Chevy 3970010 block

[ventura74]

Anyone know anything about the Mexican blocks? I have two with casting numbers 3970010. I've been told by a few people they are good blocks and some machinists say they know there harder by the way they machine. Just wondering if there good for a street strip block. Thanks

[mag2555]

Your plenty safe to 550 hp, but if boring over .030" I would get it sonic checked!

[Carnut1]

I put a mexican block in the old work truck. Still in there. I think the rational for such a heavy casting is the machining tolorance was so bad if they made the casting thicker more blocks would be useable! Think about it, if the machinist finishing the block is not highly skilled every machine operation is off and tolerance stack causes blocks to be unusable. Not all are machined badly, in fact the one in the old work truck measured more like a bowtie block. Very heavy cylinders which is why I used it. Expect to spend a full day plus deburring and detailing a Mexican block. We had a saying at the machine shop I was part of. How do you know a Mexican Chevy crank? When you pick it up you will be bleeding! The sharpest edges on any crank ever. Can you say stress riser? Same 441 casting number.

[mag2555]

Here's a question, did Chevy use Armsteel ( Nodular iron ) for there SB 4 bolt main caps , or the same iron they used for the blocks?

[Bob Hollinshead]

some of the blocks came with caps numbered 2482 which are supposed to be stronger.

[racear2865]

Dont remember seeing a 010 block from Mex but that surely doesnt mean it wasnt made there. I guess I just remember they were only 60 and 70 blocks. As I remember they came as 2 bolt and 4 bolt and had 2 types of main cap. One was supposedly nodular and grey cast. Other than that no difference. Blocks are only cast iron block, nothing special.. But hell Ive been wrong more than once
reed

[Frankshaft]

Here's a question, did Chevy use Armsteel ( Nodular iron ) for there SB 4 bolt main caps , or the same iron they used for the blocks?

I know the 400 blocks with "N" caps are made from better material and are stronger.

[Warp Speed]

some of the blocks came with caps numbered 2482 which are supposed to be stronger.

Those are the nodular iron caps.
There was another block, (048 maybe?, been too many years) they came with nodular caps and always had better core shift than the 010 blocks of the same period.

[user-612937456]

There is minimal strength difference between any of the older factory blocks. If you are concerned about building 600 horsepower instead of 550 HP or you are building a High revving high compression engine I would not be too concerned about casting #'s or Latin/maple-leaf blocks or what ever. The window of difference between the worst 010 blocks and the best 048's or 482's is small when compared to aftermarket blocks or even the factory bow-tie's.

From my experiences I would say the major reason to be picky is if you need to over bore it .040 or .060 being picky about core shift and critical of cylinder wall thickness.

If you are building north of 500+ HP and or a high RPM solid roller, consider that after you add the value of the block plus the machining cost of a full race preparation. You can add a few hundred dollars additional to the cost and you can have the insurance of an aftermarket block that can basically handle twice the horsepower reliably.

If you are building horsepower on the raged edge of what a factory block will probably handle you could risk $1,000's to sometimes $10,000+ that may potentially be a total loss if you have a catastrophic failure. I always build on the conservative side if I use a factory block.

[Barry Burch]

The 010 at the end of the part number means it
Has 10 percent nickol in the iron mix. A harder
better block.

[maxracesoftware]

Anyone know anything about the Mexican blocks? I have two with casting numbers 3970010. I've been told by a few people they are good blocks and some machinists say they know there harder by the way they machine. Just wondering if there good for a street strip block. Thanks

i ran a Hencho en Mexico 010 Block , had thicker Cylinder Walls than the USA 010 Blocks
stock GM Chevy 3.480" Crank Rod Journals turned down 2.000" small journal Carrillo 6.000 HBeam Rods
M55HV oil Pump Ed Hamburger Oil Pan full length kickout alum
4.030x3.480
made 720 HP @ 9000 RPM
483 TQ at 6700 RPM

8000 Stall 7" inch A1-Converter
9200-9300 Shift
9800 to 10000 Finish Line RPM 5.14 gears 1.82 PowerGlide 12x33 10x15 Rims
60 FT =1.070
7.56 ET at 181.459 MPH
1420 Lbs w/Driver Rear eng Dragster

surely 500+ HP is very safe , even 600+ HP

[Ericnova]

The 010 at the end of the part number means it
Has 10 percent nickol in the iron mix. A harder
better block.

That has long ago been proven to be utter hogwash, old wives tale, internet BS. No truth to it at all.

[user-612937456]

The 010 at the end of the part number means it
Has 10 percent nickol in the iron mix. A harder
better block.

Thats like saying the 666 at the end of the serial# of a dollar in your pocket means it was printed in hell by Satan NOT! They are just random numbers chosen by the luck of the draw.

[ventura74]

Good to hear maxracesoftware I probably won't be much over 500 hp. Thanks for all the replies

[Barry Burch]

I could not state with certainty the block had
nickol or bubble gum added. What I DO know
Is my machinist showed me with a rockwell tester
the block is damn