Trenton vs Mexico engine blocks

[135sohc]

Why are the Mexico cast blocks considered better than the Trenton cast blocks ?

I've read all the reasoning and personal spin everyone has put on them. But looking at the two side by side. externally they look pretty similar ?

[turbovanman²]

It is said the machining is far superior as is the metalurgy.

Per Gary's site-

Additionally: All of the T-III blocks were machined at the Saltillo plant, in Mexico. Why? They were able to keep the tight spec requirements for the forged piston application, along with other reasons. Close inspection of the cylinder machine code, (i.e. the 'A','B','C', or 'D' stamped on the under side of the block) on the T-III engines will indicate consistent machine sizes. If my memory serves me correctly nearly all of them should be "C's". In any case, they were kept very consistent (Nearly all will be the same letter). Inspection a Trenton block (i.e. most T-I, T-II, and T-IV's) may expose a cluster of cylinder combinations. For example, 'A'-'C'-'D'-'B' or 'D'-'D'-'A'-'C'. Their spec.'s were not maintained as tightly, as the Saltillo plant.

[contraption22]

Supposedly the Mexican blocks had less core shift. But I think it's hit or miss either way.

[135sohc]

Update on this with pictures of both.

Now that I have examples of both sitting around I thought I would take pictures and document the differences.

Mexico block in this comparison is a 94 casting originally 2.5L. Trenton block is a 93 casting and was a 2.2L.
Both are/were TBI engines, hooked up to automatic transmission.

94 mexico
93 Trenton

94 Mexico close up showing extra cooling passages.
93

93 Trenton with cross drill holes and nothing else.


another picture of 93 Trenton. its got 1 single extra cooling hole in the center and nothing else.


And the last pictures of the outside. Mexico block shows a much higher degree of surface finishing and overall casting quality. Theres very little 'garbage' stuck on the surface of the block.

All that roughness that looks like grease/oil/dirt is actually cast iron splatter and is all over the surface of the block. most removes with a chisel & hammer in large flat chunks.

another view of the trenton block and surface showing extra metal splatter.



Moving onto the bottom/inside of the block.

94 Mexico shows an overall smoother casting and better finish quality.


93 Trenton. lots of casting flash and mismatching on where the halves of the mold didnt quite lineup...



close up of casting. 94 Mexico


93 Trenton



Now the good part.

94 Mexico. Quite a bit of extra metal in that bulkhead


93 Trenton. Same spot.


Same bulkhead (#2) 94 Mexico


93 Trenton


Now some would say the extra metal in the Mexico block is due to it being a balance shaft equipped engine from the factory. But if you look closely there is enough metal on the trenton block to drill & tap for the extra BS assembly bolts. Just nowhere near as much. For someone looking to add the 4 bolt main caps that could make quite a difference in the overall strength and effectiveness of having the extra boltdowns for the center 3 main bearings.

Final comparison. 94 mexico block, The thickness of the 'shelf' where the bearing sits is nothing less than 10mm thick.


93 Trenton block. bearing support shelf is considerably thinner on every bearing bulkhead.

[turbovanman²]

Nice work,

[looneytuner]

Mexico was a new state of the art plant with better casting process. I think it is called vacuum forming. Much smoother castings and less shifting of the sand forms.
Aside from cheap labor there was the Nimby factor for a foundry in the US. Not in my back yard. And the US plants had to convert to electric. REALLY high energy price.

[ShelGame]

This thread needs to be combined with my tall deck thread and put into the KC - like now!

[turbovanman²]

This thread needs to be combined with my tall deck thread and put into the KC - like now!

Pitter patter,

[BadAssPerformance]

Nice work,

Agreed KC article time

[135sohc]

Before any of this is 'set in stone' as differences between the two castings. It would be better to see more examples of each to see if theres any pattern to it.
or at the very least an exact opposite of these two. 2.2 mexico, 2.5 Trenton to see if theres such a difference in the webbing on the bottom end.

[BadFastGTC]

What is the difference in weight between the two blocks?

Before any of this is 'set in stone' as differences between the two castings. It would be better to see more examples of each to see if theres any pattern to it.
or at the very least an exact opposite of these two. 2.2 mexico, 2.5 Trenton to see if theres such a difference in the webbing on the bottom end.

[135sohc]

Dont know.

just from toting them around in the garage they felt about the same.

I dont have a scale right now and there both preserved, wrapped up and in storage until warm weather returns.

[jory]

Did they stamp letters on the piston tops? All the pistons in my 84 2.2 block have the letter B on them.

[135sohc]

atleast on the later blocks its stamped on the rear block rail where the oilpan seals up to it.

http://s254.photobucket.com/albums/h...t=DSC09988.jpg

Thats the mexico block and all the bores were 'C' sized.

[thedon809]

Did they stamp letters on the piston tops? All the pistons in my 84 2.2 block have the letter B on them.

My 86 block has that too. It also has b stamped where the oil pan bolts on like the mexican block.

[CobraT93]

I think "B" designates the piston size? ie: A,B,C,D,E,etc. It is stamped on the block so the guy assembling it knows what size the bores are to install the correct piston size.

[135sohc]

Yes the letter stands for the piston size from the factory.

[R/Tony]

Its good to know this!

Those years of Chrysler Mexico were the best.

[GLHS60]

Another thing to document could be the different styles of block at the front seal retainer area. There are at least two style common blocks I have seen but don't know if it is a year or plant difference or something else. KC article sounds like a great idea with pictures of the different blocks.

As to the A,B,C,D & E stamps, after machining the blocks are meaaured and assigned a tolerence letter."A" indicates a standard bore and is assigned an "A" piston. "B" indicates a bore measuring .00025" oversize, "C" =.00050" and "D" = .00075" and each should receive a matching piston. E = .0001 and these pistons were sold through D.C. and M.P. as slightly oversize or standard high limit. I don't think there were any "E" blocks so the "E" pistons would have normally been discared by Chrysler along with the 804 injectors and H.D. engine mounts.

Thanks
Randy

[ShelGame]

^ those were probably 90's built service blocks for the early non-CB. It would be good to find one of those to document, too. I suppose it could have CB style webbing, but be setup for a fuel pump and the early seal housings.

FWIW, the Tall Deck block uses the exact same seal housings as the CB.