Mexican Block Gurus come on in...

[poneypower89]

Ok,
I just found out that I have access to a Mexican Block for a fairly decent price. I have been planning on freshening up my engine with a rebuild but now Im thinking why freshen up the stock block when I can get a stonger mexican block going on the stand while I drive the pony around? Anyways, I have a few questions.

1) What parts will interchange with my stock block to the mexican block? (I was told that the crank and flywheel are different.. is this true and is there anything else I should be aware of?)

2) Plans call for a 331 stroker, and since the mexican block apparently has a different crank, what stroker kits are out there that fit it?

3) This is of course, like always, a budget build so Im shooting for an e-cam and thumper combo with the rest of my mods in my sig. Will thumpers feed a 331 well? Remember I do have a blower to help push the air. Is a mild 400whp easily obtainable with this combo?

Thanks for your help guys. Right now, the most important thing to me is making sure what parts will interchange and what wont!

 

[stangjunkie]

im certainly no block guru but i believe all the parts are the same... only difference was where they were made and materials used... dont quote me wait for someone else to chime in

 

[RS200]

ALMOST everything is interchangable. To run an E-cam, you'll need a specialized lifter because the Mexican block isn't a roller cam ready block. Crane makes them, but they cost around $400, IIRC. With the OEM heads and mild porting you won't see 400WHP..275-300 if you've got all your bolt ons and you're very lucky. It's basically a 5.0 block with more strength and more weight. Anything that fits in the 5.0 block (5.0 is a 302, too) fits in the Mexican (302) block except the aforementioned cam.

 

[poneypower89]

im certainly no block guru but i believe all the parts are the same... only difference was where they were made and materials used... dont quote me wait for someone else to chime in

Well, I know there is more differences than that... the mains are different for sure (which I think is the reason for needing a different crank) plus they us Hi-Po caps and such.

In either case, I could only wish all the parts would be interchangable... but its a little hard to believe until I can get some back up for what u said.

 

[poneypower89]

ALMOST everything is interchangable. To run an E-cam, you'll need a specialized lifter because the Mexican block isn't a roller cam ready block. Crane makes them, but they cost around $400, IIRC. With the OEM heads and mild porting you won't see 400WHP..275-300 if you've got all your bolt ons and you're very lucky. It's basically a 5.0 block with more strength and more weight. Anything that fits in the 5.0 block (5.0 is a 302, too) fits in the Mexican (302) block except the aforementioned cam.

275-300 hp? I pretty much making that now man. Its gonna be a 331 stroker with my blower strapped to it. I hope 300 isnt the max.

So the cam is the difference? Not the crank? and 400 bucks is a large chunk for just lifters.

 

[RS200]

My mistake..I thought you said you couldn't afford a blower. Can you give me the compression ratio of your 331 as well as any other bolt-ons you haven't mentioned in your sig?

The engines are 95% the same...they are both 302s, and all 302 internals (save for cam) are interchangable from one to the other. You won't see any power increase at all just by using the Mexican block. The difference is longevity. The stock 5.0 block is a ticking time bomb at 500HP, whereas the Mexican block is known to handle over 900. Right now my suggestion is to stay with the stock block, and step up once you are at the stock block's limit. You can run your SC up to about 14 psi on a very well tuned setup (get aluminum heads), and that will put you close to the 500 mark.

 

[poneypower89]

My mistake..I thought you said you couldn't afford a blower. Can you give me the compression ratio of your 331 as well as any other bolt-ons you haven't mentioned in your sig?

The engines are 95% the same...they are both 302s, and all 302 internals (save for cam) are interchangable from one to the other. You won't see any power increase at all just by using the Mexican block. The difference is longevity. The stock 5.0 block is a ticking time bomb at 500HP, whereas the Mexican block is known to handle over 900. Right now my suggestion is to stay with the stock block, and step up once you are at the stock block's limit. You can run your SC up to about 14 psi on a very well tuned setup (get aluminum heads), and that will put you close to the 500 mark.

It's alright man. I've missed important details on post before too.

Im not looking for an HP increase because of the block itself. Im looking for the performance increase with the extra cubes that come with the 331 stroker and added realiability over the stock block at those power levels. The reason Im shooting to use the mexican block over the stock block is for the following reasons.
1) One is available to me for a good price.
2) Having the extra block would allow me to build the engine on the stand while letting me keep the stang up a running. Down time would be minimized.
3) The stock block has 120,000 miles on it and I beat it like a red headed step child. More boost is inevitable. I need something that can handle it.


The plan so far is for something simple.

-Take a mexican block, bore and stroke it to 331.

-Use Thumper Heads with an e-Cam. It sounds like u have little faith in these parts so you may not be familiar with the thumpers. Check out the thumper website, stock e7's manage to outflow gt-40s and Dart. www.thumperoforangepark.com

- Keep the stock compression ratio

- Re-use all mods I already have which include:

Vortech SC-Trim (upped boost to 11-12 psi)
Aluminum Discharge tube w/by-pass kit
BBK/WALBRO 190lph Fuel Pump
3:73 Gears
BBK H-pipe
BBK Equal Length Headers
Flowmaster Cat-Back
Spec Stage 1 Clutch
Steeda Adjustable Quadrant Clutch Kit
Cobra Intake Manifold
BBK 70mm Throttle Body
73mm Vortech/C&L MAF

Again, the power isnt my main concern. I just need to make sure this is a do-able project that isnt going to cause alot of headaches due to parts not interchanging. Are you sure the cam is the only difference?

Yeah, I could rebuild my motor... but why do that when this is my chance to get a stonger block? Who knows, future mods are alway inevitable... it would suck to keep the stock block and find myself pushing the limits in just a few years ya know? Sorry for the long post, but i gotta get all the information possible before this is attempted.

 

[RS200]

If it's available to you, then go right ahead. Just do your research to know which lifters to use, and have the engine built by a pro. Consider a custom ground cam en lieu of the E-cam. The E303 is getting older and more outdated. A custom grind gives you a lot more power, for only a few bucks more. With all the mods, you should be around 400HP. Good luck!

 

[bobcatv8]

The Mexican 302 block will completely interchange with a '70s era 302. It uses all non-Mexican 302 parts save the main caps. All it really is is a thicker & heavier cast block in the main bearing webbing area including the caps. I have heard but that they are cast with a higher nickel content but I don't think that is true. It would make a nice upgrade as long as you got it cheap and will have all the same swap issues with an '80s roller block as any '60s and '70s era 302 would. No more, no less. You must also remember it is a 30+ year old block so be careful there!

 

[Blk91stang]

Your recipe for a combo tells me you should make at least 450rwhp. I'm making 405rwhp with a stock cam and a 130k mile 302.

 

[poneypower89]

The Mexican 302 block will completely interchange with a '70s era 302. It uses all non-Mexican 302 parts save the main caps. All it really is is a thicker & heavier cast block in the main bearing webbing area including the caps. I have heard but that they are cast with a higher nickel content but I don't think that is true. It would make a nice upgrade as long as you got it cheap and will have all the same swap issues with an '80s roller block as any '60s and '70s era 302 would. No more, no less. You must also remember it is a 30+ year old block so be careful there!

Ok, I know I might start sounding repeatitive here... but when you say "you will have all the same swap issues with an 80's roller block as any 60's and 70's era 302 would" what does that entail ENTIRELY! Im talking, part for part and piece by piece. The description is a little vague to me cuz I dont know what that swap entails ya know?

If the block checks out on the magnaflux what else is there to worry about? I dont think its been in a car running for at least 15 years. My machinist has a few of these mexican blocks stored away at his shop. Willing to get rid of one just to me because we're family friends for 100-150. I do believe thats a decent deal considering they go for about 400 on ebay minus shipping.

I dunno, whats everyones opinion on this plan? Worth the work? Worth the money? Im freshening up the powerplan in my car regaurdless this summer anyways, just hoping the mexican block route isnt gonna put me too far out.

 

[poneypower89]

Your recipe for a combo tells me you should make at least 450rwhp. I'm making 405rwhp with a stock cam and a 130k mile 302.

Lets hope

For a long time I really wanted to just mimick ur setup... If you remember I sent you a few PMs a while back. But, now that my engine is getting old with numerous oil leaks and such, a rebuild is in order so Im playing with going a lil bigger and stronger.

 

[RS200]

The roller issue just means that the Mexican block has no provisions for a roller block (that spider thingy in the lifter valley), which is fixed by using the special lifters. Only "problem" you'll run into.

 

[57fairlane]

The cranks will work. The mains are the same size.
Go with an F-cam for the increased cubic inch size and it being on a 112 with a blower vs. the 110 of the E.

The mexican block is an exceptional piece that IMO is better than the sportsman.

 

[Blk91stang]

Lets hope

For a long time I really wanted to just mimick ur setup... If you remember I sent you a few PMs a while back. But, now that my engine is getting old with numerous oil leaks and such, a rebuild is in order so Im playing with going a lil bigger and stronger.

I'll be following you in the next year or so. rebuild with a 331 and custom cam on top of my existing combo. If your not satisfied remember you can always upgrade to an S-trim trim for not much more money which is capable of over 500rwhp.. You'll be happy!

 

[bobcatv8]

'80s 302--1 piece rear main seal, '70s 302--2 piece rear main seal.
'80s 302--hole drilled in lh side of block for rear sump dipstick. '70s 302 no hole, must use pan with dipstick provision.
Thats about all, no biggie but you might want to know.

 

[mikemustang289]

When you buy your kit be aware of the differences between the balance factors of the engines.

Roller blocks are 50oz, what you have now. The Mexican block is designed for 28oz applications

I believe stroker kits come in either balance, but you may run into a slight issure using a 50oz crank in an early block. From what I've been told the two piece rear seal in the 28oz application is designed for the earlier 28oz cranks which are machined differently than the 50oz cranks which accommodate a different seal.

I remember reading this somewhere but in order to use a 50oz crank in an older block some grinding may need to be done. But don't quote me on that, maybe someone here can set this straight.

If you buy a 28oz kit, you will need a new balancer along with a new flywheel/flexplate to match.

 

[mikemustang289]

just a side note to your question about power.

MM&FF dynoed a 331 with bone stock E7's and a comp 274hr cam.

Peak power 351 hp @ 5300rpm
Peak torque 400 @ 4400 rpm.

With ported heads, similar cam, and a blower, 450+ hp easy

 

[poneypower89]

When you buy your kit be aware of the differences between the balance factors of the engines.

Roller blocks are 50oz, what you have now. The Mexican block is designed for 28oz applications

I believe stroker kits come in either balance, but you may run into a slight issure using a 50oz crank in an early block. From what I've been told the two piece rear seal in the 28oz application is designed for the earlier 28oz cranks which are machined differently than the 50oz cranks which accommodate a different seal.

I remember reading this somewhere but in order to use a 50oz crank in an older block some grinding may need to be done. But don't quote me on that, maybe someone here can set this straight.

If you buy a 28oz kit, you will need a new balancer along with a new flywheel/flexplate to match.

Wow, ok... So ill prolly need a new oil pan, 28oz crank in the stroker kit, balncer, flywheel/flexplate, AND the special lifters?

Im just wondering how much extra is gonna cost to make the mexican 331 work over just the stock block... so far, it seems the mexican block is gonna run about 6-700 more...

 

[bobcatv8]

Aftermarket block startin' to look a little better now, aint it?
Yes the 2 piece rear main seal cranks are machined a little differently so that is one more area you would have to address using a '70s era block. Get with your stroker kit people and see what they say about that first.
Sometimes a good deal on a part may not be just what you need!
Good luck!