Replaced engine?

[Linas]

Hello,

My 1973 AMC Javelin's documents say that it has 5.7 liter (343 cu inch) engine. However, according to VIN number, the engine should be 304. Based on the photos of the engine, would you be able to tell which size is it? I would appreciate any opinions on this topic. Thanks

[FL_Javelin]

343's only available 67-69. Not sure what documents you are talking about. In V8's only 304/360/401 were available in 1973.

Every AMC block is stamped with the cubic inches on the block. I think it is drivers side near the motor mount. Someone correct me if I'm wrong.

Hard to tell from the photos, I mostly see after market stuff anyways.

[Linas]

343's only available 67-69. Not sure what documents you are talking about. In V8's only 304/360/401 were available in 1973.

Every AMC block is stamped with the cubic inches on the block. I think it is drivers side near the motor mount. Someone correct me if I'm wrong.

Hard to tell from the photos, I mostly see after market stuff anyways.

I know, that 343 were available only between 67 and 69. What I mean by documents are the current registration car papers with indicated technical parameters of the engine (size 5,7 liter; 209 kw). I will check for the stamp near driver's side engine mount.

Thing that got me confused was the mismatch between VIN number for 304 engine and documents, saying that it is 343.

[a440plus6®]

A 5.7 is a 360 not a 343...

[Linas]

A 5.7 is a 360 not a 343...

Are you sure? I converted this number with the tool I found in the internet and it showed 343. Maybe I'm wrong...

[a440plus6®]

ooops, I think I'm wrong....5.9 is 360....sorry
Jerry

[Linas]

Every AMC block is stamped with the cubic inches on the block. I think it is drivers side near the motor mount.

I was looking for this number everywhere I can reach on the block (driver side), but still did not find it...

[a440plus6®]

It is actually "cast" into the block. Reach between the motor mount and trace the raised surfaces with you fingers to tell. You will feel raised numbers. You almost have to be a contortionast to do it but that's the easiest way.
Jerry

[donsjave]

As already stated the numbers are underneath the motor mounts on either side. If you do not see any numbers being either in CI or Metric, then you have what is called a Service replacement block. These blocks came from AMC for replacement of defective motors within the warranty time of the engine itself. These motors will not have any identifying numbers to tell you what you actually have.
Also, my bet is if this is the case then you may have a 304 in it. Not the 343 as you may think. But this all depends on previous owners and what they did to the car. On some rare case, someone could have actually put in a 343 but I would find that somewhat confusing because the 360 was probably a better motor and it was available at the time.

[Linas]

As already stated the numbers are underneath the motor mounts on either side. If you do not see any numbers being either in CI or Metric, then you have what is called a Service replacement block. These blocks came from AMC for replacement of defective motors within the warranty time of the engine itself. These motors will not have any identifying numbers to tell you what you actually have.
Also, my bet is if this is the case then you may have a 304 in it. Not the 343 as you may think. But this all depends on previous owners and what they did to the car. On some rare case, someone could have actually put in a 343 but I would find that somewhat confusing because the 360 was probably a better motor and it was available at the time.

Thanks for explanation. So now I can say it for sure - there are no numbers on any side of the block identifying the size of it. Therefore I assume that the engine was replaced, as you wrote. How to identify, what size is this Service replacement block? Were they always replaced with the same size, as the original block, which might have had a defect?