Yes. The mexican blocks have more nickle in the blocks making them much stronger. Also, they have huge main caps. They are not 4 bolt mains, but they are so big and thick they act like a 4 bolt main. Many people compare them to 289 Hipo blocks, or Boss 302 blocks. I have heard of people using a Mexican block instead of a Boss block to preserve the boss block for later use, but they can use it because its almost as strong as the boss block.
The 302 Mexican block has the thicker, Hipo 289 style main caps. Whether it's any stronger than a regular 302 block is a topic for debate. There is a 351W Mexican block, but it's no better than any other 351W block, same caps. It can be distinguished from the outside by a "knob" cast into the front of the block on each cylinder bank just below the cylinder head mating surface. The 302 Mexican block has a similar knob cast into the same spot on the left side only. It also has an odd casting number, can't think of it, but in the usual place. There might be other markings, but I can't think of them right now. It's been a while since I last saw one.
Here's a pic of my Mexican 302. The two knobs on each side of the front of the block is how you can tell without dropping the pan. The large main caps are visible here. In the liter valley it says "Hecho en Mexico". It weighs 138 lbs bare with the main caps only installed.
If in fact there was a 351W Mexican block, I've never seen it referred to as desireable for it's strength advantages. Whereas, given the choice between a stock 302 and a Mexican 302, the Mexican would be picked every time for a performance buildup.
Do you mean cylinder wall thickness? I did have it sonic tested.
Or do you mean the side thickness of the bottom of the block walls?
I got a pretty good weight from the "bathroom scale" method. I could be off a pound or two. Not 15 though. I would be curious about the standard 302 weight. Bare with just the main caps installed. Maybe we could settle the "high nodular" issue once and for all.
Yes, since bore spacing is a known quantity, one can use feeler guages in the water jackets between the cylinders to extrapolate cylinder wall thickness. Not a substitute for sonic testing for core shift but does give a general indication. I was curious if the Mexican block had thicker cylinder walls...
Regarding weight, I do believe your findings and am curious as to where the extra weight is (besides the main webs/caps)...since IIRC, a standard 289/302 block weighs around 120 or so.....I often would just grab them by the main caps, press up straight, and walk them around the shop...when I was younger, of course..*G*
Your hypothesis/reports regarding alloy are a definite possibility, as would be one regarding the nodular density of the casting material...I've never quantified this before but it is interesting nonetheless...
What I'd give for one each of all of Ford's engines...*G*
Give me a day or two and I'll see what I can do. Time is short right now. My schedule is out of wack due to a change in work hours. (Days to grave).
I have both the curiosity and the thirst for knowledge to totally evaluate the Mex 302. As you have seen here on the VMF, not everyone agrees about the strength/desireability of this block. However, I'm convinced it's a stout chunk. I can at least take some measurements of those areas that may hold a clue to the weight disparity. That may lead us to some valid conclusions.
Thanks Joe...I'd also be curious to view pictures of the main webbing (between the cylinders in the main cap area) as well as the pan rail webbing. One can tack on 10-15 lbs real easy in those areas...
I hope you don't mind but I'm pulling all related pix you post and storing them in my online VMF images folder on my web site. At some point, if you wish to do a tutorial on the Mexican block, I'll be happy to host it for you.
I think it a worthwhile endeavor. My wife just got me a new digi cam for my birthday (yesterday). She was tired of me using hers all the time. (She uses hers for her decorating business.) Nothing fancy, but gets the job done.
Interesting. I'll have to shuffle through my 351W blocks and see if one is "Hecho in Mexico". I've never heard a definitive answer to the Mexican iron quality question. Seems like if someone competent (Pat?) with the proper testing equipment had one of each side by side it would simple to find out if the iron of one was "better". Brinnell hardness tests and such.
Lay a bare pre 74 and a post 74 351W side by side and I can tell which is which just by the lack of material around the main webs on the later block. Other than miking stuff, that's about the limit of what I can contribute.