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I have a 68 El Camino with a SBC. Block casting number is 3970010 which, I've read, can be a 307, 327 or a 350. The number stamped on the front pad under the alternator is MB04800. The MB is listed as either a 1967 327 or a 1968 307. In trying to decipher this ID code I thought that the M indicated Mexico. The 0480 to be the dates of April, 1980. Not sure about the extra "0". This is the information I found while trying to solve a fuel problem. I have replaced everything from, and including, the fuel tank all the way to, and including, the carburetor. Not sure if I have the correct fuel pump. Any help will be greatly appreciated.
 

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The 010 block is a 4 inch bore casting it was used on late 302’s not 307’s, 327’s and for a long time on 350’s. It is a medium main journal casting. It is found in 2 and 4 bolt versions of the center 3 main bearing caps

Considered a heavy duty casting it found homes on high output cars like the SS Impalas, Z28 Camaros and certainly Corvettes all the way through heavy duty trucks. They were used in domestic production for model years 1969 through 80 and it lives on as a Mexican built over the counter replacement block to crate engine. Most Mexican blocks are finished as heavy duty truck engines with 4 bolt mains. All of these use the two piece main rear seal that has a history of leaking oil. This casting makes a great performance build platform the castings are a bit beefier than those used in lower power options of the production 327 and 350’s there being only high output versions of the 302. But the 302 originally grew out of the early 327 and like that motor the early 302 uses the small journal crank. But given you have a Mexican Over The Counter (OTC) block these only are machined for the medium size main journal crank.

The stamped build code only tells you this is from the Mexico assembly plant. There is no end use suffix stamp because this is a replacement engine and they don’t know what it’s going into. Basically it’s a Goodwrench engine. These came early on as a low power truck replacement engine later GMPP dressed a version up with a performance cam otherwise everything else was the same as the Goodwrench which uses the 150 to 300 horse cam power dependent on head’s, compression ratio snd carb 2bbl low compression on the low end model camel hump high compression head’s and 4bbl on the top model. The (OTC) base engine they rate at about 190 to 210 hp. This varies across the years and why this is so given none of the specs change is to be pondered? The hotter cam version is rated at 290hp with a GMPP intake and 4bbl carb with iron exhaust manifolds. These engines actually have some good parts in them but all use an ocular iron crank where some original installations had forged cranks, all have forged mild steel rods on the earlier versions with forged powder rods on the later versions. The early versions use cast low silicon alloy dish pistons the newer versions use cast hyper-eutectic dish pistons. All use the low compression SMOG head’s. For the high output version the compression is too low for the cam, a lot of power and better fuel mileage is to be had with modern 64cc, heart chambered and higher compressioned head’s.

Bogie
 

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I have a 2003 vintage GM SBC 350 Mexican-made crate in my truck and it’s been a reliable engine overall. The low compression (estimated at 8-8.2] and stock low flow GM heads are the most significant weaknesses.

You can get a good horsepower increase by adding a good dual plane intake and carburetor, and an upgraded cam (usually best to stay below about 212-214 @ .050 duration ) and headers. For any higher power gain you need better cylinder heads and more compression. Adding a big cam with stock heads might make it sound mean, but the power won’t really be there.
 

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Discussion Starter · #8 ·
The 010 block is a 4 inch bore casting it was used on late 302’s not 307’s, 327’s and for a long time on 350’s. It is a medium main journal casting. It is found in 2 and 4 bolt versions of the center 3 main bearing caps

Considered a heavy duty casting it found homes on high output cars like the SS Impalas, Z28 Camaros and certainly Corvettes all the way through heavy duty trucks. They were used in domestic production for model years 1969 through 80 and it lives on as a Mexican built over the counter replacement block to crate engine. Most Mexican blocks are finished as heavy duty truck engines with 4 bolt mains. All of these use the two piece main rear seal that has a history of leaking oil. This casting makes a great performance build platform the castings are a bit beefier than those used in lower power options of the production 327 and 350’s there being only high output versions of the 302. But the 302 originally grew out of the early 327 and like that motor the early 302 uses the small journal crank. But given you have a Mexican Over The Counter (OTC) block these only are machined for the medium size main journal crank.

The stamped build code only tells you this is from the Mexico assembly plant. There is no end use suffix stamp because this is a replacement engine and they don’t know what it’s going into. Basically it’s a Goodwrench engine. These came early on as a low power truck replacement engine later GMPP dressed a version up with a performance cam otherwise everything else was the same as the Goodwrench which uses the 150 to 300 horse cam power dependent on head’s, compression ratio snd carb 2bbl low compression on the low end model camel hump high compression head’s and 4bbl on the top model. The (OTC) base engine they rate at about 190 to 210 hp. This varies across the years and why this is so given none of the specs change is to be pondered? The hotter cam version is rated at 290hp with a GMPP intake and 4bbl carb with iron exhaust manifolds. These engines actually have some good parts in them but all use an ocular iron crank where some original installations had forged cranks, all have forged mild steel rods on the earlier versions with forged powder rods on the later versions. The early versions use cast low silicon alloy dish pistons the newer versions use cast hyper-eutectic dish pistons. All use the low compression SMOG head’s. For the high output version the compression is too low for the cam, a lot of power and better fuel mileage is to be had with modern 64cc, heart chambered and higher compressioned head’s.

Bo
The 010 block is a 4 inch bore casting it was used on late 302’s not 307’s, 327’s and for a long time on 350’s. It is a medium main journal casting. It is found in 2 and 4 bolt versions of the center 3 main bearing caps

Considered a heavy duty casting it found homes on high output cars like the SS Impalas, Z28 Camaros and certainly Corvettes all the way through heavy duty trucks. They were used in domestic production for model years 1969 through 80 and it lives on as a Mexican built over the counter replacement block to crate engine. Most Mexican blocks are finished as heavy duty truck engines with 4 bolt mains. All of these use the two piece main rear seal that has a history of leaking oil. This casting makes a great performance build platform the castings are a bit beefier than those used in lower power options of the production 327 and 350’s there being only high output versions of the 302. But the 302 originally grew out of the early 327 and like that motor the early 302 uses the small journal crank. But given you have a Mexican Over The Counter (OTC) block these only are machined for the medium size main journal crank.

The stamped build code only tells you this is from the Mexico assembly plant. There is no end use suffix stamp because this is a replacement engine and they don’t know what it’s going into. Basically it’s a Goodwrench engine. These came early on as a low power truck replacement engine later GMPP dressed a version up with a performance cam otherwise everything else was the same as the Goodwrench which uses the 150 to 300 horse cam power dependent on head’s, compression ratio snd carb 2bbl low compression on the low end model camel hump high compression head’s and 4bbl on the top model. The (OTC) base engine they rate at about 190 to 210 hp. This varies across the years and why this is so given none of the specs change is to be pondered? The hotter cam version is rated at 290hp with a GMPP intake and 4bbl carb with iron exhaust manifolds. These engines actually have some good parts in them but all use an ocular iron crank where some original installations had forged cranks, all have forged mild steel rods on the earlier versions with forged powder rods on the later versions. The early versions use cast low silicon alloy dish pistons the newer versions use cast hyper-eutectic dish pistons. All use the low compression SMOG head’s. For the high output version the compression is too low for the cam, a lot of power and better fuel mileage is to be had with modern 64cc, heart chambered and higher compressioned head’s.

Bogie
Thanks for the response. Just the information I was looking for. One more thing, however, is it safe to assume that the number (MB04800) represents a date of April, 1980?
 

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One more thing, however, is it safe to assume that the number (MB04800) represents a date of April, 1980?
From what I've seen from Chevrolet, no, that would not be correct.
Assembly line stamped application codes never have year in them, just day and month of assembly. Format is "dd/mm", 4 digits for day and month.

I've seen that "4800" section of the number on other stampings as well, appears to be just an assigned service part number for the long block engine assembly.

This quote, from the Nasty Z28 site, sheds some light on this. It is similar("2800" assembly part number.)

VF292800 - is an example of a over the counter crate engine. "2800" is the last 4 digits of the GM part # for the crate engine assembly. The final digit could be a year code.
Another example: A Targetmaster engine (p/n 14009800) built in 1985 could have a code stamped as follows:
A0198005 (A = january, 01, 9800 = pn, 5 = 1985).
 
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