LA engines?

LA engine valve cover has 5 bolts, Magnums use 10.

Posted By: a12rag

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 05:17 PM

Oil pan on 360 has different diameter ends on it. 273/318/340 are both same size. 360 car pan for A, B, E are stamped 392 on the bottom - and where the sump drops down, it is approx. 3" back from the front of the lip of the pan, C body 360 oil pan is stamped different number (think it may be 789 ???) and distance from sump to front lip is approx. 1.5" . . . . 360 truck oil pan is rear sump.

I just got schooled in this after getting a 360 rebuilt and having to locate a pan for it !

As others have stated, have to look on the side of the block to see the casting numbers (i.e. displacement size) . . .

Cheers

Mark

Posted By: jbeintherockies

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 05:54 PM

Quote:

Quote:

how can I tell a carburated magnum engine versus the LA engines?

LA engine valve cover has 5 bolts, Magnums use 10.

What about the magnum engine blocks? Do they also have the displacement cast into it?

Also, I was told the magnum engine blocks (I think they started in 91 correct?) have better oiling and cooling passages. Is this true? How do they compare to the older 360 blocks in terms of strength? This question goes out to everyone.

Posted By: HotRodDave

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 06:01 PM

Magnum block have a crank sensor mount at the rear of the block on the passenger side kind of near the top of the bell housing. Yes they have cast into the side a number and in there will be either 318 or 360.

Water passages are the same and oiling is a little different, they oil the rockers from the pushrod instead of through the shaft. To tell if it has magnu heads look for the verticle intake bolts instead of nearly horizontal ones on an LA. However, that can be changed through re-drilling and so can the valve covers, simply by putting 5 bolt covers on magnu heads because the 5 holes still line up with 5 of the ten on a magnum.

Posted By: denfireguy

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 06:05 PM

Quote:

Quote:

Quote:

how can I tell a carburated magnum engine versus the LA engines?

LA engine valve cover has 5 bolts, Magnums use 10.

What about the magnum engine blocks? Do they also have the displacement cast into it?

Also, I was told the magnum engine blocks (I think they started in 91 correct?) have better oiling and cooling passages. Is this true? How do they compare to the older 360 blocks in terms of strength? This question goes out to everyone.

Biggest advantage is the roller cam. Less worry about no zinc in modern oil.
My 318 is now a 5.2L for that reason.
BTW we are fairly close to each other in Aurora.
Craig

Posted By: 318 Stroker

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/26/11 07:18 PM

Quote:

340 only available in A bodies 68/74 or E bodies 70/74.

Also available in 71-73 B-bodies...

Posted By: Supercuda

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/27/11 11:39 PM

Quote:

Biggest advantage is the roller cam. Less worry about no zinc in modern oil.
My 318 is now a 5.2L for that reason.
BTW we are fairly close to each other in Aurora.
Craig

Hmm, mid 85 and later 318's and 89-91 360's had roller cams.

Posted By: ScottSmith_Harms

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/28/11 06:33 AM

Easy, any 60's to early 70's SB has the displacement stamped right on the front of the block. The catch is that you may have to dig off grease and scrape paint to see it and the PS pump can get in the way as well.

Attached picture 6703534-340BlockAssemblyInformation(2).jpg

Attached picture 6703534-340BlockAssemblyInformation(2).jpg

Posted By: ScottSmith_Harms

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/28/11 06:34 AM

closer look

Attached picture 6703536-340BlockID(3).jpg

Posted By: HotRodDave

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/28/11 04:25 PM

My 68 273 did not have any thing stamped there and I have seen quite a few other motors in that time period that that had nothing stamped there. Any idea why some don't have nothing there?

Posted By: GO_Fish

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/29/11 02:03 AM

Quote:

My 68 273 did not have any thing stamped there and I have seen quite a few other motors in that time period that that had nothing stamped there. Any idea why some don't have nothing there?

Maybe yours was a Warranty block? Marine block?

Actually, I've never seen a small block that did not have the stamped numbers on the front of the block. But they are often stamped shallow, or incomplete, full of paint or grease, and its very easy to miss them if you are not specifically looking for it.

Posted By: jbeintherockies

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/29/11 03:33 AM

Quote:

closer look

That was very helpful. I actually thought it was cast into the drivers (?) side of the block; more like an emboss versus a stamp.

Is the CID embossed on the engine blocks also?

Posted By: GO_Fish

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/29/11 01:05 PM

yes, the engine size is also cast in large numbers on the driver side of the block. The numbers are about 1" tall if I remember correctly. Unfortunately, they are nearly behind the starter, so they can be real tough to see if you can't get under the car and the block is greasy.

Posted By: NicksGarage

Re: How can I tell a 273 from a 318 from a 340 from a 360? - 06/29/11 08:40 PM

Quote:

340 was always a 4 barrel. 360 2 barrel had a much larger Holley 2 barrel than the small 2 barrel that the 318/273 had. 340 only available in A bodies 68/73 or E bodies 70/73.

340s were also available in B-bodies.

Getting the info off the block is a good start but other parts do get mixed in over the years. I had a '71 340 Demon that had a 318 block swapped into it under the 340 top end. I also got a 340 engine out of an A100 van (not original of course). You gotta look.